SilesianTriassic

Ichthyosauria indet. (cf. Mixosaurus sp.)

Middle Triassic, Lower Gogolin Beds, Upper Silesia, Poland

Ichthyosaur remains are extremely rare in the Muschelkalk deposits of Upper Silesia. The photos show a single vertebral centrum – though slightly damaged, it clearly displays the diagnostic features that allow for its assignment to this group of extinct marine reptiles (most likely Mixosaurus sp.).

The vertebra is notably short (discoid) and deeply amphicoelous, with the articular surface depression funneling almost to the center of the bone. Its outline is nearly hexagonal, a shape often observed in Middle Triassic mixosaurids.

A key detail is visible on the lateral edges: the presence of rib facets located directly on the centrum. This is a crucial distinction from sauropterygians (like Nothosaurus), whose ribs attached to the processes of the neural arch rather than the vertebral body itself.

I’ve noticed a consistent pattern in my collection: every ichthyosaur vertebra I’ve found has been preserved lying “flat” on its articular surface within the matrix. It seems these thin, disc-like vertebrae naturally settled in this stable orientation on the seafloor after the carcass disarticulated – Personally, I often joke that if I find a vertebra lying flat on the matrix, there must be something interesting.