Cnidarians evolved roughly 500 million years ago and have a body structure that is slightly more complex than the sponges. The representatives of the phylum cnidaria seen above are coral, giant green anemone, hydrozoa, and jellyfish.

Did cnidarians evolve first?

The oldest fossilized cnidarians were soft-bodied. Representatives of all four modern classes have been identified in Ediacaran fauna of the Precambrian Period (that is, those appearing between about 635 million and 541 million years ago) known from more than 20 sites worldwide.

What group did cnidarians evolve from?

Fortuitously, the first two cnidarian genomes to be sequenced come from Anthozoa (Nematostella) and Hydrozoa (Hydra); the last common ancestor of these two classes was the stem cnidarian (Fig. 1).