Weird worm points to Earth's biodiversity burst

PARIS (AFP) - Fossilised forms of a phallus-shaped invertebrate have shed light on a dramatic spurt in Earth's biodiversity that occurred half a billion years ago, Canadian scientists reported on Wednesday.

Remains of 10cm worm-like creatures were found in shale beds in Yoho National Park in the Canadian Rocky Mountains.

The sediment dates back to the mid-Cambrian, a period when the number of species exploded and life forms became more complex.

The long-dead animal, named Spartobranchus tenuis, is an ancestor of the acorn worm, a marine animal that thrives in shallow mud and sand, according to the study, appearing in the journal Nature.