Pararcus

Pararcus had a special backbone where the neural arches (the parts that protect the spinal cord) were not fused together, even in adults. This is called paedomorphosis and is common in animals that live in the sea.1

Its hip bones (pubis and ischium) were flat and plate-like, which helped it swim efficiently.1

The only known fossil of Pararcus was found by a fossil collector named Gerben Diepenbroek, and the species is named after him.1

Pararcus lived during the Middle Triassic period, about 247 to 241 million years ago, when the Netherlands was covered by a shallow sea.2

Unlike some other placodonts that had heavy armour plates, Pararcus only had a few small, unfused armour plates scattered in its skin.1

The vertebrae of Pararcus were deeply hollowed out on both ends (amphicoelous) and still had a notochord, a flexible rod that runs through the spine.1