A bizarre extinct creature that has mystified scientists since its 500m-year fossil was first unearthed more than a century ago has finally revealed its teeth – placing it centre stage in the evolution of many complex life-forms living today.
Hallucigenia, which owes its name to its unworldly appearance, was so odd that scientists initially confused its top from its bottom and its head from its tail. However, a study has now unequivocally identified its mouth, complete with a fearsome ring of sharp teeth.
Researchers from the University of Cambridge have also identified a pair of simple eyes on Hallucigenia’s head and have determined that it was a close relative of the last common ancestor of everything from tiny velvet roundworms to huge lobsters.
“The early evolutionary history of this huge group is pretty much uncharted. While we know that the animals in this group are united by the fact that they moult, we haven’t been able to find many physical characteristics that unite them,” said Martin Smith of Cambridge University, the lead author of the study in Nature.
“Prior to our study there was still some uncertainty as to which end of the animal represented the head, and which the tail,” Dr Smith said.
“A large balloon-like orb at one end of the specimen was originally thought to be the head, but we can now demonstrate that this actually wasn’t part of the body at all, but a dark stain representing decay fluids or gut contents that oozed out as the animal was flattened during burial,” he said.
1861: A hugely important fossil, this 147-million-year-old rock slab contains the remains of the earliest known bird. With its combination of bird and dinosaur characteristics, it is a famous snapshot of evolution in action. It's early discovery has since been queried as more complete examples were found (as above).
2/6 Ida - The Link
1983: Ida - a tiny 47-million-year-old fossil - was discovered at the Messel Pit southeast of Frankfurt am Main in Germany. But it was only in May 2009 that she was introduced to the world, at the head of a whirlwind publicity campaign as the supposed "missing link" in human evolution.
3/6 Australopithecus sediba
2010: A partial cranium which belonged to human ancestor Australopithecus sediba, which was unearthed from a pit in South Africa
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2010: The discovery of the fossil of the Darwinopterus filled a 155 million-year evolutionary gap
5/6 Fossil fight
2013: 'Astounding' fossil find from Montana revealing two dinosaurs locked in mortal combat
6/6 Ichthyosaur graveyard
2014: One of the 46 fossils found at the site in southern Chile