850 mln yr old fossil traces solve major problem for origin of animal lifeMay 12th, 2009 - 12:52 pm ICT by ANI
London, May 12 (ANI): Scientists have discovered 850 million year old fossil traces in Canadian rocks, which have potentially solved a major problem for the origin of animal life.
The previous oldest animal fossils date from “only” 650 million years ago, although “molecular clocks” based on rates of genetic divergence indicate that animals should have originated about 850 million years ago.
According to a report in New Scientist, the new findings may therefore help solve the problem of the 250 million-year-gap.
Palaeontologists have looked long and hard for traces left by the first multi-celled organisms, fully aware that the soft-bodies might have left very few fossils.
The breakthrough came when Elizabeth Turner, of Laurentian University in Sudbury, Ontario, spotted odd patterns in the rocks of 850-million-year-old limestone reefs in the Mackenzie Mountains of Canada’s Northwestern territory.
She has spent the last 15 years, with Fritz Neuweiler of University Laval in Quebec, trying to deduce their origin.
Now, Turner and Neuweiler, along with David Burdige of Old Dominion University in Virginia, have shown that the patterns match the distinctive textures found in reefs built by sponges.
Studies of modern sponges show that when their collagen structure decays it calcifies and leaves a signature pattern.
Since collagen is a fibrous protein found only in animals, some ancestral animal must have lived in the ancient reef, argue researchers.
The animal consisted of “cells living embedded in a scaffold of collagen, which they extruded to make their home,” said Turner.
“There probably were more than one type of cell, but we can’t tell. Nothing like it lives today, but if we saw one, it would look like a little blob of gelatinous goo,” she added.
The presence of animals this early in Earth’s history would resolve the long-standing disparity between molecular clocks and the fossil record, and show that the evolution of animals began before the Earth slipped twice into a global deep freeze.
“I applaud the approach of looking for distinctive textures seen along with sponge skeletons in younger rocks,” said Andrew Knoll of Harvard University. “It’s a good first step, but it’s not yet proof, he added. (ANI)
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