Tech UPTechnologyThey discover a strange armored worm that lived 518...

They discover a strange armored worm that lived 518 million years ago

 

518 million years ago lived a somewhat stocky , earthworm-like creature just over a centimeter in length that could give us clues about the evolution of the ancestors of several animal stem groups. Let us remember that the so-called Cambrian Explosion, in which there was a very rapid rate of evolution during which these large groups of animals originated, was about 550 million years ago.

An international team of experts, including researchers from the Universities of Bristol and Oxford and the Natural History Museum, found this well-preserved fossilized worm which they have named Wufengella and comes from an extinct group of animals known as tommotidae (seashell fossils). Cambrian).

 

a beefy worm

The approximately 1/2-inch-long fossil worm was discovered in China and seemed to indicate that the animal was quite robust in life, given its dense array of regularly overlapping plates on its back. It also featured, surrounding this asymmetrical armor , a fleshy body with a series of flattened lobes protruding from the sides, as well as tufts of bristles emerging from the body between the lobes and the armor. The number of lobes, the tufts of bristles and the variety of shells on the back are evidence, according to the researchers, that the worm was originally segmented, much like an earthworm.

“It looks like the unlikely offspring between a bristle worm and a chiton mollusk. Curiously, it does not belong to either group ,” say the authors in their paper published in the journal Current Biology.

The animal kingdom consists of more than 30 main body plans (phylum or phyla), where each group harbors a set of specific characteristics. Only a few are shared between more than one group, which is evidence of their very rapid rate of evolution.

Tracking the evolution

“Wufengella belongs to a group of fossils from the Cambrian that is crucial to understanding how lophophores evolved. They are called tommotidae, and thanks to these fossils we have been able to understand how brachiopods evolved to have two-shelled ancestors with many shell-like plates arranged in a cone or tube”, clarifies Luke Parry, from the University of Oxford, co-author of the work.

This discovery is a bit like putting the final puzzle piece in a puzzle, as the researchers knew there was a missing relative out there, but they hadn’t been able to find him. The scans show that Wufengella, dating to 518 million years ago, is a complete camenellan tommotid and reveal what the long-sought ancestor looked like.

“When it first became clear to me what this fossil was that I was looking at under the microscope, I couldn’t believe my eyes,” explains Parry. “This is a fossil that we have often speculated about and hoped that one day we would see it.”

The fossil fulfills the paleontological prediction that the ancestral lineage of lophophores (because of their folded tentacles that filter water into a horseshoe-shaped organ) was an agile, armored worm. The common ancestor of lophophorates and annelids had an anatomy very similar to that of annelids , according to their conclusions.

“We get an incomplete picture by looking only at living animals, with relatively few anatomical characters shared between different phyla. With fossils like Wufengella, we can trace each lineage back to its roots , realizing how they once looked completely different and had modes of survival.” very different lives, sometimes unique and sometimes shared with more distant relatives”, continues the expert.

Referencia: Jin Guo, Luke A. Parry, Jakob Vinther, Gregory D. Edgecombe, Fan Wei, Jun Zhao, Yang Zhao, Olivier Béthoux, Xiangtong Lei, Ailin Chen, Xianguang Hou, Taimin Chen, Peiyun Cong. A Cambrian tommotiid preserving soft tissues reveals the metameric ancestry of lophophorates. Current Biology, 2022; DOI: 10.1016/j.cub.2022.09.011

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