Chinese scientists have discovered the world’s oldest bilaterian fossil, which provides valuable clues on the origin of early life.

Although it is a mere 0.2 millimeter long, the fossil depicts an organism that lived some 580 million years ago. With a single pair of body cavities and symmetrically arranged sensory pits, this creature was bilaterian, or characterized by bilateral symmetry in its organs.

Researcher Chen Junyuan, of the Nanjing Institute of Geology and Paleontology, said this find has added 40 million years to the evidentiary history of bilaterian fossils.

Officially known as Vernanimalcula guizhouena, this life form provides valuable evidence of genetic innovations towards bilateral symmetry. These innovations, Chen said, are crucial to tracking the three early development stages of life: sponges, diploblastic radiates (organisms with radial symmetry and tissues that arose from two germ layers) and triploblastic bilaterian (having bilateral symmetry and three germ layers).

(China Daily June 7, 2004)