pelycosaur
Concise Oxford English Dictionary © 2008 Oxford University Press:
pelycosaur /ˈpɛlɪkəsɔː/
▶noun a fossil reptile of the late Carboniferous and Permian periods, typically having a spiny sail-like crest on the back.
– origin early 20th cent.: from Gk pelux, peluk- ‘bowl’ + sauros ‘lizard’.
'pelycosaur' also found in these Oxford entries:

