Researchers have identified traces of what they believe is the earliest known prehistoric ancestor of humans — a microscopic, bag-like sea creature found in China, which lived about 540 million years ago.
Named Saccorhytus, after the sack—like features created by its elliptical body and large mouth, the species is new to science and was identified from microfossils found in China.
It is thought to be the most primitive example of a so—called “deuterostome” — a broad biological category that encompasses a number of sub—groups, including the vertebrates.
The study by researchers from University of Cambridge in the UK and Northwest University in China suggests Saccorhytus was the common ancestor of a huge range of species, and the earliest step yet discovered on the evolutionary path that eventually led to humans, hundreds of millions of years later.
Its features were spectacularly preserved in the fossil record.
“We think that as an early deuterostome this may represent the primitive beginnings of a very diverse range of species, including ourselves,” Simon Conway Morris, Professor at University of Cambridge, said.
“Saccorhytus now gives us remarkable insights into the very first stages of the evolution of a group that led to the fish, and ultimately, to us,” Degan Shu, from Northwest University, added. Most other early deuterostome groups are from about 510 to 520 million years ago, when they had already begun to diversify into not just the vertebrates, but the sea squirts, echinoderms (animals such as starfish and sea urchins) and hemichordates (a group including things like acorn worms).
Saccorhytus microfossils were found in Shaanxi Province, in China, and pre—date other known deuterostomes, researchers wrote in in journal Nature. By isolating the fossils from the surrounding rock, and then studying them both under an electron microscope and using a CT scan, team was able to build up a picture of how Saccorhytus might have looked and lived.
Source: The Hindu