Protognathosaurus

Protognathosaurus is known only from a single fossil: the front part of a left lower jaw, called a dentary.1

This dinosaur had 18 to 20 teeth in its lower jaw, and some of them were sharp replacement teeth still growing in.12

Its teeth had a sharp point and small serrations (like a steak knife) on the front and back edges.2

The name Protognathosaurus was first used in 1991 by George Olshevsky, because the original name Protognathus was already taken by a beetle.1

Most scientists consider Protognathosaurus a nomen dubium, meaning the fossil is too incomplete to be sure it is a distinct species.1

The jaw bone is thick and heavy, with a deep groove called the Meckelian canal, which is a feature of some early sauropods.2