A monster ? No, the oldest ancestor of the human being

Science 1 February, 2017

A big mouth and a tiny waist: Here Saccorhytus coronarius, the oldest known ancestor of man, according to British researchers.

Who could have imagined that our grandfather was like this? Despite its nightmarish appearance with its bag-shaped body pierced with eight holes, without anus but with an enormous mouth, this microscopic marine creature (it measured less than 1 mm) could well be the first of the deuterostomists, the biological group to which the Vertebrates and therefore humans.

“This group is enormously diverse, with starfish, sea-worms and sea urchins,” says Simon Conway Morris, a professor at Cambridge University in the United Kingdom and co-author of the study Published in the journal Nature.

A remarkable level of organic complexity

Fossils of the Saccorhytus coronaries have been found “incredibly well preserved” in China. “With the naked eye, the fossils we studied resembled small black grains, but under the microscope, the level of detail was staggering, to make us unhook the jaw,” marveled Professor Conway Morris, Who noted “a remarkable level of organic complexity at such an early stage in animal evolution”.

Complex, this little beast was: it was probably feeding by engulfing organic particles and various creatures, when the eight openings in the shape of a cone distributed along the body. They would have allowed her to evacuate the water she was swallowing, for she did not seem to have anus.

The study of Saccorhytus coronaries “brings us important information on the very early stages of the evolution of a group that led to the appearance of humans,” assures the University of Cambridge on its website.