Scuola di Dottorato in Scienze della Terra, Dipartimento di Geoscienze, Università degli Studi di Padova – A.A. 2013-2014

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EARLY PERMIAN VERTEBRATE ICHNOFAUNA FROM SOUTH ALPINE REGION

(NORTHERN ITALY): ICHNOSYSTEMATICS, PALEOECOLOGY AND

STRATIGRAPHIC MEANING

Ph.D. candidate: LORENZO MARCHETTI, III course

Tutor: Prof. STEFANO MONARI Cycle: XXVI

Abstract

The Early Permian vertebrate ichnofauna of Italy is known since the 19th century, but a comprehensive study has never been tempted. This work of revision, on classical collections, specimens never described and new sampling, pointed to better reconstruct the real significance of the Italian ichnoassociation, in a wider global context. Two ichnogenera new for the Southern Alps were identified: Hyloidichnus and Limnopus. Those confirmed are: Amphisauropus, Batrachichnus, Dromopus, Erpetopus, and Varanopus. Optimally-preserved specimens allowed taxonomical and behavioral studies. All the data indicate that the Italian ichnofauna is larger and better preserved than previously known. The stratigraphic meaning is important, because it is well time-constrained (Early Kungurian, from radiometric dates). The main difference with contemporary associations is the lack of some bigger forms, like Ichniotherium and Dimetropus. This could have a stratigraphic or a paleoenvironmental explanation. The differences observed in different Italian basins and sites seem to be facies-related. Introduction

The Early Permian of the Southern Alps is characterized by the development of some continental pull-apart basins, along a E-W transect. The deposition was strongly controlled by tectonic forces, and volcanic and plutonic activity was very intense. The sedimentary infilling of the basins reflects alluvial-fan to sand sheet and floodplain-lacustrine environments, passing from unsorted conglomerates to stratified sandstones and laminated siltstones and mudstones. These latter preserve common evidences of subaerial exposure, like rain drops, mud cracks and fossil footprints of vertebrates and invertebrates. The fossiliferous basins are, from the E to the W: the Orobic Basin, the Collio Basin and the sedimentary sub-basins of the Athesian Volcanic Group. The first documented studies are from the 19th century (Curioni, 1870). Subsequent works proved the poorness of the Italian ichnoassociation, further accentuated in the younger strata (Conti et al. 1997, Nicosia et al., 2000, Avanzini et al., 2008). The studies on Early Permian Italian ichnofauna are generally descriptions of new material from a specific site, or works of partial revision, so a real comprehensive study on all the Early Permian material of the Southern Alps has never been tempted. The purpose of this study was to revise all the material coming from the Italian sites, with a mixture of modern and traditional techniques and following a precise and uniform approach. This was associated with new field work, necessary to better locate the fossiliferous localities, in a precise stratigraphic and paleoenvironmental context. Material and methods

The specimens analyzed (about 1000), are stored in different museums and institutions, which are: Natural History Museum of Milano, Natural History Museum "E. Caffi" of Bergamo, Natural History Museum of Brescia, Natural History Museum of Morbegno, Natural History Museum of Bolzano, Museum of Sciences MUSE of Trento, Ecomuseum of Val Gerola, Paleontological Museum of the University "La Sapienza" of Rome, and University of Pavia. The methods include a mixture of traditional (free line drawings, photos) and modern techniques (computer drawings, 3D acquisition and modelling), to obtain the most precise interpretative drawings and 3D models, necessary to the measure of the ichnologic parameters (Leonardi, 1987). The state of preservation of the material and the extramorphologies were carefully evaluated. The 3D acquisition methods include laser scanning and photogrammetry.

Scuola di Dottorato in Scienze della Terra, Dipartimento di Geoscienze, Università degli Studi di Padova – A.A. 2013-2014

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Discussion

The results of this complete work of revision strongly modifies the previous ideas on the Early Permian Italian ichnoassociation. Two ichnospecies, previously unknown for these basins, were identified: Hyloidichnus bifurcatus Gilmore, 1927 and Limnopus heterodactylus (King, 1845). They correspond to captorhinomorphs and temnospondyls (basal amphibians) of medium size, respectively. These ichnogenera were confirmed: Amphisauropus, Batrachichnus, Dromopus, Erpetopus, and Varanopus. Taxonomic studies on extensive material prove the existence of both the ichnospecies Erpetopus willistoni and E. cassinisi, as supposed by Santi (2007); also Varanopus is present, but it seems different from both the known ichnospecies, so another name should be utilized. Behavioral studies proved the existence of simultaneous gait of Amphisauropus and Erpetopus, and peculiar sinusoidal arrangement of tail impression in some Amphisauropus specimens (the only similar impression is from Canada, Van Allen et al., 2005). The stratigraphic meaning of the association is important, because it is strongly age-constrained (at least in Collio Basin and Athesian District), and so highly correlable. The age is Early Kungurian (from U-Pb radiometric dates on volcanic rocks). The most remarkable difference with Early Permian ichnofaunas of Europe and USA, is the lack of some bigger forms, like Dimetropus and Ichniotherium. Two hypothesis could be advanced: the trackmakers were declining or were extinct in the Kungurian (Gand & Durand, 2006, Lucas, 2007) or the paleoenvironment was different. The ichnoassociation lists the same forms in the two main Basins (Orobic and Collio Basins), but the proportions are quite different. The Collio Basin is characterized by a predominance of areoscelid traces (Dromopus, 81% of specimens), the Orobic Basin of captorhinomorph traces (Erpetopus-Hyloidichnus-Varanopus, 63% of specimens), this probably have an environmental explanation, since the stratigraphic position is similar.

FIG 1. Photos and interpretative drawings of Hyloidichnus bifurcatus Gilmore, 1927. FIG 2. Photos and interpretative drawings of Limnopus heterodactylus (King, 1845).

Scuola di Dottorato in Scienze della Terra, Dipartimento di Geoscienze, Università degli Studi di Padova – A.A. 2013-2014

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New field work interested three sections in the Trentino-Alto Adige region (Val Aperta, Tregiovo, Monte Luco), in the context of the project: "The Permian-Triassic ecological crisis in the Dolomites: extinction and recovery dynamics in Terrestrial Ecosystems". The new data indicate that the ichnofauna of this region is poorer, but the cause is probably not stratigraphic or paleoenvironmental, it is likely a bias. Field work also interested the Val Gerola, Laghi Gemelli, Val Brembana and Val Trompia sites, with the purpose of better relate the fossil localities with the study of stratigraphy and facies. These preliminary studies emphasize the richness of the Val Gerola and Laghi Gemelli sites, and indicate that the distribution of forms is facies-related. Conclusions

The Italian Early Permian ichnoassociation results larger and better preserved than previously known, and it is well comparable to contemporary associations of Germany, France and USA. The age is Early Kungurian, and it is composed by seven different ichnogenera: Amphisauropus, Batrachichnus, Dromopus, Erpetopus, Hyloidichnus, Limnopus,Varanopus. The ichnofaunal composition is similar in the Orobic and Collio Basins, although with different proportions, instead taxa from the Athesian Complex are fewer, but this seems a bias. The main difference with contemporary associations is the lack of the ichnogenera Dimetropus and Ichniotherium, this could have a stratigraphic or paleoenvironmental explanation. References

AVANZINI, M., NERI, C., NICOSIA, U. and CONTI, M.A. 2008. A new Early Permian ichnocenosis from the “Gruppo vulcanico atesino” (Mt. Luco, Southern Alps, Italy). Studi Trentini di Scienze Naturali. Acta Geologica, 83: 231-236. CURIONI, G. 1870. Osservazioni geologiche sulla Val Trompia. Rendiconti Istituto Lombardo di Scienze e Lettere, Arti, Memorie , Serie 3(2): 1-60. CONTI, M. A., MARIOTTI, N., NICOSIA, U. and PITTAU, P. 1997. Succession of selected bioevents in the continental Permian of the Southern Alps (Italy): improvements in intrabasinal and interregional correlations. In: Dickins J.M., Zunyi Y., Yhongfu Y., Lucas S.G. and Acharyya S.J. (Eds), Late Paleozoic and Early Mesozoic Circumpacific events and their global correlation. Cambridge University, p: 51-65. GAND, G., and DURAND, M. 2006. Tetrapod footprint ichno-associations from French Permian basins. Comparisons with other Euramerican ichnofaunas. Geological Society, London, Special Publications, 265(1): 157-177. LEONARDI, G. 1987. Glossary and manual of tetrapod footprint palaeoichnology. Departamento Nacional de Produção Mineral, Brasilia, 117 p. LUCAS, S.G. 2007. Tetrapod footprint biostratigraphy and biochronology. Ichnos, 14(1-2): 5-38. NICOSIA, U., RONCHI, A. and SANTI, G. 2000. Permian tetrapod footprints from W Orobic Basin (Northern Italy). Biochronological and evolutionary remarks. Geobios , 33 (6): 753-768. SANTI, G. 2007. A Short Critique of the Ichnotaxonomic Dualism Camunipes-Erpetopus, Lower Permian Ichnogenera from Europe and North America. Ichnos , 14: 185-191. VAN ALLEN, H. E. K., CALDER, J. H. and HUNT, A. P. 2005. The trackway record of a tetrapod community in a walchian conifer forest from the Permo-Carboniferous of Nova Scotia. New Mexico Museum of Natural History and Science Bulletin, 30: 322-332.

Scuola di Dottorato in Scienze della Terra, Dipartimento di Geoscienze, Università degli Studi di Padova – A.A. 2013-2014

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SUMMARY OF ACTIVITIES

Courses: F. REMONDINO, A. RIZZI, F. MENNA, G. AGUGIARO: "Fotogrammetria e 3D Laser Scanning". Dipartimento di Geoscienze, Università degli Studi di Padova L. SALMASO, L. CORAIN, S. BONNINI, R. ARBORETTI: "Statistica applicata alla sperimentazione scientifica". Centro Studi per l'Ambiente Alpino di S. Vito di Cadore (BL) E. CALANDRUCCIO: "Corso di Inglese Parlato" Dipartimento di Geoscienze, Università degli Studi di Padova S. MILLI, F. FONNESU: "Processi ed architetture deposizionali in sistemi torbiditici" X convegno annuale dei geologi del sedimentario - Geosed 2012, Città di Feltre W. HELLAN-HANSEN: “Sequence stratigraphy: principles and applications” Dipartimento di Geoscienze, Università degli Studi di Padova. R. J. ANGEL: "Scientific Communication in English" Dipartimento di Geoscienze, Università degli Studi di Padova L. GULICK: "Corso Avanzato di Inglese Scientifico", Università degli Studi di Padova

Communications: MARCHETTI, L., AVANZINI, M. and BERNARDI, M. 2012. Impronte di tetrapodi nel Permiano inferiore del Sudalpino: nuove scoperte e siti di interesse. In: Giornate di Paleontologia XII Edizione. Abstracts. Catania, Italy. MARCHETTI, L. and AVANZINI, M. 2013. Revision of Early Permian tetrapod ichnofauna, new insights from Lombardy and Trentino Alto-Adige (N Italy). In: Giornate di Paleontologia XIII Edizione. Abstracts. Perugia, Italy. MARCHETTI, L., AVANZINI, M., CONTI M. A. and SANTI, G. 2013. Early Permian vertebrate ichnology of the Southern Alps (N Italy): new discoveries and sites of interest. In: Second Latin-American Symposium on Ichnology, SLIC 2013. Abstracts. Santa Rosa, Argentina.

Posters: MARCHETTI, L., SANTI, G. and AVANZINI, M. 2012. The problem of small footprints in paleoichnology related to extramorphologies: new data from the Early Permian Erpetopus. In: X annual meeting of sedimentary geologists "Geosed 2012". Abstracts. Feltre, Italy. MARCHETTI, L., BERNARDI, M. and VOIGT, S. 2013. On locomotion of seymouriamorpha: An unusual trackway of Amphisauropus from the Early Permian of northern Italy. In: Giornate di Paleontologia XIII Edizione. Abstracts. Perugia, Italy. MARCHETTI, L., RONCHI, A, SANTI, G. and VOIGT, S. 2013. The Early Permian Gerola Valley ichnosite (W Orobic Basin, N Italy): taxonomical revision and paleoenvironmental reconstruction. In: Second Latin-American Symposium on Ichnology, SLIC 2013. Abstracts. Santa Rosa, Argentina. Publications: MARCHETTI, L., BERNARDI, M. and AVANZINI, M. 2013. Some insights on well-preserved Amphisauropus and Erpetopus trackways from the Eastern Collio basin (Trentino-Alto Adige, NE Italy). Bollettino della Società Paleontologica Italiana, 52(1), 55-62. MARCHETTI, L., AVANZINI, M. and CONTI, M. A. 2013. Hyloidichnus bifurcatus Gilmore, 1927 and Limnopus heterodactylus (King, 1845) from the Early Permian of Southern Alps (N Italy): A New Equilibrium in the Ichnofauna. Ichnos, 20(4), 202-217. MARCHETTI, L., SANTI, G. and AVANZINI, M. The problem of small footprints in paleoichnology: remarks on the Early Permian ichnotaxon Erpetopus cassinisi, a local morphotype from Southern Alps (northern Italy). Rivista Italiana di Paleontologia e Stratigrafia, accepted

Teaching activities: Teaching assistant: 21 hours, “Paleontologia”, Laurea di primo livello in Scienze Geologiche (2012/2013). Teaching assistant: 21 hours, “Paleontologia”, Laurea di primo livello in Scienze Geologiche (2013/2014).

Scuola di Dottorato in Scienze della Terra, Dipartimento di Geoscienze, Università degli Studi di Padova – A.A. 2013-2014

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Other: Collaboration with Natural History Museums of Bolzano and Trento for the project: "The Permian-Triassic ecological crisis in the Dolomites: extinction and recovery dynamics in Terrestrial Ecosystems" financed by the Promotion of Educational Policies, University and Research Department of the Autonomous Province of Bolzano - South Tyrol. Temporary assignment at the Natural History Museum "E. Caffi" of Bergamo, to reclassify the Permian fossil footprints collection of the Museum. Study of the Early Permian vertebrate footprint collection of the "Universidad Nacional de La Pampa", Santa Rosa, Argentina. Field work in a new Early Permian ichnosite in Austria.