Mystery of half-billion year old creature with no anus solved

Scientists claim to have found the evolutionary explanation for a tiny, spiky creature with a mouth but no anus that has been around for 500 million years.

The tiny fossil of this sack-like aquatic creature was found in 2017, and it was speculated that it would be the earliest known progenitor of humans.

Saccorhytus coronarius, an ancient animal, was provisionally assigned to a class known as the deuterostomes. These are the earliest vertebrate species, including humans.

According to a recent study, Saccorhytus should be classified with a completely another group of animals. The creature was subjected to a very thorough X-ray examination by a team of researchers from China and the UK, who came to the conclusion that it belonged to a class of organisms known as ecdysozoans, which are the relatives of spiders and insects.

The animal’s absence of an anus was one factor contributing to this evolutionary conundrum.

It’s a bit odd because ecdysozoans have an anus, so why didn’t this one? According to researcher Emily Carlisle, who extensively researched Saccorhytus.

She referred to the “intriguing possibility” that Saccorhytus arose after an even older ancestor of this entire group did not possess an anus.

The fundamental justification for Saccorhytus’ “repositioning” on the Cambrian tree of life is that, at initial inspection, the holes that encircled its mouth were mistaken for gill pores, a basic trait of deuterostomes.

When researchers used strong X-rays to inspect the 1mm organism closely and peered closer, they discovered that they were actually the bases of snapped-off spines.

By putting each animal on a “tree of life,” which is akin to a family tree, scientists studying these fossils may create a picture of the animal’s origins and evolutionary history.

The University of Bristol’s Ms Carlisle stated that Saccorhytus would have lived in the oceans, in the sediment, with its spines holding it in place.