Scientists from the University of Cambridge believe that all vertebrates are descended from a 2-inch-long worm.
Pikaia gracilens, as the worm-like creature is called, used to swim along the sea floor over 500 million years ago. As the oldest known ancestor to vertebrates, it’s the granddaddy of all mammals, reptiles, amphibians, fish, and birds.
When its fossils were discovered in 1911, scientists first believed the creature was related to leeches or earthworms. However, a series of accumulated clues have led scientists to confirm that Pikaia has a lot more going for it.
Namely, the organism has a vascular system (blood vessels), as well as a notocord (the embryonic beginnings of a spinal cord). The last piece of the puzzle was the identification of myomeres (muscle tissues arranged in a zig-zag pattern) that are common to vertebrates and also present in Pikaia.
The 114 fossil specimens used in the study came from Yoho National Park in British Columbia, where all known Pikaia fossils were found. Not a bad spot for solving the latest piece in the evolutionary puzzle.