The Collaborative International Dictionary of English v.0.48:
Paleosaurus \Pa`le*o*sau"rus\ (p[=a]`l[-e]*[-o]*s[add]"r[u^]s),
n. [NL., fr. Gr. palaio`s ancient + say^ros a lizard.]
(Paleon.)
A genus of fossil saurians found in the Permian formation.
[1913 Webster]