First occurrence of ornithocheirid pterosaur teeth in the Dmitrov Formation (Santonian) of Ryazan Oblast, Russia

Remains of Late Cretaceous toothed pterosaurs such as ornithocheirids and lonchodectids are almost unknown for post Cenomanian strata. Here we describe teeth referrable to ornithocheirid pterosaurs from the Upper Cretaceous (Santonian) Dmitrov Formation of Ryazan region, European Russia. The teeth are somewhat worn, but retain sufficient features to satisfactorily refer them to Ornithocheiroidea, including their slender curved shape, presence of faint reticulated ribbing and a curved margin of the enamel - dentine contact. Although occurring in a Santonian deposit, the teeth are most likely derived from the underlying Cenomanian Yakhroma Formation. Although ornithocheirid teeth have been reported previously from European Russia, these teeth are the first from this region and the first evidence for Pterosauria in the Dmitrov Formation, which is better known for its elasmobranch and marine reptile assemblage.