Question

Which extant chordates are postulated to be most like the earliest chordates in appearance? A) lanceletsB) adult tunicatesC) amphibiansD) chondrichthyans

Answer 1

The correct answer is - A) lanceletes.

The first chordates came in the shape of the lancelates. They were small, lost their bony exoskeleton, and started to be jawless. The main trait though that distinguished them from the other animals was the newly developed spinal chord, which mean that the bones were now inside the body and the flesh was covering them, not as it was prior to that when the flesh was on the inside while the bones were on the outside. This development happened around 530 million years ago in the oceans, in the early Cambrian period. These little pioneers that developed the first internal bone structure gave rise to all of the chordates that evolved letter on, including the human species as well.