Ancient Multicellular Animals

Newly discovered fossils from China may be the oldest evidence yet of multicellular animals complex enough to have a two-sided body plan instead of a round one.

These surprisingly tiny animals appear in a rock formation approximately 50 million years older than the Cambrian Period — when multicellular life diversified rapidly — and may have been the parents of embryos previously found in the same formation.

Jun-Yuan Chen and colleagues in China and the Unites States identified ten fossils from the Doushantuo Formation and named the animal Vernanimalcula, or "small spring animal," since they appeared after a time of extensive glaciation sometimes called "Snowball Earth." The animals were shaped like flattened turtle shells, and although the fossils are not quite 200 micrometers across, the authors identified several internal organs. Thus, it appears that the genetic toolkit required for the diversification of animal body shapes and sizes may have developed well before the Cambrian period.

This paper was published online by the journal Science, at the Science Express website, on Thursday, 3 June 2004.

3 June 2004