Earliest known European mammals: a review of the Morganucodonta from Saint-Nicolas-de-Port (Upper Triassic, France)

Abstract

The Rhaetian locality of Saint-Nicolas-de-Port (France) has yielded the most abundant and diverse mammalian assemblage known from the Late Triassic. Most of the material remains undescribed. We review here the morganucodonts from Saint-Nicolas-de-Port. We identify the upper and lower molariforms of the genus Brachyzostrodon. We also identify in the site Morganucodon peyeri, previously known from the Late Triassic of Hallau (Switzerland), as well as the genera Paceyodon and Paikasigudodon. The description of the new species Megazostrodon chenali sp. nov. extends the stratigraphical and geographical range of the genus, previously known from the Early Jurassic of southern Africa. Finally, another new morganucodont, Rosierodon anceps gen. et sp. nov., is described. The Morganucodonta is recognized as the most diverse order of Late Triassic mammals. Current fossil data suggest that Europe was the centre of initial diversification of morganucodonts at the end of the Triassic, and that morganucodonts were not much affected by the extinction event at the Triassic/Jurassic transition.

http://zoobank.org/urn:lsid:zoobank.org:pub:0D30F723-7D65-49B7-8375-BF916BFA0BBA

Keywords:

• teeth
• Early Jurassic
• Rhaetian
• Triassic/Jurassic transition
• mammalian origins
• occlusion

Acknowledgements

The authors thank Emmanuel Chenal for reactivating research on fossils from Saint-Nicolas-de-Port at the MNHN, for his invaluable help in the field, and in developing the PhD thesis of MD on which this publication is based. MD's thesis was supervised by the doctoral school of the MNHN ‘ED 227, Sciences de la Nature et de l’Homme’. We also thank the following: Jerry Hooker and Pip Brewer for their help during a visit to the NHMUK; Thomas Martin for his translation of the German diagnosis of Morganucodon by Kühne, and along with Julia Schultz for welcoming MD to the Steinmann Institute for Geology, Mineralogy and Palaeontology (Bonn); Renaud Vacant for his restoration of SNP 324 W; Jocelyn Falconnet for sharing his knowledge of the ICZN; Miguel Garcia Sanz for his work on the AST-RX platform ‘Plate-forme d‘accès scientifique à la tomographie à rayons X’ supervised by the UMS 2700 ‘outils et méthodes de la systématique intégrative CNRS-MNHN’, as well as Florent Goussard and Damien Germain for their help in the processing of 3D images; and thank Zhe-Xi Luo and an anonymous reviewer for their helpful and relevant comments, and Philippe Janvier for his help in the revision. This study has been supported by the ATM ‘Biodiversité actuelle et fossile. Crises, stress, restaurations et panchronisme: le message systématique’ and by the UMR 7207 ‘Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements’.