A Triassic stem turtle with an edentulous beak.

Li, Chun; Fraser, Nicholas C; Rieppel, Olivier; Wu, Xiao-Chun · Nature · 2018

basic_science · Level V

Where this comes from

Abstract

The early evolution of turtles continues to be a contentious issue in vertebrate palaeontology. Recent reports have suggested that they are diapsids<sup>1-6</sup>, but the position of turtles within Diapsida is controversial<sup>7-12</sup> and the sequence of acquisition of turtle synapomorphies remains unclear<sup>1-3</sup>. Here we describe a Triassic turtle from China that has a mixture of derived characters and plesiomorphic features. To our knowledge, it represents the earliest known stem turtle with an edentulous beak and a rigid puboischiadic plate. The discovery of this new form reveals a complex early history of turtles.

Medical subject headings