A group of scientists said they have solved an evolutionary puzzle related to a 500 million-year-old spiny microscopic creature with a mouth but no anus.
When this species was discovered in 2017, it was reported that the tiny fossil of this “sea monster” could be the oldest known ancestor of humans.
The animal, named Saccorhytus Coronarius, is tentatively classified into a group called deuterostomes.
They represent the primitive ancestors of vertebrate animals – including humans.
However, a new study now suggests that Saccorhytus should be placed in a completely different group than other animals.
A team of researchers in China and the UK conducted a very detailed radiographic analysis of the creature and concluded that it belongs to the exozoan group – the ancestors of spiders and insects.
One source of this evolutionary confusion was the animal’s lack of an anus.
Researcher Emily Carlisle, who has studied Saccorhytus in detail, explained to the BBC Radio 4 Inside Science podcast that the topic was still “a bit confusing”.
He asked, “Most of the Ikizuzu have an anus, so why isn’t there one?”
The expert notes that the “interesting answer” is that one of the older ancestors of this entire group did not have an anus, and that Saccorhytus evolved much later.
“Maybe he lost [o ânus] During the evolution itself – she probably didn’t need one because she would only need one hole in her body to do everything.”
The main reason for Saccorhytus’ “repositioning” on the tree of life is that, on initial examination, the holes around its mouth were interpreted as the pores of the gills (or gills) – an early feature of deuterostomes.
When the scientists took a closer look – using powerful X-rays to get a closer look at the millimeter-long creature – they realized that these structures were actually the base of some of the spines that had been severed.
Scientists who study these fossils attempt to classify each animal into groups – which work almost like a family tree – allowing them to build a picture to understand where all the species came from and how they evolved over time.
Carlisle, who works at the University of Bristol in the UK, explained that “Sacorhytos would have lived in the sea, with spines near its mouth, which would make it grab onto ocean sediments.”
“We suppose he was ‘sitting’ in an alien environment, with different animals that might look like some living things today, but others would be completely alien to us.
Artist’s reconstruction of Saccorhytus Coronarius, based on original fossil finds. The actual creature was probably no more than a millimeter in size – Photo: University of Cambridge
The rocks containing these fossils are still being studied.
“We can still learn a lot about the environment in which they lived,” Carlisle added.
“The more I study paleontology, the more I realize how much it is missing. When we think about this creature and the world it lived in, we are only on the surface. [do conhecimento]. ”
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