Braincase anatomy of extant Crocodylia, with new insights into the development and evolution of the neurocranium in crocodylomorphs

• DOI: 10.1111/joa.13490
• Publication Date: 2021-06-27T18:30:40Z
• Authors: Ivan T. Kuzmin; Elizaveta A. Boit...; Victor A. Gombole...; Evgeniia V. Mazur; Sergey P. Morozov; Andrey G. Sennikov; Pavel P. Skutschas; Hans‐Dieter Sues
• Keywords: Neurocranium; Quadrate bone; Endocast; Theropoda; Vomer; Autapomorphy; Buttress; Sauropoda

Abstract Present‐day crocodylians exhibit a remarkably akinetic skull with highly modified braincase. We present comprehensive description of the neurocranial osteology extant crocodylians, notes on development individual skeletal elements and discussion terminology used for this project. The quadrate is rigidly fixed by multiple contacts most braincase elements. parabasisphenoid sutured to pterygoids (palate) (suspensorium); as result, basipterygoid joint completely immobilized. prootic reduced externally concealed quadrate. It has verticalized buttress that participates in canal temporal vasculature. ventrolateral processes otoccipitals cover posteroventral region braincase, enclose occipital nerves blood vessels narrow bony canals also provide additional sutural between further consolidate posterior portion crocodylian skull. otic capsule characteristic cochlear prominence corresponds lateral route perilymphatic sac. Complex internal structures otoccipital (extracapsular buttress) additionally arrange neurovascular periotic space cranium. Most are excavated paratympanic pneumatic sinuses. various an overall similar structure some consistent variation taxa. Several newly observed features Gavialis gangeticus members Crocodylidae exclusion alligatorids: exposure floor canal, sagittal nuchal crest supraoccipital projecting posteriorly beyond postoccipital pneumaticity. distinctive (fixed joint, consolidated occiput) evolved relatively rapidly at base Crocodylomorpha accompanied initial diversification clade during Late Triassic Early Jurassic. hypothesize profound rearrangements braincases basal crocodylomorphs underlie these rapid evolutionary modifications. These likely reflected embryonic include involvement neomorphic dermal anlagen different portions developing chondrocranium, extensive ossification palatoquadrate cartilage single expanded anteromedial inclination