[dinosaur] Rastodon (dicynodont from Permian of Brazil) endocranial morphology

Ben Creisler
[email protected]

A new paper:

Daniel de Simão‐Oliveira, Leonardo Kerber & Felipe L. Pinheiro (2019)
Endocranial morphology of the Brazilian Permian dicynodont Rastodon
procurvidens (Therapsida: Anomodontia).
Journal of Anatomy (advance online publication)
doi: https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1111_joa.13107&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=IYzP6gE1p3_50Ujef634K3NV6IBvEqY-Gt58MY9Qadk&s=uoGhzkC-9blSh0o_m1tKTt_onoErQOgbKbmChjp78R0&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__onlinelibrary.wiley.com_doi_10.1111_joa.13107&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=IYzP6gE1p3_50Ujef634K3NV6IBvEqY-Gt58MY9Qadk&s=kf9yUJ1B6BjA5HpaCP4AJYw6T8Ibp_PJOxr4csMz6S8&e= 


Dicynodontia is a major clade of terrestrial tetrapods that greatly
diversified during the Permian and Triassic periods, reaching a worldwide
distribution. In this study, the endocranial cavity of the Brazilian
Permian dicynodont Rastodon procurvidens is described based on a digital
endocast obtained using digital imaging (X‐ray computed tomography) and 3D
modeling. It was possible to reconstruct the brain, olfactory bulbs, inner
ear, some neurovascular canals, cranial nerves, the nasal cavity, and the
maxillary recesses. The endocast of R. procurvidens preserves a typical
plesiomorphic morphology of non‐mammaliaform therapsids, being
predominantly tubular and displaying a relatively short and robust
hindbrain. Encephalization quotients (EQs) were calculated for R.
procurvidens, resulting in EQs of 0.09 ± 0.03 and 0.13 ± 0.05 (Jerison’s EQ
and Manger’s EQ, respectively). Finally, some biological implications of
the endocast morphology were inferred for R. procurvidens. Its inner ear is
especially small, and its orientation implies a slightly downturned head
posture in life. Furthermore, the presence of uncompressed maxillary
recesses in R. procurvidens indicates a correlation between the enlargement
of the recesses and the reduction of the tusks, also seen in other
dicynodonts with reduced tusks.

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