A Chinese research team has discovered four fossils of a species
of fish believed to be 400 million years old. The discovery could
provide clues to understanding the evolution of fish.
Dr. Zhu Min, the leading scientist from the Chinese Academy of
Sciences (CAS) Institute of Vertebrate Paleontology and Pale
anthropology, said on Sunday that the newly discovered species
might represent a bridge between the two vertebrate lineages that
are predominant today.
The find made by Zhu and his colleagues was published in the
latest issue of the British journal Nature.
The fossilized creature, found in southwest China's Yunnan Province, combines features shown by
ray-finned bony fishes, including the majority of modern fish
species, and by lobe-finned bony fishes, the group that spawned the
ancestors of today's land vertebrates, Zhu said.
The ancient fish, represented by chunks from four separate
skulls, has a skull roof much like that of actinopterygian, the
group that includes most modern fish, Zhu said.
But the fine features of its anatomy might also shed light on
the evolutionary origin of cosmine -- a hard surface-tissue found
in many fossil sarcopterygians, or fish that later evolved into
land vertebrates, he said.
Cosmine is characterized by a network of pores and canals in the
tissue, overlaid by a single enamel-based layer, Zhu explained.
The 405 million-year-old fossil possessed several such layers
over the pore-canal network, suggesting that the cosmine arose
after all but one of these layers disappeared, he said.
Zhu named the ancient fish after his mentor, Prof. Meemann
Chang, China's most prominent paleontologist and also a CAS member.
Prof. Chang laid the foundation of modern research on ancient bony
fishes.
With the latest find, Zhu and his team are trying to prove that
lobe-finned bony fishes originated from south China.
Zhu's research is sponsored by the National Science Foundation
of China, the Ministry of Science and Technology, and the CAS.
(Xinhua News Agency May 8, 2006)