Burgess Shale - Cradle of Early Life
Website Co-editor Martin Shugar (L) discusses Burgess Shale with R.O.M's Des Collins - 07/1992
Some 510 million years ago, on a shallow off-shore plateau located in what is now the Rocky Mountains of British Columbia, a legion of strange, almost other-worldly creatures ate, swam, procreated and did just about everything within their limited powers in order to survive. Possessing neither the hard outer shells of their trilobite cousins nor the size, strength or smarts to assure their continued existence, life may well have been short and not-particularly-sweet for these primitive sea-dwelling inhabitants.
One can imagine the tenuous times led by these creatures, playing hide-and-seek with predators as they darted in and out of ancestral sponge beds and under swaying crinoid stems in their attempts to simply make it through one more day. Some made it...some didn't. And even those that managed to survive attacks by the mud-dwelling carnivorous worm known as Ottoia or the fast-swimming predatory giant called Anomalocaris, may have still suffered a disastrous fate. The fossil record tells us so.
The Middle Cambrian was a time of great instability on a fast-changing planet, and underground volcanic eruptions and major earthquake activity may well have been a daily fact-of-life for the inhabitants of the earth's primeval seas. Indeed, the threat of sub-oceanic seismic activity and habitat-destroying landslides may have presented a far greater challenge to these minute and apparently fragile soft bodied creatures than all the era's predators put together. Alas, how exasperating it must have been to spend the vast majority of your short existence escaping from razor-fanged sea monsters, only to be done in by a rampaging pile of mud.
In retrospect, however, that mud was far more than merely an inconvenience to the local constituency. Without it our knowledge of the planet's primitive seas -- and of its amazingly diverse invertebrate inhabitants -- would be severely limited. Current scientific thought postulates that a vast majority of the soft-bodied specimens that we now know of through the fossilization process were at one time or another buried by mudslides -- underwater avalanches that quickly covered everything in their vicinity. By doing their dirty work so quickly and effectively, these landslides often served as natural time capsules, burying nearly the complete array of flora and fauna present within their path of destruction. Indeed, in sites like western Canada's famed Burgess Shale, virtually every other overturned rock presents some evidence of ancestral life -- perhaps a diminutive soft-bodied arthropod, most often a disartculated remnant of trilobite species such as Olenoides serratus or Ogygopsis klotzi, some with their soft appendages still preserved.
Occasionally this process of obliteration was even accomplished with a minimal degree of damage being perpetrated upon the various "specimens" trapped within that slide's suffocating grasp. Over the ensuing eons, layer upon layer of sediment slowly built up over these trapped life forms. As the pressure upon them grew, the tiny creatures -- which ranged is size from a few millimeters to perhaps ten centimeters in length and except for the trilobites, possessed no hard outer shell to provide three-dimensional substance -- were slowly transformed into little more than razor-thin films of calcium aluminosilicate, or delicately detailed blotches of mineral-rich phosphate and limonite.
How lucky for science-- and for anyone fascinated by the earth's primitive past-- that such "accidents" of nature occurred. Without them, the complex jigsaw puzzle that is our planet's earliest history would be lacking some of its most critical edge pieces. Indeed, some of these Burgess Shale soft-bodied specimens now rank among the most revered, studied and famous fossils in the entire history of paleontology.
"Soft bodied specimens like the ones you find in the Burgess Shale provide us with a spectacular and unexpected look at early ocean life forms," said Utah-based collector Terry Abbott. "The odds of any soft bodied creature becoming fossilized is extremely remote, and that is why such specimens, especially those from Burgess, have become so well-known. They are without question the most famous invertebrate fossils ever discovered -- kind of the Rosetta Stone of Cambrian history."
It seemingly wouldn't be going too far out on a limb to state that everyone, everywhere who is even remotely familiar with the fossil realm possesses at least some awareness of the Burgess Shale's renowned fauna. After all, the shale contained within this half-billion year old outcrop of the Stephen formation is home to the most legendary soft-bodied creatures in the world. Since it was first discovered in 1886 by explorers working for the Geological Survey of Canada (in association with the construction of the Trans-Canada Railway), it has enjoyed more mainstream focus and scientific study than any other invertebrate locale on earth.
Much of that interest can be attributed to the groundbreaking work of the legendary Charles Walcott, who first visited the site in 1907 and over the ensuing years found literally thousands of specimens of trilobites and soft bodied arthropods, many of which are now housed in Washington D.C.'s Smithsonian Institution. Indeed, it was Walcott's other responsibilities at the Smithsonian -- where he served as Secretary from 1907 until his death in 1927 -- that kept him away from further research at the Burgess quarry and led somewhat indirectly to the 1924 excavations at the site by Harvard's Percy Raymond. It has been estimated that the combined efforts of the Walcott and Raymond digs produced well over 100,000 fossil specimens, virtually all of animals never before seen by the eyes of science… or anyone else.
However, as is too often the case with scientifically important specimens (think of the last scene in the initial Indiana Jones movie), for the next four decades, these finds languished unstudied and virtually forgotten in a back room at the Smithsonian. It wasn't until another Harvard paleontologist, Harry Wittington, undertook his own Burgess expedition in the 1960s, that fresh attention began to be placed on these historic finds. In fact, in the wake of Wittington's efforts, the first scientific papers focused on the Middle Cambrian fossils of the Stephen Formation were published in the 1970s.
These scholarly documents confirmed that much of the Burgess fauna consisted of previously unknown creatures, many of which represented new phyla. This new research thrust the Burgess Shale back into the limelight, with detailed microscopic photos revealing soft tissue preservation that astounded both scientists and laymen alike. Even in the 21st century, on-going Burgess excavations -- these led by Des Collins of Toronto's Royal Ontario Museum -- have drawn international interest, with paleontologists coming to the hallowed site from around the world. According to Collins, in some cases, these scientists make the sojourn merely so that they can tell their students someday, that they once dug at Charles Walcott's Burgess Shale quarry.
“The allure of these soft bodied creatures is unmistakable,” said Fred Collier, formerly of the Smithsonian. “Those, along with the trilobites found at the Burgess site, tell us of an amazing time in earth history. No matter how much study is done, this period of our planet's development is just riddled with fascinating questions.”
It would almost appear as if their enigmatic origins represent a proud calling card for Burgess' legion of soft-bodied specimens. Perhaps no other paleontological finds have ever generated more debate, speculation and outright awe than these bizarre life forms. Think about it; as strange and wondrous as dinosaurs may seem, at least they possessed some elements to which we can relate -- things like skin, bones, and teeth. But some of these soft-bodied creatures were really out there! One Burgess species seemingly enjoyed the use of no less than six stalked eyes, while others "walked" on tentacles growing along their backs.
The simple fact is that the Burgess Shale has produced thousands of miraculously preserved soft-bodied specimens -- along with abundant supplies of such trilobite species as Kootenia burgessensis, Ehmaniella waptaensis and the previously mentioned Olenoides serratus -- all of which help provide a unique view of Middle Cambrian oceanic life. Such creatures as Marrella, similar to a lace-crab; Aysheia, a lobe-limbed "caterpillar"; and Hallucigenia, a bizarre multi-spined creature that still remains something of a mystery to science, have become as famous in paleo circles as the likes of Brad Pitt and Angelina Jolie have become to the Hollywood movie crowd. Yet both scientists and amateur Burgess aficionados (often forced to examine specimens exclusively through photos or during museum visits, since the Canadian government keeps a tight control on the distribution of all Burgess material -- at least those specimens found after restrictions were imposed in the mid-20th Century) remain as mystified as ever concerning the true roles that many of these unique creatures assumed during their lifetime in those ancient seas.
Due to the very nature of their soft bodies (by definition lacking the chitinous exoskeleton that may have first emerged with trilobites some 20 million years after the beginning of the Cambrian Explosion), fossilization of such creatures is extremely rare in sedimentary outcroppings world-wide. Thus the estimated 150,000 Burgess specimens that have been excavated by dedicated scientific teams in the century since Walcott's initial efforts (containing over 25,000 Marrella specimens alone) represent one of the most hallowed laggerstatte in fossil lore.
"We're just beginning to understand a little about the way these creatures may have lived," stated Abbott. ”But some of them, like Wiwaxia (which looked rather like a pin cushion), Hallucigenia and the predatory Anomalocaras are still something of a mystery. But that's part of the fun. It's truly like dealing with an alien civilization. Virtually all our traditional points of reference are thrown out the window."
Since the very beginning of Burgess study, many paleontologists have focused their efforts on trying to decipher the riddles presented by these mystifying soft-bodied creatures, only to occasionally have their initial interpretations completely overturned by subsequent discoveries. Often the work of these scientists has been dedicated to deciding within which class or phylum each of these tiny remnants of earth's earliest population explosion might best be placed. Other scholarly efforts have attempted to discover which soft-bodied species may have survived long enough to provide the rootstock for future, more sophisticated animal forms. As amazing as it may seem, recent studies have even fostered the notion that one of these delicate creatures (most likely Pikaia, a Burgess resident now assigned to the phylum Chordata and sporting what might well be the first primitive example of a "spinal column") may have played a role in the eventual emergence of vertebrates.
Today, however, other scholars have turned their attentions away from the dizzying and often controversial classification of soft-bodied material and towards an equally puzzling question -- why, and perhaps even more importantly how, this amazing array of life forms first emerged. Why did this proliferation of sea-borne activity occur after more than four billion years of Earth history -- the vast majority of which was characterized by nonexistent life or agonizingly slow evolutionary change... and how did it happen?
Earlier in the fossil record -- perhaps best exemplified in the Precambrian by the 600 million year old Ediacaran layers of South Africa -- no more than the slightest hint is offered concerning the variety or complexity of life to be witnessed with the dawning of the Cambrian. Yet a "mere" 80 million years later, the seas are literally teeming with an incredible array of sophisticated life forms. As best paleontologists can tell, rather suddenly, for whatever still-mysterious reason, just as the Cambrian era began, all the oceans on Earth seem to blossom with life.
Actually, it is this "blossoming" that signals the beginning of the Cambrian, so at least in this case it appears as if the "chicken"-- or shall we say the Wiwaxia -- comes before the proverbial egg. Yet we must wonder, from where did this proliferation of strange soft-bodied forms emanate? Did a wide range of biologically complex organisms exist prior to the dawning of the Cambrian -- organisms that never succumbed to the kind of quick-kill landslides that subsequently produced the world's best-known soft bodied fossil faunas? Did the currently fashionable "Frozen Earth" theory -- which espouses that our planet was little more than an ice world for millions of years prior to a volcanic defrosting just in time for the dawning of the Cambrian -- serve as the biological springboard for this sudden flowing of life forms?
Despite the on-going efforts of dedicated scientific crews working with Cambrian-age soft bodied material not only at Burgess, but also in China and Australia, these queries remain among the great mysteries of the paleontological world. They probably will remain so until when by either hard work or accidental happenstance, someone with enough knowledge to recognize the significance of their discovery, will stumble upon the next key to further unlocking this timeless story of mystery and intrigue. Then, and perhaps only then, will the true tale of life's soft-bodied origins begin to reveal itself in all its boneless glory.
Mount Wapta (background). Shugar holding Anomalocaris claw, one of hundreds lying on ground.
Standing on ice on The Burgess Shale in July. Hanging Glacier in background.