Paleontologists were baffled when they uncovered fossils of a 500 million year old worm called Hallucigenia in the Burgess Shale of Canada since they did not really know what they were looking at. At first, scientists believe that the worm's head was its tail and its spiky spine was its legs.
This ancient worm was discovered in the 1970s where scientists intensively examined its anatomy but were still uncertain over which end is the head or tails. Now, in this new study, scientists have finally figured out which is the head and the tail upon closer inspection of the fossils where they found teeth.
According to Jean-Bernard Caron from the Royal Ontario Museum and Earth Sciences and Ecology and Evolutionary Biology at the University of Toronto, initially when the team placed the fossils under an electron microscope, scientists were searching for a pair of eyes but the team was surprised to see teeth smiling back.
However, this worm's "smile" is not cute at all as this smile is made up of sharp, needle like teeth that line the whole throat which makes this creature even more intriguing for evolutionary biologists.
Caron explains that this kind of teeth resemble those ancient animals who were early molters that suggests that this tooth lined throat was also observed in a common ancestor.
The Hallicigenia worm is classified under a group of "velvet worms" where prior to this study, scientists did not think that velvet worms nor their ancestors possess teeth.
Caron explains that these new findings suggest that velvet worm ancestors did possess teeth where they just evolved and lost them over a period of time.
This new study is published in the journal, Nature.