Pahasapasaurus

Pahasapasaurus was a plesiosaur, not a dinosaur. It was a marine reptile that lived in the ocean.1

Its name comes from the Lakota words 'Paha Sapa', meaning 'Black Hills', where the first fossil was found.1

The first specimen was discovered in 1934 by Charles Haas and his son Arthur while they were looking for shark teeth.1

Pahasapasaurus had a long snout and a mouth full of many similar teeth, perfect for grabbing slippery fish.2

Its flippers were long and paddle-shaped, and the bones in the lower part of the flipper were longer than wide, which helped it swim fast.1

The fossil was once covered in shellac and sugar sacks, and scientists had to carefully clean it to study the bones.1

A second species of Pahasapasaurus was named in 2025 from a complete skull found in Utah.1