Reassessing the earliest Oligocene vertebrate assemblage of Monteviale (Vicenza, Italy)

Abstract

The faunal assemblage of Monteviale (Vicenza, northern Italy) represents a rare condition among the earliest Oligocene assemblages of south-eastern Europe at the ‘Grande-Coupure’. The lignitic fossiliferous strata lie above explosive basaltic breccias produced by a volcanic complex raised within a lagoon where the Calcareniti di Castelgomberto Formation (earliest Oligocene in age) was deposited. Systematic revision of the vertebrate remains from Monteviale reveals the presence of 15 taxa belonging to ?Butidae, Palaeobatrachidae, Trionychidae, Geoemydidae, Diplocynodontinae, Dugongidae, ?Pantolesta, Chiroptera, Rhinocerotidae, Anthracotheriidae and Palaeochoeridae. The fossiliferous deposit of Monteviale probably originated in a coastal lagoon characterized by salinity fluctuations, from brackish to fresh water, the latter evidenced by the presence of palaeobatrachid larvae. The terrestrial vertebrate assemblage indicates a humid forest environment with an age close to the Eocene–Oligocene boundary, lowermost Rupelian, MP21. Some of the mammal taxa (e.g. Epiaceratherium, Anthracotherium and ?Propalaeocherus) of Monteviale show a clear affinity with older (late Eocene) southern Asian species, suggesting a dispersal pattern across the several plates of south-eastern Europe and western Asia. By contrast, the herpetofauna (e.g. Trionyx, Bergouniouxchelys and Diplocynodon) suggests a closer relationship to European taxa.

Keywords:

• systematics
• palaeobiogeography
• biochronology
• palaeoenvironment
• earliest Oligocene
• Italy

Acknowledgements

We thank Viviana Frisone who kindly provided information on specimens housed at the Museo di Montecchio Maggiore; Mariella Del Re (Museo di Paleontologia, Università di Napoli) for information on trionychids housed at the Museo di Paleontologia, Università di Napoli; and Elisabetta Cioppi (Museo di Storia Naturale, sezione di Geologia e Paleontologia, Università di Firenze). Thanks also go to Tomáš Přikryl (Institute of Geology, Academy of Sciences of the Czech Republic, Praha) for kindly providing information about the holotype of ‘Lepidocottus’ papyraceus. The research of GC was supported by grants (ex-60% 2014) from the Università degli Studi di Torino. EG and LR acknowledge the support of National Grant PRIN 2010×3PP8J_003 (responsible D. Rio/E. Fornaciari, Università di Padova). LP thanks the European Commission's Research Infrastructure Action, EU-SYNTHESYS project AT-TAF-2550, DE-TAF-3049, GB-TAF-2825, HU-TAF-3593, ES-TAF-2997; part of this research received support from the SYNTHESYS Project (http://www.synthesys.info/) which is financed by European Community Research Infrastructure Action under the FP7 ‘Capacities’ Program. Stefano Castelli (Dipartimento di Geoscienze; Università di Padova) took the photographs of the specimens housed at the MGP-PD.