The most ancient African turtle

Abstract

ALTHOUGH turtles obviously differ greatly from other tetrapods in their shell, the turtle skull is so highly modified that turtle origins are difficult to resolve without evidence about the order of charac-ter acquisition. We report here the discovery of a turtle in the Early Jurassic Elliot Formation, South Africa, which extends the history of turtles in Africa by 60 million years, and reveals a previously unknown stage in the early evolution of turtles. This new skull is dominated by primitive characters held in common with the most primitive turtle known, the Late Triassic Proganochelys but, more notably, it is advanced in some important features. Previous turtle phylogenies suggest that most of the typical chelon-ian skull features evolved after turtles split into the two major groups, the Cryptodira and the Pleurodira. But this skull demon-strates that important cranial reorganization unexpectedly took place before the origin of the modern turtle groups. The reasons for this are unclear, but it may be related to the early evolution of hearing adaptations.