Histological study of the oral teeth and their bony support in the Mexican Jurassic gar †Nhanulepisosteus mexicanus (Ginglymodii, Lepisosteidae)

Brito P.M., Alvarado-Ortega J., Meunier F.J.

Date de parution: mai 2022
Volume: 46
Number: 1
Pagination: 013-018
Editeur: Société Française d'Ichtyologie
doi: https://doi.org/10.26028/cybium/2022-461-002

The palaeohistology of the teeth and bony skeleton of the Late Jurassic gar †Nhanulepisosteus mexi­canus is described in detail from thin sections. The teeth are composed of a cone of orthodentine with a pulp cavity filled with parallel canals of osteodentine as variety of eusthenodont type plicidentine. These conspicu­ous histological features differentiate †Nhanulepisosteus from the majority of extant and fossil lepisosteids. The teeth are crowned with a small apical cap of acrodine, and are surrounded by a ridged layer of enamel. The bony tissues contain star-shaped osteocytes and canaliculi of Williamson matching exactly those in living lepisosteids, other holosteans, and some basal teleosts. Although the dental histology is distinct from that of extant gar spe­cies, we consider these differences are related to eco-morphological factors, noting that this pattern of histologi­cal arrangement is also found in other fossil gar species.

Mots-clés: Bone - Jurassic - Lepisosteidae - Palaeohistology - Plicidentine - Teeth - †Nhanulepisosteus
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