The Burgess Shale fossils, a Rocky Mountain treasure trove found in 1909 just west of the B.C.-Alberta border, represent the planet’s single most important snapshot of life as it existed during the so-called “Cambrian explosion” of organisms about 530 million years ago.


African find shades of B.C.’s Burgess Shale: Paleontologists


MAY 18, 2010

The bizarre, long-extinct creatures that make up Canada’s world-famous Burgess Shale fossil site have been given a new lease on life after a half-billion years or so — thanks to a major paleontological discovery in Africa that resets the clock on a key moment in animal evolution.

The Burgess Shale fossils, a Rocky Mountain treasure trove found in 1909 just west of the B.C.-Alberta border, represent the planet’s single most important snapshot of life as it existed during the so-called “Cambrian explosion” of organisms about 530 million years ago.

But because nearly all of the exquisitely preserved animals at the B.C. site have been absent from the fossil record after the 500-million-year mark, the Burgess Shale animals are typically seen as evolution’s losers — a flash-in-the-pan community of trilobites and other ill-adapted, doomed dwellers on the ancient ocean floor.

Now, an international scientific team’s discovery of a much younger fossil bed — which appears to include scores of species also found at the renowned Canadian site — has added at least 20 million years to the evolutionary timeline of the Burgess Shale fauna.

The new fossil bonanza, located near the Atlas Mountains of southeastern Morocco, dates from about 480 million years ago and includes a huge array of Ordovician-era sponges, worms, mollusks and other soft-bodied organisms, many typical of the Burgess Shale site and thought to have died out eons earlier during the Cambrian age.

The discovery, which so far includes more than 1,500 individual specimens, was made by a team of eight researchers from the U.S., Britain, France, Ireland and Morocco. An article detailing the “exceptionally preserved fossils” and highlighting their significance in rewriting the Burgess Shale story appears in the latest issue of Nature.

The African fossils “indicate that Burgess Shale-type taxa continued to play an important role in the diversity and ecological structure of deeper marine communities well after the Middle Cambrian,” say the authors, led by Yale University paleontologist Peter Van Roy.

The team’s discovery “upends a long-held belief” that the Burgess Shale organisms went extinct abruptly, a summary of the study states.

“There was an anomaly in the fossil record,” states Van Roy. “Most of these animals just seemed to disappear.”

Now protected within Yoho National Park as part of a UNESCO World Heritage Site, the Burgess Shale fossil bed is considered one of the planet’s most important sites for the study of evolution.

The B.C. fossils were created at a time when the future Canadian land mass was situated near the Earth’s equator. The Burgess Shale creatures were preserved when an entire marine ecosystem was buried in mud that eventually hardened and became exposed hundreds of millions of years later in an outcrop of the Rockies.

U.S. paleontologist Charles Walcott, following reports of fabulous fossil finds by Canadian railway workers laying tracks through the mountains in the late 19th century, is said to have tripped over a block of shale that revealed the area’s remarkable supply of specimens.

Scientists have gathered or recorded tens of thousands of fossils from the site, capturing in remarkable detail the rich diversity of organisms that suddenly filled the world’s oceans a half-billion years ago, before their subsequent eclipse.

Among the imprints of animal remains excavated from the Burgess Shale is one called pikaia, an eel-like creature that has been classified as the earliest known, identifiable ancestor of modern vertebrates, including humans.

Last year, in celebration of the 100th anniversary of the site’s 1909 discovery, the limited edition Shale Ale brand of beer was unveiled at a geologists’ conference in Calgary.

© Copyright (c) Canwest News Service

The New York Times

Creatures of Cambrian May Have Lived On


May 17, 2010

Ever since their discovery in 1909, the spectacular Burgess Shale outcrops in the Canadian Rockies have presented scientists with a cornucopia of evidence for the “explosion” of complex, multicellular life beginning some 550 million years ago.

The fossils, all new to science, were at first seen as little more than amazing curiosities from a time when life, except for bacteria and algae, was confined to the sea — and what is now Canada was just south of the Equator. In the last half century, however, paleontologists recognized that the Burgess Shale exemplified the radiation of diverse life forms unlike anything in earlier time. Here was evolution in action, organisms over time responding to changing fortunes through natural experimentation in new body forms and different ecological niches.

But the fossil record then goes dark: the Cambrian-period innovations in life appeared to have few clear descendants. Many scientists thought that the likely explanation for this mysterious disappearance was that a major extinction had wiped out much of the distinctive Cambrian life. It seemed that the complex organisms emerging in the Cambrian had come to an abrupt demise, disappearing with few traces in the later fossil record.

Not everyone was convinced, however, and now a trove of 480-million-year-old fossils in Morocco appears to strike a blow to the idea of a major extinction. The international team of scientists who discovered the 1,500 fossils said their find shows that the dark stretch in the fossil record more probably reflects an absence of preservation of fossils over the previous 25 million years.

The team reports in the current issue of the journal Nature that the large number of “exceptionally preserved” Moroccan species exhibits apparently strong links to Cambrian species known from fossil beds in China, Greenland and, most notably, the Burgess Shale. The scientists think this solves the mystery. The Moroccan fossils, they said, establish that Burgess Shale-type species “continued to have an important role in the diversity and ecological structure of deeper marine communities well after the Middle Cambrian.”

The Moroccan fossils include sponges, worms, trilobites and mollusks like clams, snails and relatives of the living nautilus. Another fossil was similar to today’s horseshoe crab, a biological throwback familiar to beachcombers. Now, the scientists said, its antiquity appears to be even greater — some 30 million years earlier than previously thought, possibly in the late Cambrian.

The discovery team’s principal scientist and lead author of the journal article was Peter Van Roy, a Belgian paleontologist who is a postdoctoral fellow at Yale University. He has worked in Moroccan fossil beds the last 10 years, but it was only last year on a field trip, financed by the National Geographic Society, that he and other scientists uncovered the riches of a site near the Atlas Mountains and the city of Zagora.

Scientists from Britain, France, Ireland, Morocco and the United States participated in the research and were co-authors of the team report. A local fossil collector, Mohammed Ou Said Ben Moulal, directed Dr. Van Roy to the rock outcrops he had scouted.

Soon it became clear, Dr. Van Roy said last week in an e-mail message from Morocco, that the team had “really discovered the whole gamut of these Burgess animals, the majority of which had never been found after the Middle Cambrian.”

A leading member of the team, Derek E. G. Briggs, director of the Peabody Museum of Natural History at Yale, cut his academic teeth studying the Burgess Shale. Dr. Briggs figured prominently in “Wonderful Life: The Burgess Shale and the Nature of History,” the 1989 book by Stephen Jay Gould about what the author called the “weird wonders” of the Cambrian period.

In the book, Dr. Gould, who died in 2002, pondered the mystery of the relatively sudden burst of new life designs in the Cambrian, followed by their apparent disappearance. “What turned it off so quickly?” he asked. A few pages before, quoting Charles Darwin, he seemed to despair of finding the fossils to answer the question.

“Darwin wrote,” Dr. Gould recalled, “that our imperfect fossil record is like a book preserving just a few pages, of these pages few lines, of the lines few words, and of those words few letters.”

Darwin’s metaphor pertained to the chances of preservation for bones and teeth. So referring to the predominance of soft-body anatomies of Cambrian life, Dr. Gould asked, “What hope can then be offered to the flesh and blood amidst the slings and arrows of such outrageous fortune?”

Dr. Briggs said in an interview that scientists for some time have suspected that “we were just not finding the right deposits and only seeing a small piece of the picture of what was going on in life back then.”

For that reason, Dr. Briggs said, he expected other scientists would be less surprised by the discovery than reassured. The fossil record for a long stretch after the Middle Cambrian may be spotty and minimal, but has not vanished. The Moroccan fossils not only reveal the continuation of many Cambrian life forms, he said, but show “the high potential that there are other places for finding these Cambrian-like organisms persisting in time.”

As a consequence, the discovery team wrote, the Moroccan sediments offer promising links between the Cambrian Explosion of multicellular life, exemplified in the Burgess Shale, and the early stages of what is known as the Great Ordovician Biodiversification Event, which is considered “one of the most dramatic episodes in the history of marine life.”

This led to the emergence of fish about 400 million years ago and the migration of four-limbed vertebrates from water onto land 360 million years ago. After the catastrophic mass extinction at the end of the Permian period, about 250 million years ago, the dinosaurs came to the fore in a reptilian world, and after their extinction 65 million years ago, mammals came into their own, hominids evolving probably less than 8 million years ago, modern humans less than 200,000 years ago.

That any of these early Ordovician remains endured verges on the miraculous. Some with shells could be expected to fossilize, but most of these were soft-bodied creatures, prone to rapid decay. The Moroccan fossil beds, Dr. Briggs noted, were once the muddy bottom of an ocean. Storms stirred up the seabed, burying doomed creatures safe from scavengers and in recesses with little or no oxygen to promote decomposition. The sediment chemistry transformed iron and sulfide into pyrite, which coated and preserved the shapes of the animals, including their appendages, and mineralized internal tissue.

“The exquisite preservation of the soft anatomy,” Dr. Van Roy said, “allows more complete, accurate reconstructions of their genetic affinities and ecology than has hitherto been possible.”

Hard at work last week in the Moroccan fossil beds, Dr. Van Roy said, “I obviously intend to exploit this fantastic research opportunity to the fullest.”

Newly discovered fossil revealed as the mother of modern-day molluscs

Steve Connor, Science Editor

27 May 2010

It looks like something out of a Salvador Dali dreamscape but this bizarre sea creature, which lived about 500 million years ago, turns out to have been the mother of all squids – indeed it is the ancestor of octopuses, cuttlefish and all other cephalopod molluscs.

Scientists discovered the creature, named Nectocaris pteryx, after studying samples of fossilised rocks from the famous Burgess Shale of Canada, which provides a remarkably preserved snapshot of the weird and immensely diverse forms of life that evolved during the Cambrian period of geological history.

Nectocaris, which grew to a length of about 5cm, including its two front tentacles, is thought to have been a fast-moving predator which swam using its undulating, wing-like fins.

But crucially it could also shoot a jet of water from a funnel-like nozzle which it could swivel in various directions – a hallmark of modern-day cephalopods.

The researchers believe that this key anatomical detail, discovered by analysing 91 newly discovered fossils of Nectocaris, strongly suggests that it must be the original common ancestor of squids, octopuses and the beautiful chambered-shelled nautilus; the reason is that no other group of animals uses this form of jet propulsion.

“Our discovery allows us to push back the origin of cephalopods by at least 30 million years, to the famous Cambrian explosion about a half-billion years ago,” said Jean-Bernard Caron of the Royal Ontario Museum in Toronto.

“Soft tissues of cephalopods tend to decay quickly, so it was difficult to know what primitive cephalopods looked like. The Burgess Shale is well known for its exceptional preservation of soft-bodied animals,” Professor Caron said.

Until 500 million years ago, most life on Earth took the form of simple, single-celled micro-organisms. But during the Cambrian period it exploded into a huge variety of macroscopic, multicellular forms, with a diverse range of body architecture; some of these life forms gave rise to the major groups of animals alive today.

The cephalopods – the word means “head-feet” – are the most intelligent of the invertebrates, animals without backbones.

They have large brains, good vision and can use camouflage to hide from predators or ambush their prey. Despite the fascination they generate, scientists had been unsure of their origins, believing that they had evolved from snail-like molluscs with shells that became filled with gas to allow them to swim freely.

However, the latest study, published in the journal Nature, suggests that all cephalopods can now be traced back to Nectocaris, which shares the ability to hunt its prey using its two stalked eyes and a sophisticated system of jet propulsion, said Martin Smith of the University of Toronto.

“It’s long been thought that cephalopods evolved in the late Cambrian period, when gradual modifications to the shells of creeping, snail-like animals made them able to float. Nectocaris shows us that the first cephalopods actually started swimming without the aid of gas-filled shells,” Dr Smith said.

Modern cephalopods are very complex, with intricate organs and startling intelligence.

“We go from very simple pre-Cambrian life forms to something as complex as a cephalopod in the geological blink of an eye, which illustrates just how quickly evolution can produce complexity,” he said.

“We think that this extremely rare creature is an early ancestor of squids, octopuses and other cephalopods. This is significant because it means that primitive cephalopods were around much earlier than we thought, and offers a reinterpretation of the long-held origins of this important groups of marine animals.

“Our findings mean that cephalopods originated 30 million years earlier than we thought, and much closer to the first appearance of complex animals in the Cambrian explosion,” he added.


4 thoughts on “The Burgess Shale fossils, a Rocky Mountain treasure trove found in 1909 just west of the B.C.-Alberta border, represent the planet’s single most important snapshot of life as it existed during the so-called “Cambrian explosion” of organisms about 530 million years ago.

  1. It shan’t cease, in this lifetime, to amaze me how silly short-sighted people seek ‘history’ in the middle east and ‘aliens’ in outer space.
    When I discovered the above knowledge several years ago, it blew my mind how it was only a few hours down the highway from Edmonton. It’s just so ‘sexy’, and one doesn’t normally correlate this particular region of the world with such incredible evidence of earth’s natural history. There have been more ‘aliens’ on earth itself (including us, i might add) that we humanoids have ever CONCEIVED of in our shared stories and imaginations–Star Trek et al. In time we shall discover more and more of our curiosities and wonders sated by wandering our planet and studying the evidence–deep in the rocks at times.

  2. The divisions between geologic periods (something done quite a while ago) are in serious need of rethinking. The history of life as shown in the fossil record is inherently fractionally partial. A bit like visual navigation at periscope depth – only a small part of the visible is possible with the science we have. Simplistic pronouncements (such as all the dinosaurs died at the end of the Cretaceous, when in fact they did not) are misleading and it should be no surprise that the Moroccan finds extend the time of Burgess organisms. Why would a single site’s results in Canada be taken for globally universal? A look at the Cambrian map shows great diversity of environment and physical separation (always a plus for rapid evolution). A delightful article, well-written, and I am happy to pass it on to others!

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