It may sound unbelievable, but microfossils found from China confirm that the ancestor of all vertebrates, including reptiles and humans, was a microscopic creature with a big mouth but no anus. The research was published in Nature, the weekly international journal that publishes groundbreaking discoveries on many scientific disciplines.

Science Alert reports that 45 fossils from the Shaanxi province in China were analyzed. The creature has been given the name Saccorhytus coronarius, taken from the description of its body.

Team member Simon Conway Morris says, " To the naked eye, the fossils we studied look like tiny black grains, but under the microscope the level of detail is jaw-dropping."

The animal species found to be distantly related to humans had a sack-like body, but its mouth looked like a crown. It would be about a millimeter in size and moved by wriggling. It would have lived on the seabed and lived between the sand grains found there.

What was peculiar, and albeit unappealing about this particular species is that the scientists could not find any anus anywhere in its tiny body. The tiny creature would have ingested its food by engulfing it in its big mouth. But after the food has been digested, because of no evidence of an anus, the waste materials from the digestion would simply go back out of the mouth again.

This small ancestor to all vertebrates existed in the early Cambrian period, roughly 540 million years ago, which makes it the oldest existing example of what scientists call deuterostome, organisms where humans and other creatures like acorn worms and starfish fall under.

Conway Morris says that there is a common ancestor for all deuterostome, which rapidly diversified making it difficult to know what the primitive ones might have looked like. But the discovery of these tiny creatures in the sedimentary rock may have answered this question of the scientists.

Upon closer inspection, the scientists believe that some features found in the Saccorhytus coronarius could be the pre-cursor to pharyngeal slits, which eventually became fish gills and is the origin of human ears.