SilesianTriassic

Sauropterygia cf. Nothosaurus, rib

Middle Triassic, Lower Muschelkalk (Anisian), Gogolin Beds, Upper Silesia, Poland

A rib fragment from a marine reptile from the Sauropterygian group. It very likely belongs to Nothosaurus. Ribs are a common find in Silesian Muschelkalk deposits; complete finds are a completely different story. In this case, I was lucky – it appears the rib retained its head.

It’s worth noting that the rib is thick and massive. This phenomenon is called pachystosis – an increase in the density and volume of (at least some) bones. This is a common feature of many sauropterygians and, at the same time, a rather primitive adaptation to aquatic life. The increased mass acts as ballast and facilitates buoyancy underwater.

Sometimes, this pachystosis took quite extreme forms, as in placodonts.

P.S. This is a roadside find. While driving, I noticed a pile of rocks that someone had brought to level the ground. My family hates these sudden stops 😉