Histology and pneumaticity of Aoniraptor libertatem (Dinosauria, Theropoda), an enigmatic mid-sized megaraptoran from Patagonia

FERNANDO E. NOVAS

JOURNAL OF ANATOMY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2020

0021-8782

Aoniraptor libertatem is a mid-sized megaraptoran that comes from the Late Cretaceous(Turonian) Huincul Formation at Río Negro province, Patagonia, Argentina. In thisstudy, we conducted a detailed analysis of pneumaticity of the sacrum and tail ofAoniraptor. This shows a complex structure within these vertebrae, being composedby small diverticulae surrounding large pneumatic canals and a central chamber thatopens outside through pleurocoels or pneumatic canals. Further, we carried out a histologicanalysis which confirms the pneumatic nature of these anatomical features.Both analyses found that chevrons in Aoniraptor were invaded by pneumaticity, a featurethat appears to be unique to this taxon. In addition, a comparative analysis betweenAoniraptor and other theropods (e.g. Gualicho and other megaraptorans) wascarried out. This resulted in the modification of previous schemes about the evolutionof pneumaticity through Theropoda, the finding of some evolutionary pneumatictraits through Megaraptora, and the usefulness of pneumatic traits as a taxonomictool.