Histological evidence of trauma in tusks of southern African dicynodonts
Date
2019-01
Authors
Whitney, Megan R.
Tse, Yuen Ting
Sidor, Christian A.
Journal Title
Journal ISSN
Volume Title
Publisher
Evolutionary Studies Institute
Abstract
Dicynodonts were a clade of globally-distributed therapsids known for their abundance in the fossil record and for surviving the
Permo-Triassic mass extinction. The group had distinctive dental adaptations including a beak and, in many species, paired maxillary
tusks. The function of these tusks has long been of interest, yet remains poorly understood.We report here on two instances of unusual
morphology in tusk dentine from specimens of: 1) Lystrosaurus from the Karoo Basin of South Africa and, 2) an unidentified
dicynodontoid from the Luangwa Basin of Zambia. In both, the cross-sectional shape of the tusk root is lobed and infolded, which
histological features suggest is a result of abnormal dentine deposition. We infer that this abnormal morphology is likely the consequence
of trauma given its reparative nature and structural similarities to trauma-related morphologies reported in the tusks of modern
elephants. This study demonstrates that histological sampling of dicynodont tusks can shed light on the biology of this important clade
of therapsids.
Description
Keywords
Dicynodontia, Triassic, South Africa, Zambia, Permian, pathology, dentine