New Crocodylomorph Material from the Fayum Depression, Egypt, Including the First Occurrence of a Sebecosuchian in African Late Eocene Deposits

Abstract

ABSTRACT During the Cretaceous and Paleogene periods, the Earth experienced tectonic and climatic changes, which included continental drift following the breakup of the supercontinents Gondwana and Laurasia, the end-Cretaceous mass extinction event, and several climatic events, including the Paleocene–Eocene Thermal Maximum and the Middle Eocene Climatic Optimum. In response to increased temperatures and vacancies of ecospace left by the extinction of non-avian dinosaurs, mammal and reptile lineages that survived into the Eocene underwent immense evolutionary radiations that led to the diversification of crown clades, such as Crocodylia. Late Eocene deposits in northern Africa provide insights into how crocodyliforms responded to these tectonic and climatic events. Specifically, the Birket Qarun Formation in the Fayum Depression of Egypt contains several species of crown crocodylians as part of its rich fossil record of vertebrates. This study provides description of new material attributable to crocodylian taxa previously known from this formation, as well as newly recognized non-crocodylian mesoeucrocodylian material referable to Sebecosuchia. The sebecosuchian material provides important evidence attesting to the diversity of crocodyliforms in the late Eocene of Africa and expands the known biogeographic range of sebecosuchians.