Bizarre ‘Nude’ Fossil Of A Sponge-Like Creature May Help Settle A 100-Year-Old Mystery

The weird and 'naked' fossil of a giant chancelloriid could finally tell scientists where to place these confounding creatures in the tree of life.

Tubular sea sponges.
Amanda Nicholls / Shutterstock

The weird and 'naked' fossil of a giant chancelloriid could finally tell scientists where to place these confounding creatures in the tree of life.

Researchers have uncovered a new species of ancient primitive creatures that lived half a billion years ago, during the Cambrian Period, Science Daily reports.

The newfound species, dubbed Allonnia nuda, has been identified as a chancelloriid, a peculiar group of sea creatures that has been puzzling scientists for nearly a century because no one knows where exactly to place them in the tree of life.

Like most animals that emerged during the “Cambrian Explosion” — a major life-bursting event that took place nearly 541 million years ago and practically shaped the course of life on Earth, the Inquisitr previously reported — chancelloriids were very weird fellows.

These mysterious marine animals, which didn’t last for very long and went extinct almost immediately after they appeared, had small, tubular bodies covered in spikes and showed some similarities to modern sea sponges. For instance, they lived attached to the sea floor and had simple, hollow bodies.

Belonging to the Chancelloria genus, these early animals didn’t have any internal organs, their bag-like, spiny bodies being fitted with just a single orifice that served all their physiological purposes, notes Live Science.

Yet, even for a Cambrian “oddball,” Allonnia nuda was still pretty unusual.

Weird And ‘Naked’

First of all, it was surprisingly big compared with other chancelloriids. While a typical chancelloriid was around eight inches (20 centimeters) long, Allonnia nuda was more than double that size and could reach impressive lengths of up to 20 inches (50 centimeters).

If you don’t think that’s such a big deal, it’s worth remembering that the biggest, baddest predator of the Cambrian, the radiodontan Anomalocaris, was only 3.2 feet (97 centimeters) long — as the Inquisitr reported earlier this month, when another team of researchers discovered the world’s smallest radiodontan fossil in the famous Chengjiang UNESCO World Heritage Site in China.

Secondly, let’s address the “nude” thing, shall we? The reason why scientists are calling Allonnia nuda the “nude” fossil is because, unlike other chancelloriids, this creature only had a few short spines. This revealed a larger portion of its “naked” body, hence the moniker, which even made it into the species’ name.

More Sponge-Like Than Previously Imagined

Described in a study published today in the journal Proceedings of the Royal Society B, this new chancelloriid species was identified from six separate fossils unearthed from the same Chengjiang site in the Chinese Yunnan Province as the world’s smallest radiodontan.

“The Chengjiang deposits of Yunnan Province continue to reveal surprising new fossils we could hardly have imagined. Together, they provide a crucial snapshot of life in the oceans during the Cambrian explosion,” said study lead author Dr. Peiyun Cong, a paleobiologist at Yunnan University in Kunming, China, and The Natural History Museum in the U.K.

One of the most striking things about these fossils, which were discovered incomplete, is that they exhibited a ring-shaped “growth zone” at one end, where all their new spines were formed. This growing pattern is very close to that of sponges and seems to be a biological feature found only to the two groups.

This suggests that chancelloriids had more in common with modern sponges than the researchers previously believed.

“Fossil chancelloriids were first described around 100 years ago but have resisted attempts to place them in the tree of life. We argue that their pattern of body growth supports a link to sponges, reinvigorating an old hypothesis,” said study co-author Dr. Tom Harvey, from the University of Leicester in the U.K.

Because of this discovery, scientists may now have more clues as to where chancelloriids belong in the tree of life. In this respect, Allonnia nuda could help researchers finally solve this 100-year-old mystery, the University of Leicester points out.

“We’re not suggesting that it’s ‘case closed’ for chancelloriids, but we hope our results will inspire new research into the nature of the earliest animals,” notes Dr. Harvey.