Mandibular biomechanics of Acheroraptor temertyorum (Theropoda: Dromaeosauridae) with implications for the feeding ecology and behaviour

Acheroraptor temertyorum is a dromaeosaurid theropod, probably a saurornitholestine, found in the upper Maastrichtian Hell Creek Formation of Montana. This enigmatic dromaeosaurid is known from only a partial maxilla and dentary, as well as referred isolated teeth, making even the general aspects of its palaeobiology largely elusive. In this work, beam theory is applied to the lower jaw of Acheroraptor temertyorum to document the biomechanical properties of the mandible of this taxon and to infer the feeding mechanism of this dinosaur. This work suggests the lower jaw of Acheroraptor temertyorum is mainly adapted to produce rapid, slashing bites, as previously inferred for other dromaeosaurids. Intriguingly, despite having a closer phylogenetic affinity with Saurornitholestes langstoni, overall biomechanical properties of the lower jaw of Acheroraptor temertyorum are found to be weaker than the former taxon, but rather comparable to Asian velociraptorines. Such results may indicate Acheroraptor temertyorum preyed on smaller animals compared to other saurornitholestines, and suggest diets or predation methods of saurornitholestine dromaeosaurids might have been more diverse than previously assumed.