Abstracts (first author)
Insights on neuroanatomy evolution of early mammalian ancestors from a new Permian dicynodont from Mozambique
A nearly complete skull and mandible, with a series of 19 articulated dorsal, sacral and tail vertebrae, ribs, ilia, partial pubis and femur (ML1620) was collected from the Late Permian Karoo sediments, Metangula Graben, northern Mozambique (Niassa Province), Cádzi Formation. The 3D visualization of the internal cranial bones, via µ-CT, combined with a phylogenetic analysis demonstrates a set of characters shared with Emydopoidea, a restricted clade of small-sized dicynodonts. Brain morphology and location of main cranial nerves is visualized by a virtual 3D model of the fossilized endocranial cavity. The brain is delimited by the basioccipital, exoccipital, supraoccipital and opisthotic posteriorly; by the postparietal, parietal, preparietal, and frontal dorsally; prootic and epipterygoid laterally; parasphenoid and basisphenoid ventrally; the olfactory tracts are delimited by the ethmoid ventrally. The brain is narrow and the cerebellum is broader than forebrain, resembling the condition of other non-mammalian therapsids. The orbits are located far anteriorly relative to the olfactory bulbs. The olfactory bulbs are separated from the cerebrum by a long olfactory tract. The anatomy of osseous labyrinth, pristinely preserved, is compared with the scarce data published on synapsid inner ear anatomy. These are the first detailed brain and auditory apparatus model of dicynodonts based on µ-CT. The preliminary observations indicate that there is a conservative reptilian-grade brain morphology governing the anatomy of non-mammalian synapsids.