A long-snouted dyrosaurid (Crocodyliformes, Mesoeucrocodylia) from the Campanian Quseir Formation of Egypt

Abstract

Dyrosauridae, a clade of neosuchian crocodyliforms, was a significant component of terrestrial and aquatic ecosystems across the latest Cretaceous to Paleogene of North Africa. Here, we report a dyrosaurid mandibular symphysis recovered from the middle–upper Campanian Quseir Formation near Kharga Oasis in the southern Western Desert of Egypt.

This is a partial mandible (MUVP 635), including dentaries and splenials, assigned to Dyrosauridae based on its dental pattern, size, and the shape of the splenial in the symphysis. MUVP 635 exhibits alveolar diameters shorter than the interalveolar distances within the same row. Moreover, the seventh dentary alveolus is significantly large, comparable in size to the fourth dentary alveolus, while the sixth dentary alveolus is positioned close to the seventh dentary alveolus and is as small as the eighth dentary alveolus, which is adjacent to the ninth dentary alveolus. Phylogenetic analysis places MUVP 635 as an early-diverging member of Dyrosauridae, consistent with its middle–late Campanian age. It aligns with a polytomy with Chenanisuchus lateroculi and Anthracosuchus balrogus identified as the most basal members of Dyrosauridae. The discovery of new dyrosaurid material in the Quseir Formation extends the range of Dyrosauridae to the middle Campanian, highlighting the taxonomic richness of the dyrosaurid clade across North Africa and supporting hypotheses of the African origin for this family.