(from the article `Caudata`) ...ypsiloid cartilage present; Oligocene (36.6–23.7 million years ago) to present; North America; 1 genus, Ambystoma, and about 32 species.Family ... Salamanders are very ancient survivors of a Mesozoic (245 to 66.4 million years ago) radiation. The cryptobranchids, sirenids, proteids, and ... [2 rel... Found on http://www.britannica.com/eb/a-z/a/65