What is "sauropsida"

Sauropsida \Sau*rop"si*da\, n. pl. [NL., fr. Gr. ? a lizard + ? appearance.] (Zo["o]l.) A comprehensive group of vertebrates, comprising the reptiles and birds.

Sauropsida ("lizard faces") is a group of amniotes that includes all existing birds and reptiles as well as their fossil ancestors and other extinct relatives. Large land animals are either in this group or in its sister group, Synapsida, which includes mammals and their fossil relatives. This clade includes Parareptilia and other extinct clades. All living sauropsids are members of the sub-group Diapsida, the Parareptilia clade having died out 200 million years ago. The term originated in 1864 with Thomas Henry Huxley, who grouped birds with reptiles based on fossil evidence.