Discovery of the “lost link of evolution” of multicellular living beings has been refuted

(ORDO NEWS) — Paleontologists re-examined the body prints of animals of the species Saccorhytus coronaries and found that this creature was not a “lost link in evolution” between protostomes and deuterostomes, but a primitive relative of roundworms and loricifera.

The work was published in the journal Nature. The press service of the US Virginia Tech University (VT) announced the results on Wednesday.

Five years ago, paleontologists discovered in China body prints of ancient primitive multicellular creatures Saccorhytus coronarius, similar to toothy bags.

According to the authors of the discovery, these inhabitants of the Earth’s primary ocean during the “Cambrian explosion” are the first deuterostomes, groups of multicellular living creatures, including humans.

This discovery aroused great interest among paleontologists, as it claims to be the “lost link” in evolution, linking all existing deuterostomes with the first primitive coelenterates multicellular creatures.

Of particular interest to scientists were the respiratory organs of Saccorhytus coronarius, similar in shape to miniature cones.

“The Lost Link of Evolution”

The researchers analyzed the structure of these cone-shaped structures in the hope of finding inside them the so-called gill openings, one of the key elements of the anatomy of protozoans.

The interest of scientists in these structures was due to the fact that the discoverers of Saccorhytus coronaries failed to unequivocally demonstrate that the “toothed bags” have gill openings.

Guided by these considerations, scientists conducted repeated excavations in the territory of Shanxi province, where rocks of the Cambrian era occur, in the thickness of which the first imprints of the body of Saccorhytus coronaries were found.

Paleontologists managed to discover several hundred more fossilized remains of these animals and enlighten them using the Swiss SLS synchrotron.

This allowed the researchers to uncover the exact three-dimensional body shape of these creatures and study their anatomy.

Analysis showed that the supposed gill openings were actually broken skin spines. This suggests that Saccorhytus coronaries are among the primitive and unusually arranged protostomes, and not deuterostomes.

“This discovery forced us to take a big step back in the search for the remains of the first deuterostomes.

The oldest fossil of these creatures, which does not raise doubts about its origin, is about 20 million years older than the body prints of Saccorhytus coronaries that we studied,” said the VT researcher.

Xiao Shuhai, quoted by the press service of the university.

According to the current estimates of researchers, “toothy bags” are among the so-called cycloneuralia. So scientists call a group of protostomes, which include roundworms and loricifers.

Further study of the fossils, Xiao Shuhai and his colleagues hope, will help to understand how Saccorhytus coronaries acquired a shape that makes them unlike all other inhabitants of the seas of the Cambrian era.


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