Abstract
The teeth of Palaeocarcharias stromeri De Beaumont (Kimmeridgian, Upper Jurassic; southern Germany) show linear gradient monognathic heterodonty from high-cusped parasymphyseal teeth to low-crowned posterolaterals. The bifid root has holaulacorhize vascularization and is surmounted by mesial and distal extensions of the triple-layered coronal enameloid. The crowns lack lateral cusplets, but possess short vertical striations at the base of the central cusp labially and lingually. A collar is developed at the base of the central cusp lingually, and a small node in a similar position labially. It is concluded that Palaeocarcharias must represent the oldest known lamniform. The body form of Palaeocarcharias is most closely comparable to that of the orectolobiform sharks, but the teeth are lamnoid. Palaeocarcharias is best interpreted as a benthonic stem group lamniform. The lamniforms are visualized as arising from orectolobiform ancestors, probably in the middle Jurassic.
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