NEW INFORMATION ON THE BRAINCASE AND ENDOCRANIAL MORPHOLOGY OF THE LATE TRIASSIC THEROPOD ZUPAYSAURUS ROUGIERI USING CT SCANS

PAULINA CARABAJAL, A.; EZCURRA, Z.; NOVAS, F.

Diamante

Jornada; 29 Jornadas Argentinas de Palentología de Vertebrados; 2015

CICYTTP

Zupaysaurus rougieri Coria and Arcucci is a Late Triassic neotheropod from South America that preserves an almost complete skull. However, most of its braincase morphology reminded obscured by other skull bones and sediment. Recently made CT scans allowed to virtuallyreconstruct the unseen sections of the braincase showing anteroventrally divergent finger-shaped basipterygoid processes, elongate and horizontally projected cultriform process, and well developed preotic pendant, basisphenoid recess and subsellar recess. The endocranial morphology is partially reconstructed showing an anteroposteriorly short but tall brain with well-marked angles between the hindbrain, midbrain and forebrain. The inner ear preserves the labyrinth but not the lagena. The semicircular canals are large and slender. In dorsal view, the angle between the anterior and posterior semicircular canals is approximately 90−95°. Basal theropod braincases are poorly sampled and there is little information on braincase and even poorer knowledge on brain and inner ear anatomy of Triassic forms. The information that we present here will shed light on the evolutionary pattern of the neuroanatomy within Theropoda.