SilesianTriassic

Ichthyosauria indet. (cf. Mixosaurus)

Middle Triassic, Lower Gogolin Beds, Upper Silesia, Poland

A well-preserved specimen of the distal caudal vertebra centrum of a small ichthyosaur. In Middle Triassic sediments of Upper Silesia, finds associated with ichthyosaurs are significantly rarer than those of representatives of other groups of marine reptiles.

The vertebra centrum measures approximately 15 mm in height, 7 mm in width, and 4 mm in length. A slight depression of the neural canal is visible dorsally. The centrum tapers ventrally into the shape of a blunt wedge. The lateral surfaces of the centrum are smooth, no rib articulating surfaces or facets are visible. The articulating surfaces of the centrum are deeply conical.

The centrum’s length, overall subhexagonal shape, and deep amphicoelous articular surfaces are consistent with vertebrae identified as belonging to Ichthyosauria.

In the literature, vertebrae with similar shape and proportions are identified as caudal vertebrae, with the distal vertebrae being narrower and lacking visible facets, consistent with the characteristics of this specimen.

More precise taxonomic assignment is not possible, but the age (Anisian, Lower Muschelkalk, Gogolin beds), small size and morphological similarities to published Mixosaurus material (Merriam 1908) suggest an affinity with Mixosaurus.

References:

• John C. Merriam. (1908). Triassic Ichthyosauria: With special reference to the American forms.