Southern hemisphere ceratosaurs evolved feeding mechanics paralleling those of Northern hemisphere tyrannosaurids

Abstract

Abstract Ceratosaurs (Ceratosauria), including Ceratosaurus and derived abelisaurids such as Carnotaurus , were the dominant large-bodied predators in Cretaceous ecosystems of the Southern Hemisphere, paralleling the ecological role of tyrannosaurids in the Cretaceous Northern Hemisphere. They are known for their short, deep skulls and prominent cranial ornamentation. These traits have often been interpreted as potential adaptations for intraspecific combat, sexual display, and as a buttress during feeding-induced mechanical stresses. While these adaptations have often been discussed, they have been subject to little mechanical testing, particularly using 3D models due to previous limitations in software. Here we used a mixture of computed tomography (CT) scanning and surface scanning to create accurate 3D models of four ceratosaurian skulls: Ceratosaurus , Masiakasaurus , Carnotaurus , and Majungasaurus . Using finite element analysis, we assessed the mechanical performance of the skull during feeding, notably including the small-bodied noasaurid Masiakasaurus . Our results show that despite their compact shape, large abelisaurs do not exhibit low stress under bite loading. Cranial ornamentation also fails to act as a structural buttress. Additionally, functional analyses of Masiakasaurus combined with its procumbent teeth imply that it was suited for grasping small prey, suggesting niche partitioning with the large sympatric abelisaur Majungasaurus . These findings challenge prevailing assumptions about ceratosaur skull strength and suggest that large abelisaurs fulfilled ecological roles comparable to large tyrannosaurids.