Craniate with well-defined heads, thus excluding members of the chordate subphyla Tunicata (tunicates) and Cephalochordata (lancelets), but including Myxini, which have cartilaginous skulls and tooth-like structures composed of keratin. Craniata also includes all lampreys and armoured jawless fishes, armoured fish, sharks, skates, and rays, and teleostomians: spiny sharks, bony fish, lissamphibians, temnospondyls and protoreptiles, sauropsids and mammals. The craniate head consists of a brain, sense organs, including eyes, and a skull. In addition to distinct crania (sing. "cranium"), craniates possess many derived characteristics, which have allowed for more complexity to follow. Molecular-genetic analysis of craniates reveals that, compared to less complex
Lost Animals of the 20th Century such is unavailable, the live materials feature existing species that share the closest characteristics with the extinct animal. Although the show specifically deals with animals that have become extinct, there was one episode that featured the theme of animals which were thought to be extinct, but have been rediscovered. Such has also been the case of some previously featured animals in the show, as scientists have eventually rediscovered extant populations or are attempting to revive species through selective breeding/cloning. Among the animals featured are: Lost Animals of the 20th Century Lost Animals of the 20th Century is a 16-episode documentary