Histological study of the median lingual dental plate of the Cretaceous fish †Palaeonotopterus greenwoodi (Teleostei: Osteoglossomorpha) from the Kem-Kem beds, Morocco
We describe the histology of the lingual dental plate of an extinct Notopteridae, †Palaeonotopterus greenwoodi, from the Cenomanian Kem-Kem Beds in Morocco. The lingual dental plate is bulky. Its regular and more or less smooth crushing surface does not exhibit any teeth externally. The plate is composed of several superimposed layers of side-by-side teeth. The teeth are attached to each other by a small amount of cellular bony tissue that may contain some vascular canals. The teeth originate inside the plate in a large dental cavity where odontogenesis takes place. Then, new teeth move passively towards the crushing surface and thicken to reach a maximum of 1 mm in diameter and 2 mm in height. The teeth are likely worn down by crushing food. Thus, †Palaeonotopterus greenwoodi had true “coalesced teeth” that constituted a lingual chewing apparatus displaying a process of tooth renewal similar to that described in extant fish with durophagous diet, i.e. scarids, tetraodontids and the carangid fish Trachinotus teraia. We thus assume that †Palaeonotopterus greenwoodi was durophagous. The Kem-Kem levels that yielded the lingual dental plates also delivered abundant shells of molluscs and remains of crustaceans that might have constituted prey of this extinct fish.