Scientistshave discovered that strange creatures without anus are not the earliest ancestors of mankind as previously thought.
New research suggests that the mysterious microscopic creatures are part of another family tree.
Resembling an angry purple minion, Saccorhytus is a spiky, wrinkled sac with a large mouth surrounded by spikes and holes.
We went back to the beginning looking for animals with a second mouth.
Shuhai Xiao, Virginia Tech College of Science
These were interpreted as gill pores – a primitive feature of the deuterostome group – usually animals is characterized by the formation of an anus in front of the mouth – from which the ancestors of mankind arose. However, analysis of his 500 million-year-old fossils from China suggested that the holes around the mouth were the bases of spines broken off during fossil preservation.
He Yunhuan Liu, professor of paleontology at Chang'an University in Chinasaid:
"Saccorhytus was a curious beast, with a mouth but no anus, and an intricate ring of thorns around its mouth."
Virginia Tech School of Science Earth Professor Shuhai Xiao, a paleontologist in the Department of Science, said:
"The next oldest deuterostome fossil is nearly 20 million years younger."
The true story of Saccorhytus' ancestors lies in the microscopic internal and external features of this tiny fossil.
Researchers took hundreds of X-ray images of him and used powerful computers to create detailed 3D digital models of the fossil.
Emily Carlyle, a researcher in the Earth Sciences Department at the University of Bristol said:
She added: "We took hundreds of X-ray images from slightly different angles and used a supercomputer to create a 3D digital model of the fossil, which reveals small features of the fossil's internal and external structure.
Digital models show that pores once interpreted as gills are actually broken spines, challenging the only evidence supporting the deuterostome interpretation. says the researchers.
They now believe that Saccorhytus is actually a group that includes moltings, arthropods and nematodes.
The exact location of Saccolitas in the Tree of Life is not yet known
The absence of anus in ancient creatures is an interesting feature, according to Shu Hai Xiao, Professor of Science, Virginia Tech University
Scientists say.
A question that comes to mind is the alternative pathway for digestive waste (through the mouth), and this feature is important for evolutionary biology fundamental reasons. How they arose, and sometimes then disappeared, helps us understand how the body structure of animals evolved.
Professor Xiao, who co-led the study, said:
"The fact that Saccorhytus belongs to this group indicates an evolutionary regression without the anus that would have been inherited by its ancestors.
" Although the exact position of Saccolitas in trees is not yet known, it is possible that all members of this diverse group reflect the ancestral state in which they evolved."
