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World's Oldest Bilaterian Fossil Found in China

Posted on: Sunday, 6 June 2004, 06:00 CDT

World's oldest bilaterian fossil found in China

NANJING, June 5 (Xinhua) -- Chinese scientists have discovered the world's oldest bilaterian fossil, which provides valuable clues on the origin of early life.

Though only 0.2 millimeter long, this fossil demonstrated under microscope a life-form 580 million years old, with one pair of coeloms and symmetrically arranged sensory pits.

Researcher Chen Junyuan of the Nanjing Institute of Geology and Paleontology, also the discoverer, claimed this find has advanced the recorded history of bilaterian fossils, or fossils characterized by bilateral symmetry in organs, by 40 million years.

Officially named "Vernanimalcula guizhouena", this life-form has provided valuable evidence of the genetic innovations from biradial symmetry to bilateral symmetry. Such innovation, Chen said, was crucial for mankind to track early life's three development periods, namely Sponges, Diploblastic Radiates ( including Coelenterate) and Triploblastic Bilaterian.

According to Chen, this fossil was the best preserved of the 10 discovered last November at Weng'an Biota of Guizhou Province, southwest China.

Given the fossil came into being during the "Snow Ball" period when the snow-covered Earth began to melt due to rising temperature, Chen also called it the "Guizhou Spring Worm."

Chen said the "Guizhou Spring Worm" normally lived in the running water under small tides. Afraid of being swept away, just like modern microorganisms, it would hide itself among the ashes in seabed.

Research results also showed it would suck in nutrition through a "mouth" on the belly with the help of pharyngeal muscle, which Chen claimed could be a more primitive living model than those of grass eating and cave dwelling.

Judging from its structure, Chen said, the life-form had entered its adulthood and acquired reproductive capability.

Dubbed as the "Adam Garden of Paleontology," the Weng'an Biota was well known for its diverse Paleozoic resources. In 1998, Chen and his colleagues found out there are some metazoan and embryo fossils of 580 million years ago, which have been viewed as the most valuable scientific achievements in evolutionary biology of the 20th century.

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