POSTCANINE MICROSTRUCTURE IN CRICODON METABOLUS, A MIDDLE TRIASSIC GOMPHODONT CYNODONT FROM SOUTH-EASTERN AFRICA

HENDRICKX, C.; ABDALA, F.; CHOINIERE J.

PALAEONTOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016

0031-0239

Cricodon metabolus is a trirachodontid cynodontfrom the Anisian (Middle Triassic) of eastern and southernAfrica. It has labiolingually expanded (gomphodont) postcaninesbut also a sectorial tooth in the last postcanine locus.In this paper, we examine the crown microstructure of isolatedsectorial and gomphodont postcanines belonging to theholotype specimen of this taxon using scanning electronmicroscopy. The enamel of both teeth is prismless and composedof discontinuous columnar divergence units, supportingthe consistent presence of synapsid columnar enamel incynognathians. Abundant tubules and numerous irregularlyspaced incremental lines are also visible in the enamel anddentine layers in each tooth. This study reveals that the enamelthickness varies along the tooth row in Cricodon as the enamellayer of the gomphodont postcanines is 11.5 times thicker thanthat of the sectorial crown. It is likely that this difference reflectsocclusal stresses and fewer replacements in gomphodont postcaninesrelative to sectorial teeth. Approximately 100 incrementalgrowth lines of von Ebner are present in the dentinelayer, indicating that the deposition of the dentine by odontoblastsoccurred for three months before the animal?s death.