pelycosaur

noun

pel·​y·​co·​saur ˈpe-li-kə-ˌsȯr 

: any of an order (Pelycosauria) of extinct, primitive, synapsid vertebrates (such as dimetrodon) chiefly of the Permian period often having extreme development of the dorsal vertebral processes and giving rise to the therapsids

Word History

Etymology

ultimately from Greek pelyc-, pelyx bowl + sauros lizard

First Known Use

1884, in the meaning defined above