A new teleosauroid (Crocodylomorpha, Thalattosuchia) with a unique dentition from the Middle Jurassic of eastern Morocco

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The Mesozoic and early Paleogene of Morocco provides a rich and extensive record of crocodylomorphs encompassing a wide range of skull, dental morphologies, and paleoecologies. Here we describe a new longirostrine teleosaurid thalattosuchian, Ctenosuchus tenuidens, gen. et sp. nov. with a needle-like dentition from a Middle Jurassic fluvio-lacustrine sequence of the Talsint–Anoual area of Figuig Province, southeastern Morocco. The record of thalattosuchians in Laurasia is extensive, but their diversity on Gondwana remains poorly understood. The new taxon is identified as Teleosauridae on account of a short premaxilla where the maxilla occupies the majority of the rostrum length and slenderly tapering nasals. Its needle-like teeth are autapomorphic possessing an aspect width:height (w:h) ratio of ∼1:10.4, with a fine interdental spacing (2.3 mm). Scanning electron microscopy and thin-sectioning reveals prominent apicobasal and densely packed vertical ridges on the lingual surface of the tooth crowns. This combination of dental characters implies an unusual feeding ecology and specialized diet, likely of small crustaceans and fishes as well as soft-bodied organisms. This broadens the paleoecological diversity of Jurassic freshwater teleosauroid thalattosuchians and reveals previously unreported convergences between marine Jurassic and Cretaceous teleosaurs, Permian mesosaurs and perhaps some Late Jurassic ctenochasmatid pterosaurs.