Worm-like ancient `misfit` finds family in `tree of life`
Washington: The fossil of an ancient worm-like creature, which had legs, spikes and a head difficult to distinguish from its tail, has finally been placed in the evolutionary tree of life.
The animal, known as Hallucigenia due to its otherworldly appearance, had been considered an `evolutionary misfit` as it was not clear how it related to modern animal groups. Researchers from the University of Cambridge have discovered an important link with modern velvet worms, also known as onychophorans, a relatively small group of worm-like animals that live in tropical forests.
The affinity of Hallucigenia and other contemporary `legged worms`, collectively known as lobopodians, had been very controversial, as a lack of clear characteristics linking them to each other or to modern animals has made it difficult to determine their evolutionary home.
Early interpretations of Hallucigenia, which was first identified in the 1970s, placed it both backwards and upside-down. The spines along the creature`s back were originally thought to be legs, its legs were thought to be tentacles along its back, and its head was mistaken for its tail.
Hallucigenia lived approximately 505 million years ago during the Cambrian Explosion, a period of rapid evolution when most major animal groups first appear in the fossil record. These particular fossils come from the Burgess Shale in Canada`s Rocky Mountains, one of the richest Cambrian fossil deposits in the world.
Looking like something from science fiction, Hallucigenia had a row of rigid spines along its back, and seven or eight pairs of legs ending in claws. The animals were between five and 35 millimetres in length, and lived on the floor of the Cambrian oceans.
A new study of the creature`s claws revealed an organisation very close to those of modern velvet worms, where layers of cuticle (a hard substance similar to fingernails) are stacked one inside the other, like Russian nesting dolls. The same nesting structure can also be seen in the jaws of velvet worms, which are no more than legs modified for chewing.
While Hallucigenia had been suspected to be an ancestor of velvet worms, definitive characteristics linking them together had been hard to come by, and their claws had never been studied in detail. Through analysing both the prehistoric and living creatures, the researchers found that claws were the connection joining them together.
Cambrian fossils continue to produce new information on origins of complex animals, and the use of high-end imaging techniques and data on living organisms further allows researchers to untangle the enigmatic evolution of earliest creatures.
The results are published in the advance online edition of the journal Nature.
More from India
More from World
More from Sports
More from Entertaiment
- There will be earthquake if I speak on demonetisation: Rahul Gandhi
- Zee Media Exclusive: A reality check on public opinion on notes ban!
- Panel discussion on the decision of demonetisation
- DNA: Is political system root cause of corruption in the country?
- Panel discussion on the decision of demonetisation Part II
- Mongolia seeks India's financial aid, Chinese official media says it's 'insane'
- SC asks govt if demonetisation was confidential; to judge if policy unconstitutional
- OMG! Man punches Kangaroo in face to save dog – Watch video
- PoK erupts with 'azadi' slogans; Pakistan Army brutally thrashes protesters
- Aamir Khan as Mahavir Singh Phogat in 'Dangal' title track looks phenomenal!