Bolivian Trilobites - At The Top Of The World
Trilobites were perhaps the most cosmopolitan of Paleozoic inhabitants. During their 270 million year span of existence -- which ran from the Early Cambrian until the end of the Permian -- they managed to occupy just about every ocean-covered corner of Planet Earth. From warm tidal estuaries to cool continental shelves, trilobites proved themselves to be among the most adaptable and successful animal classes in history. And while our planet looked quite different in terms of its continental alignment during the Age Of Trilobites, the worldwide dispersal of their fossilized remains has done much to support current scientific notions surrounding the amazing range once enjoyed by these ancient arthropods.
Trilobites have been discovered just about everywhere that sedimentary outcrops of the proper age occur, from the steep cliffs of California's Marble Mountains, to the rolling hills of central China, to the flat plains of Oklahoma, to the rugged depths of Russia's Wolchow River valley. For scientists and collectors, however, even within this planet-spanning spread of fossil bearing strata, a select number of trilobite-rich locations-- whether due to the unique preservation of their fauna, the diversity of their specimens, or the inhospitable nature of their locale-- stand apart from the rest.
Certainly one of the most intriguing, and out-of-the-way spots ever to yield a treasure-trove of trilobite remains is located in the dry, desert-like altiplano located in the outskirts of La Paz, Bolivia. There, high up in the Andes Mountains at the breathtaking altitude of over 12,000 feet above sea level, in a variety of formations that include the Sica-Sica, Belem and El Carmen, rich outcroppings of Devonian-age trilobites have been found… specimens that emerge from their ancient burial grounds contained within small limestone concretions (usually no more than three inches in length) that when carefully cracked open, occasionally reveal positive/negative remains of outstanding preservation and detail.
“Bolivian trilobites enjoy a rather unique form of fossilization,” said Juan Colon, who has prospected for South American trilobites for over a decade. “While we do know of concretion-encased trilobites from other parts of the world-- especially Morocco-- the fact that virtually ALL the trilobites found in those South American formations are preserved in that manner is very unusual. But even after you find them -- which is far from easy considering that only a small fraction of the nodules you uncover may actually contain complete trilobites -- you need to be very skilled in order to break the concretion properly and reveal the contents.”
For many years virtually all that we knew of these unusual, three-dimensional South American trilobites was drawn from specimens sold at local markets by indigenous Bolivian merchants. At various times throughout the 20th Century, the occasional scientific expedition had explored the fossiliferous deposits that dot the La Paz area. But the inaccessibility of the terrain, the effort and expense required to assemble a paleontological team ready to travel to such a distant outpost, as well as the inherent difficulties of collecting at such a sky-scraping altitude, made trilobite specimens gleaned from these outings rather rare.
Yet, at the same time, it was possible for travelers to this out-of-the-way corner of the world to stroll down a back alley in La Paz and find trilobites for sale -- often for pennies -- on street corners or in local shops. There, lying amid an array of colorful native handiworks and for-tourists-only oddities, could often be found a dizzying display of Devonian relics. Many were partial specimens, lacking either their cephalon or pygidium, while other available examples were of the most commonly-found trilobite species. But on occasion, through luck or sheer persistence, true trilo treasures could be found.
What the more curious of these visitors to La Paz soon found out was that for decades -- if not centuries -- industrious local inhabitants had been exploring the surrounding hillsides, looking for the small, mud-colored concretions that had weathered out of the rock. While most of these discoveries would invariably prove barren, on occasion they would yield 370 million year old fossils, sometimes of crinoid parts, occasionally of a conularid or brachiopod, but predominantly of unique trilobite species. Though almost always unidentified at the source, these specimens would subsequently reveal themselves to include such trilo-types as Dipleura boliviensis, Maurotarion legrandi, Viaphacops orourensis, Eldredgia venustus, and Acanthopyge balliviani.
In a particularly poor region of a generally impoverished nation, these locals quickly discovered that there was a true hunger for their finds, both from visiting scientists and among tourists from around the globe. By the 1970s, as many as a dozen trilobite “hunters” would traverse into the surrounding hills on a daily basis in search of Paleozoic treasure. And whether their discoveries were marketed to those who viewed them as true paleontological resources or merely as native-generated curios, until the mid-'80s, when the area's drug trade started to transform the culture, the lifestyle and the economic welfare of the nation, La Paz' rich fossil formations stood as one of the local inhabitant's primary financial resources.
“It was very important work,” said Colon. “The trilobites they found -- along with work done by a few intrepid explorers from outside who truly cared about the fossils themselves -- was more than enough to start drawing serious scientific interest in the direction of Bolivia.”
For some scientists, the finds emanating out of the La Paz region have proven to be nothing less than a fossil bonanza. Indeed, judging by the quantity, quality and diversity of the specimens derived from this locale, it's easy to understand why time-and-time again, these trilobites have drawn academics back to this wayward spot on the Bolivian landscape. As it turns out, many of the trilobite species found in the area's various formations are indigenous only to these outcroppings, with their unique status apparently due to a number of factors -- perhaps most importantly, the geographic position held by what is now the high altiplano back in the Devonian.
During that period, much of what is now Bolivia was under water, and the off-shore continental shelves of what would eventually emerge as South America had become separated from similar shallow sea environments to the north for the first time in tens-of-millions of years. Over time, this degree of oceanic isolation -- along with occasional dramatic shifts in climate -- provided the opportunity for new trilobite species to emerge… an opportunity apparently seized upon with considerable relish by the area's arthropods. The Devonian also bore witness to a dramatic rise in sea levels -- after a lengthy period of diminishing levels throughout the preceding Silurian -- eradicating certain prime trilobite habitats, while simultaneously creating new environments within which new species could develop and thrive.
“When you first see the trilobites from Bolivia, you may not be that impressed,” Colon said. “When compared to many specimens coming out of Russia or Morocco they seem somewhat unexciting -- rather drab in color and unspectacular in size. But when you start to examine them more closely, and note their individual characteristics and unique qualities, you begin to understand that these trilobites come out of what may be some of the more important Devonian deposits in the world."
The fact is, that the unique characteristics exhibited by the trilobites of the Sica-Sica, Belem and other neighboring Devonian formations have inspired important scientific work, with the world-renowned paleontologist Dr. Niles Eldredge of the American Museum of Natural History doing extensive research on the area's phacopid and calmonid species. His published studies revealed previously unknown and unimagined details of trilobite morphology and lifestyle, while presenting fascinating insight into the evolutionary relationships between varied trilobite types.
In fact, his widely-hailed work with Bolivian trilobites proved vital in supporting his theory of Punctuated Equilibria (co-authored with the late Steven J. Gould), which first postulated the fits-and-starts nature of evolutionary change. While many previous hypotheses had presented the notion that evolution was a slow and steady process, with change happening at more-or-less constant intervals throughout a particular species' lifespan, Punctuated Equilibria put forth the rather radical concept that most species would exist in a state of relative calm, or stasis, for perhaps millions of years before various environmental pressures would force them to change over a relatively brief period of time.
“The Devonian faunas of the Southern Hemisphere have been studied sporadically since the mid-19th Century,” Eldredge stated in his landmark work, Calmonid Trilobites of the Lower Devonian of Bolivia.“But the basic descriptive analysis of the fauna was far from complete. Then in 1972, LeGrand Smith, then of La Paz, visited the American Museum of Natural History and donated trilobite specimens of what would be later described as Legrandella lombardii. Smith became a catalyst for much of the scientific work that followed.”
Eldredge's pioneering work on Bolivian trilobites in the mid-'70s attracted more scientific attention than ever to these distant outcroppings. Yet visitors to La Paz -- at least those with a primarily paleontological agenda -- remained few and far between. One of the more noteworthy of these visitors was the aforementioned LeGrand Smith, a minister from North Carolina, who while living in the La Paz region in the late '60 and early '70s did much to discover and introduce the area's varied Devonian-age trilobite fauna to the scientific community.
The fact is, however, that visiting any of Bolivia's trilobite-bearing formations on one's own has always presented a daunting, if not impossible challenge due to both the area's inaccessible location and the lingering dangers created by local drug lords. Yet, at certain times over the last three decades -- despite a number of growing government restrictions surrounding the exportation of their nation's natural resources -- a steady flow of top-quality Bolivian trilobites have managed to infiltrate the world's fossil market.
In recent years a new generation of fossil diggers has started to bloom in and around La Paz. Many members of this “new breed” have begun specializing in marketing the unique fauna presented within the area's Devonian formations, utilizing the internet to instantly present their latest discoveries to an international clientele. These businessmen have requested and received government permission to market their product, and by doing so, they've helped establish Bolivian reputation as a world-class outlet for trilobites.
Even a casual internet search will reveal prime examples of such rare Bolivian trilobites as Wolfartaspis cornutus, Malvinella Buddae and Bouleia dagincourti available for sale. But with more and more restrictions now being placed upon digging for paleontological treasures in and around La Paz (with many of the nation's stringent archaeological laws now being shoe-horned to carry over to the fossil realm), it would appear that many of these specimens might soon find themselves once again in short supply.
However, no matter what may happen to the availability of these South American trilobites in upcoming years, the window they have already provided to their long-gone Paleozoic kingdom has proven to be of incalculable value to both collectors and scientists around the globe. Even as recently as a few years ago, many paleontologists never would have imagined that they would be presented with the opportunity to encounter the diversity and abundance of Bolivian trilobites that has been their recent good fortune. Clearly, these ancient arthropods drawn from the fossil-rich soils of the sky-high altiplano remain more-than-enough to take any trilobite enthusiast's breath away.
“Bolivia has established itself as one of the truly unique -- and singularly important -- trilobite locations in the world,” said Colon. “The specimens themselves are beautiful, and they've already yielded some very important scientific information… with much more apparently still to come.”