Dimetrodon teeth

First record of plicidentine in Synapsida and patterns of tooth root shape change in Early Permian sphenacoodontians

In science it is important to get at the root of the problem, and that is literally what PhD students Kirstin Brink and Aaron LeBlanc (Reisz Lab) did in their recent paper in Naturwissenschaften: “First record of plicidentine in Synapsida and patterns of tooth root shape change in Early Permian sphenacoodontians”. In this paper, they used histological thin sections to examine the shape of the tooth roots in different species of Dimetrodon, a Permian sail-backed synapsid. Dimetrodon was a geologically long-lived species (~20 million years) with few obvious changes in morphology throughout its evolutionary history. They found that older, smaller species of Dimetrodon have four distinctive folds in their tooth roots, while geologically younger, larger species have elongate, rounded tooth roots without folds (see figure). This suggests that the internal morphology of the skull was changing, specifically, the architecture of the teeth and jaws, possibly reflecting changes in diet due to changes in the Early Permian paleoecosystem.

Congratulations, Kirstin and Aaron, you have rooted out an amazing discovery!

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