A partial skeleton of Temnodontosaurus cf. trigonodon in three-dimensional bone preservation from the upper Toarcian of Mistelgau, Germany

Temnodontosaurus, a large ichthyosaur from the Early Jurassic, was one of the first ichthyosaurs to be scientifically described as early as the 19 th century. Over time, various large Toarcian ichthyosaurs have been referred to Temnodontosaurus, a genus that is currently considered non-monophyletic. We describe a partial neoichthyosaurian skeleton from the Upper Toarcian, Jurensismergel Formation, Levesquei Zone, in Mistelgau, Germany.

The specimen UMO BT 011237.00 comprises exceptionally well-preserved, three-dimensional cranial and mandibular elements, pectoral girdle, both forefins, anterior vertebral column, postflexural centra, over 100 teeth and four gastroliths. The study presents previously undescribed details in the morphology of the premaxilla, palate, scleral plates, dentition, and forefins. The described specimen matches all examined characteristics of the generic diagnosis of Temnodontosaurus.

Due to some morphological differences and a slightly younger stratigraphic age than Temnodontosaurus trigonodon as well as the required taxonomic revision, we use open nomenclature and refer the specimen to Temnodontosaurus cf. trigonodon. Pathologies primarily affecting the pectoral girdle and mandibular joint likely influenced the animal’s hunting and feeding behaviour, resulting in abraded teeth and the presence of gastroliths.

The specimen confirms the presence of Temnodontosaurus in the Southwest German Basin during the late Toarcian.