A team of scientists detailed an ancient worm and named it Hallucigenia for its strange appearance, as they could not initially differentiate its head from rear.
According to Reuters, worm lived in the sea some 508 million years ago during the Cambrian Period. The researchers published their work in the journal Nature.
"The early evolutionary history of this huge group is pretty much uncharted," study lead author Martin Smith, a postdoctoral researcher of earth sciences at the University of Cambridge, said in a press release. "While we know that the animals in this group are united by the fact that they molt, we haven't been able to find many physical characteristics that unite them."
The team of scientists were not originally able to tell Hallucigenia's head from its tail, but were also mystified by its spiky body and the ring of teeth it had in its mouth that initially went unnoticed.
"It turns out that the ancestors of molting animals were much more anatomically advanced than we ever could have imagined: ring-like, plate-bearing worms with an armored throat and a mouth surrounded by spines," study co-author Jean-Bernard Caron, an associate professor of earth sciences and ecology and evolutionary biology at the University of Toronto and Curator of Invertebrate Paleontology at the Royal Ontario Museum, said in the release. "We previously thought that neither velvet worms nor their ancestors had teeth. But Hallucigenia tells us that actually, velvet worm ancestors had them, and living forms just lost their teeth over time."
The scientists believe Hallucigenia used its ring-like set of teeth to generate suction rather to chew. The teeth likely helped Hallucigenia keep its food stationary while the worm sucked it all down.
"These teeth resemble those we see in many early molting animals, suggesting that a tooth-lined throat was present in a common ancestor," Caron said. "So where previously there was little reason to think that arthropod mouths had much in common with the mouths of animals such as penis worms, Hallucigenia tells us that arthropods and velvet worms did ancestrally have round-the-mouth plates and down-the-throat teeth - they just lost or simplified them later."
