Plants and Animals

508-Million-Year-Old Fossil "Ice Cream Cone With Tentacles" Finally Classified

A weird creature resembling a tentacled ice cream cone with a lid has found a place on the Tree of Life. As reported in the journal Nature, this elusive life form, living on this planet for 280 million years, has finally been classified by paleontologists 175 years after its initial discovery.

Let’s rewind a little. Well, a lot actually – 542 million years back in the past. This was around the time of the so-called Cambrian Explosion, where complex, diverse, multicellular life appeared and proliferated rather suddenly.

Although research is increasingly pointing towards there being plenty of (poorly preserved) animal life a few million years earlier, the Cambrian Explosion is a definitive eruption of evolutionary biology, a showcase of all the blueprints creatures would work on and descend from. Some of these critters were placed in a biological class called Hyolitha, and they were seriously bizarre things.

Never more than 1 centimeter (0.4 inches) long, they were covered in a cone-shaped calcareous shell. Sprouting out of the top of this shell were its tentacles – oddly named “helens” – that were used to push the creature around the sea floor. This made them appear to be mollusks of some kind, but no one could really be sure.

These little oddballs were globally distributed – almost every part of all the world’s oceans contained them. They lived right up until the “Great Dying” mass extinction event 252 million years ago, one that wiped out 96 percent of all life and gave rise to the dinosaurs. The Hyolitha were clearly a key species, so it’s been quite irritating that no one’s been able to properly classify them.

Having a look at one particularly well-preserved example in a 508-million-year-old rock formation – a rather famous one known as the Burgess Shale in Canada – a team of researchers led by the University of Toronto noticed it had some soft tissue hiding within it.

After comparing this to 1,500 other specimens extracted from the same rock formation, the team managed to classify it as a type of lophophorata. These shell-bearing creatures all have the same mouth-dwelling tentacles in commons, which apart from locomotion are also used to catch food particles drifting past in the water.


Soft tissues belonging to a Hyolitha specimen. Stanley Glacier/University of Toronto

“Being able to place them on the tree of life, it solves this long paleontological mystery about what these creatures are,” lead author Joseph Moysiuk, an undergraduate student at the University of Toronto, told BBC News.

“We have been able to discover some new features of a very old group of fossil animals, and it’s allowed us to reveal the evolutionary history of this group of animals and where exactly they sit on the tree of life.”

Finally, the squiggly little dudes have a home.

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