Sauropsida ("lizard faces") is a group of amniotes that includes (among other things) all existing reptiles, dinosaurs, and birds. The Sauropsida is distinguished from Theropsida ("beast faces"), more commonly called Synapsida, which includes mammals. History of classification Huxley and the fossil gaps The term Sauropsida ("lizard faces") has a long history, and hails back to Thomas Henry Huxley, and his opinion that birds had risen from the dinosaurs. He based this chiefly on the fossils of H… (More on Sauropsida)