Deep heat solution to 500-million year mystery

Nov 12, 2008

Scientists from the universities of Leicester and Cambridge and from the British Geological Survey have published new research in the journal Geology this month (November) shedding new light on a 500-million year old mystery.

The 500 million year-old fossils of the Burgess Shale in Canada, discovered over a century ago, still provide one of the most remarkable insights into the dawn of animal life. The beautiful silvery fossils show the true nature of the life of that time, just after the "Cambrian explosion" of animal life.

Yet, their existence is a paradox: the fossils have been buried deep in the Earth's crust and heated to over 300oC (~600 oF), before being thrust up by tectonic forces to form a mountainous ridge in the Rockies. Usually such extreme conditions are thought to destroy fossils. But, in the Burgess Shale the most exquisite detail of soft tissues has been preserved.

Now, by careful restudy of its fossils (published in the November issue of the journal Geology) Alex Page and his colleagues Phil Wilby, Sarah Gabbott and Jan Zalasiewicz, of the universities of Cambridge and Leicester and the British Geological Survey, have solved this riddle.

They have shown that as the delicate organic tissues of these fossils were heated deep within the Earth, they became the site for mineral formation. The new minerals, forged at these tremendous depths, picked out intricate details such as gills, guts and even eyes.

Alex Page said: "This provides a whole new theory for how fossils form. The deep heating may not have cremated them, but it certainly left them stone baked"

Once an ancient sea bed, the Burgess shale were formed shortly after life suddenly became more complex and diverse – the so-called Cambrian explosion – and are of immense scientific interest.

Normally, only hard parts of ancient animals became fossilised; the bones, teeth or shells. Soft parts were rarely preserved: many plants and invertebrate animals evolved, lived for millions of years and became extinct, but left no trace in the fossil record. The Burgess Shales preserved soft tissue in exquisite detail, and the question of how this came to happen has troubled scientists since the discovery of the fossils in 1909.

Source: University of Leicester

Explore further: More than 2,200 confirmed dead in Nepal earthquake

Related Stories

500 million year old fossils discovered on new site

Sep 17, 2010

During an expedition into the Canadian Rocky Mountains in 2008, a Canadian-led team including Swedish researchers from Uppsala University found a new site with exceptionally preserved fossils. The site and ...

Ancient ecosystems organized much like our own

Apr 29, 2008

It was an Anomalocaris-eat-trilobite world, filled with species like nothing on today's Earth. But the ecology of Cambrian communities was remarkably modern, say researchers behind the first study to reconstruct ...

Recommended for you

More than 2,200 confirmed dead in Nepal earthquake

23 hours ago

A powerful aftershock shook Nepal on Sunday, making buildings sway and sending panicked Kathmandu residents running into the streets a day after a massive earthquake left more than 2,200 people dead.

Nepal quake: Nearly 1,400 dead, Everest shaken (Update)

Apr 25, 2015

Tens of thousands of people were spending the night in the open under a chilly and thunderous sky after a powerful earthquake devastated Nepal on Saturday, killing nearly 1,400, collapsing modern houses and ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

out7x
1 / 5 (2) Nov 14, 2008
Stephen Gould's book describes soft tissue preservation due to a local mudslide causing rapid burial and an anoxic environment.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.