INVESTIGADORES
PAULINA CARABAJAL Ariana
congresos y reuniones científicas
Título:
Abelisaurid theropod braincase neumaticity: phylogenetic implications based on argentinean specimens
Autor/es:
PAULINA CARABAJAL, ARIANA
Lugar:
Plaza Huincul, Neuquén
Reunión:
Jornada; Reunión Anual de Comunicaciones de la Asociación Paleontológica Argentina; 2008
Institución organizadora:
Museo Carmen Funes
Resumen:
In phylogenetic analyses
of Theropoda, the braincase of abelisaurids was considered apneumatic,
which is regarded as a plesiomorphic state. In Abelisauridae, there is
neither a tympanic caudal recess nor a basipterigoid recess, and the
basipterigoid processes as well as the paraoccipital processes are
massive structures. Nevertheless, recent studies show the presence of
three clasic pneumatic cavities in the abelisaurid basicranium: the
lateral tympanic recess, the basisphenoid recess and the subselar
recess. The basisphenoid recess is deeply excavated on the ventral
surface of the basisphenoid in Carnotaurus Bonaparte and Abelisaurus Bonaparte & Novas. In Ilokelesia Coria & Salgado and Aucasaurus
Coria, Chiappe & Dingus, this recess internally has two parasagital
cavities that invade the basisphenoid at the level of the neck of the
occipital condyle. In Carnotaurus and Abelisaurus,
there is a lateral tympanic recess on the lateral surface of the
basisphenoid. In the latter, the recess is a wide depression, divided
into two chambers (the internal carotid artery foramen opens in the
anterodorsalmost chamber). Finally, in each of Abelisaurus and Carnotaurus,
there is a deeply excavated subselar recess anteroventral to the
cultriform process that is also partially visible in the anterior view
of the braincase. Therefore, the presence of three well developed
pneumatic recesses in each of the basicrania of Abelisaurus and Carnotaurus (and other non-South American forms), and further evidence of these pneumatic cavities in fragmentary material of both Ilokelesia and Aucasaurus,
rule out the apneumatic feature for the abelisaur braincase.
Consequently, the presence of a pneumatic braincase turns out to be a
synapomorphic feature for all Neotheropoda and probably all Theropoda.