Pikaia

Pikaia is an ancient fossil creature from about 505 million years ago, considered one of the earliest known ancestors of all vertebrates, including humans. It resembled a small, soft-bodied fish with a notochord—a flexible, rod-like structure that provides support along its back. Pikaia's discovery helped scientists understand how complex animals with backbone-like features evolved from simpler, worm-like ancestors during the Cambrian Explosion, a period of rapid biological diversity. Its presence in early fossil records provides crucial insights into the evolution of the vertebrate lineage and the development of backbone structures essential to many animals today.