DESOJO Julia Brenda
congresos y reuniones científicas
NEW INFORMATION ON THE ENDOCRANIAL MORPHOLOGY OF THE TRIASSIC PROTEROCHAMPSIDS (EUREPTILIA: ARCHOSAURIFORMES) USING CTSCANS: COMPARISON WITH LIVING CROCODYLIA
PAULINA CARABAJAL, A.; TROTTEYN, M.J; BONA, P; TABORDA, J.R.A.; DESOJO, J.B
Congreso; 10th International Congress of vertebrate morphology; 2013
The braincase anatomy of aquatic proterochampsid archosauriforms has been recently revealed based on new detailed descriptions. Additionaly, new CT scans of Proterochampsa barrionuevoi (PVSJ 77), Chanaresuchus ischigualastensis (PVSJ 567), and Tropidosuchus romeri (PVL 4601), shed some light on the poorly known paleoneurology of these taxa. To better understand the endocranial morphology of this group, we compare the cranial endocast and inner ear with extant aquatic pseudosuchians, such as Gavialis, Caiman, from which we made complete artificial brain and inner ear endocasts; and Crocodylus, based on published information. Although the digital reconstructions of the fossil taxa are incomplete, the partial endocasts show similar morphology, represented by subhorizontal brains (cephalic and pontine flexures not well marked), with poorly developed dorsal expansions and relatively small pituitary. The cerebral hemispheres seem to be slightly laterally projected unlike the strongly projected ones in living crocodylians. Partial labyrhynth of the inner ear were reconstructed for Chanaresuchus and Tropidosuchus, showing slender semicircular canals. In Chanaresuchus the angle between the anterior and posterior semicircular canals is approximatly 90-100º. The CT scans showed that the middle ear of proterochampsids is poorly pneumatized relative to the studied extant forms. In Chanaresuchus and Tropidosuchus it is noteworthy the presence of a foramen on the occipital plate, dorsal to the paroccipital process, comunicating anteriorly with the middle ear. We identify this small passage as correlated with the cranioquadrate passage present in Crocodylia. Further research is necessary to determine if this structure is homologous to the cranioquadrate and its implications for an aquatic life-style.