A lepidosauromorph specimen from the Middle Jurassic (Bathonian) Moskvoretskaya Formation of the Moscow Region, Russia

ABSTRACT

A fragmentary diapsid left maxilla from the Bathonian Peski locality in Moscow Region, previously referred to Choristodera, is identified as Lepidosauromorpha indet. This specimen represents the first fossil record of basal lepidosauromorphs in the Middle Jurassic of European Russia. Among basal lepidosauromorphs, the maxilla from the Peski locality resembles those of the Middle Triassic Fraxinisaura and the contemporary Middle Jurassic (Bathonian) Marmoretta in subpleurodont tooth implantation, a relatively low dorsal process, and high keeled teeth with gently recurved apices and striae on the lingual side. This similarity suggests possible close relationships of Fraxinisaura, Marmoretta and the Peski form. The recognition of a basal lepidosauromorph in the fauna of the Peski locality extends the known geographical range of the Bathonian non-lepidosaurian lepidosauromorphs and demonstrates their wide Laurasian distribution at this time. It is additional evidence that Bathonian vertebrate faunas of Europe and Western Siberia were similar in composition.

KEYWORDS:

• Lepidosauromorpha
• Middle jurassic
• Bathonian
• Moscow Region
• Russia

Acknowledgments

We thank R. Rakitov (Borissiak Paleontological Institute, Moscow) for the help with SEM micrograph of PIN 4767/7.

Disclosure of potential conflicts of interest

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The work of PPS, DDV and RAB was fulfilled under financial support of the Russian Science Foundation (project 19-14-00020). The work of AGS was supported by the Russian Science Foundation (project 20–04–00070). The work of EVS was supported by the theme of the Zoological Institute of the Russian Academy of Sciences (AAAAA19-119020590095-9)the theme of the Zoological Institute of the Russian Academy of Sciences [AAAAA19-119020590095-9];