They solve the mystery of the creature with no more than 500 million anus…

Scientists say they have solved the evolutionary mystery of a 500-million-year-old microscopic spiny creature with a mouth but no anus.

When discovered in 2017, this small, sac-shaped fossil of a marine animal was said to be the earliest known ancestor of man.

Saccorhyntys coronarius, as this ancestral being is known, has been tentatively classified within the group of deuterostomes characterized by: her anus forms in front of her mouth during her embryonic development.

These are the primitive ancestors of vertebrates, including humans.

Now, a new study suggests that Saccorhytus should be classified in an entirely different group of animals.

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A research team in China and the United Kingdom conducted a very detailed X-ray analysis of the creature and concluded: belonging to a group called the ecdysozoaThey are the ancestors of spiders and insects.

Confusion, confusion

One of the origins of this evolutionary confusion was that the animal did not have an anus.

Emily Carlisle, a researcher who has studied Saccorhytus in detail, told BBC Radio 4’s Inside Science. «A little worrying (majority) Ecdysozoans have an anus, so why not this one?

An “interesting option” to explain this, he said, was that even before this entire group, an ancestor had no anus at all, and Saccorhytus evolved after that.

“He may have lost it during his own evolution, maybe he didn’t need it, or he could just sit in one place with one opening for everything,” he said.

However, the main reason for the “repositioning” of Saccorhytus in the Cambrian tree of life—the splitting of the Paleozoic geological timescale—was, at first review, The holes surrounding the mouth have been interpreted as gill pores, a primitive feature of deuterostomes.

When the scientists looked in more detail, using powerful X-rays to examine the 1-mm creature up close, they realized that what was actually broken was the base of the spines.

Examining these fossils, scientists try to place each animal in a tree of life, just like a family tree; it’s something that allows them to build the big picture to understand. where do they come from and how do they developRon.

“Saccorhytus used to live in the oceans, in sediment whose spines held it in place,” said Carlisle, who works at the University of Bristol in England.

“We think it’s sitting there[where it is]. in a very strange environment with many animals it may seem like some creatures live there, but others are totally weird.”

The rocks containing these Cambrian fossils are still under investigation.

“There’s so much more we can learn about its environment,” Carlisle added.

“The more I study paleontology, the more I realize how incomplete it is. In terms of this creature and the world it lives in, we’re really just scratching the surface.”