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[dinosaur] Sauroscaptor, new dicynodont from Permian of India + Cricodon (cynodont) postcanine tooth microstructure




Ben Creisler
bcreisler@gmail.com


New synapsid papers:


Christian F. Kammerer, Saswati Bandyopadhyay and Sanghamitra Ray (2016)
A new taxon of cistecephalid dicynodont from the upper Permian Kundaram Formation of India.
Papers in Palaeontology (advance online publication)
DOI: 10.1002/spp2.1055
http://onlinelibrary.wiley.com/doi/10.1002/spp2.1055/full
ZooBank: http://zoobank.org/References/4A094517-6DFF-4019-AA3A-67629BAF588B.

A new cistecephalid dicynodont, Sauroscaptor tharavati gen. et sp. nov., is described from the upper Permian Kundaram Formation of India. This taxon is represented by specimens formerly referred to the African dicynodont genera Cistecephalus and Emydops. Sauroscaptor can be distinguished from other cistecephalids by the extremely posterior position of the pineal foramen (overhanging the edge of the occiput), bipartite nuchal crest, and relatively narrow skull roof. The recognition of Sauroscaptor as a distinct cistecephalid taxon adds to the increasing evidence for high levels of basinal endemism in this family. However, dicynodont biogeographical patterns are complex, and there is no simple relationship between inferred dispersal ability based on body size and levels of endemicity within clades.

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Christophe Hendrickx, Fernando Abdala and Jonah Choiniere (2016)
Postcanine microstructure in Cricodon metabolus, a Middle Triassic gomphodont cynodont from south-eastern Africa.
Palaeontology (advance online publication)
DOI: 10.1111/pala.12263
http://onlinelibrary.wiley.com/doi/10.1111/pala.12263/full


Cricodon metabolus is a trirachodontid cynodont from the Anisian (Middle Triassic) of eastern and southern Africa. It has labiolingually expanded (gomphodont) postcanines but also a sectorial tooth in the last postcanine locus. In this paper, we examine the crown microstructure of isolated sectorial and gomphodont postcanines belonging to the holotype specimen of this taxon using scanning electron microscopy. The enamel of both teeth is prismless and composed of discontinuous columnar divergence units, supporting the consistent presence of synapsid columnar enamel in cynognathians. Abundant tubules and numerous irregularly spaced incremental lines are also visible in the enamel and dentine layers in each tooth. This study reveals that the enamel thickness varies along the tooth row in Cricodon as the enamel layer of the gomphodont postcanines is 11.5 times thicker than that of the sectorial crown. It is likely that this difference reflects occlusal stresses and fewer replacements in gomphodont postcanines relative to sectorial teeth. Approximately 100 incremental growth lines of von Ebner are present in the dentine layer, indicating that the deposition of the dentine by odontoblasts occurred for three months before the animal's death.