Braincase anatomy of Pterodaustro guinazui, pterodactyloid pterosaur from the Lower Cretaceous of Argentina

LAURA S. CODORNIÚ; ARIANA PAULINA CARABAJAL; FEDERICO A. GIANECHINI

JOURNAL OF VERTEBRATE PALEONTOLOGY

SOC VERTEBRATE PALEONTOLOGY

Lugar: Lawrence; Año: 2015

0272-4634

The braincase anatomy in pterosaurs is poorly known due to the fact that very few specimens of these flying reptiles had been preserved with this region of the skull. The information is even scarcer for most basal pterodactyloid pterosaurs (Archaeopterodactyloidea). We present novel information on the braincase morphology of the Early Cretaceous Argentinean ctenochasmatid Pterodaustro guinazui. The morphological evidence collected from several specimens has allowed for the recognition of many features of this area of the skull. The braincase of Pterodaustro is characterized by a skull roof with subtriangular, elongated frontals and rounded posteroventrally oriented parietals; low nuchal crest; ossified ethmoidal elements; ossified interorbital septum; short and fan-like shaped paroccipital processes with wavy lateral and medial surfaces; occipital condyle formed mainly by the exoccipitals; fork shaped basioccipital; long anteroventrally directed basisphenoid body, with keeled ventral surface and short basipterygoid processes; well-developed rostral tympanic recess; rod-like shaped columella; separate foramina for cranial nerves XII and IX-XI within a common sub-divided recess. We were able to identify foramina for cranial nerves II, V, VI and VII; vascular foramina, such as the caudal middle cerebral vein, the dorsal head vein, and the internal carotid artery; and the columellar recess. This research reveals many features of the braincase of Pterodaustro - some of which were considered as potential autapomorphies - for the first time. It also provides new insights into the neurocranial morphology of pterosaurs, and in turn, it aims to contribute to the understanding of the evolution of the braincase in Pterosauria.