SUSAN T U R N E R & WALTER Y O U N G Q U I S T

LATE DEVONIAN PHOEBODONT (PISCES : CHONDRICHTHYES) FROM

THE CONFUSION RANGE, UTAH

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TURNER S. & YOUNGQUIST W. 1995 - Late Devonian phoebodont (Pisces Chondrichthyes) from the Confusion Range, Utah. [Phoebodonte (pisces : chondrichthyes) du Ddvonien supdrieur de Confusion Range, Utah]. GEO- BIOS, M.S. 19 : 389-392.

ABSTRACT

A small sample of phoebodontiform teeth confirms a Late Devonian (presumed late Frasnian rhenana conodont zone) site in the Confusion Range of Utah, western U.S.A.

KEY-WORDS : DEVONIAN, FRASNIAN, UNITED STATES, CHONDRICHTHYES, PHOEBODONTIDAE.

R~,SUM~,

Un petit lot de dents de phoebodontiforme de Confusion Range de 12Jtah, U.S.A. occidentale confirme un Ctge d~vonien supdrieur (Frasnien sup~rieur, rhenana zone).

MOTS-CLI~S : DI~VONIEN, FRASNIEN, I~TATS-UNIS, CHONDRICHTHYES, PHOEBODONTIDAE.

INTRODUCTION Devonian ver tebrates have long been known from Lower to Middle? Devonian Water Canyon Fm. (late Lochkovian-Emsian or younger) of Utah, USA (e.g., Ilyes & Elliott 1993). Miller (1981) reported the oldest shark from Utah which was a cladodont tooth of Carboniferous (late Mississippian) which he called "Cladodus" (actually a Symmor ium sp.) from the Chesterian Great Blue Limestone Fm. This paper records the first Late Devonian fish and the first Devo- nian shark remains from the State from a res- tricted outcrop on the north east flank of the Confusion Range most probably from the late Frasnian.

In 1950 one of us (WY, then of the Universi ty of Idaho) with his summer research assis tant Je r ry Haegele visited the Confusion Range at the re- quest of Phillips Petroleum to investigate cepha- lopods from an Upper Devonian locality in desert country discovered by field geologists Edward Zeller and J ack Mann, which WY identified as Manticoceras sp. Youngquist collected for cono- donts and in the residue found instead several

small shark teeth which were t ransmit ted to Dr Bobb Schaeffer of the American Museum of Natu- ral History (AMNH), New York. In 1983 the se- nior author visited AMNH and discovered the specimens which were named Phoebodus? sp. Subsequent s tudy and renewed field work to lo- cate the original site has been in operation since 1993. The junior author has visited the Range on two occasions but as yet no new material has been located. The possibility tha t the shark teeth came from a small lens which has subsequently been eroded cannot be ruled out. New collecting of a contemporaneous site in Nevada (by WY in 1994) now under s tudy should help to confirm the stratigraphic horizon of the original specimens.

GEOLOGY The tee th came from a restricted outcrop on the nor theas t f lank of the Confusion Range most pro- bably from the late Frasnian '(rhenana Zone) at the base of the Pilot Shale, (section in Sandberg et al. 1988, fig. 13). In an a t tempt to rediscover the original site and to explore the setting Youn- gquist has re-collected in the Confusion Range

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Figure 1 - SEM pho tomic rog raphs of t ee th of U t a h La te Devonian phoebodont , P h o e b o d u s b i f u r c a t u s G~N'PH~ & IVANOV. 1, A M N H 371.1, l ingual view ; 2, A M N H 371.1, l a te ra l view ; 3, AMNH 371.2, apical view ; 4, AMNH 371.2~ l ingual view ; 5, A M N H 372.1, l ingual view ; 6, A M N H 372.1, l a t e ra l view ; 7, AMNH 372.1, labial view ; 8, AMNH 372.2, l ingual v iew ; 9, A M N H 372.1, lab ia l view. Microphotographie S E M de dents de Phoebodon.te.~ du D(~vott.ien sup&ieur de l'Utah, P h o e b o d u s b i f u r c a t u s GINTHER (~ IVANOV. 1, A M N H 37l . l, rue linguale ; 2, A M N t I 37l . l, rue latdrale ; 3, A M N H 371.2, rue apicale : 4, A ~ I N H 371.2, rue linguale ; 5, A M N H 372,1, vtte linguale ; 6, A M N H 372.1, vue lat&ale ; 7, ~ F I N H 372.1, utte labiale ; 8, A M N H 372.2, vtte lingttale : 9, A M N H 372.1, uue labiale.

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Figure 2 - Ske tches of basal view of t ee th of U t a h Late De- vonian phoebodonte Phoebo- dus b i furca tus GINTHER IVANOV. 1, AMNH 371.1 ; 2, AMNH 372.2 (Scale ba r = 0.2 m m ; both approximate ly to scale). Dessins en vue basale de dents de Phoebodus bifur. ca tus GINTHER • IYANOV, du Dgvonien supgrieur de l'Utah. 1, A M N H 371.1 ; 2, A M N H 372.2 (E, chelle = 0,2 ram).

(CON on Sandberg et al. 1988, map 12). At a site in the lower member of the Pilot Shale of Nevada (Manticoceras Zone ; section in Sandberg et al. fig. 11) occurs a thin siliceous band about 120 mm thick rich in Palmatolepis sp. (presumably P. semichatovae) associated with fish remains in the top 15 mm preserved in vivianite (see also Hil- pman 1956), which are now under investigation.

S Y S T E M A T I C P A L E O N T O L O G Y

Class CHONDRICHTHYES Huxley, 1880 Family PHOEBODONTIDAE Williams, 1985

P H O E B O D U S B I F U R C A T U S GINTER • IVANOV, 1992 : Figs 1, 2.

M a t e r i a l - Five teeth, one a broken cusp : Youn- gquist & Haegele coll. 1950 AMNH 371- 372.

L o c a l i t y - Approximately 114 37' W 39 28' N, 8 km north of Skunk Springs, north east flank of western Confusion Range, Utah

Stratigraphy - basal member Pilot Shale, rhena- na Conodont Zone, upper Frasnian, Upper Devo- nian.

M e a s u r e m e n t s - Largest tooth is lmm across the (AMNH 372a) others 0.5mm or less.

Description - Crown of three to five cusps. Each cusp has a rhombic cross-section towards the tip; more rounded proximally on the lingual side. La- bial lip prominent. Dorso-Lingual round-elongate raised torus with 2-3 prominent foramina at the lingual basasl rim. Base shape strongly bifurca- ted or horshoe shaped (Fig. 2). Basal concavity rounded with few 2-3 prominent foramina housed in elongate pits. Only one specimen shows well- preserved cusps and these are widely separated and all have a distinct lateral carina (Figs. 1.3,4)

; this tooth (372a) has an elongated ovoid base which is not bifurcated. The specimen with widely-spaced cusps (Figs. 1.3,4) can only tentat ively be referred to P. bifur- catus because of its damaged base.

R e m a r k s - Phoebodus bifurcatus was described from the Frasnian of Poland and Russian platform and is known also from Lesni Lom Quarry in the Czech Republic (Ginter in Hladil et al. 1991, pl. 8.1) but is not previously known from the U.S.A. The Utah specimens can be com- pared especially with the so-called juvenile tooth from Timan (Ginter & Ivanov 1992, fig. 4A) from certain gigas (now rhenana) conodont zone. Clearly the smaller (juvenile/early ontogentic teeth) are more strongly birfurcated which might reflect a difference in the juvenile diet of these sharks. The phoebodont occurs with palmatolepid cono- donts and Manticoceras. We postulate that either conodont animals or more likely cephalopods made up the diet of these sharks with grasping teeth in a comparable manner to the modern Frilled shark Chlamydoselachus which eats squids and has an extremely similar tooth pat- tern.

S i gn i f i c ance - Phoebodont sharks were first de- cribed from the USA by St John & Worthen (1875) and under the name "Diplodus" by East- man (1899) from late Middle (now presumed ear- ly Frasnian of Illinois and Iowa) (see discussion in Turner in press) and Upper Devonian. Phoebo- dus species are now known to be widespread in the mid to late Devonian of central and eastern Europe, South-east asia and Austral ia (e.g. Gin- ter & Ivanov 1992, this volume). This is the far- thest west in continental North America that a phoebodont has been recorded. The record of a phoebodont shark in relatively deep water shales confirms the spread of the massive IId transgression of Johnson & Murphy

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(1984), Johnson & Sandberg (1988), and Sand- berg et al. (1988) into the wes te rn U.S.A. The eus ta t ic rise which b rough t pos tu la ted connec- t ions wi th Midcont inen t USA (Sandberg et al. 1988, fig. 12) would have allowed the rapid dis- persal of phoebodont sharks . The subsequen t eus- ta t ic fall in the la tes t F ra sn i an / ea r ly F a m e n n i a n resu l ted in the most severe Palaeozoic extinction recorded ( Johnson & S a n d b e r g 1985) and certain- ly no definite Lower F a m e n n i a n phoebodonts are known from the U.S.A. a l though p r e s u m e d Laza- rus species appea r in the La te F a m e n n i a n (e.g., E a s t m a n 1899, Gross 1973).

A c k n o w l e d g e m e n t s - We heartily thank Edward Zeller (now Space Technology Center, University of Kansas), Michal Ginter (Faculty Geology, Warsaw), Gary Webster (Washington State University) for information and discussion, and Kathy Wolfram and John Maisey (AMNH) for loan of specimens in their care. Dora Aitken carried out SEM work at the Queensland Museum under the auspices of Australian Research Coucil grant n ° A39132723.

This is a contribution to IGCP 328. Palaeozoic Micro- vertebrates.

R E F E R E N C E S

EASTMAN C.R. 1899 - Descriptions of new species of Diplodus teeth from the Devonian of northeastern Illinois. Journal Geology, 7 : 489-493.

GINTER M. & IVANOV A. 1992 - Devonian phoebodont shark teeth. Acta Palaeontologica Polonica, 40 : 69- 81.

GINTER M & IVANOV A. 1995 - Middle/Late Devonian phoebodont-based ichthyolith zonation. VIIIth E/LV Symposium, Paris 4-8 Sept. In H. LELII~VRE, S. WENZ, A. BLIECK & R. CLOUTIER (eds.) : Premiers Vertebras et Vertebras inf~rieurs. Geobios, M.S. 19: 351-355.

GROSS W. 1973 - Kleinschuppen, Flossenstacheln und Z~hne yon Fischen aus europ~iischen und nordame- rikanischen Bonebeds des Devons. Palaeontogra- phica Abteilung A, 142 : 51-155.

HILPMAN P.L. 1956 - Geology of the Easy Ridge Area, White Pine County, Nevada. Master's Thesis, Uni-

versity of Kansas, Lawrence, Kansas : 72 p. (unpu- blished).

HLADIL J., KREJCI Z., KALVODA J., GINTER M., GALLE A. & BEROUSEK P. 1991 - Carbonate ramp environ- ment of Kellwasser time-interval (Lesni Lom, Mo- ravia, Czechoslovakia). Bulletin de la Socidt~ belge de Gdologie, 100 : 57-119.

ILYES R.R. & ELLIOTT D.I~ 1993 - The significance of Lower Devonian vertebrate-bearing deposits of wes- tern North America. In S. TURNER (ed.) : IGCP328 : SDS The Gross Symposium, Scientific Sessions, GNttingen 4-6 Aug. 1993, Abstracts, University of Lille.

JOHNSON J.G., KLAPPER G. & SANDBERG C.A. 1985 - Devonian eustatic fluctuations in Euramerica. Bul- letin of the geological Society of America, 96 : 567- 587.

JOHNSON J.G. & SANDBERG C.A. 1988 - Devonian eus- tatic events in the western United States and their biostratigraphic responses. Devonian of the World. Canadian Society of Petroleum Geologists, Memoirs 14, (3) : 171-178.

JOHNSON J.G. & MURPHY M.A. 1984 - Time-rock model for Siluro-Devonian continental shelf, western Uni- ted States. Geological Society of American Bulletin 95 : 1349-1359.

MILLER W.E. 1981 - Cladodont shark teeth from Utah. Journal. of Paleontology, 55 : 894-895.

ST JOHN O. & WORTHEN A.H. 1875 - Descriptions of fossil fishes. Geological Survey of Illinois 6, part 2 Palaeontology, 1 : 245-488.

SANDBERG C.A., POOLE F.G. & JOHNSON J.G. 1988 - Upper Devonian of western United States. Devo- nian of the World. Canadian Society of Petroleum Geologists, Memoirs, 14, (1) : 183-20.

TURNER S. (in press) - "Dittodus" species of Eastman 1899 and Hussakof and Bryant 1918 (Mid to Late Devonian). In W. WIMBLEDON, S. TURNER & A. BLIECK (eds) : IGCP 328 : SDS, The Walter Gross Symposium. Modern Geology.

S. TURNER Queensland Museum

P.O. Box 3300 S. Brisbane, Qd 4101, Australia

W. YOUNGQUIST P.O. Box 5501

Eugene, Oregon 97405, U.S.A.