Amber Myanmar

Copyright q American Museum of Natural History 2002 ISSN 0003-0082

P U B L I S H E D B Y T H E A M E R I C A N M U S E U M O F N AT U R A L H I S T O RY

CENTRAL PARK WEST AT 79TH STREET, NEW YORK, NY 10024

Number 3361, 71 pp., 44 figures, 2 tables March 26, 2002

Fossiliferous Cretaceous Amber from Myanmar(Burma): Its Rediscovery, Biotic Diversity, and

Paleontological Significance

DAVID A. GRIMALDI,1 MICHAEL S. ENGEL,2 AND PAUL C. NASCIMBENE3

CONTENTS

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Materials and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Taphonomic Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Taxonomic Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Plantae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Animalia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Nematoda . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Mollusca . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Onychophora . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Arthropoda . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Chelicerata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27Insecta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Orthoptera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31Zoraptera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31Embiidina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

1 Curator, Division of Invertebrates, American Museum of Natural History. e-mail: [email protected] Research Associate, Division of Invertebrates, American Museum of Natural History; Assistant Professor, De-

partment of Ecology and Evolutionary Biology and Curator, Division of Entomology, Natural History Museum andBiodiversity Research Center, Snow Hall, 1460 Jayhawk Boulevard, University of Kansas, Lawrence, KS 66045-7523.

3 Curatorial Specialist, Division of Invertebrates, American Museum of Natural History. e-mail: [email protected]

2 NO. 3361AMERICAN MUSEUM NOVITATES

Plecoptera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Dermaptera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Isoptera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35Hemiptera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35Neuropterida . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42Coleoptera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Hymenoptera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48Diptera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58Biostratigraphic Chronology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58Taxonomic Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61Paleoenvironment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

2002 3GRIMALDI ET AL.: BURMESE AMBER

ABSTRACT

Amber from Kachin, northern Burma, has been used in China for at least a millennium forcarving decorative objects, but the only scientific collection of inclusion fossils, at the NaturalHistory Museum, London (NHML), was made approximately 90 years ago. Age of the materialwas ambiguous, but probably Cretaceous. Numerous new records and taxa occur in this amber,based on newly excavated material in the American Museum of Natural History (AMNH)containing 3100 organisms. Without having all groups studied, significant new records andtaxa thus far include the following (a † refers to extinct taxa): For Plants: An angiospermflower (only the third in Cretaceous amber), spores and apparent sporangia of an unusual butcommon fungus, hepatophyte thalli and an archegoniophore of Marchantiaceae, and leafyshoots of Metasequoia (Coniferae). Metasequoia is possibly the source of the amber. ForAnimals: Mermithidae and other Nematoda; the oldest ixodid tick (a larval Amblyomma); birdfeathers; and the only Mesozoic record of the Onychophora (‘‘velvet’’ worms), described as†Cretoperipatus burmiticus, n. gen., n. sp. (Peripatidae). Poinar’s classification of the Ony-chophora is substantially revised. Still largely unstudied, the fauna of mites (Acari) and spiders(Araneae) appears to be the most diverse ones known for the Mesozoic. For Insecta: Odonataindet. (wing fragment); Plecoptera indet.; new genera of Dermaptera, Embiidina, and Zoraptera(the latter two as the only definitive Mesozoic fossils of their orders). Within Hemiptera, thereare primitive new genera in the Aradidae, Hydrometridae, Piesmatidae, Schizopteridae, andCimicomorpha (Heteroptera), as well as in †Tajmyraphididae (Aphidoidea), and †Protopsyl-lidiidae. An adult snakefly (Raphidioptera: †Mesoraphidiidae) is the smallest species in theorder, and new genera occur in the Neuroptera: Coniopterygidae, Berothidae, and Psychopsi-dae, as well as larvae of apparent Nevrorthidae. Coleoptera are largely unstudied, but areprobably the most diverse assemblage known from the Cretaceous, particularly for Staphylin-idae. An adult lymexylid, the most primitive species of Atractocerus, is the first Mesozoicrecord of the family. In Hymenoptera there are primitive ants (Formicidae: Ponerinae n. gen.,and †Sphecomyrma n.sp [Sphecomyrminae]), the oldest record of the Pompilidae, and signif-icant new records of †Serphitidae and †Stigmaphronidae, among others. Diptera are the mostdiverse and abundant, with the oldest definitive Blephariceridae and mosquito (Culicidae), aswell as new genera in the Acroceridae, Bibionidae, Empidoidea; a new genus near the enig-matic genus Valeseguya, and an unusual new genus in the †Archizelmiridae. †Chimeromyia(Diptera: Eremoneura), known previously in ambers from the Lower Cretaceous, is also rep-resented.

The stratigraphic distribution of exclusively Mesozoic arthropods in Burmese amber is re-viewed, which indicates a probable Turonian-Cenomanian age of this material (90–100 Ma).Paleofaunal differences between the NHML and AMNH collections are discussed, as is thedistinct tropical nature of the original biota. Burmese amber probably harbors the most diversebiota in amber from the Cretaceous, and one of the most diverse Mesozoic microbiotas nowknown.

INTRODUCTION

Of all the world’s amber deposits, perhapsnone has more mystique than those fromnorthern regions of Myanmar. ‘‘Burmite,’’along with jadeite from nearby mines, wasexported to China since at least the first cen-tury A.D. for use in jewelry and carved objetsd’art (Laufer, 1906; reviewed in Grimaldi,1996; Zherikhin and Ross, 2000). Baltic am-ber had been prized for 10 millennia beforethis in northern Europe, but in Asia the prox-imity of Burmese amber, and probably itsdeep red color, hardness, and glassy polish,made it particularly sought along with ivory

and jade. Use of it as a precious and semi-precious substance abruptly ended, though,by approximately 1940, and despite the workof an insightful entomologist made 80 yearsago, its scientific significance has been con-fused and only recently recognized.

The first significant geological investi-gation of Burma’s amber was by Noetling(1892, 1893), who reported the most pro-ductive sites in the Hukawng Valley of thenorthern state of Kachin, specifically south-west of Maingkhwan (268209N, 968369E).Four other regions in Burma have histori-cally yielded amber (reviewed in Zherikhinand Ross, 2000), but none as prolific and


commercially exploited as in the HukawngValley. Noetling mentioned inclusions ofinsects and plants, and perceptively noticedthat the newly excavated amber pieces ap-peared weathered and may have been trans-ported some distance before redeposition.H.L. Chhibber visited the Hukawng Valleyin 1930, and made many additional obser-vations. He reported the amber to occur inthin lignite seams among clays and shales(Chhibber, 1934). The larger, transparentpieces of amber were buried between 10–15 m, and to reach it miners excavated nar-row shafts with walls supported by bambooscreens. Beyond this depth, ground waterwould fill the shaft. Presence of the fora-miniferan Nummulites biarritzensis indicat-ed a middle Eocene age of the sediments,though Chhibber acknowledged that theamber was possibly reworked from oldersediments. He also reported that amber wasmined most abundantly near the villages ofKhanjamaw (268159500N, 968339370E),Ladummaw (268119190N, 968289480E), andLajamaw (268159N, 968289E). His obser-vation that some areas reported by Noetlingwere pocked with abandoned mines mayhave led to the popular notion that the min-ing of Burmese amber, by and large, wasdepleted or abandoned (e.g., Fraquet,1987).

According to the records of the GeologicalSurvey of India, 82,000 kg of Burmese am-ber were excavated between 1898–1940(summarized by Zherikhin and Ross, 2000).Curiously, only one collection of Burmeseamber is known that was made for scientificpurposes. This collection consists of 117pieces containing approximately 1200 organ-isms in the NHML. It was assembled byR.C.J. Swinhoe of Mandalay between 1915and 1916, and sent to a prolific entomologistin Colorado, T.D.A. Cockerell (1866–1948).Cockerell is renowned for having writtennearly 4000 articles on various subjects (We-ber, 1965), but particularly the systematics ofliving and fossil insects. Between 1916 and1921, Cockerell published 13 papers on 41new arthropods in Swinhoe’s collection, thendonated the collection to the NHML. Cock-erell described perhaps 7000–8000 speciesduring his lifetime, but also had an uncannyability to recognize natural relationships

among the plethora of taxa with which heworked. As a result, he was able to recognizethat the arthropods in Burmese amber (andtherefore the amber itself) were older thanthe surrounding sediments, perhaps evenCretaceous in age:

They [the arthropods in Burmese amber] are, indeed,related to living forms; but in practically every caseto precisely those forms which we have thought of asancient, as remnants of a very old fauna. So . . . it isdifficult to avoid a strong suspicion that the amber,though found in Miocene clay, is actually very mucholder, conceivably even Upper Cretaceous. (Cocker-ell, 1917a: 360).

Until approximately the 1960s, the Creta-ceous was one of the poorest known geolog-ical periods for insects; now there are over30 major Cretaceous deposits yielding in-sects (see, for example, the summary in Ev-enhuis, 1994). Despite this deficiency, andCockerell’s early suggestion that Burmeseamber was Cretaceous, there was very littleresearch on the NHML collection between1921 and 1995, nor were there any recordedattempts to excavate additional Burmese am-ber for study of the inclusions. In 1995, Al-exandr Rasnitsyn, of the Paleotological In-stitute, Moscow, and Genady Dlussky, ofMoscow State University, studied Hymenop-tera and specifically ants, respectively, in theNHML collection of Burmese amber. Ras-nitsyn (1996b) noted the presence of the ex-tinct Cretaceous family †Serphitidae and thesubfamily †Iscopininae (Hymenoptera).Dlussky (1996) described a bizarre ant,†Haidomyrmex, from the NHML collection,which he placed in the Cretaceous subfamily†Sphecomyrminae. Mounting evidence thatBurmese amber was Cretaceous led to a co-ordinated study of the NHML collection, or-ganized by Andrew Ross (NHML). Produc-tive as Cockerell was, he touched on but afraction of the organisms in the NHML col-lection of Burmese amber. In a recent issue(vol. 56, no. 1) of the Bulletin of the NaturalHistory Museum (Geology Series) [London],eight papers describe 15 new species of ar-thropods in six orders from that collection.Therein are also extremely useful summariesof described species in Burmese amber (Rossand York, 2000), and a list of arthropod fam-ilies (Rasnitsyn and Ross, 2000).

Adding to the renewed interest in Burmeseamber, we are able to report a new collection


TABLE 1Summary of Major Fossiliferous Cretaceous Amber Deposits

of fossils in amber assembled from materialthat was recently excavated from the Hu-kawng Valley in northern Burma—the onlynew scientific specimens of the material ob-tained in over 80 years. The collection con-tains nearly three times the number of inclu-sions as the NHML collection, and manynew taxa and records not represented in theNHML collection. Moreover, our findingsnot only corroborate a Cretaceous age ofBurmese amber, but also suggest an originthat is probably mid-Cretaceous.

The Cretaceous is one of the most bioti-cally significant periods in the evolution ofterrestrial life since the angiosperms explo-sively radiated in the upper part of the LowerCretaceous (Crane et al., 1995). Given thegreat diversity of extant insects intimately as-sociated with angiosperms, evolution of thetwo groups would presumably be inextrica-bly linked. One study found, however, thatthere was no increase in the number of insectfamilies in the Cretaceous during or imme-diately following the angiosperm radiations(Labandeira and Sepkoski, 1993), but in factthere was a slight slump in family numbers.Other taxic analyses found a profound radi-ation of Cretaceous insects (Jarzembowskiand Ross, 1993, 1996; Ross et al., 2000).Phylogenetic studies on speciose families ofinsect pollinators (Engel, 2001; Grimaldi,1999), herbivores (Farrell, 1998), and majorconsumers (Grimaldi and Agosti, 2000; Gri-maldi et al., 1997; Thorne et al., 2000) in-dicated explosive radiation of these groups in

the Cretaceous. Disparity in the results isprobably due to approaches that use taxicanalyses (e.g., numbers of insect families)versus phylogenetic analyses (see Grimaldi,2000a). Compared to dramatic extinctions ofnon-avian dinosaurs, ammonites, rudist bi-valves, and other taxa by the K/T boundary,extinctions of insects are barely noticeable,and may be obscured by the impressive ra-diations of insects just prior to this time.

Besides preserving a rich fauna from a bi-ologically important time period, Burmeseamber preserves organisms with a lifelike fi-delity for which amber is renowned (Gri-maldi, 1996). Such complete preservationvastly improves interpretation of extinct spe-cies.

Lastly, the location of Burmese amber alsomakes it highly significant. It is the only ma-jor, fossiliferous deposit of Cretaceous amberin southeastern Asia, and one of two of themost southerly deposits of fossiliferous Cre-taceous amber. All other major deposits ofCretaceous amber occur between 348 and 748N latitude (Table 1), but why they are re-stricted to the Northern Hemisphere is anenigma. Paleolatitude of the Burmese andLebanese amber deposits (10–158N) are themost southerly of all major Cretaceous am-ber deposits. As discussed at the end of thispaper, climatic effects from paleolatitudewere probably profound. Ages, locations,and references for the major deposits of fos-siliferous Cretaceous amber are the follow-ing:


LOWER CRETACEOUS: LEBANON andJORDAN, ranging from the Lower to UpperNeocomian (Berriasian to Aptian, and a mi-nor incursion into the Albian; Azar, 2000);SPAIN (Nograro Formation of Alava, upperAptian and middle Albian; Alonso et al.,2000); and RUSSIA, Taimyr Peninsula ofnorthern Siberia (Ogneva Formation, Aptianto Albian; Zherikhin and Eskov, 1999). Sev-eral smaller deposits in Japan and Englandhave also yielded insect fossils (summarizedby Grimaldi, 1996; Ross, 1998).

UPPER CRETACEOUS: CANADA (western),Cedar Lake, Manitoba and Medicine Hat, Al-berta (McAlpine and Martin, 1969), andGrassy Lake, Alberta (Pike, 1995). TheGrassy Lake and Medicine Hat deposits be-long to the Foremost Formation, Judith RiverGroup (Campanian, possibly Santonian).RUSSIA: Taimyr Peninsula, Siberia, fromAgapa and belonging to the Dolgan Forma-tion (Cenomanian), and from Yantardakh,Kheta Formation (Santonian). Zherikhin andEskov (1999) also reviewed other localitiesin the former USSR. USA: New Jersey (Rar-itan Formation, Turonian; Grimaldi et al.,1989; 2000a). The paleobiota of New Jerseyamber is the most diverse one reported thusfar, even though the deposit that yielded mostof the amber was extremely localized. Verylikely the Burmese amber biota will be foundto be more diverse than any other Cretaceousamber deposit, including amber from NewJersey.

MATERIALS AND METHODS

Bags of crude amber were purchased byLeeward Capital Corporation, a Calgary-based mining company, from local sourcesnear the village of Tanai. Tanai is on theLedo Road in Kachin State, close to the his-torical sources of Burmese amber in the Hu-kawng Valley (fig. 1). Mining specifically oc-curs approximately 32 km southwest of Tanainear Noije Bum (‘‘hill’’, approx. 250 m).Since initial exploration in 1999, Leewardhas joined with a local Kachin mining com-pany (Buga Company Ltd.) for exploitationof the amber deposits, under the jurisdictionof the Myanmar Ministry of Mines and mil-itary officials. Methods of mining the amberremain traditional, just as were described by

Chhibber (1934). Apparently, miners need toreach lignitic seams some 30–40 cm thick toobtain the amber, which can occur at depthsof up to 12 m. In 2000, nearly 80 kg of crudeamber was mined. Samples of various colorswere analyzed using Pyrolysis-Gas chroma-tography (PyGC) and PyGC-Mass Spectros-copy (e.g., Shedrinsky et al., 1991; Grimaldiet al., 2000a), which matched identically toeach other and to samples from the NHMLcollection (A. Shedrinsky, unpubl. data onfile in the Invertebrates Division, AMNH).Material from the outcrops of the 1999 and2000 excavations may be different from thatreported by Chhibber (1934) and earlierworkers, but their proximity and chemicalidentity indicates an identical botanical ori-gin with the historical collections and, thus,probably a very similar or identical age.

Approximately 75 kg of raw Burmese am-ber were shipped to the AMNH by LeewardCapital, where it was treated in lots of ap-proximately 3 kg, using a 50% solution ofmuriatic acid (HCl) to dissolve veins of cal-cite that permeated most pieces. This greatlyimproved visibility into the amber. The am-ber was then washed thoroughly with water,and carefully screened for organismal inclu-sions piece by piece. The amber was keptwet during screening in order to improve vis-ibility. Screening was done under a stereo-scope (approximately 203 magnification) us-ing transmitted and oblique reflected light.For many pieces, one or more surfaces need-ed to have a ‘‘window’’ polished into the sur-ficial rind in order to locate and view inclu-sions. This was done using a Buehler Ecometwater-fed flat lap with abrasive discs (320,600, 800, 1200 grits). Because Burmese am-ber is exceptionally hard compared to otherambers, it was generally possible to trim offsome amber surrounding an inclusion with-out the piece splitting or crumbling. Hard-ness of Burmese amber allows surfaces to bepolished with a glassy finish. Trimming wasdone with a fine (1.5 mm thick) diamond,water-fed, circular trim saw; the sawed sur-faces were ground with successively finergrits, and then polished with a 1mm aluminapolish. This optimized the penultimate stepin preparation: embedding the piece in ahighly stable epoxy (Buehler) under vacuum,as described in detail elsewhere (Nascimbene


Fig. 1. Location of Burmese amber deposits. Above: inset shows approximate area in southeastAsia. Below: detail within inset.


and Silverstein, 2000). In this process, epoxypenetrates most fine cracks and thus helpsprevent fracturing during the final trimming,grinding, and polishing. Optimal prepara-tions resulted in a cubic shape, with gener-ally no more than a millimeter or two be-tween the inclusion and one or more surfacesof the amber, these surfaces being generallyparallel to the plane of critical structures.However, many pieces had multiple inclu-sions that could not be separated, and thiscompromises preparation and observation.This appears to be a particular problem withthe pieces from the NHML collection, sincemost inclusions occur in large pieces thatwere sliced into polished slabs for viewing,but no further.

All AMNH pieces were given unique, se-quential numbers; for pieces with multipleinclusions each inclusion was lettered (a, b,c,. . . ). Identifications were done, where pos-sible, to at least family level, and a collectionof 1200 pieces and 3100 inclusions was cat-alogued using the database MS Access.Printed or diskette copies of the database areavailable from the senior author for qualifiedresearchers; an electronic version will even-tually be available at www.amnh.org. Fortaphonomic purposes we included counts of308 arthropod specimens too partial or de-graded to be of systematic use, and so theywere not accessioned, cataloged, or databa-sed. Some were identifiable to insect family,or just as ‘‘Insecta incertae sedis’’ or ‘‘Ar-thropoda incertae sedis’’. Systematic descrip-tion and discussion of various taxa will bemade in separate papers.

RESULTS

TAPHONOMIC OBSERVATIONS

Some 72.21 kg of acid-washed amber (mi-nus the dissolved calcite) yielded, on aver-age, 46 organismal inclusions per kg (a totalof 3,408 organisms). This count includes 308partial specimens, such as isolated wings ofinsects, as well as specimens too poorly pre-served for identification beyond order or tofamily. Other inclusions (not included in thisfigure) were plant stellate trichomes (moreabundant than in any other Cretaceous am-bers studied thus far), bark fibers, wood frag-ments, and insect frass. Individual pieces of

amber varied in color from light, transparentyellow to deep, blood red, but the most abun-dant kind was an orange-colored amber con-taining swirls of fine bubbles and differenthues. Pyrolysis gas chromatography–massspectroscopy on the different forms of amberindicate a chemically identical substance (T.Wampler and A. Shedrinsky, unpubl. data),so all of the amber was probably formed bya single species of tree. Botanical identity ofthe tree that produced Burmese amber is un-known, but presence of diagnostic coniferouscompounds indicates it certainly was a co-nifer, and possibly a cupressaceous tree likeMetasequoia (see below). Variations may bea result of amount of predepositional expo-sure and of geothermal energy during depo-sition (for color), and whether the resin wassecreted subcortically or externally (forform). Insects were comparatively rare in the‘‘swirly’’ amber, and when present they wereoften distorted from moderate to extremecompression, and often also disarticulated.This type of amber preservation is similar tothat in Paleocene amber from Wyoming (Gri-maldi et al, 2000b) and putatively Paleoceneamber from Sakhalin Island (Zherikhin andEskov, 1999). For Wyoming amber, it is be-lieved that extremely deep sediments createdtremendous pressures, which compressedmost organisms and even organic debriswithin the amber into unrecognizable‘‘smears.’’ Another type of Burmese amberconsisted of flattened, lens-shaped pieces,which rarely contained insects. Insects weremost commonly found in pieces shaped likeflows or runnels; these compromised nomore than 3–4% by mass of all the amberbut yielded approximately 85% of the arthro-pods. Insects in runnel pieces were usuallywell preserved, and sometimes numerous or-ganisms were found in such a piece merely3 cm long and 1 cm diameter. Clearly, therunnel pieces were flows of resin secreted inareas or under conditions optimal to entrap-ment of insects.

TAXONOMIC DIVERSITY

The recent collections have yielded signif-icant new, higher-level taxonomic records forBurmese amber, including several plants, thephyla Nematoda and Onychophora, and near-


ly 30 families of Arthropoda (table 2). Col-lectively based on the NHML and AMNHcollections, the Burmese amber fauna pre-serves a remarkable diversity of organisms,including numerous records of earliest oc-currence and other significance. We brieflyreview below those taxa for which at leastsome family-level identifications were done,and ones we considered especially signifi-cant. We have not discussed the followingtaxa represented in the new AMNH collec-tion, simply because they still require study:Aves (feathers, currently under study by Car-la Dove, Smithsonian Institution), Reptilia(skin), Myriapoda, Collembola, Archaeog-natha and Thysanura, Ephemeroptera, Odon-ata (wing fragments only), Blattodea andMantodea, Auchenorrhyncha, Pscoptera,Thysanoptera, Trichoptera and Lepidoptera.

Kingdom PLANTAE

Plant Antheridia or Fungal Sporangia?The most common organismal inclusion inthe material we screened were polyp-shapedstructures, ranging in size from 2 to 6 mm inwidth, which are almost certainly the sporan-gia of a fungus or possibly plant (figs. 2–7).Similar structures occur in the NHML col-lection (A.J. Ross, personal commun.). Theywere never branched or joined at the base,nor were vegetative/leafy structures foundassociated with them. One type of abundantspore (figs. 8, 9) in this amber must be pro-duced by these sporangia.

The sporangia grew on and through thewood of the tree that produced the amber.Several pieces of amber contained sporangiaand thin, delaminated layers of wood con-taining circular holes the same diameter asthe base of nearby sporangia (fig. 3c). Doz-ens, and up to approximately 100 sporangia,can be found in a piece of amber (fig. 2c).Many pieces contained groups of sporangiaarranged radially, with the bulbous ends to-ward the center (fig. 2c). This suggests thatthe sporangia were growing in narrow chan-nels into which resin flowed, either in deepgrooves in the bark, or within decayed pock-ets near the surface of wood (fig. 4). Basesof sporangia were very rarely preserved, ap-parently having decayed when buried withthe wood on which they were growing. Thus,

the portion of the polyp preserved in the am-ber almost always has a cross section of thebase exposed at the surface. This exposureallowed decay of the internal tissues in mostspecimens; occasionally specimens werefound with intact internal contents.

The sporangia in Burmese amber have noapical ostiole, as is found in some antheridiaof hepatophytes having roughly similarshape (e.g., Sphaerocarpaceae). Cuticleswere better viewed using scanning electronmicroscopy (SEM). This was done by takingthree pieces with sporangia and cutting a finegroove in each amber piece along variousaxes close to the sporangium, then splittingthem open. This caused fracturing betweenthe cuticle and the amber (fig. 6), or throughthe sporangium (fig. 7), depending on howthe groove was cut. The exposed sporangiawere then gold coated for examination usinga Zeiss DSM-1 SEM. The external surfaces(cuticle) of the sporangia have a very finegeometric sculpturing, similar to herringbonepatterns (fig. 6). Under stereoscope magnifi-cations (50–1003), this pattern resemblesfingerprints. Under the SEM at magnifica-tions of 100–10003, no cellular/epithelialstructure was visible, although in some viewsminute openings, 3–4 mm in diameter, werefound in fairly regular distribution (fig. 6b),though nothing resembled stomata.

The interior of well-preserved sporangiawas whitish and somewhat granular understereoscopic magnifications; under the SEMat magnifications of 1,000–3,0003 some bi-ological structure was apparent. Significantlooking structures were short, fibrous bun-dles (figs. 7b, f) and small, compressed, ir-regular ‘‘flakes’’ approximately 5 mm in di-ameter (figs. 7a, c–e). Serial sections fortransmission electron microscopy (TEM)would probably be useful, although if a hy-menium were present even at these SEMmagnifications columns of paraphyses andasci would be apparent, as is found in theapothecia of certain ascomycetes like Pyro-nema.

Sporangia were always found either com-pletely intact, or dehisced into empty, hemi-spherical halves (longitudinally; figs. 2, 5).Spores were never found within or oozingout of dehisced sporangia, though clumps ofa very distinctive and uniform type of spore


TABLE 2Numbers of Specimens of Organismal Inclusions in Burmese Amber in the Two Major Collections


TABLE 2(Continued)


Fig. 2. Photomicrographs of sporangia. a, b. Dehisced sporangia. c. Cross section through an amberpiece, showing sporangia growing on the perimeter of the flow.

were common in the amber, or layers of thesespores occurred where they adhered to afresh resin surface before being covered byanother flow of resin (fig. 8). In fact, thespores and sporangia very rarely occurred inthe same piece of amber, but the abundanceof these two types of inclusions makes theircommon identity quite probable. Some of thebetter preserved dehisced sporangia con-tained a U-shaped structure, suggestive of aspring mechanism for the explosive ruptureof the sporangium (fig. 5). The spores arequite large (diameters ranging from 40–70mm, mean of 45 mm), have an irregular

shape, and an apparently thick coat (SEM,fig. 9) without sculpturing (fig. 9). There isno evidence of the spores being trilete oreven monolete. Often found proximal to rup-tured spores are small nucleated cells, someof which occur in tandem of two or three andforming a bacilliform shape (figs. 8a, b, c).Diameter of the cells is approximately 0.15–0.203 the diameter of the spore.

Though no apparent hymenium was foundin longitudinally exposed sporangia, it ismost likely that the sporangia are the apo-thecia of xylophagous ascomycete fungi, orpossibly the sporangia of a myxomycete, like


Fig. 3. Sporangia of a probable fungus (not to the same scale). Specimens in c show circular holesin wood or bark fibers adjacent to the sporangia, indicating they grew directly on the amber tree.


Fig. 4. Possible sequence for the preservationof sporangia in a radial array. Top: the sporangiagrow on the surface of the wood within groovesand cavities, into which resin flows and encap-sulates the sporangia (middle). Bottom: wood de-cays around the hardened resin during burial.

Lycogala. The sporangia are very doubtfullyplants, since no epithelial cell structure norvegetative structures were ever found withthem, as always occur with hepatophytes andbryophytes, for example. Also, no elaterswere found among the numerous spores,which are distinctive, spiral, asexual cells ofhepatophytes that aid in the dispersal of de-hisced spores. Although elaters are not foundin the Ricciaceae, they occur in all other he-patophytes. The sporangia also lack featuresdistinctive of other similarly shaped plantsporophytes, such as the operculum inSphagnum. Isolated thalli of hepatophytes dooccur, rarely, in Burmese amber (below).

An explosive discharge of spores by thesesporangia, as suggested by the U-shapedspring mechanism, may explain why sporesand polyps are rarely found together: sporeswere probably dispersed far from the polyps,such that it would have been very unlikelyfor a resin flow to have enveloped polyps inthe moment of spore discharge. Pyronemaand other ‘‘cup’’ fungi also have explosivedischarge of spores.

Hepatophyta (Hepatopsida): Several spec-imens of liverwort thalli have been recentlyfound (e.g., AMNH Bu11; fig. 10a), as wellas a portion of a distinctive sporophyte. Thethalli are Frullania-like jungermannialeans,with saclike ventral lobes (lobules), which inextant forms facilitate water storage. Frul-lania and related genera grow on tree barkand other substrates that encounter waterstress. Though the fossils are not necessarilyrelated to Frullania, their presence in amberand the possession of lobules indicate theyalso grew on the surface of tree trunks. Spec-imen AMNH Bu324 is apparently an isolatedarchegoniophore of a Marchantia-like liver-wort (fig. 10b). The structure is star-shapedwith 10 ‘‘arms’’ (archegoniophores of extantMarchantiaceae possess 9–11), and 1.5 mmin diameter. Because the structure is black(carbonization occurs in some amber fossils),reflective lighting is insufficient to detect thetypical presence of rhizoids or scales on thelower surface or air chambers and pores onthe upper surface. The thalli distinctive tomany Marchantiaceae (having polygonal airchambers with a central pore, gemma cups,etc.) have not been found in Burmese amber,but the distinctive shape of this isolated


Fig. 5. Detail of a typical sporangium in Burmese amber. Specimen is dehisced, revealing a thin,straplike structure within. The structure is possibly a hinge involved in explosive discharge of spores.Scale is 1.0 mm.

structure allows this taxonomic assignmentwith some confidence. Though fossils of he-patophytes are rare, particularly from theMesozoic and Paleozoic, the group is an-cient, with the oldest definitive taxa being

from the Devonian (reviewed in Kenrick andCrane, 1997).

Bryophyta: In the AMNH collection aretwo specimens of leafy shoots of a moss witha growth form like Polytrichum and An-


Fig. 6. Scanning electron micrographs of exposed cuticular surfaces of three sporangia in Burmeseamber. a, c, and e show most of the sporangium; b, d, and f are details of cuticular surfaces of eachspecimen, respectively.

dreaea. The shoots are among the largest in-clusions in the AMNH collection, 34 mm inlength. Long-stalked sporophytes with apicalcapsules, so typical of bryophytes, have notbeen found. A specimen of Hypnodendronoccurs in the NHML collection. Like hepa-tophytes, Mesozoic and Paleozoic bryo-

phytes are rare, but occur since at least theDevonian.

Pterophyta: The presence of leptosporan-giate ferns (e.g., Polypodiaceae) is indicatedby several sporangia distinctive to this groupin pieces AMNH Bu342 and Bu731 (e.g., fig.11). The sporangia have the typical ribbed


Fig. 7. Scanning electron micrographs of exposed interior contents of three sporangia in Burmeseamber (1000–35003).

annulus, attached to a dehisced, membra-nous, sac-like portion. Diameters of the de-hisced sporangia are approximately 220 mm.Annulate sporangia first appear in the LowerCarboniferous, and are among the earliest ev-idence of pterophytes. By the Upper Carbon-iferous, pterophytes were diverse and abun-dant (reviewed in Kenrick and Crane, 1997).

Coniferae: AMNH Bu794 contains twoimpressive fragments of leafy shoots of‘‘dawn redwood,’’ Metasequoia (Taxodi-aceae, or Cupressaceae s.l.) (fig. 12). Oneshoot is 5 cm long, the other is 1.7 cm, andthey bear two rows of opposite leaflets sodistinctive to this genus of ‘‘living fossils’’.(Metasequoia, like the coelacanth, was first


Fig. 8. Photomicrographs of abundant type of spore in Burmese amber, probably produced by theunusual fungal sporangia (figs. 2–7). a-c. showing nucleated cells that derive from the spores. Sporesare often found in thick clumps (e, f). Diameter of spores is approximately 50 mm.

known from fossils about a century beforethe sole living species was discovered; thetree was later found growing in southernChina.) The leaves are shorter, broader, andmore crowded than occurs in the most wide-spread, Cretaceous species, M. †occidentalis;also, the Burmese amber species has the tipsof the leaves broadly rounded, not pointed asin M. †occidentalis. This is the only type ofconifer inclusion found in the AMNH col-lection of Burmese amber. Metasequoia has

been definitively associated with severaltypes of fossil resins, from the Paleocene ofAxel Heiberg Island, Canadian arctic (An-derson and LePage, 1995), and from the Cre-taceous of peninsular Alaska (D. Grimaldi,unpubl. data). Chemical analyses of Burmeseamber have yet to be compared to these othersamples. Though inference of botanical ori-gin based on botanical inclusions can be mis-leading, it does offer rare macrofossil evi-dence about possible botanical origins. Meta-


Fig. 9. Scanning electron micrographs of spores (fig. 8) with interior contents exposed on freshlyfractured surfaces of amber (1500–60003).

sequoia should be seriously considered as apossible source of Burmese amber.

Angiospermae: Angiosperms from theCretaceous are known mostly from dissoci-ated pollen in sedimentary strata and com-pression-fossilized leaves, occasionally ascompression-fossilized flowers. The most in-

formative Cretaceous specimens are fusaini-zed flowers in clays, preserved with com-plete relief and microscopic fidelity (e.g.,Crane and Herendeen, 1996; Crane et al.,1995; Crepet and Nixon, 1998). FusainizedCretaceous flowers are diverse, but oddlyconsistently small (2–4 mm). Only two flow-


Fig. 10. Plant inclusions in Burmese amber. a. Portion of hepatophyte, AMNH Bu11. b. Probablearchegoniophore of Marchantiaceae (Hepatophyta), AMNH Bu324. c. Portion of undetermined leafyshoot, AMNH Bu181. d, e. Portions of long leaf blades of undetermined plants, AMNH Bu204, 205,respectively. f. Angiosperm flower, AMNH Bu338.

ers are known in Cretaceous ambers, one apartial specimen in Burmese amber of un-determined identity (AMNH Bu338, figs. 10,13). Typical of the fusainized Cretaceousflowers, AMNH Bu338 is small, approxi-mately 5 mm diameter. Only three petals arepreserved, though it appears to have beenpentamerous, since the area where two petalswere apparently attached was lost at the sur-face. The petals possess a faint reticulate ve-

nation. No obvious reproductive parts likestamens or pistils can be seen (they may havebecome detached), though the center of thecorolla has several rounded areas (ovules?).The other Cretaceous amber flower is a finelypreserved, complete inflorescence of a prim-itive fagalean in New Jersey amber (Grimaldiet al., 2000a). There are also several uniden-tified, small angiosperm leaves in the AMNHBurmese amber collection.


Fig. 11. Photomicrographs of fern leptospor-angium in Burmese amber, AMNH Bu342.

Fig. 13. Detail of angiosperm flower in Bur-mese amber, AMNH Bu338. Scale is 1.0 mm.

Fig. 12. Leafy shoots of Metasequoia sp. in Burmese amber, AMNH Bu794b.


Fig. 14. Various animal remains in Burmese amber. a. Two mermithid nematode parasites emergingfrom abdomen of a female chironomid midge, AMNH Bu320. b. Snail, AMNH Bu099. c. Onychoph-oran, Cretoperipatus burmiticus holotype (cf. fig. 17), AMNH Bu218. d. Reptile skin, AMNH Bu337.e. Bird feathers, AMNH Bu183. Scale is 1.0 mm.

Kingdom ANIMALIA

Phylum Nematoda

Nematodes occur rarely in amber, partic-ularly in Cretaceous ambers. The oldest fos-sil nematode is reported from Lebanese am-ber (Poinar et al., 1994), which belongs tothe Mermithidae, a family to which belongtwo exceptionally well-preserved specimens

in the AMNH Burmese amber collection(AMNH Bu320). Mermithids are obligate,internal parasites of terrestrial and freshwaterarthropods (especially insects), some crusta-ceans, molluscs, and annelids. During theirpreparasite, postparasite, and adult stagesthey are free-living (Rubzov, 1972). In theextant fauna there are 32 genera and approx-imately 200 described species, but are too


Fig. 15. Detail of AMNH Bu320, two mermithid nematodes (a, b) captured while emerging fromthe abdomen of a female chironomid midge. Detail shows array of spicules on apex of specimen b.

poorly surveyed to determine actual diversi-ty.

Both nematodes in specimen AMNHBu320 were preserved while emerging fromthe abdomen of a female chironomid midge(figs. 14a, 15), a family of common mermi-thid hosts today (Rubzov, 1972; Nickle,1972). These new specimens are the onlyother Cretaceous record of the Mermithidaebesides †Heleidomermis libani in Lebaneseamber (Poinar et al., 1994). †Heleidomerislibani was described on the basis of a coiled,putatively postparasitic juvenile female (thesex ‘‘suggested’’ by its length), in the abdo-men of a female chironomid inclusion. It wasplaced into this extant genus on the basis ofmorphological characteristics (final molt inthe host, absence of cuticular cross fibers,and lack of a tail projection), and host type(Ceratopogonidae). Poinar et al. (1994) attri-buted a modern genus of mermithids in theLower Cretaceous to the morphological con-servatism of nematodes, though morpholog-ical simplicity by nature is conservative.Body proportions of the coiled specimen arewithin the range of two extant species ofHeleidomermis. Interestingly, with the ex-ception of Leptoconops (the most primitiveliving genus of Ceratopogonidae), all generaof ceratopogonids in Lebanese amber arephylogenetically basal and extinct (Borkent,2000). On this basis, one might expect theLebanese amber mermithid to likewise be anextinct genus.

The AMNH specimens are very similar inwidth (approximately 50 mm) and length (3.3and 3.4 mm). One end of specimen ‘‘a’’ isstill enclosed in the midge’s abdomen; oneend of specimen ‘‘b’’ has at least four preap-ical spicules (fig. 15). The other nematodesin Burmese amber are approximately 20 mi-nute individuals of undetermined identity(430–520 mm length) in a single piece of am-ber, AMNH Bu020.

Despite remarkable preservation, nema-todes in amber are unlikely to be a significantsource of information for the evolutionaryhistory of this group. They are extremelyrare in Cretaceous ambers, and definitive fos-sils (amber or otherwise) are unknown fromearlier periods, even though the group isprobably at least Cambrian in age judgingfrom the ages of related phyla. The fossilscontribute useful information on the mini-mum ages of particular lineages (e.g., Mer-mithidae) and their host associations.

Phylum Mollusca

Though molluscs are abundant in the ma-rine record, fossils of terrestrial taxa are rel-atively sparse. Shells of terrestrial gastropodsoccur sporadically in Cenozoic ambers, butonly three records are known in Cretaceousambers. A species of possibly the familyPupillidae occurs in Lebanese amber (Rothet al., 1996). Burmese amber contains theother two Cretaceous records. Neither the


NHML (figured in Ross, 1998: fig. 59) northe AMNH (Bu009) specimens have beenidentified. The AMNH specimen is slightlyoblong in shape and rather large (5.03 3 3.53mm)(fig. 16). Six fecal pellets near the ap-erture indicate that the snail was preservedwhile it was alive.

Phylum Onychophora

The significance of the single new speci-men (AMNH Bu218; figs. 14d, 17) in thisphylum is exceptional. Several enigmatic,marine fossils from the Cambrian, such as†Aysheaia and †Xenusion from the Burgessshale4have been attributed to the Onychopho-ra5 (e.g., Dzik and Krumbiegel, 1989; Ram-skold and Hou, 1991). The overall structureof these fossils is similar to that of extantonychophorans, but given the lack of pre-served details and their marine origin (allmodern onychophorans occur in tropical orsubtropical forests) it is probably best to con-sider the Cambrian taxa as stem-group ony-chophorans in a Superphylum Lobopodia(Snodgrass, 1938). AMNH Bu218 is the ear-liest definitive and only Mesozoic fossil ofthe phylum.

Only the anterior half of the specimen ispreserved, the posterior half having been de-composed. Portions of the anterior half, par-ticularly the head, are extremely distorted bycompression. Nonetheless, the ventral mouth

4 Ramskold and Chen (1998) unnecessarily proposedthe name Alphonychophora for a group including Ay-sheaia (and, tentatively, Xenusion, Luolishania, and On-ychodictyon). The name Protonychophora had alreadybeen proposed by Hutchinson (1930) and modified byHou and Bergstrom (1995), for a group including Ay-sheaia and Xenusion. Rather than emending and usingthis name to correspond with their phylogeny, Ramskoldand Chen (1998: 143) argued that, so as to avoid con-fusion, they would employ new names based on the‘‘phylotaxonomy’’ of de Queiroz and Gauthier (1994).A proliferation of names—particularly ones not definedby characters—contributes even more serious confusionto a literature that ‘‘. . . abounds in names . . . ’’ (Ram-skold and Chen, 1998: 142), one criticism that theseauthors have about a formal Linnean taxonomy. A cri-tique of the misguided attempts of ‘‘phylotaxonomy’’ isprovided by Nixon and Carpenter (2000).

5 This grouping is sometimes referred to as PhylumLobopodia with two classes; Xenusia for the likely par-aphyletic, marine Cambrian fossils, and Onychophorafor the terrestrial lineages (e.g., Hou and Bergstrom,1995). As mentioned in the text, we prefer to considerxenusians as stem-group Onychophora.

surrounded by peribuccal papillae, a finelyannulate body with dermal papillae, and fivepreserved pairs of lobopods make the iden-tity of the specimen in this phylum unques-tionable (fig. 17). Although with less thanoptimal preservation, the specimen is furtheridentifiable as a species of the modern, cir-cumtropical family Peripatidae. The lobo-pods are particularly informative and allowidentification of the specimen as unlike anymodern peripatid genus. Unique within thefamily is the combination of three spinouspads (the third subequal in size to the firsttwo and undivided by a urinary papilla), asingle distal papilla, and five basal papillae(the basalmost two more weakly developed).The foot structure of AMNH Bu218 is ap-parently autapomorphic and without clearhomologues to any lineage of extant peripa-tids, thus justifying formal description of anew taxon. Morphological terminology fol-lows that of Storch and Ruhberg (1993).

Cretoperipatus Engel and Grimaldi,new genus

TYPE SPECIES: †Cretoperipatus burmiticus,new species.

DIAGNOSIS: A true onychophoran (i.e., ter-restrial, with antennae, ventral mouth withentognathous jaws, oral papillae, paired lo-bopods each with a pair of terminal claws)of the family Peripatidae, having the follow-ing characteristics: Approximately 12 com-plete annuli on each segment or less (no in-complete annuli), annuli not fusing laterally;integumental papillae with round bases andof variable sizes. Nephridial opening presentat base of legs. Coxal organ not apparent onany leg. Crural papilla not present on pre-served legs (pairs 1–3); consistent with as-signment to Peripatidae in which crural pa-pillae are found in the posterior segments.Three spinous pads present distally on leg;third (i.e., basalmost) spinous pad not divid-ed by nephroporous (urinary) papilla on anyleg; third spinous pad approximately sube-qual in size to first and second spinous pads.Five basal papillae present (two basalmostpapillae weakly developed) and a single dis-tal papilla present on posterolateral border;claws strong, elongate, and curved.

ETYMOLOGY: The new genus group name


Fig. 16. Detail of snail AMNH Bu009, opposite sides. Scale is 1.0 mm.

is a combination of creto- (in reference to theCretaceous) and Peripatus (type genus of thefamily).

COMMENTS: Feet and claws were not in-cluded in the original descriptions for mostfossils in the phylum, including the Carbon-iferous †Helenodora (Thompson and Jones,1980), which may be just a taphonomic ar-tifact. Nonetheless, Poinar (2000) stated (byinference) that claws in the fossils were def-initely absent, and on this basis he classifiedthe Tertiary amber fossils †Tertiapatus and†Succinipatopsis as intermediate betweenliving velvet worms and early Paleozoicforms (Poinar, 2000). To accommodate hisinterpretation, he placed the amber genera ina separate order, ‘‘†Ontonychophora,’’ inter-mediate between an order ‘‘Euonychophora’’(for the living families Peripatidae and Per-ipatopsidae) and an order ‘‘†Udeonychopho-ra’’ (for the Paleozoic forms). This is pecu-liar for several reasons. First, virtually allwell-studied insects in Miocene Dominican

amber belong to modern genera or to extinctgenera nearly identical to living taxa, andthose in Eocene Baltic amber belong almostexclusively to modern families (e.g., Lars-son, 1978). Second, the Cretaceous fossilhere clearly belongs in the living family Per-ipatidae, with clearly defined feet.

The ‘‘absence’’ of claws in †Tertiapatusand †Succinipatopsis is almost certainly anartifact of preservation (likely true as well ofthe dubiously assigned †Helenodora). Forexample, the feet of Onychophora are retrac-tile, and most ethanol-preserved modern spe-cies (e.g., AMNH collection, pers. obs.) havefeet retracted with claws frequently protrud-ing. Thus, we consider the original descrip-tions of †Tertiapatus and †Succinipatopsisflawed, and place the Udeonychophora andOntonychophora as newly synonymized un-der Euonychophora (NEW SYNONYMY). Statusof Tertiapatidae and Succinipatopsidae mustawait competent examination of those amberfossils, since critical characters were omitted


Fig. 17. Cretoperipatus burmiticus n. gen., n. sp., holotype, AMNH Bu218. Scale is 1.0 mm.


from the original descriptions and illustra-tions. Given that we have a Cretaceous spe-cies in the living family Peripatidae, extinctfamilies of Onychophora from the Eoceneand Miocene are highly improbable. A Cre-taceous member of the Peripatidae is consis-tent with an ancient, Cambrian origin of Lo-bopodia. This record is also further evidenceof the tropical paleoenvironment in whichBurmese amber was produced.

Cretoperipatus burmiticus Engel andGrimaldi, new species

Figures 14d, 17

DIAGNOSIS: As for the genus (see above).DESCRIPTION: The above description char-

acterizes the genus and species (ICZN, 1999:Art. 13.4). To the generic description we addthe following minor measurements (based onthe third pair of feet): foot length 0.15 mm;distance between second and third pairs oflobopods (as measured from middle of lo-bopods) 0.69 mm, distance between third andfourth pairs 0.77 mm.

HOLOTYPE: Sex indeterminate; AMNHBu218; Myanmar (Burma), Kachin, TanaiVillage (on Ledo Road, 105 km NW Myit-kyina).

ETYMOLOGY: The specific epithet is a ref-erence to Burmite, the amber from which thisfossil originates.

PHYLUM ARTHROPODA

SUBPHYLUM CHELIERATA

CLASS ARACHNIDA

ORDER ACARI

Because of the small size of mites, and themicroscopic details required for identifica-tion, useful fossils of them occur mostly inamber. Remains of Devonian mites are ex-ceptional for their age and cuticular preser-vation (Kethley et al., 1989; Norton et al.,1988). Mites occur in probably all Creta-ceous ambers, but Burmese amber containsthe greatest abundance and diversity. Leba-nese amber contains Anystidae, Bdellidae,Erythraeidae, Erythracaridae, and Smaridi-dae (Azar, 2000), the first three also occur-ring in Burmese and New Jersey ambers.Rasnitysn and Ross (2000) (identificationsby A.L. Kartsev and O.L. Makarova) also re-

ported Cheyletidae and Eupodidae in Bur-mese amber. Most acarines from the AMNHcollection have yet to be studied, but it ap-pears that the Burmese amber fauna of Acariis likely the most diverse one for the Meso-zoic (e.g., fig. 20).

Particularly significant acarines in Bur-mese amber are two specimens of Ixodida,or ticks (NHML In. 19125 and AMNHBu325 [fig. 20f]), both juveniles. TheAMNH specimen belongs to the large, extantcosmopolitan genus Amblyomma (HansKlompen, personal commun.). Unfortunate-ly, taxonomic features of larval ixodids arefew, so attempting to place these fossils with-in a phylogenetic scheme of living taxawould be extremely difficult. The only otherCretaceous parasitiform is a finely preservedjuvenile of the ‘‘soft-tick’’ family Argasidae,in New Jersey amber (Klompen and Grimal-di, 2001). Its apparent close relationship toliving species in Carios indicates it wasprobably a parasite of birds or feathered di-nosaurs.

ORDER SCORPIONES

Despite the antiquity of this group, fromthe Lower Devonian (i.e., Størmer, 1977),there are remarkably few Mesozoic fossils ofscorpions. The Lower Cretaceous limestoneof Brazil’s Santana Formation contains sev-eral described and undescribed taxa, and isprobably the most diverse Mesozoic faunaknown. Despite the relief and microscopicpreservation for which even the Santana For-mation fossils are well known, systematicplacement of the Mesozoic rock fossils ishampered by so few available characters.Only one virtually complete scorpion occursin Cretaceous amber—a specimen of a buth-oid (missing only the tip of the tail) in a pri-vate collection of Lebanese amber (Louren-co, 2001). Though no complete scorpion hasyet been found in Burmese amber, a fragmentof one is in the NHML collection (In. 20174;Ross, 1998: fig. 100), and two additional,isolated fragments occur in our material(AMNH Bu215c, 710). These fragments area dorsal sclerite of the telson, and a stingwith part of the telson (fig. 19). The frag-ments allow no definitive identification sub-ordinate to the rank of order, but indicate that


Fig. 18. Select spider (Araneae) specimens in the AMNH collection of Burmese amber. a. Male?Mysmenidae/?Aranaeidae, AMNH Bu234. b. Family indet., AMNH Bu252. c. Male Archaeidae, AMNHBu256. d. Araneoidea family indet., AMNH Bu258. e. Lagonomegopidae, AMNH Bu707. f. Familyindet. Scales are 1.0 mm.

there is significant potential with Burmeseamber for another complete Cretaceous scor-pion to surface.

ORDER PSEUDOSCORPIONES

Like mites, these small arthropods requiremicroscopic details for accurate identifica-tion, and cuticular remains of them also oc-cur from the Devonian (Schawaller et al.,

1991). Cretaceous amber contains the onlyMesozoic specimens of the group. Threespecimens are known from Lebanese amber(Azar, 2000) and four specimens, mostlyfragmentary, occur in New Jersey amber(Grimaldi, unpubl. data). Burmese amber hasfossilized two species that have been de-scribed, though several more exist. Cockerell(1917a, 1920) described †Electrobisium acu-


Fig. 19. Various chelicerates and tracheates inBurmese amber. a. Pseudoscorpion, AMNHBu230. b. Scorpion tail, AMNH Bu710. c. Mil-lipede, AMNH Bu206. Scale is 1.0 mm.

tum and †Garypus burmiticus from theNHML collection, and Judson (2000) re-cently revised one of those species based onCockerell’s material. According to Judson,†Electrobisium acutum is closely related toseveral species in the extant genus Crypto-cheridium Chamberlin (Cheridiidae), whichmay not be a monophyletic genus. †Garypusburmiticus is probably a species of the extantgenus Amblyolpium Simon (Olpiidae). Theonly other species of pseudoscorpion report-

ed from Cretaceous amber is an unnamedchernitid in Canadian amber (Schawaller,1991). Burmese amber contains the mostabundant and diverse fauna of Mesozoicpseudoscorpions, with 38 specimens in theNHML collection (four of the pieces con-tained 5, 6, 6, and 11 specimens alone), and11 in the AMNH, many of them fragmentary(fig. 19a).

ORDER ARANEAE

Spiders are among the most ancient landanimals, with Devonian fossils of true Ara-neae and their close, extinct relatives, the†Trigonotarbida. Nonetheless, the well-pre-served specimens in Cretaceous amber offerunique insight into Mesozoic Araneae. Pro-visional identifications to family of many ofthe better-preserved specimens in the AMNHcollection indicates at least eight families(David Penney, unpubl.): Archaeidae(AMNH Bu256), Dictynidae (Bu714, juve-nile),? †Lagonomegopidae (Bu707, juve-nile),? Linyphiidae (Bu716, male),? Mys-menidae/?Araneidae (AMNH Bu234), Oon-opidae (Bu706, juvenile; and Bu708,male?),? Telemidae (Bu712, juvenile), andTheridiidae (Bu676, juvenile; and Bu713,male). These are but 8% of the 128 spiderspecimens in the Burmese amber at theAMNH, so the list is minimal. Rasnitsyn andRoss (2000) listed seven families in theNHML collection. Families in common toboth collections are the Oonopidae and Ther-idiidae; unique to the NHML collection arethe Sparassidae (5Eusparassidae), Corinni-dae (5Myrmecidae), Pisauridae, Tetragnath-idae, and Thomisidae. Thus, at least 11 fam-ilies of Araneae occur in Burmese amber,which is probably the most diverse Mesozoicdeposit for the Araneae.

Burmese amber taxa representing the oldestapparent fossils of particular families are theTheridiidae, Dictynidae, Linyphiidae, and?†Lagonomegopidae. If AMNH Bu234 is anaraneid, this would be the oldest one in amberand possibly in the fossil record (the attribu-tion being uncertain of †Juraraneidae Eskov[from the Jurassic of Transbaikalia] to the Ar-aneidae). The oldest Oonopidae occurs inLebanese amber (D. Penney, unpubl.). The†Lagonomegopidae (AMNH Bu707) has a


Fig. 20. Representative Acari in Burmese amber. a. AMNH Bu342. b. AMNH Bu516. c. AMNHBu519. d. AMNH Bu009. e. AMNH Bu582. f. Juvenile tick (Ixodida), genus Amblyomma, AMNHBu325. Scale is 1.0 mm.

body form closely resembling a salticid, butinstead of having a pair of large, forward-di-rected anterior median eyes, these have a pairof large anterolateral eyes. Salticidae are themost diverse spider family. The oldest truesalticid, and only Cretaceous one, is in NewJersey amber (AMNH NJ835; D. Penney, per-sonal comm.). †Lagonomegopidae are knownin amber from Siberia and New Jersey.

A particularly exciting record is AMNHBu256, an excellently preserved male of the

primitive and relict family Archaeidae. Thefamily today is restricted to southern Africa,Madagascar, and Australia. Archaeidae wasoriginally discovered in 1854 by Koch andBerendt, occurring in Baltic amber, and aspecimen is also known from the Jurassic ofKazakhstan (Eskov and Golovatch, 1986).The implications of Baltic, and now Bur-mese, records for a group showing classicaustral disjunction was discussed by Eskovand Golovatch (1986) and Grimaldi (1992).


Fig. 21. Assorted paleopterous and lower Neoptera insects in Burmese amber. a. Ephemeroptera,AMNH Bu303. b. Portion of wing of Odonata with rhagionid fly, AMNH Bu031. c. Plecoptera, AMNHBu269. d. Orthoptera: nymphal Grylloidea, AMNH Bu323. e. Orthoptera (Grylloidea?), AMNH Bu278.f. Zoraptera: Zorotypus n. sp., AMNH Bu341a. Scales are 1.0 mm.

CLASS INSECTA

ORDER ORTHOPTERA

Insects of this order are rare in both theNHML and AMNH collections of Burmeseamber, with five and three specimens, re-spectively. The NHML specimens were iden-tified as Grylloidea, but only one of theAMNH specimens may belong to this group.AMNH Bu323 (fig. 21d) is an early instar

nymph of what appears to be a tettigonioid.AMNH Bu278 (fig. 21e) is much more un-usual, having an elongate head and body,three tarsomeres, and cerci without segmen-tation, similar to what is found in the Phas-mida. The specimen, however, possesses nodefinitive characters of the Phasmida, butmay belong to the Grylloidea (Erich Tilgner,personal commun.). For example, the poste-rior tentorial arms lack tubercles near the


posterior tentorial pits distinctive for Phas-mida; the probasisternum is shaped like an‘‘x’’ (as in Orthoptera and some lower Neop-tera), and is not a broad plate as in Phasmida;the arolia are absent (present in Phasmida);and small stalked scales occur at the base ofthe cerci (occurring, for example, in somegrylloids, but not in Phasmida). Also, thehind femora appear to be saltatorial, as theyare narrowed dorsally and have the trochan-ters virtually fused to them, and the secondtarsomere is lobed (as in some grylloids).The oldest definitive Phasmida are from theLower Tertiary (reviewed by Tilgner, 2001),though they should occur by the Jurassic.Various Mesozoic fossils have been de-scribed as Phasmida, and some plausibly be-long to this order, but they do not possessdefinitive features of Phasmida. Rasnitysnand Ross (2000) record phasmid eggs in theNHML collection but these require confir-mation. The Grylloidea extend to the Triassic(reviewed by Carpenter, 1992).

ORDER ZORAPTERA

This is a small circumtropical insect orderof only 32 modern species. Distributions ofa few species (i.e., Zorotypus hubbardi Cau-dell, Z. sinensis Hwang, and Z. medoensisHwang) extend to warm temperate regions.Relationships of the order have been contro-versial, the most recent hypothesis being thatthe Zoraptera are most closely related to thewebspinners, order Embiidina (Engel andGrimaldi, 2000). The only zorapteran fossilsknown were several very rare specimens inMiocene Dominican amber (Poinar, 1988;Engel and Grimaldi, 2000), so the discoveryof four Burmese amber specimens is of con-siderable significance.

The Burmese amber fossils are the oldestfossils of the order, and further remarkablein that three of the specimens (AMNHBu44o, 341a, and 966a, the first one beingapterous) each represent an extinct species inthe living genus Zorotypus. Species are clear-ly definable by segmentation of antennae andspination of the hind femur. Another speci-men, AMNH Bu182 is a distinctive new ge-nus with apomorphic metafemoral spinationand male genitalia, but plesiomorphic for thehind wing venation. The presence of several

species of Zoraptera in Burmese amber isfurther evidence that the Burmese amber for-ests were tropical. Systematics of the Bur-mese amber Zoraptera have been treated indetail in a separate article (Engel and Gri-maldi, 2002).

ORDER EMBIIDINA

As for Zoraptera, the Embiidina in Bur-mese amber are the only Mesozoic, and alsothe oldest definitive, fossils of the order. Em-biidina are rare in Dominican and Baltic am-bers; they are correspondingly rare in Bur-mese amber, with two specimens in theAMNH (Bu200, and Bu227; fig. 22a), andone described specimen in the NHML (In.19132; Ross and York, 2000: fig. 4), whichis the holotype of †Burmitembia venosaCockerell. The best preserved AMNH spec-imen (Bu227) is a male and is genericallydistinct from Cockerell’s specimen and rep-resents either an independent lineage withinBurmitembiidae, or a separate, yet undescri-bed family. Both the male terminalia andwing venation are completely unlike that ofB. venosa or modern families (Engel andGrimaldi, unpubl.). The second AMNH spec-imen (Bu200) preserves only the forelegsand apical portion of a wing of an embiid.As such, it is unassignable to family but isundoubtedly a webspinner owing to the dis-tinctive glandular foretarsus.

A Permian fossil of a putative Embiidinawas reported by Kukalova-Peck (1991: fig.6.19B). The figure of the specimen is con-sistent with the overall shape of embiids,such as the homonomous wings with narrowbases, and apparently asymmetrical malegenitalia (characteristic though not unique tothe order, e.g., Grylloblattodea). The geolog-ical distribution of related orthopteroid andpolyneopteran lineages makes the existenceof Permian Embiidina certainly feasible.However, the venation (which is distinctivefor all living Embiidina) is obscure in thatspecimen, and it is unclear if genitalic asym-metry is due to incomplete preservation. Thehallmark synapomorphy of the Embiidina isa pair of swollen, glandular foretarsi, whichare not preserved in the Permian fossil butare revealed in microscopic detail in the Bur-mese amber specimens.


Fig. 22. Assorted lower Neoptera and dictyopteran insects in Burmese amber. a. Embiidina, newgenus, AMNH Bu227. b. Dermaptera (Pygidicranoidea), AMNH Bu274. c. Partially preserved nymphal?Mantodea, with exceptionally long cerci, AMNH Bu155. d. Blattodea, ootheca (left) and nymph (right),AMNH Bu322. e. Blattodea nymph, AMNH Bu202. f. Isoptera: Kalotermes (?swinhoei), AMNH Bu313.Scales are 1.0 mm.

ORDER PLECOPTERA

The cosmopolitan order Plecoptera, orstoneflies, comprises approximately 2000species whose naiads typically live on orunder stones in cool, flowing freshwater,and which leave the water for the finalmoult to an imago. The order is plesiom-orphic in overall structure, perhaps not sur-prising considering their relatively basal po-sition in neopteran phylogeny and their an-

cient geological occurrence and geographi-cal distribution. Plecoptera may even be theliving sister group to all other Neoptera(e.g., Zwick, 1980). Taxa assigned to thePlecoptera date back to the Lower Permian(e.g., Carpenter, 1992: as Order Perlaria),and are known on the basis of both adultsand naiads. The two major clades of stone-flies, Arctoperlaria and Antarctoperlaria(Zwick, 1980, 2000) probably reflect an an-


cient, pangaean distribution early in the or-der’s history.

Although species of several modern fam-ilies are known from Tertiary amber ofnorthern Europe and the Dominican Repub-lic (Weitschat and Wichard, 1998; Stark andLentz, 1992), none have previously been re-corded from Cretaceous amber. Diverse Cre-taceous Plecoptera preserved in rocks havebeen described by Sinitschenkova (1987).The two Burmese amber specimens in theAMNH are the oldest stoneflies in amber,and the most completely preserved MesozoicPlecoptera. The higher-level systematics ofPlecoptera is relatively well established(Zwick, 2000), which will facilitate interpre-tation of these specimens.

ORDER DERMAPTERA

Like the Zoraptera and Embiidina, the ear-wigs (Dermaptera) are an autapomorphic,isolated order of Polyneoptera. Their truephylogenetic position remains obscured, butit is for just such lineages that early fossilswill prove most critical for elucidating rela-tionships. To date, no such analysis incor-porating information from extinct groups hasbeen undertaken, although Haas (1995) hasevaluated various character systems for Der-maptera phylogeny.

Numerous compression fossils of earwigshave been described from deposits rangingin age from the Lower Jurassic to the Mio-cene (e.g., Whalley, 1985; Ping, 1935; Vish-niakova, 1980; Popham, 1990; Carpenter,1992, Zhang, 1994). Three undescribed andputatively Dermaptera elytra from the UpperTriassic of Australia occur in the NHML col-lections (A.J. Ross, personal commun.). Sev-eral Cenozoic amber fossils from EoceneBaltic amber (Burr, 1911) have been de-scribed, and ones also occur in Miocene Do-minican amber (Schlee, 1980; AMNH andNHML collections). Several compressionfossil species from the Upper Jurassic andLower Cretaceous of Asia were placed in anextinct suborder, the †Archidermaptera,which plesiomorphically have segmentedcerci, pentamerous tarsi, and retain venation(albeit reduced) on their tegmina (Bey-Bien-ko, 1936; Carpenter, 1992). All other fossilsare of the suborder Forficulina (sometimes

referrred to as the ‘‘true earwigs’’), with thetypical synapomorphies of reduced tarsi, un-segmented cerci, and veinless tegmina,among other characters.

Four specimens of Forficulina are knownfrom Cretaceous amber, two unstudied onesin Lebanese amber and two in Burmese am-ber. The first Burmese amber specimenknown is the holotype of Labidura electrinaCockerell (NHML In. 20146; Ross and York,2000: fig. 2); the second is an adult femalepygidicranoid in the AMNH collection(Bu274: fig. 22b). The NHML specimen isnot well preserved and its assignment to theliving genus Labidura may be incorrect, assuspected by Cockerell (1920), owing to anapparent unbent pygidium, though it may belabidurid of some sort. The AMNH specimenis remarkably well preserved, easily recog-nizable as a pygidicranoid and distinct fromCockerell’s species. Interestingly, the Pygi-dicranoidea is the basalmost superfamily ofthe suborder Forficulina (Haas, 1995). Theother two living suborders are Hemimerinaand Arixeniina and are, not surprisingly, un-known from the fossil record. Both are ec-toparasitic on mammals, the Arixeniina onmolossid bats in southeast Asia, and Hemi-merina on certain rodents in Africa. At leastArixeniina is well established to be a mono-phyletic derivative of the Forficulina andshould be reduced in rank to a family of thislatter group (e.g., Popham, 1965, 1985). Itwould not be suprising if Hemimerina werelikewise found to be subordinate within anexisting taxon of Forficulina.

Modern pygidicranoid species have aroughly pantropical distribution, occurring insoutheast Asia, central Africa and Madagas-car, and Central and South America (e.g., Po-pham, 2000). Some additional species of Py-gidicranidae also occur in southern Africaand Australia, including Western Australia.The AMNH specimen intermingles somecharacters of the pygidicranoid families andperhaps represents a distinct lineage of thissuperfamily. Although several Lower Creta-ceous and younger fossils from Asia havebeen described as pygidicranoids, none ofthem preserve characters that could defini-tively place them in this superfamily (e.g.,see discussion by Willmann, 1990).


ORDER ISOPTERA

This order is of global ecological signifi-cance in the processing of lignocellulosicplant matter and in humification (e.g., Woodand Sands, 1978; Bignell and Eggleton,2000). The group appears to be relativelyyoung, with the oldest fossils occuring in theLower Cretaceous (reviewed in Thorne et al.,2000). With the exception of Burmese amber,all Cretaceous termites belong to the primi-tive families Hodotermitidae, Termopsidae,and possibly the Mastotermitidae. This strati-graphic occurrence corresponds with recentand even traditional phylogenetic hypothesesof isopteran families: Mastotermitidae (Ho-dotermitidae (Termopsidae (Kalotermitidae(all other termites)))) (e.g., Donovan et al.,2000; Thompson et al., 2000). The Burmeseamber termites are of great significance be-cause they are definitive Kalotermitidae fromthe Cretaceous, though kalotermitids puta-tively occur in Lebanese amber (A. Nel, per-sonal commun.).

The two termite species described byCockerell from the Burmese amber in theNHML were revised by Williams (1968),and are now known to belong to the Kalo-termitidae: Kalotermes †swinhoei (Cocker-ell) and Kalotermes †tristis (Cockerell). Atleast one specimen in the AMNH collectionis K. †swinhoei (fig. 22f) or near this species,but most of the other seven specimens aredifficult to evaluate because they are eithertoo partial or poorly preserved. There is alsoa specimen belonging to a very unusual, un-described genus of Rhinotermitidae in theNHML collection (K. Krishna and D. Gri-maldi, unpubl. data). This specimen is of ex-ceptional significance as the first Cretaceousrepresentative of the ‘‘higher’’ termites, fam-ilies Rhinotermitidae 1 Termitidae.

Occurrence of Kalotemitidae in the mid-Cretaceous, possibly Cenomanian, indicatesdivergence of the basal four families of Is-optera by this time. Isoptera have yet to befound in the Jurassic6, despite intensive study

6 Ren (1995) described six genera of putative Hodo-termitidae and Termopsidae from wing remains from theYixian Formation of Beipiao, southern China. Originallybelieved to be Upper Jurassic, this Formation is nowbetter known to be Lower Cretaceous, probably Barre-mian in age (ca. 120 Ma; Barrett, 2000).

of Upper Jurassic deposits from Eurasia. Thissuggests that earliest diversification of ter-mites in the Lower Cretaceous was quite rap-id. Kalotermitidae are often referred to as‘‘dry wood’’ termites, since they excavategalleries in dry, dead wood, in which theyhouse their small colonies and where theyfeed. Though most abundant and diverse intropics around the world, they also occur intemperate regions. The tropical nature of theBurmese amber paleobiota may account forthe rare presence of Kalotermitidae amongCretaceous amber deposits.

ORDER HEMIPTERA

†Protopsyllidiidae: This is a large, diversefamily of putatively sternorrhynchan affini-ties, occurring from the Permian to LowerCretaceous (reviewed in Carpenter, 1992).Two specimens, in amber from the UpperCretaceous of Burma and New Jersey, are themost recent occurrence of the group.

Specimen AMNH Bu137 (fig. 24e) is anentirely preserved male, but slightly clearedand compressed in parts. Specimen AMNHNJ623 is a beautifully preserved female.Both belong to an apomorphic new genus ofthe family. The genus could be characterizedby veins of the forewings having rows ofstiff, thick, erect setae on the upper surface(the hind wing is completely bare); the mar-gin of the forewing has a fringe of long setae,which are slightly longer and thinner than thesetae along the veins. Such setae have beenreported from †Aphidulum steoptiliumShcherbakov, known from compression fos-sil wings from the Lower Cretaceous ofMongolia, though its marginal setae weremuch smaller and fewer, possibly dislodged(Shcherbakov, 1988). †Aphidulum occurs inthe Lower Cretaceous of Mongolia and Low-er Purbecks of Dorset, England (Coram etal., 1994). The Lower Purbecks is nowknown to be Lower Cretaceous rather thanUpper Jurassic (Rasnitsyn et al., 1998).These last two occurrences were the most re-cent records of the family. Venation of thetwo amber specimens is very similar andconsistent with protopsyllidiids, thoughmissing the small apical fork of R (as alsooccurs in †Aphidulum). Venation of the newgenus differs most from †Aphidulum by hav-


Fig. 23. Assorted adult and nymphal Auchennorhyncha (Hemiptera) in Burmese amber. a. AMNHBu511. b. AMNH Bu964. c. AMNH Bu510. d. AMNH Bu512. Scales are 1.0 mm.

ing a three-branched M, instead of twobranches. Carpenter (1992) placed †Aphidu-lum into Hemiptera incertae sedis; Shcher-bakov (1988) placed the genus in the †Pro-topsyllidiidae.

The new genus is highly apomorphic inmany other respects. The vertex of the headbristles with numerous long, thick, stiff setae.The meso- and metathoracic legs are longand slender, but the prothoracic legs areabout half the length and with a row of spine-like setae on the ventral surface of the femur.Tarsomeres are 2–3–3. The antenna is longand slender, with eight flagellomeres, and theclypeus has a distinctive pair of long, stiff,projecting setae. The probosocis appears typ-ically sternorrhynchan-auchenorrhychan, be-ing extremely opisthognathous and ending atthe third pair of coxae. The eyes are extreme-ly large. After comprehensive study, thesetwo unique specimens will clearly reveal agreat deal about the phylogenetic affinities ofthis unusual extinct group.

Suborder Sternorrhyncha

Coccoidea: Though they represent onlyabout 1% of the arthropods in the NHMLcollection (Rasnistyn and Ross, 2000), Coc-coidea were 3.6% of all inclusions in theAMNH collection of Burmese amber. Mostspecimens are winged males (e.g., fig. 24f);apterous females are very rare in any amber.Because of their minute size (,1 mm bodylength), amber is the only consistently infor-mative type of fossil for this group. The onlyother Cretaceous amber deposit with a com-parable abundance of coccoids is from NewJersey, which contains eight families andgenera, and at least 12 species (Koteja,2000), representing at least 10% of all or-ganismal inclusions in that amber (Grimaldiet al., 2000a). Burmese amber preserves thenext most abundant and diverse record forthe group. The proportions of Coccoidea inall other Cretaceous ambers are far less than1%.

There are two interesting ecological pat-


Fig. 24. Assorted adult and nymphal Sternorrhyncha (Hemiptera) in Burmese amber. a–d: Aphi-doidea. a. nymph, AMNH Bu007. b. alate (Tajmyraphididae), AMNH Bu963. c. nymph, AMNHBu1094. d. nymph, AMNH Bu962. e. Protopsyllidiidae, AMNH Bu137. f. Coccoidea male, AMNHBu114. Scales are 1.0 mm.

terns shared between Burmese and New Jer-sey amber, both involving Coccoidea. First,Aphidoidea (aphids) in both these ambers arevery rare (,0.5%), in contrast to the abun-dance of aphids in Siberian and Canadianambers (5, 10% [Yantardakh, Kresty/Zhda-nikha] and 35–40%, respectively). This mayreflect the more tropical paleoclimates of theNew Jersey and Burmese ambers, since to-day coccoids are more abundant in tropical

than temperate forests—a distribution oppo-site that of aphids. Secondly, New Jersey(Grimaldi, 2000b) and Burmese ambers bothhave an impressive abundance of predatoryBerothidae (see below, Neuroptera).

Aphidoidea: Aphids are an ancient groupthat extend to the Triassic (two species), havemodest diversity in the Jurassic (six species),and first become abundant and diverse in theCretaceous (70 species, ten families [eight


extinct]). Despite this antiquity, they seem tohave undergone a major radiation in the mid-Tertiary, as a result of proliferation of theAphididae (representing 55% of extant spe-cies) on the Asteraceae (composits) and Po-aceae (grasses)(Heie, 1996). In fact, Heie(1996) hypothesized extinction of Mesozoicaphids (presumably mostly conifer feeders)near the K/T boundary or in the early Tertia-ry, resulting from floras dominated by coni-fers to ones dominated by angiosperms.

No Aphidoidea are reported in the NHMLcollection, but eight specimens are in theAMNH collection (0.2% of all inclusions).This low abundance is comparable to whatis found in the Lebanese and New Jersey am-bers. Five of the specimens are alates(AMNH Bu022, 188, 963, 1300, and 1301).The remainder of the specimens comprisesnymphs, all of which bear waxy terminal fil-aments (e.g., fig. 24c). Affinities of thenymphs have yet to be determined, but all ofthe alates belong to the extinct family Ta-jmyraphididae (fig. 24b), known otherwise inamber from northern Siberia, western Cana-da, and Lebanon (e.g., Heie and Azar, 2000).Among alates there are approximately fivespecies in three genera. All bear typical fea-tures of the Tajmyraphididae: seven antennalsegments (five flagellomeres); abdomen sim-ple; apically rounded (not bilobate); no si-phunculi; wing venation with short pterostig-ma, Rs originating at distal half of pterostig-ma, M with only two branches and stem orig-inating in proximal half of pterostigma, CuAand CuP widely separated, CuP nearly per-pendicular to main vein. In one species(AMNH Bu188), the rostrum projects wellbeyond the apex of the abdomen; the rostrumof another species (AMNH Bu1301) ends atthe abdominal apex (in the other species therostrum cannot be observed).

Though not nearly as diverse as aphid pa-leofaunas from Siberia and Canada, five spe-cies represented by five alates indicate a di-verse aphid community in Burmese amber.Their rarity in Burmese amber, though, isvery similar to that in the other major Cre-taceous amber deposits from low paleolati-tudes. This pattern suggests tropical rarity ofaphids in the Cretaceous, as is found today.

Suborder Heteroptera

Enicocephalidae: Several specimens existof this family in the AMNH and NHML col-lections (AMNH Bu110a, 131a, 212e, 268,451a, and 960a)(e.g., figs. 25a, b). Cockerell(1917a, 1917b) described four fossil speciesfrom the NHML collection alone: †Dis-phaerocephalus constrictus, D. macropterus,D. swinhoei, and †Paenitotechys fossilis. Theoriginal specimens of these species havebeen redescribed in detail by Stys (1969), butidentities of the AMNH specimens have yetto be determined.

Enicocephalidae should be expected fromthe Triassic, but the oldest fossils are fromthe Lower Cretaceous, specifically Neocom-ian amber from Lebanon (Grimaldi et al.,1993; Azar et al., 1999). The specimens inBurmese amber are among the only other en-icocephalids known from the Cretaceous,since they have not yet been found in ambersfrom Canada, New Jersey, Siberia, or Spain.The family Enicocephalidae7 is the sistergroup to the rest of the Heteroptera (Schuhand Slater, 1995). Since definitive Nepomor-pha occur in the Upper Triassic, we shouldexpect Enicocephalidae to be at least this oldand perhaps Lower Triassic to Upper Perm-ian in age. Small size may obscure their rec-ognition in sedimentary matrix.

Schizopteridae: This is a new family re-cord for Burmese amber, not represented inthe NHML collection. Specimen AMNHBu720a (fig. 25c) is more finely preservedthan the others (AMNH Bu87f, 723c, 965),showing features typical of the family. Forexample: forewings tegminal, barely differ-entiated into a corium and membrane, withdistinctive venation; antennal segments oneand two short; forewing without C or medialfractures; parameres long, fingerlike, andasymmetrical. The family belongs to the Dip-socoromorpha, which also includes the fam-ilies Stemmocryptidae (Australia), Hypsip-

7 Enicocephalidae is sometimes split into the Aenic-topecheidae and Enicocephalidae s.s. (Stys, in Schuhand Slater, 1995). This appears to be unnecessary split-ting, since the group appears definitively monophyletic,based alone on the bilobed head (with hind lobe bearingocelli) and the foreleg structure (tarsi spinose, stronglychelate, apical tarsomere with pair of subequal claws).It is highly unlikely that these unique structures evolvedconvergently in Aenictopecheidae and Enicocephalidae.


Fig. 25. Assorted Heteroptera in Burmese amber. a, b: Enicocephalidae. a. AMNH Bu268. b.AMNH Bu960. c. Schizopteridae, AMNH Bu720. d. Aradidae, n. gen., AMNH Bu167. e. Piesmatidae,AMNH Bu958. Scales are 1.0 mm.

terygidae (Africa, Asia), Ceratocombidae(cosmopolitan, mostly tropical), and Dipso-coridae (cosmopolitan). The Dipsocoromor-pha is one of the most primitive groups inthe Heteroptera, as reflected by the extensivevenation. Relationships appear to be as a sis-ter group to the Neoheteroptera (sensu Schuhand Slater, 1995): Enicocephalidae (Dipso-coromorpha (Neoheteroptera)). The fossil re-cord is sparse, with the only other Mesozoicfossils being undescribed species in Neocom-

ian amber from Lebanon. Like Enicocephal-idae, their small size (0.8–2.0 mm) may ob-scure or prevent preservation of dipsocoro-morphs in sedimentary matrices.

Hydrometridae: The Gerromorpha is agroup of approximately 1600 extant speciesin eight families, commonly called the semi-aquatic bugs and including the familiar waterstriders (Gerridae), water measurers (Hydro-metridae), and less familiar forms. SpecimenAMNH Bu1098 is unique, and only the


Fig. 26. Assorted Heteroptera in Burmese amber. a. Family near Cimicidae, AMNH Bu728. b.Family indet., AMNH Bu1092. c, d: Hydrometridae, n. gen., detail of body and entire habitus, AMNHBu1098b.

fourth definitive Mesozoic gerromorphan (asthe only one in Mesozoic amber it is also themost completely preserved Mesozoic fossilof the infraorder; fig. 26c, d). The specimenis well preserved, although a lateral view isobscured. Typical of the Gerromorpha, thebug possesses long legs and well-developedpairs of trichobothria on the head. Typical ofthe Hydrometridae it has three pairs of headtrichobothria, a prolonged head, long legsand antennae, and reduced wing venation(N.M. Andersen, personal commun.). Thespecimen is brachypterous and has vestigialocelli, which are correlated features. Theposterior two pairs of trichobothria have ex-tremely long trichs (the posterior pair tuber-culate), and there is a slight preapical artic-ulation of the second antennal segment intothe first. These features indicate the fossil isprobably within the Heterocleptinae, themost primitive subfamily of Hydrometridae.Heterocleptines are represented by two ex-tant genera: Veliometra (Brazil), and Heter-

ocleptes (western and central Africa, withthree species; and one species on Borneo).The fossil appears to be the most primitiveknown hydrometrid, living or extinct (N.M.Andersen, personal commun.).

Andersen (1998) recently monographedthe fossil Gerromorpha, including descrip-tions of various new taxa from the Paleoceneof Denmark. Based on the phylogenetic po-sition of the Gerromorpha as the sister groupto the Panheteroptera (Nepomorpha 1 Lep-topodomorpha 1 Pentatomorpha 1 Cimico-morpha [Schuh and Slater, 1995]), theyshould be present in the Triassic. DefinitiveNepomorpha occur in the Triassic. Oddly, theonly Mesozoic Gerromorpha are three Cre-taceous records: †Duncanovelia (Mesoveli-idae: Koonwarra bed, Aptian of Australia),†Cretaceometra brasiliensis Nel and Popov(Hydrometridae: Santana Formation, Aptianof Brazil), and a possible Veliidae also fromKoonwarra. Interestingly, the Santana For-mation fossil is apparently a hydrometrine,


or at least sister group to this derived sub-family.

Andersen’s (1998) phylogenetic analysisof the fossils and closely related living fam-ilies allows an excellent basis for extrapolat-ing ages. He estimated Jurassic divergence ofmost gerromorphan families, so clearly thereare huge gaps in the fossil record of thisgroup of Heteroptera. Though some tropicalhydrometrids live among vegetation distantfrom water, most species of this related fam-ilies live on the water surface or amongemergent vegetation, so there would presum-ably be far better representation of gerro-morphs in lacustrine fossil beds. Hydrome-tridae are cosmopolitan; two closely relatedfamilies are relict, with only two and threespecies each from Chile and western NorthAmerica (Macroveliidae), or southern Africa(Paraphyrnoveliidae). Andersen (1998) hy-pothesized divergence of these three familiesin the Lower Cretaceous, with apparent Hy-drometrinae already appearing by the Aptian.Thus, by the mid-Cretaceous, the primitivefossil in Burmese amber probably represent-ed a relict taxon. Description and discussionof the unique fossil is provided elsewhere(Andersen and Grimaldi, 2002).

Aradidae: One finely preserved specimen(AMNH Bu167; fig. 25d) represents a newgenus of the Aradidae, having the plesiom-orphic presence of pulvilli, as well as a longclypeus, free and unfused mediotergites III–VI, and lack of metapleural scent glandopenings. The only other Mesozoic aradid isAradus †creticus from the Cenomanian ofnortheast Siberia (Kormilev and Popov,1986). Aradids are highly flattened pentato-morphan bugs with approximately 1800 spe-cies in 211 genera, the greatest diversity be-ing in southeastern Asia (Schuh and Slater,1995). They live among forest floor leaf litterand under the bark of injured, dying, or deadtrees, where they feed on fungal mycelia.Some species of Aradus feed on the phloemand xylem of Pinus and Larix. A separatearticle treats this unique specimen (Heiss andGrimaldi, 2002).

Piesmatidae: A tiny species is representedby a unique specimen (AMNH Bu958, fig.25e), which is typical for the family with thedorsal surface of the head, pronotum, andmost of the forewings covered with a dense,

fine, areolate punctation. Ocelli cannot bedistinguished (they are present in modernspecies), but elongate mandibular plates anda ‘‘dorsal crest’’ on the head are also dis-tinctive for the family. The ventral view af-fords excellent observation of the abdomen,in which trichobothria should be observableif present. None appear to be present, orthere are only a few, reduced trichobothria—another feature of the family. This is the onlyMesozoic piesmatid, which is not unusualbased on their small size alone. Phylogeneticposition of the family in the Pentatomorphamakes a Cretaceous fossil of considerablesignificance for the phylogeny and chronol-ogy of the ‘‘higher’’ Heteroptera (Panheter-optera, sensu Schuh and Slater, 1995). Thereare 50 extant species in six genera. The fam-ily is cosmopolitan and where known all arephytophagous, with many on Chenopodi-aceae, some on Acacia, and various other an-giosperm families.

Cimicomorpha, near Cimicidae: SpecimenAMNH Bu728 is very peculiar and appar-ently a very primitive relative of extant Ci-micidae (bed bugs). The specimen is com-pressed and distorted, but apparently was abroad, flat bug, similar in shape to extant Ci-micidae (figs. 26a, 27). Like Cimicidae, ithas a dense vestiture of fine, long setae, aswell as a spinelike aedeagus. A stiff seta oc-curs just posterior to the eye (seen for itsright eye), as is found in the primitive sub-family Primicimicinae (Usinger, 1966). Oth-erwise, the bug is entirely plesiomorphic tothe Cimicidae. There are long basal portionsof the male genitalia (well preserved and vis-ible through the sheer cuticle), which is sim-ilar to the condition in other cimicomorphs;extant Cimicidae have quite short genitalia.Also, legs are fairly long (not as short as inCimicidae), and the rostrum extends to thehind coxae (in Cimicidae it generally extendsat best to the first pair of coxae). Most strik-ing of all is the macropterous condition, al-beit with weakly sclerotized hemelytra. Aclavus, cuneus, and medial fracture are pre-sent, though the membrane is too faint to ob-serve. Wings are as densely pubescent as therest of the body.

Extant Cimicidae are parasitic on bats andcertain birds, particularly swifts and swal-lows (Apodidae, Hirundinidae), although


Fig. 27. AMNH Bu728, family near Cimicidae. Ventral view, with dorsal view of hemelytra.

some other bird families are also parasitized(summarized in Usinger, 1966). Vestiture ofthe fossil species suggests it was parasitic,but if so, its host was almost certainly sometype of bird. The earliest fossil bats are fromthe Eocene, and perhaps first evolved in thePaleocene (Simmons and Geisler, 1998).

ORDER NEUROPTERIDA

Suborder Neuroptera

The lacewings (Neuroptera, Planipennia)are today represented by approximately 17

families and 6000 species occurring in allhabitats and on all continents except Antarc-tica. The order has a long geological history,extending into the Permian and with consid-erable diversity of early Mesozoic families.Despite the relatively common occurrence ofNeuroptera as compression fossils in the Me-sozoic, usually with only wings preserved,the order has not been well represented asamber inclusions. The most diverse amberfauna is that of the mid-Eocene Baltic amber,although new taxa are regularly discoveredin that amber and basic monographic work


is ongoing (Engel, 1999). Neuroptera are rarein Miocene Dominican amber, which con-tains two orders, seven families, and 13 spe-cies (Engel and Grimaldi, in prep.). Neurop-tera have a sporadic occurrence in Creta-ceous ambers. Rasnitsyn and Ross (2000),for example, listed only a few specimens inthe NHML collection of Burmese amber. Themost diverse fauna in Cretaceous amberknown thus far is from New Jersey (Grimal-di, 2000b), though it is likely that the Bur-mese fauna will be more diverse for this or-der. Like the New Jersey amber fauna, theAMNH collection of Burmese amber con-tains a remarkable number of neuropteranspecimens and taxa. In particular, it includesadult or immature representatives of the Ber-othidae, Rhachiberothidae, Osmylidae, Con-iopterygidae, Nevrorthidae, and Psychopsi-dae (the latter three not in the NHML col-lection; Engel, in prep.).

The berothids are particularly abundant inBurmese amber and are generally more di-verse and common in Cretaceous ambersthan in Tertiary ambers. Rasnitsyn and Ross(2000) listed only three berothids (i.e., inclu-sive of Rhachiberothidae, of which one spec-imen, In. 20177, is representative), out of1198 arthropod inclusions in the NHML col-lection (0.2%). In the Burmese amber at theAMNH, berothids are much more common,with 34 specimens, representing some 1% ofall arthropod inclusions. Of the specimensstudied thus far in New Jersey amber, thereare five species and three genera of beroth-ids, representing nearly 2% of all organismalinclusions. Only one or two specimens ofBerothidae have been found in each of theother Cretaceous ambers, in which coccoidsare also rare. Where plants have large infes-tations of coccoids, the larvae and adults ofthese small lacewings are commonly foundpreying among the aggregations, so the ber-othids in New Jersey and Burmese ambersprobably were feeding on the abundant coc-coids.

The Rhachiberothidae is a group of rap-torial lacewings today restricted to sub-Sa-haran Africa. Interestingly, their discovery inBurmese amber (NHML In. 20177 [M.S. En-gel in Rasnitsyn and Ross, 2000] and anAMNH specimen) bolsters the evidence fora Cretaceous age of Burmese amber. Fossil

rhachiberothids are known only from theCretaceous of the Northern Hemisphere (e.g.,in amber from France, Lebanon, New Jersey,and now Myanmar), so this group was onceglobally distributed.

Several dustywing specimens (Coniopter-ygidae; e.g., AMNH Bu198: fig. 28a) repre-sent another index taxon for the Cretaceousage of Burmese amber. They possess the ple-siomorphic arrangement of three branches tovein M, similar to Glaesoconis and Apoglae-soconis, which occur only in the Cretaceous(Grimaldi, 2000b; Engel, in press). Like ber-othids, coniopterygids also feed as larvaeand adults on sessile sternorrhynchans suchas Coccoidea.

Suborder Raphidioptera

The Mesozoic record of snakeflies (Raphi-dioptera) is quite extensive, but specimens inamber are exceedingly rare. At present onlyone species, †Mesoraphidia luzzii Grimaldi, ofthe extinct family †Mesoraphidiidae, is de-scribed from Cretaceous amber (from New Jer-sey; Grimaldi, 2000b). Mesoraphidiids andother Raphidioptera are diverse and commonin Mesozoic rocks but defined largely on thebasis of wing venation and therefore not en-tirely comparable with the modern classifica-tion of snakeflies, which is based heavily ongenitalic structures (Aspock et al., 1991). Theorder today is relict, consisting of approxi-mately 206 described species in two families(the Inocelliidae and Raphidiidae), with a dis-junct Holarctic distribution.

The discovery of a second adult snakefly(AMNH Bu092: fig. 28c) is significant forseveral reasons. First, this is only the secondrecord of an adult, mesoraphidiid snakefly inCretaceous amber, and so provides detailedcharacter information for a family otherwiseknown only from compression fossils. Sec-ond, AMNH Bu092 and †M. luzzii are theonly mesoraphidiids from the Late Creta-ceous, all other fossils being from the LowerCretaceous and Jurassic (Engel, 2002).Third, the specimen is further documentationof the past occurrence of snakeflies in trop-ical habitats. Today the order is restricted totemperate regions of the Northern Hemi-sphere (Aspock et al., 1991; Aspock, 1998).Snakefly fossils, however, have been recov-


Fig. 28. Assorted Neuropterida in Burmese amber. a. Coniopterygidae, AMNH Bu198. b. Psychop-sidae (wings), AMNH Bu309. c. Partial adult Raphidioptera, n. gen. in the Mesoraphidiidae†, AMNHBu092. d. Berothidae, AMNH Bu1291. e.? Nevrorthidae (larva), AMNH Bu1297. f.? Osmylidae (larva),AMNH Bu267. Scales are 1.0 mm.

ered from subtropical paleoenvironments ofthe Southern Hemisphere (e.g., Oswald,1990), as well as tropical to subtropical re-gions elsewhere during the Cretaceous. Thetropical origin of the Burmese amber paleo-biota is discussed towards the end of this pa-per. What factors might have led to the ex-tinction of Southern Hemisphere and tropicalsnakeflies is not entirely understood (As-pock, 1998). Baltic amber snakeflies (Engel,1995), for example, indicate that tropical orsubtropical snakeflies survived into the early

Tertiary, although they perhaps were relicteven at that time.

Last, the significance of AMNH Bu092 isits uniquely small size. The forewing lengthof the specimen is 4.26 mm, the smallest ofany raphidiopteran living or extinct! In theNHML Burmese amber collection is a ra-phidiopteran larva, undetermined to family(In. 20150), but perhaps a mesoraphidiid.The NHML specimen is significantly largerthan the AMNH adult (body length 13.83mm) and the two are likely not congeneric.


Fig. 29. Assorted Coleoptera in Burmese amber. a. Cupedoidea, AMNH Bu345. b, c: Staphylinoidea.b. AMNH Bu248. c. AMNH Bu259. d. Rhipiphoridae, AMNH Bu368. e, f. Lymexylidae, habitus anddetail of anterior end. Scales are 1.0 mm.

A separate article provides further details ofthese specimens (Engel, 2002).

ORDER COLEOPTERA

There is a far greater diversity of beetlesin Burmese amber than in any other Creta-ceous amber (e.g., figs. 29–31). Azar (2000)listed 19 families in Lebanese amber; Gri-maldi et al. (2000a) listed ten families inNew Jersey amber, though the great majority

of specimens are still unstudied. In contrast,Rasnitsyn and Ross (2000) listed 28 familiesin the Burmese amber at the NHML (alsowith many specimens still undetermined),representing 6% of all organismal inclusions(4% and 8% for Lebanese and New Jerseyamber, respectively).

Many beetles in Cretaceous ambers aresmall, with body lengths 1–3 mm. Since thesystematics of Coleoptera is highly depen-


Fig. 30. Assorted Coleoptera in Burmese amber. a. Horned beetle (Ciidae?), AMNH Bu232. b.Larva, family undetermined, AMNH Bu366. c. Family indet., AMNH Bu062. d. Family indet., AMNHBu069. e. Family near Platypodidae?, AMNH Bu235. f. Family indet., AMNH Bu236.

dent on minute features, like the segmenta-tion and structure of palps and tarsomeres,and hind wing venation is generally not pre-served or observable in beetle fossils, pres-ervation in rock greatly compromises thesystematics of fossil beetles. Carpenter(1992), for example, listed 234 genera of Co-leoptera as incertae sedis, and several hun-dred more as doubtfully assigned to moderngenera, the great majority of all of these be-ing rock fossils. Thus, the Burmese Coleop-

tera fauna appears to have unique signifi-cance, and compliments other diverse, Me-sozoic rock-fossil faunas, such as from theJurassic of Karatau, Kazakhstan (Arnol’di etal., 1977). Of the families Rasnitsyn andRoss (2000) listed, eight have records fromthe Jurassic, or even the Triassic. All otherfamilies in their list are the only or amongthe few records from the Mesozoic.

Unfortunately, only a small proportion ofthe AMNH Coleoptera has been identified to


Fig. 31. Assorted Coleoptera in Burmese amber. a. Family indet., AMNH Bu257. b. Family indet.,AMNH Bu284. c. Mordellidae, AMNH Bu363. d. Family indet., AMNH Bu367. Scales are 1.0 mm.

family as yet, so we present below only themost obvious and significant records.

Staphylinidae: Beetles of this family areknown from the Triassic (Fraser et al., 1996)and Jurassic (Tichomirova, 1968), but theBurmese fauna is probably the most abun-dant and diverse Mesozoic one of this hugeextant family (e.g., figs. 29b, c).

Lymexylidae: A unique record for Bur-mese amber is a single specimen in theAMNH (fig. 29e, f), the only Mesozoic fossilknown for the Lymexylidae. Wheeler (1986)monographed the genera in the family andstudied their phylogenetic relationships. Bythe impressive standards of present beetle di-versity, the Lymexylidae is a very modestgroup, with only seven extant genera andabout 50 species. The family, however, hasbeen of considerable interest because of con-troversial relationships, largely due to theirunusual long, soft bodies, reduced elytra, andmany other derived features. Definitive as-signment of the Burmese amber specimen tothe pantropical genus Atractocerus is based

on its extremely brachypterous elytra; short,spindle-shaped antennae; female maxillarypalp organs; and lack of tibial spurs. Of the23 described species, 14 occur in Asia.Wheeler (1986) concluded that there was lit-tle correspondence between phylogenetic re-lationships of lymexylid genera, their distri-butions, and geological relationships of thecontinents (‘‘area cladograms’’). He attribut-ed the widespread distribution of Atractoce-rus to dispersal, and that it ‘‘may be later inorigin’’ (Wheeler, 1986: 198). The new fossilestablishes that Atractocerus is of sufficientage for its distribution to have been affectedby continental drift. This is merely permis-sive evidence for tectonic vicariance, foreven if past distributions of the genus wereaffected by drifting continents these mayhave been erased by dispersal. Phylogeneticrelationships hypothesized by Wheeler areHylecoetus 1 [(Atractocerus 1 Lymexylon)1 all other genera], so a definitive Creta-ceous species of Atractocerus is consistent


with Crowson’s (1981) suggestion of a Ju-rassic origin of the family.

ORDER HYMENOPTERA

Hymenoptera are relatively common in-clusions in amber, including Burmese amber,but this is primarily true for the groups ofsmaller, parasitoid wasps. The NHML col-lection contains representatives of the Dia-priidae, Embolemidae, Megaspilidae, My-marommatidae, Pelecinidae, Scelionidae,Serphitidae, Evaniidae, Aulacidae (listed asGasteruptiidae in Rasnitsyn and Ross, 2000),undetermined Chalcidoidea, and of the acu-leate families Bethylidae, Tiphiidae, Formi-cidae, and Sphecidae. The AMNH collectioncontains representatives of all of these fam-ilies except for the Tiphiidae, Pelecinidae,and Megaspilidae, while adding to this listrecords of Stigmaphronidae, Megalyridae,and Pompilidae. The families Serphitidaeand Stigmaphronidae are significant strati-graphic indicators, as both families areknown only from Cretaceous ambers.

It is not surprising that the Burmese amberinclusions are all apocritans, as symphytansare exceptionally rare in all Cretaceous am-bers (specimens known only from Siberian,New Jersey, and Spanish ambers). The xy-lophagous symphytans are a paraphyletic as-semblage of families from which the para-sitoid Apocrita arose, specifically with theparasitic superfamily Orussoidea being theextant sister group to the Apocrita. Owing tothe diversity of Mesozoic symphytans, par-ticularly from the Upper Jurassic and LowerCretaceous, and the association of most ofthem with trees, it is unusual that symphy-tans are actually rare in amber.

Among the non-aculeate lineages, it is lit-tle wonder that the Scelionidae are amongthe most abundant in Burmese amber. Sce-lionids (e.g., figs. 32a, b) are diverse andcommon in all Cretaceous amber depositsand typically outnumber all other Hymenop-tera inclusions. Scelionids appear to have ex-perienced their greatest diversity in the Me-sozoic and dwindled in diversity during theCenozoic. The presence of evaniids in Bur-mese amber, a group that is today exclusivelyparasitoids of cockroach oothecae, probably

relates to the abundance of Blattodea in Bur-mese amber.

Pompilidae: The AMNH collection con-tains a single specimen of an enigmatic andremarkably autapomorphic pompilid (fig.33f). The specimen is excellently preservedand exhibits some peculiar modifications ofthe head capsule that have no apparent func-tional significance (Engel et al., in prep.). To-day pompilids are principally ectoparasitoidsof spiders, although a few species develop onspecies of other arachnid orders. The familyoccurs throughout the world but primarily inthe tropics. This is the oldest definitive re-cord of the Pompilidae.

Formicidae: Among the most interestingaculeate Hymenoptera in Burmese amber arethe ants (family Formicidae). Two generaand species have been described from theNHML collection (In. 19125 and In. 20182),and are the holotypes of †Burmomyrma rossiand †Haidomyrmex cerberus, respectively(Dlussky, 1996). †Haidomyrmex has mandi-bles unique for the Formicidae, and was de-scribed as belonging to the †Sphecomyrmi-nae, the most primitive subfamily of ants andwhich is exclusively Cretaceous in occur-rence (Grimaldi et al., 1997; Grimaldi andAgosti, 2000). The ocelli, mandibles, andscape were inconsistent with other spheco-myrmines, so Grimaldi et al. (1997) indicat-ed only that †Haidomyrmex ‘‘may’’ be in thisprimitive subfamily, pending more conclu-sive evidence. †Burmomyrma is based on afragmentary specimen, so relationships areuncertain. In the AMNH collection is anotherunusual ant (AMNH Bu014), which also hasdistinctive mandibles, a slight constrictionbetween the first and second segments of thegaster (as in Ponerinae), and a gracile bodywith very long legs (fig. 33d). Another spec-imen, AMNH Bu351 (figs. 33e, 34), is a de-finitive sphecomyrmine, possessing the dis-tinctively long second funicular segment(first flagellomere), but the plesiomorphicallyshort scape. If Burmese amber is Cenoman-ian in age, as is hypothesized (see Discus-sion, below), these would be the oldest de-finitive ants.

Sphecoidea: The diversity of spheciformwasps in Burmese amber is remarkable (An-tropov, 2000). This fact, plus the tropical pa-leoenvironment of Burmese amber, makes


Fig. 32. Assorted Hymenoptera in Burmese amber. a, b: Scelionidae. a. AMNH Bu224. b. AMNHBu282. c. Serphitidae, AMNH Bu313. d. Family indet., AMNH Bu049. e. Family indet., AMNH Bu089.Scales are 1.0 mm.

the possibility quite tantalizing of discover-ing a fossil bee (Apoidea) in this amber.Presently, the only definitively Cretaceousbee is a single specimen preserved in puta-tively Maastrichtian-aged amber from NewJersey (Michener and Grimaldi, 1988; Engel,2000). The spheciforms in Burmese amber(e.g., fig. 33c) consist of forms interminglingtraits of several subfamilies, as well as defin-itive representatives of the Ampulicinae andPemphrodoninae. No crabronines (i.e., the

lineage most closely related to the bees[Prentice, 1998; Melo, 1999]) are knownfrom Burmese amber.

†Serphitidae: The presence of this familyand the †Stigmaphronidae, which are knownonly from Cretaceous ambers, provide someof the most compelling evidence for the Cre-taceous age of Burmese amber.

The †Serphitidae are an extinct lineage ofparasitoid wasps allied to the Proctotrupo-idea, Mymmaromatoidea, Chalcidoidea, and


Fig. 33. Apocrita, mostly aculeate (b-f), Hymenoptera in Burmese amber. a. Stigmaphronidae,AMNH Bu677. b. Bethylidae, AMNH Bu047. c. Sphecidae. d, e: Formicidae. d. Ponerinae, n. gen.,AMNH Bu014. e. Sphecomyrma n. sp. (Sphecomyrminae), AMNH Bu351. f. Pompilidae, AMNHBu051. Scales are 1.0 mm.

Platygastroidea. Serphitids are entirely re-stricted to the Mesozoic and fossils areknown only in Cretaceous amber from Si-beria, Canada, New Jersey, and northernSpain. The family intermingles traits of sev-eral lineages and has been difficult to placein a phylogenetic framework but is perhapsnearest the base of the platygastroids, andwith this group as sister to the Mymarom-matoidea 1 Chalcidoidea. In fact, owing to

some distinctive characters present in bothmymarommatoids and serphitids, the twowere once considered a single family (e.g.,Kozlov and Rasnitsyn, 1979). In a forthcom-ing work (Engel et al., in prep.) the serphitidsare assigned to a separate superfamily, Ser-phitoidea near the Platygastroidea, Myma-rommatoidea, and Chalcidoidea. The hosts ofserphitids are entirely unknown. The discov-ery of 22 serphitid specimens in Burmese


Fig. 34. AMNH Bu351, Sphecomyrma sp. (worker), right lateral habitus and details of antenna,mouthparts, and disarticulated sting.

amber in the AMNH, plus two in the NHMLcollection (one figured by Ross, 1997),strongly reinforces the Cretaceous age of thisfossil resin.

†Stigmaphronidae: Burmese amber speci-mens in this Cretaceous family are unique tothe AMNH collection. They are considerablyrarer than Serphitidae in Burmese amber, withonly two specimens known (AMNH Bu671a,677). Like the serphitids, the family consists oflittle-understood parasitoids, known from Cre-taceous amber of Siberia, New Jersey, Canada,and Lebanon. Stigmaphronids are related to thesuperfamily Ceraphronoidea and, in fact, onespecies was originally assigned to the Cera-phronidae before being recognized as a stig-

maphronid (e.g., Muesebeck, 1963). Like the†Serphitidae, the stigmaphronids are best clas-sified in their own superfamily, sister group tothe Ceraphronoidea (Ceraphronidae and Me-gaspilidae).

ORDER DIPTERA

Diptera are the most common and diverseorganismal inclusions in ambers, so it is notsurprising that so many significant new re-cords and taxa have been found in Burmeseamber. As in most other ambers, Cecidomyi-idae, Ceratopogonidae, Chironomidae, andPsychodidae dominate in Burmese amber(8% of all inclusions, NHML coll.; 20% of


all inclusions, AMNH coll.). Full apprecia-tion of the diversity in each of these familiesrequires detailed, comprehensive study ofspecies and genera, similar to those done onthe Ceratopogonidae in Cretaceous ambers(Borkent, 1995; 1996; 2000a, 2000b; Szad-ziewski, 1994, 2000; Szadziewski and Arillo,1995; Szadziewski and Schluter, 1992) andon Cretaceous Brachycera (e.g., Grimaldiand Cumming, 1999).

Blephariceridae: A beautifully preservedmale specimen, AMNH Bu310 (fig. 35b), isthe only Cretaceous amber fossil of the fam-ily. Jarzembowski (1978) reported, but didnot formally describe, a compression-fossil-ized blepharicerid, from the Eocene-Oligo-cene of the Isle of Wight. Evenhuis (1994)cited Alexander (1958), regarding putativeblepharicerids described by Cockerell fromseveral North American deposits as ‘‘ques-tionably’’ in this family, being perhaps Ti-pulidae or Bibionidae. Hogue (1981) adoptedAlexander’s decision. The only other ble-pharicerid fossil is from the Turonian- agedOla’ Formation of Magadan (Upper Creta-ceous), Megathon zwicki (Lukashevich andShcherbakov, 1997). Based on wing venationMegathon appears related to the living gen-era Agathon and Bibiocephala. Blepharicer-idae is a small extant family, with the habits‘‘confined to areas in the immediate vicinityof rapidly flowing streams’’ (Hogue, 1981:193). Larvae are highly modified for clingingto the smooth surfaces of rocks in streams,where they graze on algae and diatoms.Though known principally in temperate are-as, blepharicerids also occur throughout thetropics, but usually only in mountainous re-gions where the streams are cool and clear.Thus, this is an unusual fossil record.

New genus near Valeseguya (fig. 35f): Va-leseguya is a very unusual genus that hasbeen tentatively placed in the Anisopodidae(s.l.) by Colless (1990) and Grimaldi (1991).Its relationships are actually obscure, andmay not be at all with the Anisopodidae; itand a new one from Burmese amber proba-bly represents a new family of Diptera. Thegenus was originally discovered on the basisof two living males from Queensland, Aus-tralia, Valeseguya rieki (Colless, 1990),which is the only material of the genusknown thus far from the extant fauna. Soon

thereafter, V. †disjuncta was described froma large series of males and females in Mio-cene amber from the Dominican Republic(Grimaldi, 1991). Valeseguya †disjuncta isnot particularly rare in Dominican amber,and, indeed, more is known of the extinctthan the living species. Females of V. †dis-juncta are unique in Diptera by possessing along, fine ovipositor with two valves. Thenew fossil, AMNH Bu108, also possessesthis type of ovipositor (fig. 35f), even withthe same bulbous base and bifid tips of thevalves. The Burmese fossil, however, is dis-tinctly plesiomorphic relative to the extantand the Miocene species and represents anew genus closely related to the enigmaticTertiary genus. It has eyes without medialemargination; 15 (vs. 12/14) flagellomeres;only the basal flagellomeres are serrate; andit has a plesiomorphic, more generalized ve-nation (veins M1 and M2 have a commonstem rather than being connected to the basalcell; the basal cell is much larger; and Sc iscomplete or nearly so).

Mycetophilidae sensu lato: ‘‘Fungusgnats’’, often classified in six families in theMycetophiloidea, occur in forested environ-ments in tropical and temperate regions. Lar-vae of most feed on fungal mycelia, thoughsome are predatory. Rasnitsyn and Ross(2000) recorded 15 specimens in the NHMLcollection, or slightly more than 1% of allarthropod inclusions; a very similar propor-tion of these flies is found in New Jerseyamber (Grimaldi et al., 2000a). In theAMNH collection of Burmese amber myce-tophilids comprise nearly 5% of all arthropodinclusions, with at least eight genera and tenspecies in the Diadocidiidae, Lygistorrhini-dae, and Mycetophilidae s.s. (Vladimir Bla-goderov, personal commun.)(e.g., fig. 35e),though much of the material is still unstud-ied. The lygistorrhinid primitively possessesa very small proboscis; most living speciesand an Eocene species possess long mouth-parts (the exception being Seguyola, whichhas lost the proboscis). Mycetophiloids areknown from the Jurassic, but as extinct fam-ilies only; living families and some generaappeared in the Cretaceous. The abundanceof Mycetophilidae s.l. in Burmese amber isapproximately the abundance seen in Balticamber (see catalogue by Evenhuis, 1994).


Fig. 35. Assorted nematocerous Diptera in Burmese amber. a. Tipulidae, AMNH Bu003. b. Ble-phariceridae, n. gen., AMNH Bu310. c. Culicidae, n. gen., AMNH Bu032. d. Archizelmiridae, AMNHBu178. e. Mycetophilidae (Macrocerinae), AMNH Bu314. f. New genus near Valeseguya, AMNHBu108. Scales are 1.0 mm.

Culicidae: The significance of mosquitoesas vectors of some devastating diseasesmakes any fossils of them of interest. Even-huis (1994) reviewed the fossil record of theCulicidae, all substantiated records of de-scribed taxa being Cenozoic. Jurassic (com-pression) fossils attributed to the Culicidaeby Bode and Hong are of highly questionableidentity. A significant, largely undescribeddiversity of Culicidae occurs in Dominican

amber, but these belong to modern genera,subgenera, and even species groups. Thereare only two Cretaceous Culicidae known:one in Canadian amber (Pike, 1995; Poinaret al., 2000), and a new specimen in Burmeseamber. The Canadian amber specimen, †Pa-leoculicis minutus, is believed to be closer tothe Culicinae than to the Anophelinae orToxorhynchinae.

The new Burmese specimen, AMNH


Bu032 (figs. 35c, 36), is the most primitiveknown Culicidae, and perhaps reflects an agesignificantly older than the Canadian amberspecimen. Unlike all other culicids, the Bur-mese specimen lacks scales on the wingveins, margin of the wings, or anywhere onthe body (instead there are setae). Wing ve-nation is rather similar to that of primitiveCulicidae and to Chaoboridae (fig. 36), in-cluding several recently described in Bur-mese amber from the NHML, though thereare various, small differences with the latter.This is somewhat expected, given the con-sistent grouping of Chaoboridae 1 Culicidaeas sister groups on the basis of morphologi-cal (Wood and Borkent, 1989; Saether, 2000)and molecular (Pawlowski et al., 1997; Mill-er et al., 1997) phylogenetic studies. Vena-tional similarity between the Burmese fossilculicid and Chaoboridae, thus, is probablysymplesiomorphic resemblance.

Most significant is the long proboscis inAMNH Bu032 (fig. 36). Though shorter thanin any living culicid, its proboscis is consid-erably longer than the head, with very longpalps that are at least equal to the length ofthe labium 1 labellum (this is difficult to de-termine, since the latter structures arecurved). All Chaoboridae have proboscidesconsiderably shorter than the head. The spec-imen is incompletely preserved, with most ofthree legs, the entire head, and the right wingpreserved. Most of the thorax and abdomenare preserved as an impression on the surfaceof the amber, though there is enough of theabdomen to determine that the gut containsa mass of granular material, probably a bloodmeal.

†Archizelmiridae: This is a Mesozoic fam-ily, probably basal within the Sciaroidea,which was described on the basis of a wingin rocks from the Upper Jurassic of Karatau(Rohdendorf, 1962). Fortunately, the wingvenation is distinctive, consisting of heavy Cand R veins, with C ending abruptly at theapex of R415; a large basal cell, to which par-allel bases of M, CuA1 and CuA2 connect;and incomplete anal veins. Though not re-ported, the group also occurs in Lower Cre-taceous sediments from Baissa (Transbaika-lia) and the Upper Jurassic of Shara-Teg(Mongolia). The distinctive venation, plusseveral new species and genera we have ex-

amined in New Jersey and Lebanese amber,allowed identification of an unusual archi-zelmirid species in Burmese amber, based onseven partial and complete specimens in theAMNH. The antenna of the Burmese amberarchizelmirid is exceptional among nemato-cerous Diptera, being remarkably convergentto the aristate antenna of higher Brachycera,especially Eremoneura. Inspection underhigh (160–4003) magnification, though, re-veals the thick, conical base of the antennato be a compact fusion of 12 flagellomeres,distinguished by slight annuli. The arista isthe last one or two flagellomeres, extremelyelongated. Interestingly, the antenna of theKaratau species shows little differentiation offlagellomeres; that of the Lebanese amber ar-chizelmirid has flagellomeres strongly butevenly tapered apicad (moreso than is typicalin Nematocera); and the New Jersey amberspecies has an abruptly tapered flagellum,with the apical flagellomere being very thinand equal in length to the preceding eightflagellomeres. This morphocline or transfor-mation series corresponds to the stratigraphicchronology of the species. The Burmese am-ber archizelmirid is an excellent biostrati-graphic indicator of the Cretaceous age ofthis amber. A separate article discusses Ar-chizelmiridae in detail.

Suborder Brachycera

Recent comprehensive study of Brachy-cera in Cretaceous ambers (Grimaldi andCumming, 1999) greatly facilitates study andinterpretation of the Burmese fauna. Creta-ceous ambers, for example, contain an im-pressive diversity of Empidoidea (e.g., figs.38–40), which fossilize poorly in sediments.These ambers also have preserved the bestrecord of earliest Cyclorrhapha. Here we dis-cuss only the taxa of greater stratigraphic orsystematic significance.

Acroceridae: AMNH Bu332 (fig. 37c)contains two complete, small specimens ofan unusual new genus of ‘‘hump-backed’’flies, family Acroceridae. This is a small ex-tant family of approximately 50 genera and500 species, which are larval parasitoids ofspiders. Some genera have vestigial mouth-parts; others have extremely long probosci-des, which they use for feeding from deep


Fig. 36. AMNH Bu032, Culicidae. Ventral habitus and details of proboscis, antenna, and wing.

flowers. These two specimens reveal typicalacrocerid features of a large head with largeeyes, minute antennae, a strongly hump-backed scutum, very large calypters, finelypleated wing membrane, and various features

of wing venation. They have very smallmouthparts. Some aspects of the rather com-plete wing venation are unique for acrocer-ids, though venation of the Eocene genus†Glaesoncodes (in Baltic amber) is readily


Fig. 37. Assorted lower Brachycera (Diptera) in Burmese amber. a. Rhagionidae (male), AMNHBu128. b. Rhagionidae (Bolbomyia group), AMNH Bu039. c. Acroceridae, n. gen. AMNH Bu332. d.Hilarimorphites (Hilarimorphidae), AMNH Bu098. Scales are 1.0 mm.

derivable from this Cretaceous genus. In†Glaesoncodes, for example, R213 is lost, theanterior radial cell is very thin, the vein be-tween the discal and posterior radial cells isbarely developed, and R4 and R5 are widelydivergent (as in most modern species), Theoldest acrocerid appears to be †Juracyrtuskovalevi (Upper Jurassic: Karatau). The orig-inal description of †Juracyrtus indicates ithad a long proboscis, though not well pre-served. However, wing venation of †Jura-cyrtus is not of the hovering type, which alllong-proboscid acrocerids have, so the puta-tive proboscis of †Juracyrtus is probably ex-traneous material (Grimaldi, 1999). Wing ve-nation of AMNH Bu332 is more completethan in †Juracyrtus, and it also possessesseveral venational features apomorphic to†Juracyrtus.

Hilarimorphidae: AMNH Bu098 (fig. 37d)is the third Mesozoic record of the family,the first being from Turonian-aged amberfrom central New Jersey. The New Jersey

and Burmese amber species belong to †Hi-larimorphites (four species occurring in NewJersey amber). The other Mesozoic hilari-morphid is †Apystomima, from the Upper Ju-rassic Karabastau Formation of Karatau, Ka-zakhstan (Mostovski, 1999b). Venation ofthe two genera is very similar, but with†Apystomima having peculiarly small wings,and apomorphically with long cerci. AMNHBu098 is additional evidence for the mid-Cretaceous age of Burmese amber. Hilari-morphidae today comprise 33 mostly Nearc-tic species, perhaps closely related to theBombyliidae; alternatively they are the sistergroup to the Eremoneura (Empidoidea 1 Cy-clorrhapha; D. Yeates, unpubl. data).

Empididae: These small, predatory fliesare the most abundant and diverse Brachy-cera in Cretaceous ambers, including Burma(e.g., figs. 38–40). Among the various generaand species represented in Burmese amber,three are particularly significant. †Alavesia(figs. 40a, b) is a distinctive genus of hybo-


Fig. 38. Assorted Empidoidea in Burmese amber. a. Empididae, n. gen. with highly reduced vena-tion, AMNH Bu339. b. Empididae, near Cretoplatypalpus. c. Empididae, near Cretoplatypalpus, AMNHBu169. d. Hybotidae, n. gen. near Meghyperus, AMNH Bu172. Scales are 1.0 mm.

tine recently described from Aptian-aged am-ber of northern Spain (Waters and Arillo,1999). This genus has a very large first fla-gellomere; a very small, three-segmentedarista; and venation with a distinctive, smalldm cell and widely divergent veins M1-CuA1.†Nemedromia is known from one species inNew Jersey amber and two in Canadian am-ber (Grimaldi and Cumming, 1999), with adistinctive new species in Burmese amber.Besides AMNH Bu169 (fig. 38c), †Cretopla-typalpus is known from two species: one inSiberian amber (Dolganian Formation: Cen-omanian), the other in Canadian amber (Gri-maldi and Cumming, 1999).

Dolichopodidae sensu lato: We are includ-ing within the large family of long-leggedflies the Microphorinae, since detailed mor-phological studies indicate they are the sistergroup or stem group to the Dolichopodidae(Chvala, 1983; Ulrich, 1984; Woodley, 1989;J. Cumming and B. Sinclair, unpubl. data).Microphorinae have traditionally been placedwithin the Empididae or in a family of their

own. Although there are only five genera andapproximately 70 species of extant Micro-phorinae, they are strikingly diverse in Cre-taceous amber (Grimaldi and Cumming,1999; unpubl. data), suggesting that the pre-sent fauna is relict. An exceptional new tax-on of microphorine is represented by AMNHBu029 and Bu175 (figs. 40c, d). This specieshas grossly inflated fore femora and tibiaebearing rows of spines, and was probablyraptorial like Ochthera (Ephydridae) andsome genera of Empididae are today. Ob-scure relationships among living and extinctmicrophorines precludes estimates of the af-finities of the Burmese amber microphorines.

†Chimeromyia: This is an unusual genusthat probably deserves a family of its own,possessing features of the Empididae and theCyclorrhapha (Grimaldi and Cumming,1999). It is known thus far only from theLower Cretaceous, based on three species inLebanese amber and one species in Alavaamber. The type genus is distinctive for var-ious veinal reductions or losses (M2, mcu and


Fig. 39. Assorted Empididae in Burmese amber. a. Genus indet. b. Trichopezinae, AMNH Bu006.c. Genus indet., AMNH Bu339. d. Genus indet., AMNH Bu052.

cell d, CuA2, A, and an anal lobe). Recently,a plesiomorphic new genus has also beenfound in Alava amber. The new Burmeseamber †Chimeromyia (figs. 41d, e) is anotherimportant index taxon, the age of whichwould be consistent with a Cenomanian ageof Burmese amber.

Phoridae: †Prioriphora and several relatedgenera of the most primitive phorids (e.g.,†Euliphora) occur exclusively in Cretaceousambers, from Siberia, Canada, New Jersey(these reviewed by Grimaldi and Cumming,1999), Alava (Arillo and Mostovski, 1999),and Burma (32 specimens in the AMNH:figs. 41a–d). Rasnistyn and Ross (2000) list-ed ‘‘Phoridae’’ but no generic determinationfor specimens in the NHML; examination ofthe specimens by DG indicates they are also†Prioriphora. This genus at present is notdefined by any apomorphic features (Gri-maldi and Cumming, 1999), and may in factrepresent a paraphyletic stem-group that isancestral to the large extant family of truePhoridae, some 5,000 species. Modern sub-

families and genera of Phoridae proliferatedin the Tertiary. Occurrence of one or morenew species of †Prioriphora in Burmese am-ber is additional evidence for the Cretaceousage of Burmese amber.

CONCLUSIONS

BIOSTRATIGRAPHIC CHRONOLOGY: There isnow little doubt about the Cretaceous age ofBurmese amber. This is partly revealed byprimitive new species groups, like genera, ofZoraptera; Embiidina; Aradidae, Hydrome-tridae, and Cimicomorpha near Cimicidae(Heteroptera); Lymexylidae (near Atractoce-rus: Coleoptera); and Acroceridae, Culicidae,Lygistorrhinidae, and other Diptera. Manygroups still require examination, particularlyAmphiesmenoptera (Trichoptera 1 Lepidop-tera; e.g., fig. 42). The only group of sur-prisingly derived status in the Burmese am-ber are the kalotermitid termites (which arestill quite primitive compared to the ‘‘high-er’’ termites Rhinotermitidae and Termiti-


Fig. 40. Empidoidea in Burmese amber. a, b: Hybotidae: Alavesia n. sp. a. AMNH Bu496. c, d:Raptorial males of n. sp. of Microphorinae (Dolichopodidae s.l.). c. AMNH Bu175. d. AMNH Bu029.Scales are 1.0 mm.

dae), and a probable rhinotermitid in theNHML collection. Other evidence providesan estimate for age within Cretaceous ep-ochs.

Figure 43 summarizes the stratigraphicdistribution of various Cretaceous insecttaxa. This is a minimal sampling, since thereare many arthropod taxa that have not beenstudied sufficiently or at all, which might al-low additional chronological inference. Com-paring exclusively Mesozoic taxa in Burmeseamber with their occurrence in other, well-dated, Late Mesozoic deposits (especiallyamber), Burmese amber was found to containan interesting mix of paleofaunal elementsfrom the Upper and Lower Cretaceous.Among the older, Lower Cretaceous (evenJurassic-aged) elements are the †Mesoraphi-diidae (Raphidioptera), †Protopsyllidiidae(Hemiptera), and in the Diptera, †Archizel-miridae, †Chimeromyia, and †Alavesia (Hy-botidae; see discussion and references undereach of these). The first two families are sim-ilar in their occurrence throughout most of

the Mesozoic, with the most recent occur-rences being in the New Jersey amber. †Ar-chizelmiridae are known from Upper Jurassicand Lower Cretaceous rocks, and in amberfrom the Lower Cretaceous of Lebanon(Neocomian) and Upper Cretaceous of NewJersey (Turonian). †Chimeromyia and †Ala-vesia occur exclusively in Lower Cretaceousambers, as well as in Burmese amber.

Insect taxa found in Burmese amber thatare of intermediate or extensive stratigraphicoccurrence in the Cretaceous are the †Tajmy-raphididae (Aphidoidea: Sternorrhyncha),†Hilarimorphites (Diptera: Hilarimorphidae),and the extinct hymenopteran families †Ser-phitidae and †Stigmaphronidae. With the ex-ception of †Hilarimorphites and a related Ju-rassic genus, they are known entirely fromambers spanning the Cretaceous from Leba-non to Canada (the latter Campanian). †Hi-larimorphites has so far been found only inNew Jersey and Burmese ambers. Burmeseamber also contains elements that are exclu-sively Upper Cretaceous: the primitive ant


Fig. 41. Assorted eremoneuran Diptera in Burmese amber. a-c: Prioriphora sp. (Phoridae). b.AMNH Bu296. c. AMNH Bu005. d-e: Chimeromyia n. sp. d. AMNH Bu298. e. AMNH Bu352. f.Sciadoceridae n. gen., AMNH Bu499. Scales are 1.0 mm.

genus †Sphecomyrma, the empidoid fly gen-era †Nemedromia and †Cretoplatypalpus,and the most primitive phorid fly genus,†Prioriphora.

Based on the distributions of these indextaxa, it is likely that the Burmese amber ismid-Cretaceous in age, approximately Turon-ian to Cenomanian. This estimate is consis-tent with the apparently Cenomanian-agedstrata that are in close proximity to the amberdeposits in northern Burma (summarized by

Zherikhin and Ross, 2000). We predict thatthose strata will eventually reveal the sourceof Burmese amber.

TAXONOMIC DIVERSITY: Abundance of ar-thropod groups in the NHML and AMNHcollections of Burmese amber is dispropor-tionate, with at least 13 ordinal-level taxahaving proportions that differ 3–4 fold (fig.44). There are five taxa heavily representedin the NHML collection (Rasnitsyn andRoss, 2000), due to numerous individuals in


Fig. 42. Assorted Amphiesmenoptera in Burmese amber. a, b: Trichoptera, families indet. a. AMNHBu128. b. AMNH Bu727. c. Lepidoptera (Micropterigidae), AMNH Bu701. d. Lepidoptera (Glossata,family indet.), AMNH Bu187. Scales are 1.0 mm.

one or more pieces. These include the fol-lowing: Acarina (six pieces with 8, 11, 14,and 25 individuals each), Myriapoda (fourpieces with 5, 6, 18, and 24 individuals eachof Synxenidae), Pseudoscorpionida (fourpieces with 5 or more individuals each), Is-optera (three pieces with 11, 15, and morethan 50 individuals each), and Auchenor-rhyncha (three pieces with 4, 5, and 8 indi-viduals each). This sampling bias is probablyrelated to differences in the sizes of piecesbetween the two collections. The NHML col-lection has far fewer pieces (117, less than10% the number in the AMNH), but they aremuch larger and were sliced into slabs forviewing inclusions. This mode of preserva-tion is more conducive to capture of aggre-gations and swarms, particularly of largerspecies as in Isoptera and Auchenorrhyncha.In contrast, the AMNH collection containssignificantly higher proportions of four otherorders. These are: Sternorrhyncha (4.8% ofall arthropod inclusions vs. 1.7%), Heterop-

tera (1.2% vs. 0.6%), Neuropterida (1.2% vs.0.5%), and especially Diptera (40% vs.16%). The higher abundance in the AMNHcollection of Sternorrhyncha is due largely tothe Coccoidea (3.6% of all inclusions) and tothe Berothidae for the Neuropterida. Thoughthe proportions of Coccoidea in the AMNHcollection of Burmese amber is approximate-ly 6% less than in New Jersey amber (10%of all inclusions in that amber), the Burmeseamber Coccoidea are still inordinately abun-dant and diverse compared to all other Cre-taceous ambers. As pointed out earlier, theabundance of Berothidae (which prey onCoccoidea) is no doubt related to coccoidabundance—a correlation also seen in NewJersey amber.

The much greater proportions of Dipteraseen in the AMNH collection are largely dueto a predominance of Ceratopogonidae (6%of all inclusions vs. 1% in the NHML col-lection), Cecidomyiidae (5% vs. 1%), andMycetophilidae (5% vs. 1%). Possibly, many


Fig. 43. Stratigraphic occurrence of various Cretaceous insect taxa in major amber deposits. Withexception of the Burmese deposits, all have been well dated palynologically. The distributions of theseCretaceous ‘‘index taxa’’ suggest a Turonian-Cenomanian age for Burmese amber.


Fig. 44. Proportions of major arthropod taxa in Burmese amber, based on collections in the AMNHand NHML.

of the tiny ceratopogonids and cecidomyiidsdeep inside the large NHML pieces escapednotice, but this is unlikely given scrutiny tothat collection, nor would this account for theMycetophilidae. Mycetophilid fungus gnatsare much larger than cecidomyiids and cer-atopogonids, and should be obvious in evenlarge amber pieces containing myriad inclu-sions. Smaller pieces in general are derivedfrom small resin flows, so it is most likelythat the AMNH collection represents a moredispersed medium into which wafted tinywinged arthropods. This explanation wouldalso account for the higher proportion of pti-liids (the smallest of all beetles) in theAMNH collection (1.5% of all inclusions vs.0.2%). The proportions of Diptera in theAMNH Burmese amber collection are closer

to what is seen in other major deposits ofamber: 34% in New Jersey amber, 44% inCanadian amber, 50% in Lebanese amber,and 70% in Baltic (Eocene) and Siberian am-bers (Azar, 2000; Grimaldi et al., 2000a).

The proportions in the two Burmese ambercollections of Hymenoptera and Coleopteraare identical: 8% and 16% of all arthropodinclusions, respectively. For the Hymenop-tera, this abundance is slightly lower, but stillcomparable to that in other ambers: 10%(Baltic), 11% (Lebanese), 13% (Siberian),14% (Canadian), with 24% of all inclusionsin New Jersey amber being Hymenoptera.The preponderance of Hymenoptera in mostof these ambers is due to Scelionidae. Veryinteresting is the very high abundance of Co-leoptera in Burmese amber, far higher (16%)


than in any other amber deposit: Canada(1%), Siberia (1.6%), Lebanon (4%), Baltic(5.5%), and New Jersey (8%). Abundancealso appears related to diversity. Though theAMNH Burmese amber beetles have notbeen fully identified, this collection is likelyto contain the 30 or more families found inthe NHML collection (Rasnitsyn and Ross,2000)—far more than in any other Creta-ceous amber deposit. Clearly, Burmese am-ber will be of exceptional significance in thefossil record of Coleoptera, particularly fornumerous families of tiny Cucujoidea.

Lastly, the minute proportions of ants andtermites in Burmese amber relates to an im-portant evolutionary trend of increasing di-versity and abundance of these ecologicallyimportant eusocial groups, from the Creta-ceous to the Tertiary. The 7% estimate of is-opteran abundance in the NHML collectionis skewed because of preservation of aswarm of one species. The 0.2% abundanceof Isoptera in the AMNH collection closelymatches their relative abundance in otherCretaceous deposits, not just amber. Thesame trend is found for ants: though they ap-peared in the mid Cretaceous (and termitesin the Lower Cretaceous), they remainedrare, primitive, and very modestly diverseuntil the Eocene (Grimaldi and Agosti,2000). Several of the ants in Burmese amberare highly unusual, and the Kalotermitidaeand rhinotermitid in Burmese amber repre-sent the most derived Isoptera in the Meso-zoic.

PALEOENVIRONMENT: Rasnitsyn (1996a) in-dicated that the Burmese amber was notformed in a tropical environment. Our resultsindicate quite the opposite: this amber wasformed under conditions that were probablymore tropical than any other major depositof Cretaceous amber. Distinctly tropical taxafound thus far include Onychophora, Zorap-tera, Embiidina, Sclerogibbidae, Atractoce-rus, n. gen. near Valeseguya, and an impres-sive diversity and abundance of Coccoidea(with corresponding rarity of the temperategroup Aphidoidea).

The Cretaceous has been identified as oneof the warmest periods in the last 500 Ma ofearth history, and this period has often beenregarded as globally tropical. Indeed, accord-ing to Spicer et al. (1996) below approxi-

mately 408N average temperatures rangedfrom 32 to 558C. Krassilov (1996) indicatedthat temperate deciduous forest during themid-Cretaceous occurred north of approxi-mately 558N latitude. Major Cretaceous am-ber deposits with paleolatitudes approximate-ly near or below 408N are Burma (128), Leb-anon (10–158), northern Spain (25–358), andNew Jersey (408) (table 1). Based on physi-ognomic features of fossil plants, however,such high temperatures apparently causedevaporative stress, and lower latitudes hadfrequent droughts with xeromorphic floras(Spicer et al., 1996; Krassilov, 1996). Inthese regions, xeric, microphyllous plantslike Cheirolepidiaceae (Coniferae) and Wei-chselia ferns predominated, with more mesicforests occurring northerly. Apparently, Cen-omanian-aged rainforests were barely devel-oped, except for isolated regions in what arenow Colombia and southeast Asia, whichwere subject to moist air flows from nearbyoceans (Spicer et al., 1996; Krassilov, 1996).

Spicer et al.’s (1996) Cretaceous climatemodel has implications for interpreting thediversity of the Burmese amber paleoenvi-ronment. As we have established, the pa-leoenvironment was distinctly tropical,which supports their model. While the highdiversity of the Burmese amber paleobiotacan be attributed to a fully tropical environ-ment at the time, the distinct nature of thepaleobiota, with many autapomorphic spe-cies, is possibly due to the ecological isola-tion of this part of Asia during the Ceno-manian. Various insect taxa having biogeo-graphic connections to other Cretaceous am-ber deposits indicate that such isolation wasnot complete.

Lastly, we have found several taxa in Bur-mese amber whose Recent distribution is dis-junct among or restricted to one of the south-ern temperate regions: Rhachiberothinae(Berothidae) in southern Africa; Sciadoceri-dae (Diptera) in southern South America,Australia, and New Zealand; Archaeidae(Araneae) in southern Africa, Madagascar,and Australia; and a new genus near the Aus-tralian genus Valeseguya (Diptera). This isadditional evidence for formerly widespreaddistributions of ‘‘austral’’ taxa (Grimaldi,1992), whose Recent distributions have rou-


tinely and probably naıvely been interpretedas entirely a vestige of gondwanan drift.

Though our intentions in studying the Bur-mese amber paleobiota were purely explor-atory, we can confirm the insight of Cock-erell (1917a) and the later conclusions ofZherikhin and Ross (2000), that Burmeseamber is Cretaceous. Originally sought as aprecious substance, Burmese amber retainsits mystique, but now scientifically as a win-dow to a unique, highly diverse Mesozoicmicrobiota worthy of intense exploration.

ACKNOWLEDGMENTS

Without the resourcefulness of Jim Davisand Doug Cruikshank (Leeward CapitalCorp.), this new material would never havebeen studied. We are grateful, too, to theMyanmar authorities who promoted the ex-cavation and export of the amber. RobertGoelet, member and Chairman Emeritus ofthe AMNH Board of Trustees, generouslyfunded acquisition of the amber.

Simone Sheridan, AMNH curatorial assis-tant, cheerfully and skillfully handled the te-dious task of boxing and labeling specimens,cataloguing, and databasing the collection.Andrew Ross loaned NHML material forstudy and comparison and hosted visits byDG and MSE; Alexander Shedrinsky andTom Wampler provided PyGC-MS analyses.Simone Sheridan, Keith Luzzi, and the lateSteve Swolensky provided help with the me-ticulous work required in screening piecesfor inclusions. Tam Nguyen, AMNH SeniorScientific Assistant, provided the scanningelectron micrographs, composed many of thephotomicrographic plates, and helped with li-brary references. Tam has been a constantsource of superb technical assistance. SteveThurston composed the graphics. Dany Azarkindly provided a copy his dissertation onLebanese amber.

For their identifications and/or advice onvarious taxa we are grateful to David Penney(spiders), Erich Tilgner (Orthoptera), Vladi-mir Blagoderov (Archizelmiridae, Myceto-philoidea), Dalton de Souza Amorim (Archi-zelmiridae, Anisopodidae), Kumar Krishna(termites), Lee Herman (Staphylinoidea), andNils Møller Anderson (gerromorphan).Charles Michener and Molly Rightmyer pro-

vided useful discussion, and important com-mentary on the manuscript was provided byAndre Nel, Vladimir Blagoderov, and espe-cially by Andrew Ross.

Lastly, without generous funding by theU.S. National Science Foundation (DBI-9987372, D. Grimaldi, PI), which supportedthe work of Paul Nascimbene and lab ex-penses, this and many other papers in prep-aration on Burmese amber would not havebeen possible.

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