An international team of scientists has discovered in China the fossil of a mysterious marine animal of the Cambrian period, about 500 million years old, according to a study published by the journal Proceedings of the Royal Society B.
The research, led by the British universities of Leicester and Oxford and the Chinese Yunnan, suggests that this creature belongs to the group of animals known as “chancelloriids”, whose evolutionary process still divides the experts.
The “chancelloriids” are spiny, tube-like animals that appeared during the Cambrian evolutionary explosion and became extinct shortly afterwards, leaving little clue to their evolution, the authors of this study recall. In a way, they point out, they look like sponges, simple organisms that feed by filtration, although the finding of the aforementioned fossil, baptized as Allonnia nuda, suggests that this group was more diverse than previously believed.
The new species was discovered at the archaeological site of Chengjiang in the Chinese province of Yunnan (southwest), and although its size is surprisingly large, about 19 inches, it only has a few tiny spines. Its unusual “naked” appearance indicates that perhaps there are more similar fossils “hidden in plain sight”, while raising the possibility that they are more complex organisms than expected.
Also, the Allonnia nuda provides clues about the growth pattern of this new species, as it has clear links with modern sponges. The authors specify that it is still early to confirm that the mystery has been solved, but they point out that the discovery of fossils similar to sponges plays a central role in the debate on the early evolution of animals.
“The fossils of chancelloriids were first described about a hundred years ago, but they have resisted attempts to include them in the tree of life, and we maintain that their growth pattern links them to sponges, which revitalises an old hypothesis,” explained Tom Harvey, of the University of Leicester.
According to the expert, the “case is not closed”, so more studies are needed to shed more light on “the nature of these primitive animals. “The Chengjiang deposits in Yunnan province continue to provide new and more amazing fossils than we ever imagined, and together they provide a crucial picture of life during the Cambrian explosion,” added Peiyun Cong of Yunnan University. .