Serpent

Snakes are squamates. They moved by losing limbs, not by failing to grow them. Heat pits, venom, and a jaw that walks over prey are ordinary physics and chemistry in an unusual body.

The same shape is a second language: ouroboros, caduceus, the thing under the tree. Like Raven, Serpent is kept on the card because it is a deep human symbol as well as an animal. Other reptiles and shed skins on the map can feed it without each becoming a type.