An early bothremydid from the Arlington Archosaur Site of Texas

Brent Adrian,Heather F Smith,Christopher R Noto,Aryeh Grossman

doi:10.1038/s41598-021-88905-1

Brent Adrian, Heather F Smith + Show 2 more

Open Access

https://doi.org/10.1038/s41598-021-88905-1

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Abstract

Four turtle taxa are previously documented from the Cenomanian Arlington Archosaur Site (AAS) of the Lewisville Formation (Woodbine Group) in Texas. Herein, we describe a new side-necked turtle (Pleurodira), Pleurochayah appalachius gen. et sp. nov., which is a basal member of the Bothremydidae. Pleurochayah appalachius gen. et sp. nov. shares synapomorphic characters with other bothremydids, including shared traits with Kurmademydini and Cearachelyini, but has a unique combination of skull and shell traits. The new taxon is significant because it is the oldest crown pleurodiran turtle from North America and Laurasia, predating bothremynines Algorachelus peregrinus and Paiutemys tibert from Europe and North America respectively. This discovery also documents the oldest evidence of dispersal of crown Pleurodira from Gondwana to Laurasia. Pleurochayah appalachius gen. et sp. nov. is compared to previously described fossil pleurodires, placed in a modified phylogenetic analysis of pelomedusoid turtles, and discussed in the context of pleurodiran distribution in the mid-Cretaceous. Its unique combination of characters demonstrates marine adaptation and dispersal capability among basal bothremydids.

Highlights

Four turtle taxa are previously documented from the Cenomanian Arlington Archosaur Site (AAS) of the Lewisville Formation (Woodbine Group) in Texas
Pleurochayah appalachius gen. et sp. nov. has a unique combination of characters, including many shared with Kurmademydini and Cearachelyini, as well as some traits shared with later derived bothremydids, Bothremydini and Taphrosphyini
The fossils derive from the Arlington Archosaur Site (AAS) in sediments most likely deposited near the middle of the Lewisville Formation [Fm] of the Upper Cretaceous Woodbine Group

Summary

Introduction

Four turtle taxa are previously documented from the Cenomanian Arlington Archosaur Site (AAS) of the Lewisville Formation (Woodbine Group) in Texas. The new taxon is significant because it is the oldest crown pleurodiran turtle from North America and Laurasia, predating bothremynines Algorachelus peregrinus and Paiutemys tibert from Europe and North America respectively. This discovery documents the oldest evidence of dispersal of crown Pleurodira from Gondwana to Laurasia. The fossils derive from the Arlington Archosaur Site (AAS) in sediments most likely deposited near the middle of the Lewisville Formation [Fm] of the Upper Cretaceous Woodbine Group.

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