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
Really Wild Animals it home (Bird's-Eye View); and the fourth is about the importance of keeping the rainforest safe (This Must Be the Place). This episode takes a look at the North American continent from its deserts and swamps to its cities and tundra. Ground squirrels, polar bears, alligators, beavers, woodpeckers, Arctic wolves, rattlesnakes, musk oxen, raccoons, black bears, corn snakes and red-bellied turtles are all featured. The diversity of the North American landscape, and how all its animals have adapted to it, are all key points in the film. This episode contains four songs. The first one is about what animals need