The first sponges, pioneers of animal life on earth, would be similar to the modern sponge, according to new evidence.
Ancient chemical signs confirmed the appearance of the first animals on Earth. Sponges emerged 541 million years ago.
As sponges From the sea are, confirmed, the true pioneers of animal life on planet Earth. More than 541 million yearsduring the neoproterozoic.
The conclusion is a new MIT investigation, which may finally have resolved one of the greatest puzzles of evolutionary biology by counteracting that ctenophores-also known as seamambolas and cousins distant from the hails-arrived before sponges.
Both highly simple structures, both sponges and carambolas have always been difficult to rebuild: having no hard structures, they did not leave fossils behind that they could be studied by scientists, who were forced to orchestrate a plane B: look for fossilized chemical signatures.
In 2009, a team led by the biologist Roger Summonsfrom the same institute of Massachusetts, Numas Rochas do Oman, traces of sterols – fat organic compounds – with 30 carbon atoms (C30), typical of modern sponges and absent in simpler organisms. These “chemical fossils” suggested that primordial sponges already inhabited the oceans long before other animals appeared, explains the.
“We do not know exactly how these organisms would have been at that time, but certainly would have lived in the ocean, would have a soft body and assume that they did not have a silica skeleton“Explains the investigator.
But other researchers questioned this conclusion. Said the compounds concerned could actually originate in algae, until the team of Lubna Shaway Also from MIT, he sought and found a second marker: a 31 carbon atoms (C31), produced by the same sponges gene that generates the C30. In other words, confirmation was found that the sign was really of animal origin.
Scientists then recreated in the laboratory the process of fossilization of sterols, simulating millions of years of geological transformation. Two of the synthetic samples reproduced exactly the structure of the traces found in ancient rocks. The coincidence between laboratory data, modern sponges and fossil samples provides, according to researchers, “Three consistent lines of evidence” Which point to sponges as the first known animals on planet Earth, they write in the PNAS study.
Tomás Guimarães, Zap //
