Oklahoma Trilobites - Devonian Delights
Black Cat Mountain Quarry, Haragan and Bois d'Arc Formations, Coal County, Oklahoma
Near the southern border of Oklahoma, tucked neatly within the surrounding Arbuckle Mountains, sits Coal County, one of 77 such counties that checkerboard the Sooner state. From the local hamlet of Clarita it's less than a two-hour drive north to Oklahoma City, and about a three-hour trek south to Dallas. But in all honesty, such sojourns may as well be measured in light years in terms of cultural outlook and attitude. Fewer than 6,000 people live in the county's 521 square mile parameters, and those who do reside within this dusty stretch of land tend to both accept and revel in their decidedly blue-collar status.
At a very different time in US history, the land that now comprises Coal County was part of the once-thriving Choctaw Nation, located in the heart of what was then officially known as Indian Territory. Obviously, much has changed about the area and its demographics since those distant days, though certain elements of Coal County seem perpetually mired in the mists of time.
As one might imagine from its name, coal mining has played a significant role in this county's story dating all the way back to when the Native American population still had a major say about the way things were done in and around these parts. The pinnacle of coal production lasted for a relatively short period of time, however, basically from 1870-1920, after which virtually all the mines seemed to ostensibly disappear. Since then, things have often been economically challenging in this part of the state, with even the county's stabs at agriculture being limited by occasional boll weevil infestations.
The fact of the matter is that just about any way you choose to look at it, not much of note goes on within this remote corner of Oklahoma… but things aren't always as they may initially appear. And if you happen to be interested in trilobites, then this arid, hilly spot of land should be a place near and dear to your heart. You see, much of Coal County sits on rich Lower Devonian limestone layers that just so happen to be filled with some of the best-preserved trilobites in the world.
One of the fortuitous by-products of the extensive digging that occurred in the state more than a century ago was that during the process of excavation, a number of promising fossil locales were uncovered. The resulting finds included everything from Triassic-age dinosaur deposits to the region's impressive array of Devonian trilobite outcrops. In all honesty, few if any of these sites were properly explored at the time, but by the mid-years of the 20th Century, a number of intrepid souls had begun to more fully investigate the state's fossiliferous holdings.
What these explorers quickly discovered was that both the 417 million year old Haragan and the closely aligned Bois D'arc Formations were heavily represented in this area. They also noted that the formations offered a wonderfully detailed look at a diverse Devonian fauna that presented compelling evidence of a thriving off-shore community. The sedimentary layers were brimming with bryozoans, bivalves and brachiopods as well as trilobites, all perfectly preserved within a finely grained limestone matrix.
Slowly but surely, more awareness of this material started to filter through the paleontological community, and by the 1960s scientists working at the University of Oklahoma's Sam Noble Museum had launched their own preliminary investigation into the layers. These efforts revealed fragmentary evidence of such trilobites as Dicranurus hamatus, Huntonia lingulifer, Ketternaspis williamsi and Kainops deckeri. Despite these initially promising results, however, it would take another 20 years before the proper degree of attention began to be paid to the trilobites of Oklahoma.
Indeed, perhaps the most significant figure in the further development of the area's trilobite “industry” proved to be a fellow named Bob Carroll, who for the last three decades has diligently worked these famed formations located deep within Coal County. Each year Carroll spends countless hours from early March until late October laboring outside in the harsh elements that too-often sweep through the 20 acres of leased quarry land that surround his home near Clarita.
There, upon what has become known as Black Cat Mountain, he carefully breaks apart layer-upon-layer of the formation's characteristic, pale yellow rock in search of the caramel-colored calcite remnants of his often elusive Paleozoic prizes. Then after finding a requisite number of cross-sections of what he hopes will be complete trilobites, he will retire to his on-location prep lab, gazing through his high-powered binocular microscope until he has artistically transformed the best of his various fossil finds into some of the most intricate and desirable trilobites ever found… anywhere.
“People see the finished product of my work, but they usually don't even consider the amount of time and labor that goes into finding and then cleaning even the smallest trilobite,” Carroll said. “I love what I do, but it can also be very frustrating. I'm a perfectionist when it comes to my trilobites, so sometimes I think I'm working on what will turn out to be a great specimen, and then when I'm about 90 percent done, I'll find that a genal spine will be missing, or the pygidium will be slightly disarticulated. It can really piss me off. But even the ones that I think aren't perfect, people really do seem to like.”
There's good reason that over the last 30 years the trilobites emerging from Black Cat Mountain have created a veritable “feeding frenzy” among those who collect and study trilobites. With their lifelike preservation, golden color, free-flowing spines and intricate surface textures, these ancient relics are beautiful enough to be the star attractions in just about any major museum exhibit or private trilobite display.
In addition, the information gleaned from Carroll's on-going work has been more-than-sufficient to continually amaze paleontologists from London to Los Angeles. Prior to Carroll's efforts, rarely -- if ever -- were complete trilobites featuring the bizarre morphology seen in the “ram horned” Dicranurus hamatus, the big-eyed Reedops deckeri and the spinose Ceratonurus sp. available for scientists to examine. And even paleontologists who garnered their doctorate degrees upon the study of incomplete, surface-collected specimens will admit that partial material can only offer tantalizing hints regarding a trilobite's true tale. Once Carroll began full-scale operations in the heart of Coal County back in 1986, however, it became almost immediately apparent that not only would his quarry produce an amazing array of never before seen trilobite species, but that it would produce them in both quality and abundance.
Carroll won't even hazard a guess as to how many examples of each of the more than 20 different trilobite species from the Haragan and the Bois D'Arc he's discovered and prepared over the last three decades. When pushed on the subject, he surmises that he's “probably found thousands” of the quarry's most common trilobite, Kainops raymondi, and he admits that he's prepped more than a hundred complete examples of each of the two types of Huntonia (recently changed, for whatever reason, to the less trippingly-off-the-tongue Huntoniatonia) that inhabit Black Cat Mountain.
This numbers game gets a lot easier for Carroll when he begins to focus his attentions on the quarry's truly rare species; there have been perhaps a dozen complete examples found of the diminutive lichid Acanthopyge consanguinea, and only a handful of the small, circular Breviscutellum oklahomae… while there's been but a single complete example of the spectacular one-inch long spiny odontopleurid, Laethoprusia sp.
“Finding that Laethoprusia was one of the highlights of my collecting life,” Carroll said. “It's kind'a small, so there was a good chance that you could miss it. But I'm glad I didn't. There's still a species of large lichid that I've been finding pieces of for years, but I've never found anything near complete. Every time I break a rock I'm hoping to find something really special, but to be honest, I'm pretty happy with anything I find.”
Somewhat ironically, at virtually the same time that Carroll was beginning operations at Black Cat Mountain in the mid-'80s, equally rich Devonian trilobite reserves of almost the exact same age were being discovered more than 5,000 miles away in the Atlas Mountains of Morocco. Back almost 420 million years ago, what is now Morocco was part of the land mass known as Gondwana, while present-day Oklahoma was attached to the continent of Euramerica -- both of which then existed in relatively close geographic proximity, on similar equatorial latitudes and presented almost identical marine environments.
Thus the fact that many similar trilobite species (including Dicranurus, Ceratonurus, Phacops and Breviscutellum) lived, and apparently thrived, in both locales would seem far from surprising. Yet, the similarities between the trilobite fossils found in these two now-disparate localities -- though the Moroccan material is generally preserved in a black calcite -- is something that continues to amaze even the most seasoned collectors. This Paleozoic confluence also serves as a comfort to scientists who believe that this rock-hard fossil evidence confirms their confidence in such foundational geologic concepts as continental drift and plate tectonics.
In all honesty, while Carroll finds such scientific discourse to be interesting, it's far removed from what motivates him to get out into the field each morning. In the eyes of his many admirers, Carroll is more of an artist than a scientist, one of the few fossil preparators who have taken the job of cleaning trilobites to new levels of virtuosity and craftsmanship. He, perhaps more than anyone else, has helped put the tiny town of Clarita, Oklahoma on the map of significant trilobite localities.
Of course, true to his nature, Carroll will quickly shrug off such praise with an off-handed “thanks” before adding, “I'm just doing the best I can. Hey, this is what I do for a living.”
Overburden strata in Bob Carroll's quarry