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Abajudon, new dicynodont from Permian of Tanzania



Ben Creisler
bcreisler@gmail.com

In the new JVP:


Abajudon kaayai


Kenneth D. Angielczyk, Sébastien Huertas, Roger M. H. Smith, Neil J.
Tabor, Christian A. Sidor, Jean-Sébastien Steyer, Linda A. Tsuji &
Neil J. Gostling (2014)
New dicynodonts (Therapsida, Anomodontia) and updated tetrapod
stratigraphy of the Permian Ruhuhu Formation (Songea Group, Ruhuhu
Basin) of southern Tanzania.
Journal of Vertebrate Paleontology 34(6): 1408-1426
DOI:10.1080/02724634.2014.880448
http://www.tandfonline.com/doi/full/10.1080/02724634.2014.880448



Permian tetrapod fossils were discovered in the Tanzanian Ruhuhu
Formation in 1963, but they have received far less attention than the
tetrapods of the overlying Usili (formerly Kawinga) Formation. Here,
we describe two dicynodonts collected in the Ruhuhu Formation in 2008.
Abajudon kaayai, gen. et sp. nov., is represented by a partial skull
and mandible and is characterized by autapomorphic upper teeth that
are triangular in cross-section, have procurved tips, and bear a deep
groove on the mesial surface. Although it shows similarities to taxa
such as Endothiodon and Chelydontops, the exact relationships between
A. kaayai and other dicynodonts are uncertain. The second specimen
also consists of a partial skull and mandible. We refer it to cf.
Endothiodontia based on the medial placement of the long maxillary
tooth rows, the presence of depressions on the palatine pad, a long
posterior dentary sulcus, and similarities of the mandibular
dentition. Tetrapods occur in three fossiliferous horizons in the
Ruhuhu Formation. The likely Middle Permian lower horizon includes
dinocephalians, temnospondyls, and the dicynodonts described here. The
middle horizon includes a new, tusked species of Endothiodon and at
least one other dicynodont. The upper horizon appears to sample an
assemblage similar to that of the Usili Formation and therefore may be
of Late Permian age. The discovery of Middle Permian fossils in
Tanzania and Zambia provides the opportunity to test whether southern
Gondwana was characterized by a cosmopolitan tetrapod fauna for an
extended period of time before the biogeographic restructuring caused
by the end-Permian mass extinction.