Paleothyris lived during the Carboniferous Period, about 300 million years ago in North America. It measured 1 foot (30 centimeters) in length. Paleothyris had large eyes and sharp teeth. It probably preyed on small insects and other small invertebrates. Even though Paleothyris is considered a reptile, it still possessed features that were more amphibian-like than a reptile-like, specially its skull.