Pikaia
Pikaia gracilens is an extinct, primitive chordate animal known from the Middle Cambrian Burgess Shale of British Columbia (about 530 million years old). Averaging about five centimetres in length, Pikaia was a sideways-flattened, somewhat eel-like animal. The flattened body is divided into a series of segmented muscle blocks seen as S-shaped lines that lie on either side of the notochord which runs along most, if not all of the body length. Once thought to be closely related to the ancestor of all vertebrates, Pikaia has received particular attention among the multitude of animal fossils found in the famous Burgess Shale and other Cambria...read more