Question

What are the oldest living chordates?

Answer 1

Chordates:

1. A vast phylum of animals includes vertebrates, sea squirts, and lancelets. The presence of a notochord at some stage during growth can be used to identify them.
2. Pikaia gracilens, a primitive cephalochordate, is one of the oldest chordates known. It existed about 530 million years ago and was fairly little (38 mm in length). It is now considered the ancestor of all vertebrates.