A new species of the mud terrapin Pelusios offers insights into early hominin habitats at the Pliocene Hadar Formation of Ethiopia

A novel extinct species of mud terrapin Pelusios awashi sp. nov. is described from the Hadar Formation in Ethiopia. Referred specimens include articulated and isolated specimens from multiple individuals that represent most elements of the shell and a holotype skull, which is the first known from the fossil record of Pelusios. The new species is distinct from extant Pelusios species by a unique combination of: a broad maxilla with an extensive triturating surface, a neural series reaching the suprapygal, and moderately convex lateral hypoplastral margins. Pelusios is unique among pleurodires for its kinetic plastral hinge at the hyo-mesoplastral junction, and the angled hinge of the new species demonstrates a plesiomorphic condition. Specimens found at the “First Family” locality (A.L. 333) in the Denen Dora Member suggest overlap between hominins and terrapins in habitats with aquatic resources. Crocodile bite marks denote likely chelonivory by Crocodylus and may indicate increased predation risk for sympatric hominins. The paleoecology of Pelusios awashi sp. nov. probably resembled that of P. sinuatus, consistent with phylogenetic and climatic niche conservatism in modern turtles. However, the broader maxilla of the new species suggests a more durophagous diet.