The Collaborative International Dictionary
Gyrodus
Gyrodus \Gyr"o*dus\ (j[i^]r"[-o]*d[u^]s), n. [NL., fr. Gr. gyro`s round + 'odoy`s tooth.] (Paleon.) A genus of extinct o["o]litic fishes, having rounded teeth in several rows adapted for crushing.
Wikipedia
Gyrodus
Gyrodus is an extinct genus of pycnodontiform ray-finned fish that lived in the Jurassic and Cretaceous.