New insights into the early morphological evolution of sea turtles by re-investigation of Nichollsemys baieri, a three-dimensionally preserved fossil stem chelonioid from the Campanian of Alberta, Canada.

ABSTRACT: The early evolution of Pan-Chelonioidea (sea turtles) is poorly understood. This is in part due to the rarity of undeformed skulls of definitive early stem chelonioids. In this work, we redescribe the holotype of Nichollsemys baieri using µCT scans and segmentations of the skull. This fossil is the best 3D preserved skull of any Campanian sea turtle, and includes partial "soft tissue" preservation. Nichollsemys is morphologically similar but clearly distinct from Toxochelys spp., and both show a mosaic of plesiomorphic and derived chelonioid features. The internal cranial anatomy documents the presence of derived characters in Nichollsemys baieri that are absent in Toxochelys spp., such as the loss of the epipterygoids and the rod-like shape of the rostru

SUBMITTER: Menon JCL 

PROVIDER: S-EPMC11245440 | biostudies-literature | 2024

REPOSITORIES: biostudies-literature