MUSEO ARGENTINO DE CIENCIAS NATURALES "BERNARDINO RIVADAVIA"
Unidad Ejecutora - UE
New information on the braincase and endocranial morphology of the Late Triassic neotheropod Zupaysaurus rougieri using computed tomography data
NOVAS, FERNANDO E.; PAULINA-CARABAJAL, ARIANA; EZCURRA, MARTÍN D.
JOURNAL OF VERTEBRATE PALEONTOLOGY
SOC VERTEBRATE PALEONTOLOGY
Año: 2019 vol. 39
Zupaysaurus rougieri is an early neotheropod from the middle Norian Los Colorados Formation ofnorthwestern Argentina represented by an almost complete skull and several postcranial bones. Most of its braincasemorphology has remained obscured by other skull bones and sediment. Additional mechanical preparation and X-raycomputed tomography on the single known specimen of Zupaysaurus has allowed a detailed description of the braincase,the cranial endocast, and the inner ear of this Triassic dinosaur. Basal theropod braincases are poorly sampled and there islittle information on this region, and even poorer knowledge on the brain and inner ear anatomy of Triassic forms. Thevirtual reconstruction of the braincase of Zupaysaurus shows anteroventrally oriented, finger-like basipterygoid processes,an elongate and horizontally projected cultriform process, and well-developed preotic pendant, basisphenoid recess, andsubsellar recess. The endocranial morphology is partially reconstructed, showing an anteroposteriorly short butdorsoventrally tall cranial endocast, with well-marked demarcations between the forebrain, midbrain, and hindbrain. Theinner ear preserves the three semicircular canals, but not the lagena. The posterior semicircular canal is proportionallylarge when compared with that of other theropods. The new information presented here on Zupaysaurus rougiericontributes to the knowledge of the neuroanatomy of basal theropods and sheds light on the evolutionary patterns of thebraincase morphology in nonavian Theropoda