Scientists from Northwest University in Xi'an may have found the earliest evolutionary link between invertebrates and vertebrates, a topic which has caused worldwide academic dispute for several decades.

The British scientific journal Nature yesterday published the latest findings of Shu Degan, which described how Shu and his research team stumbled upon a fossilized soft-bodied creature in fauna from the Lower Cambrian period.

Shu is director of the Early Life Institute of the university's Department of Geology.

Their report says the 530-million-year-old creature, probably a marine animal, was found in the fauna in Yunnan Province. It might be the earliest known fossil evidence of primitive chordates.

"There was little anatomical or molecular support for evolutionary relations between invertebrates and vertebrates before. Therefore, our research is pioneering," said Shu in an interview with Xinhua news agency.

He said the primitive ascidian possesses characteristics of both invertebrates and vertebrates.

The creature's entire body, 25 millimeters in length, consists of a stout stem and a sub-spherical main body supported by the stem.

It has a prominent rectangular dark area, covered with numerous lighter dots and located in the upper part of the body cavity. The lower ventral corner of the dark area extends downward like "tail" structure, which could be summarized as one feature.

"The dark area, compared to modern ascidians, with its dextral configuration, large size and appropriate location in the body, is consistent with its identification as the pharynx," Shu said.

The animal inhabited a higher energy, sandy sea floor and was transported to its point of burial.

(www.eastday.com.cn 05/25/2001)