Daily Mail

London

A bizarre worm-like animal that lived 505 million years ago has been definitively categorised on the ‘Tree of Life’ by scientists.

Known as Hallucigenia the creature has legs, spikes, a head and a tail, and has been linked with a group of modern animals for the first time. It had once been considered an ‘evolutionary misfit’ but now researchers have found an important link with modern velvet worms, which live in tropical forests.

The discovery published in the journal Nature was made by scientists at the University of Cambridge. The similarity of Hallucigenia to other contemporary ‘legged worms’, collectively known as lobopodians, has been very controversial.

This is because a lack of clear characteristics linking them to each other or to modern animals has made it difficult to determine their evolutionary home. What is more, 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.

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.