The Jurassic Shield

Some dinosaurs are better at hiding than others. There’s no single reason for their edge. Some were rare. Others too small to gain much notice from the paleontologists who were set on finding large, imposing specimens for museum centerpieces. Still more became preserved in slices of rock that haven’t gained the attention of the most famed quarries. Whatever the reasons, though, a big, heavily-armored dinosaur was able to escape the notice of paleontologists despite over a century of Jurassic exploration.

North America’s Morrison Formation is a fossiliferous wonderland. Spectacular bonebeds dot its reach from Canada to Mexico, and it was one of the focal points for the great Bone Wars between O.C. Marsh and E.D. Cope in the late 19th century. Apatosaurus, Allosaurus, Camarasaurus, Diplodocus and more were the products of that feud.

Strangest of all was Stegosaurus – a 30-foot-long quadruped with a tiny head, flashy plates along its back, and a set of four spikes jutting from the tip of its tail. Marsh named the bizarre animal in 1877, and ever since Stegosaurus has held the banner for the plated, spiky armored dinosaurs that were eventually replaced by ankylosaurs.

Often thought of as Cretaceous creatures, ankylosaurs were low-slung dinosaurs bore dense coverings of osteoderms from snout to tail, giving them greater protection from the teeth and claws of the predators they evolved alongside. It seemed they were the improved successors of the stegosaurs, taking over the same niche of prickly browser in the same places, but the tale isn’t so clean cut. Ankylosaurs were already present when Stegosaurus was trundling around, 150 million years ago.

I was hoping to get an up-close look at one of these early ankylosaurs as I sat down to work the edge of eastern Utah’s Hanksville-Burpee Quarry in the late May heat. Last year, while scratching away in the spot I selected, a McLennan Community College student uncovered a set of rounded osteoderms. The Jurassic skin bones gave away the dinosaur almost immediately. The student had uncovered the first signs of an ankylosaur in the quarry. It seemed a good bet that there’d be still more waiting in the Morrison Formation’s coarse sandstone, and I got the ok from expedition lead Scott Williams to try for more ankylosaur.

Mymoorapelta at the Dinosaur Journey museum in Fruita, Colorado.
Mymoorapelta at the Dinosaur Journey museum in Fruita, Colorado. Photo: Brian Switek

Up until 1994, no one expected that an ankylosaur would be found in these rocks. The Morrison Formation had been frequently prospected and excavated by generations of paleontologists. All the same, while working in western Colorado’s Mygatt-Moore Quarry, paleontologists found bones that were unquestionably ankylosaur. Jim Kirkland and Ken Carpenter named it Mymoorapelta maysi, and, along with a later find dubbed Gargoyleosaurus, the dinosaur pushed the age of North American ankylosaurs back into the Late Jurassic.

Once paleontologists knew what to look for, Mymoorapelta started turning up at other sites. It’s a rare dinosaur, but so far it has been found in at least seven different localities within the Morrison Formation. The Hanksville-Burpee Quarry, excavated by the Burpee Museum of Natural History, is the latest spot Mymoorapelta has appeared.

I had done some prep work on a big ankylosaur osteoderm before, but I had never found the remains of one in the field. I would have been happy to find any bone – the quarry is brimming with the bones of Jurassic celebrities – but I was really hoping for some armored dinosaur. Given that the 11-foot-long ankylosaur had curved shoulder spikes and rounded scutes pebbling its body in addition to the limbs, vertebrae, and other bones that come standard in a dinosaur, I was hoping that skeletal statistics would be in my favor.

But excavation can’t be rushed. The dinosaurs of HBDQ have been waiting for about 150 million years. I figured that they could be patient as I carefully applied an air-powered microjack to the pebbly sandstone, watching every grain fly off the surface in the hope that it’d reveal pale bone. The quarry is so dense that it didn’t take long before the first piece of skeleton started to peek out of the sand, but what was it? Field identification is tricky, and often initial guesses turn out to be wrong. I decided to leave it as “bone” as I tried to excavate around the fossil to find its full extent.

The trouble was that I kept finding bones. It became impossible to uncover one without running into another unidentified piece. They were almost as pale as the surrounding sand, meaning that I had to hold my face so close to the sediment that I had to occasionally snort out the sand the airscribe sent flying up my nostrils.

A little bit of bone armor, likely from Mymoorapelta. Photo: Brian Switek.
A little bit of bone armor, likely from Mymoorapelta. Photo: Brian Switek.

By the second-to-last day, I had a set of at least six little mystery bones. They were not limb bones, ribs, or skull pieces. “Vertebrae” was my best guess, but of what? That’s when I found the cutest scute I’ve ever seen. It looked like nothing more than a little sliver of white bone. I figured it was just a weathered bone shard, a broken piece that had been rounded as it tumbled along with the pebbly sand that buried it. I popped it off its little Jurassic perch with my awl in the expectation that it was set for the “frag bag”, but when I turned it over I saw a little keel coming up to a point. This was a tiny piece of armor that was once carried in the skin of an armored dinosaur. What the other bones turn out to be will have to wait for preparation and identification in the lab, but I could leave the quarry content that I had found my Mymoorapelta.


Foster, J. 2007. Jurassic West. Bloomington: Indiana University Press. pp. 119-120, 215-216

Kirkland, J., Carpenter, K. 1994. North America’s first pre-Cretaceous ankylosaur (Dinosauria) from the Upper Jurassic Morrison Formation of Western Colorado. BYU Geology Studies. 40: 25-42

Museum of Western Colorado Unearths a Jurassic Record-Breaker

Apatosaurus was an enormous dinosaur. That’s something easily said, but can’t be understood without spending time in the shadow of the sauropod. To read that adult individuals of the Jurassic dinosaur reached lengths of 75 feet and had a heft of 16 tons is one thing. To actually be in the presence of those old bones – to see the parts of your own body totally dwarfed by those of the extinct herbivore – is quite another. So I can only imagine the awe paleontologists and volunteers at the Museum of Western Colorado felt as they excavated the largest Apatosaurus leg bone yet discovered.

Museum volunteer Kay Fredette found the first signs of bone poking out of the rock that would lead to the femur in western Colorado’s Mygatt-Moore Quarry. The site, overseen by the Bureau of Land Management, is a Jurassic treasure trove that contains the bones of dinosaurs who went for a drink and instead met their doom.

Julia McHugh, the new Curator of Paleontology at the Museum of Western Colorado, likens the site to “a watering hole in the African savanna.” The quarry’s geology is a major giveaway.

Like other Late Jurassic bonebeds scattered across the American west – such as Dinosaur National Monument, the Cleveland-Lloyd Dinosaur Quarry, and the Hanksville-Burpee Dinosaur Quarry – the Mygatt-Moore Quarry is in the upper part of the Morrison Formation, but with dinosaur bones scattered through a gray shale rather than the tough sandstone of other boneyards. Along with abundant plant material and the orientation of the bones, McHugh says, the shale suggests that the site was once “a continually wet seasonal pond.”

Allosaurus, the most common carnivore in the Late Jurassic of western North America. Photo by Brian Switek.
Allosaurus, the most common carnivore in the Late Jurassic of western North America. Photo by Brian Switek.

The refreshing pool was a major dinosaurian attraction. “We have a lot of animals drawn to this pond to drink water, to eat plants,” McHugh says, “and Allosaurus and other predators were feeding on the herbivores.” That would explain the fact that most dinosaur bones found at the quarry are isolated elements attributed to Apatosaurus, with Allosaurus as a close second, not to mention the toothmarked bones that testify to theropod feeding.

But Mygatt-Moore bones aren’t found articulated with other elements. This isn’t a place to find intact skeletons. Water and dinosaur depredations broke up the bodies. The Mygatt-Moore Quarry, McHugh Says, is an “accumulation of bone that’s been broken up, disassociated, that’s been fed on, trampled down into the mud, and piled up. It’s a far cry from what people see in Jurassic Park.”

So when Fredette found the first signs of the huge femur in the summer of 2010, the fossil looked like an isolated and unremarkable Apatosaurus bone. Although what the paleontologists had discovered wasn’t immediately clear. Initially, McHugh says, the team thought the element was a vertebra – notoriously difficult to excavate due to their delicate anatomy – “and the first reaction was ‘Oh no, not another vertebra!'” But as Fredette and volunteer Dorothy Stewart excavated around the bone they found that this wasn’t part of a dinosaur’s backbone, but a femur. This was the thigh bone of one of the biggest animals to ever walk the Earth.

Museum of Western Colorado field crew readies the Apatosaurus femur for extraction. Photo courtesy the Museum of Western Colorado.
Museum of Western Colorado field crew readies the Apatosaurus femur for extraction. Photo courtesy the Museum of Western Colorado.

It took the museum field crew five whole summers to uncover the whole extent of the Apatosaurus bone. When finished, the femur measured six feet, seven inches in length. There isn’t another Apatosaurus femur that can match it.

“The next closest we have is a reference to a six foot long femur” from another Apatosaurus, McHugh says, making the Mygatt-Moore specimen the largest known. And since paleontologists know Apatosaurus from relatively complete skeletons, as well as the relationship between the animal’s femur size and total length, McHugh and former Museum of Western Colorado paleontologist John Foster estimate that their big Apatosaurus stretched between 80 and 90 feet in length.

Removing such a massive bone is a monumental challenge. For starters, the excavators kept running into more bones as they worked to create a trench around the bone. The quarry is a “jackstraws pile” of bone, McHugh says, noting “We had to take out three other jackets just to get the femur ready.”

That was the easy part. The bone was so massive that the museum had to create special wooden struts to keep the bone from twisting during transport. “We literally built a ladder and plastered it into the jacket,” McHugh says, which kept the bone stable as a backhoe from the City of Fruita Public Works tugged the block out of the quarry and placed it onto a truck last week. The whole operation went smoothly. “It was really quite a dream roll,” McHugh says.

The crew weighed the truck before and after the jacket was placed on. The total weight – bone, rock, wood, plaster, and all – was 2,800 pounds.

Whether or not there’s more of the giant in the quarry is a mystery.  A lower leg bone of about the right size to match was found near the femur, McHugh says, but so far the quarry hasn’t turned up any parts that can be definitively attributed to the same dinosaur. “We think we have an isolated femur,” McHugh says, and the calling card of another dinosaur in the same jacket might explain why that’s so. “When we flipped the jacket over and put it in the trailer,” McHugh says, “there was an Allosaurus tooth in the bottom mud.” What may be the largest Apatosaurus ever, preserved in rock for 150 million years, comes down to us as leftovers.

Digging Eastern Utah’s Dinosaur Logjam

Dinosaurs are supposed to be remote. Documentaries and paleontological memoirs revel in the quest to dig them out of the badlands – the further into the desert the fossils are, the more romantic the tale.

But that’s not the story of the Hanksville-Burpee Dinosaur Quarry. This is a dinosaur graveyard anyone can get to.

I’ve only been out at the Late Jurassic quarry for a day now. I expect the rest of the week to start like today, with a jarring dawn chorus of squawking avian dinosaurs around 6AM, shortly followed by the camp’s groundskeeper walking by my tent to water the lawns behind the nearby steakhouse. Add warm showers across the parking lot, and this is the height of luxury for fieldwork.

The quarry itself is a half hour drive away. The first ten minutes are on Hanksville, Utah’s main drag, past dinosaurs made out of car parts and a dilapidated rock shop to a quick turn onto the unmarked Cow Dung Road. That’s when the drive gets interesting. The dirt track weaves and dips through the purple, gray, tan, and maroon rocks of the Late Jurassic Morrison Formation. The hills and gulleys are so otherwordly that the Mars Desert Research Station thought it was the perfect place to simulate the red planet.

A junkyard dinosaur on Hanksville's main drag. Photo by Brian Switek.
A junkyard dinosaur on Hanksville’s main drag. Photo by Brian Switek.

I’ve yet to stop along the way to reenact Barsoom tales. I’m always too excited to get to the dinosaurs scattered by the dozens through the Hanksville-Burpee Quarry. Locals knew about the site over a century ago, and paleontologists poked around during the mid-20th century, but it wasn’t until 2007 that the Rockford, Illinois’ Burpee Museum of Natural History started to dig in and realize how rich the site really is. Their team has uncovered scores of bones over the past seven years, most of which belong to juveniles of the sauropod dinosaurs Diplodocus, Camarasaurus, and Apatosaurus.

Sauropods are only part of the story, though. Early on, the Burpee crew excavated what seems to be a Ceratosaurus – a carnivorous dinosaur with three horns – and just last year they retrieved an Allosaurus braincase. Armored dinosaurs wound up in the 150 million year old jumble, too. In addition to a possible Stegosaurus, the crew has also just started to uncover a rare Late Jurassic ankylosaur.

What assembled all these dinosaurs? No one yet knows. The Hanksville-Burpee Quarry is still in the early days of excavation. How the bonebed formed, and why it holds an unusual mix of dinosaurs, has yet to be determined by expedition leader Scott Williams and his crew. But the project is making plans to find out. Stony Brook University sauropod expert Mike D’Emic joined the team this year and started cutting bone sections to take back to the lab and investigate how the young sauropods were growing. In time, the biology and ecology of this special place will come into focus.

But I’m here to dig. For the next week I’ll be picking and brushing at the bonebed to carefully reveal as many new dinosaur bones as I can. (I hope I can do better than last year.) You can follow my finds each day on Twitter and Instagram with the #HBQ2014 tag, I’ll write a wrap-up when I get home, and, if you like, you can come out and see the site for yourself.

For the rest of the week, until Saturday, the quarry will host daily public tours at 11AM, 1PM, and 3PM. A sign at the Cow Dung Road turnoff will point the way. I hope those of you nearby can come and take a look. The Bureau of Land Management and Burpee Museum of Natural History are working hard to preserve and understand this site for the benefit of everyone, scientists and the public alike, befitting a fantastic quarry that forms a part of our planet’s awesome backstory.

Come See an Allosaurus Excavation in Action!

It’s the time of the year for dinosaurs. As the weather warms and the days grow long, paleontologists strike out across the west in search of fossils ready to be exhumed from their Mesozoic tombs. I spend as much time as I can among the outcrops, too, and this year I’m especially excited about volunteering at an exceptionally-rich Allosaurus bonebed.

Eastern Utah’s Cleveland-Lloyd Dinosaur Quarry has yielded the remains of over 46 individual Allosaurus of various ages and sizes, not to mention bones from other dinosaurian contemporaries. But why Allosaurus should be so abundant in this one place is a mystery, and University of Wisconsin-Oshkosh paleontologist Joe Peterson has been returning to the site for several years to dig up new clues about the 150 million year old grave.

The active Cleveland-Lloyd Dinosaur Quarry bonebeds are kept safe beneath these buildings. Photo by Brian Switek.
The active Cleveland-Lloyd Dinosaur Quarry bonebeds are kept safe beneath these buildings. Photo by Brian Switek.

I was lucky enough to spend a day at the quarry with Peterson and his crew last summer. (A dream come true, especially given that the remains at the quarry inspired my science ink.) Now I’m going back for a week of scraping away at the Jurassic jumble. Both Peterson and I will be sharing updates from the field on Twitter with the hashtag #CLDQ2014, and I’ll post a summary of the trip sometime after I return, but there’s another option for those in the beehive state. If you’re intrepid enough to drive out to the site this week, you can see the excavation in action.

About an hour outside of Price, Utah, and one of the many stops on the Dinosaur Diamond Scenic Byway, the Cleveland-Lloyd Dinosaur Quarry is run by the Bureau of Land Management and open to the public. If you’re in Utah and have the time, you can drive right up to the visitor center and pop down to the quarry to see Peterson’s crew and I digging away at the exposed bonebed from Monday to Friday. You’ll want to call ahead to check the quarry’s operating hours, but if you’ve ever wanted to see dinosaurs as they’re coming out of the ground, this is your chance.

Chasing After Allosaurus

A little more than a year ago, in the corner of a Salt Lake City tattoo parlor spattered with sci-fi ephemera and fantasy art, I watched as artist Jon McAffee inked an Allosaurus onto my arm. The bloody art was a celebration of a dream realized and a promise to myself.

The giant, sauropod-rending theropod Allosaurus is the state fossil of Utah, and a symbol of why I transplanted myself to the state. I moved west for the dinosaurs. But the tattoo represents more than that. I’m not content only writing about dinosaurs. I need to seek them out; to dig them from their resting places and contribute something to our understanding of prehistory. Allosaurus – the most common terror of 150 million year old Utah – was at the top of the list of the dinosaurs I wanted to meet among the badlands.

I had coaxed dinosaurs from rock before I was artistically scarred, and spent much of the summer of 2012 continuing my search. But I was always in the wrong rocks to find any trace of Allosaurus. I scuffed over and scratched at the 220 million year old Triassic rock of Utah and New Mexico – early dinosaurian days when their kind was small and had only a marginal role in the habitats in which they lived – and ambled over the 75 million year of strata of Grand Staircase-Escalante National Monument, searching sections of stone that record a profusion of non-avian dinosaurs near their Cretaceous curtain call. These exposures were far too early and too late, respectively, to contain any sign of allosaurs or any other of my Jurassic favorites.

For my third western summer, I resolved to get to the Jurassic. I had to. Besides being the heyday of dinosaur giants, I had developed a growing affection for Allosaurus. The “different reptile” has often been treated as a lesser predecessor of Tyrannosaurus, a mere shadow of the bone-crushers that would come later. Yet rare specimens suggest that Allosaurus reached sizes comparable to the more celebrated Cretaceous carnivore, and the abundance of their remains in Jurassic rock hinted that Allosaurus were quite successful and formidable predators of their time. I wanted to find one. So during a lull in my June schedule, I signed up to help pull a few more bones out of a Jurassic-age bonebed in the alien landscape outside Hanksville, Utah. The site was dominated by young sauropods – little long-necked herbivores of the Apatosaurus sort – but at least I’d be in the right temporal territory to stumble across some sign of Allosaurus.

But not long before I was due to strike east for Hanksville, I got an email from Bureau of Land Management paleontologist Mike Leschin. Would I be interested, Leschin asked, in visiting the Cleveland-Lloyd Dinosaur Quarry to see new excavations run by University of Wisconsin Oshkosh researcher Joe Peterson? I tried to keep the exclamation points in my response to a minimum. Not only is Cleveland-Lloyd another Jurassic mass burial tucked within the cracked and colorful exposures of Utah’s San Rafael Swell, but the site is totally dominated by Allosaurus.  Based on bare bones, a minimum of 46 Allosaurus of different ages were entombed here, and that’s only counting the fraction of the site that has been exposed to date. Yes, I replied to Leschin and Peterson; I’d be delighted to drop in at the CLDQ.

I had seen the historic quarry’s bones before. Last November, for a behind-the-scenes event at the Natural History Museum of Utah, I stood in front of a long row of cabinets carefully piled with the distinctive black bones of Cleveland-Lloyd so I could show off some Allosaurus jaws to visitors. Most of these bones were collected over decades of sporadic work by different institutions. The University of Utah was the first to work the site, pulling about 800 bones from the sandstone in 1927, and was followed by a Princeton University team that extracted a further 1,200 fossils between the summers of 1939 and 1941.

Ultimately, the UU purchased the Princeton collection and re-opened the site during the 1960s, upping the collected total to over 10,000 bones from this single site. With the efforts of paleontologist James Madsen, Jr. and others, the dinosaur graveyard became a National Natural Landmark in 1965. More than that,  Madsen used the slew of bones in the UU collections to eventually write the definitive monograph on the anatomy of Allosaurus fragilis, and casts created from Cleveland-Lloyd bones became the definitive image of the dinosaur. When artist Glendon Mellow went about designing my Allosaurus tattoo, he went to the Royal Ontario Museum to study a reconstruction based on bones from the eastern Utah quarry.

A reconstruction of Allosaurus menaces visitors to the CLDQ visitors center. Photo by Brian Switek.
A reconstruction of Allosaurus menaces visitors to the CLDQ visitors center. Photo by Brian Switek.

Other teams have picked at the site on and off through the years, and other dinosaur species have been found there. (The Ceratosaurus that joins the Allosaurus on my arm, for instance, is based on specimens found at Cleveland-Lloyd, and the small carnivores Marshosaurus and Stokesosaurus were described from material first found in the deposit.) Yet, despite the wealth of fossils in the boneyard and the persistent mystery of why any one place should be so rich in Allosaurus, the Cleveland-Lloyd quarry has often been forgotten or neglected. Perhaps, as had for so long been the case with the Hanksville-Burpee quarry further south, the familiarity of the Late Jurassic dinosaurs enclosed within the rock failed to spark the interest of researchers who were out to find new species from other ages.

But I couldn’t wait to join Peterson’s group. I had driven out to the quarry once before – on a sweltering June afternoon last summer – to see the recently-built visitors center and the exposed bones inside a small metal building propped up over part of the original quarry. Dinosaur National Monument, it’s not, but I’m dinosaur-crazed enough that I was still enthused at seeing dusty bones poking out of the stone and carefully-arranged replicas marking the places of fossils already excavated. If I was going to have any chance of turning up a bit of Allosaurus, there was no surer bet than working the Cleveland-Lloyd quarry.

There was just one snag. Peterson was working at Cleveland-Lloyd during the same week that I had signed up for Hanksville. I didn’t want to back out on the Burpee Museum of Natural History crew, but I couldn’t give up on Allosaurus. So I made a lopsided compromise. I decided to cut off the last day of my time in Hanksville to skip camps and join Peterson’s efforts. At least the quarries were close – only a three-hour stint from each other along Utah’s Dinosaur Diamond byway system.

I met Peterson and his van full of undergraduate assistants next to the high-kicking Utahraptor just outside Price, Utah’s Prehistoric Museum. Inside, the reconstructed representations of the dinosaurs found at Cleveland-Lloyd were slowly having their spines straightened and limbs re-adjusted to bring the old mounts into accord with 21st century dinosaur visions, but I’d have to come back to see them some other time. The museum was closed for the evening, and there were as-yet-uncovered bones pulling me after Peterson’s lead on the highways and dirt roads out to camp.

For the past few days, I had worked with a crew who – depending on their personal comfort needs – stayed in campers or motels and went out every night for dinner. Peterson’s camp was more like what I was accustomed to – a scattered array of tents and a fire ring, just over the hill from the quarry visitor center. Camp, sweet camp. For a night, anyhow.

After setting up my tent and presenting Peterson with a bottle of whiskey – I believe that good field etiquette requires a tribute of booze to host camps – I asked the Wisconsin-based paleontologist for his interpretation of what happened at Cleveland-Lloyd. At other Jurassic quarries, seasonal droughts and local flooding seem to explain the tangled distributions of dinosaur bones. But what was it about this one particular spot that was so attractive to Allosaurus?

In Utah, at least, there are almost as many hypotheses as there are experts. The Natural History Museum of Utah, where I typically volunteer, devotes an entire interactive display to the competing ideas. Where some see a death trap – a sucking mire that enticed hungry Allosaurus with the scent of putrefying flesh – others see the victims of a drought, an assemblage created by mass poisoning, or the strewn remains of animals that died elsewhere, expanded with gases from decomposition, and were carried like reeking balloons by water flow in a process called “Bloat and Float.” No one has been able to make an irrefutable case for any of these scenarios.

Sunset from the CLDQ camp. Photo by Brian Switek.
Sunset from the CLDQ camp. Photo by Brian Switek.

Since Peterson has been coming out to Cleveland-Lloyd for a few weeks the past few summers to specifically study what happened to the Allosaurus, I wanted to hear his view. Aside from his team, the quarry rests undisturbed for the whole year – a locality rich with possibilities that have only been barely realized in the 86 years since the first UU team dug in here.

Sipping a bit of bourbon from a plastic cup and lit by the orange and purple sunset behind the outcrop, Peterson said that he currently favors the “Bloat and Float” hypothesis. Forgetting about the preponderance of Allosaurus, he explained, the geology of the site and distribution of the bones suggests that the dinosaurs within were transported and tossed together at this one place. Rather than being a deadly predator trap, a drying watering hole, or a toxic quagmire, the Cleveland-Lloyd quarry might be the burial ground for tragedies that unfolded elsewhere on the Jurassic landscape.

But then Allosaurus stomps back into the picture. Why are over 75% of the Cleveland-Lloyd dinosaur bones referable to Allosaurus of all ages? Other Jurassic bonebeds are dominated by herbivores and seem to more closely represent our expectations of the Jurassic landscapes we revive from the fossil record – long-necked sauropods, armored stegosaurs, and other plant-pluckers everywhere, with a rare carnivore lurking among the conifers or brashly tearing strips of muscle from a downed Camarasaurus on the fern-covered floodplain. But, Peterson pondered aloud, what if Allosaurus was far more common than we ever expected? Maybe the African savanna model – innumerable big herbivores, relatively few carnivores – doesn’t apply to the Late Jurassic.

I’m not sure Allosaurus was so ubiquitous and social to readily explain over 46 individual animals – and probably many more – dying en masse at some distant site and floating downriver into an osteological pileup. For one thing, dinosaurs such as Allosaurus grew quickly and apparently had hot-running metabolisms (even if we don’t know all the details of their physiology yet). How would an enormous flock of Allosaurus possibly find enough food to eat, or even manage to share a single kill?

But maybe Cleveland-Lloyd represents a kind of event that we can’t yet tease out from the fossil record, or even a circumstance that we will never know. Could all these Allosaurus come together – over one season or many – to this particularly place to lek or otherwise attract mates? Or might there have been a mass die-off of huge sauropod dinosaurs, providing a feast that somehow turned tragic and later scattered the bones of the toothy revelers? Whatever the immediate causes of their death and deposition, we’re still left with the perpetually-vexing question of why so many Allosaurus are found here and are rare elsewhere.

My addiction to technical quandaries temporarily sated, campfire conversation turned to paleo gossip and lurid tales of other camps. (Someone could write a Hunter S. Thompson-esque account of the boozing and lascivious behavior of paleontologists in the field, Peterson suggested.) After dark, the team members sleepily walked back to their tents over the rough cobblestones of the campground, leaving only me and one of the annual Cleveland-Lloyd interns awake. We continued to chat for a while, watching the fire slowly dim, when the intern saw a pair of red lights zip along the road in front of camp, accompanied by the grinding of tires over dirt. This was well past midnight, and the camp wasn’t expecting any other visitors. The lights carried a concerning possibility – maybe someone was planning to rob the quarry.

Dinosaur theft and vandalism is frustratingly common. The problem isn’t only restricted to far-off sites in the Gobi Desert, where thieves snatch scientifically-important specimens and funnel them to black market dealers. Rock shop owners hungry for new items and selfish passersby who want a piece of their own dinosaur will raid quarries for whatever they can break off and carry. Even worse are the lackwits who simply smash and shatter. This has made paleontologists wary of quarry visitors. We want the public to visit our sites, to see the science of dinosaur excavation in action, but outreach also runs the risk of giving hints to those who wish to steal and destroy.

The intern roused a friend from his tent and the pair of them drove off to see if they could spot the intruder. They were expecting to find ATV tracks around the fences and locked quarry buildings. Half an hour later, they came back to camp without seeing a definite sign of any fossil rustlers. Worries at least somewhat relieved, those of us left awake retired to our tents for the night.

After slathering myself with sunscreen and packing some water, crackers, and jerky for lunch, I had my choice of duties the next day. I could go with Peterson to see a new fossil site nearby, work in the quarry building open to the public, or dig in a second fossil shack that is used for storage most of the year and, I was told, smelled of packrat pee. I picked the public quarry. With so little time at Cleveland-Lloyd, I wanted to devote my hours to searching for Allosaurus bones away from rodent odors.

My corner of the quarry. Photo by Brian Switek.
My corner of the quarry. Photo by Brian Switek.

After Peterson’s quick tour of what he and his team were working on this year, I lifted the latch to the orange gate in the public quarry building and found a cramped spot just to the left side of the shady structure. I had to constantly watch my step so as to not to trample on a pair of Allosaurus femora – thigh bones – uncovered a few days before. Despite the thousands of dinosaur pieces already exposed over the course of decades, fossils were still crowded just below the sandstone surface of the rock.

I struck bone almost immediately. A few scratches of an awl and a thin piece of black bone seemed to pop from the surrounding stone. I followed the usual process of pick, brush, vinac until the fragment was secure. Much like my experience at Hanksville earlier in the week, I had found yet another weird, thin enigma.

Poking and swiping at the sandstone, I still believed that an Allosaurus claw, hip fragment, or skull element was just beneath where I was working. I scored and popped off the rock to only find more small bones, fragments and tubular bits of belly ribs technically known as gastralia. The student next to me chose her spot more wisely. Every fifteen minutes, or so it seemed, she found another isolated Allosaurus element. Some volunteers have all the luck.

At least the gnats weren’t bad. Say the word “Gnat” around a paleontologist, and if they don’t immediately shriek “WHERE?!”, they’ll take on a grim expression as they remember bug bites past. Growing up, “gnat” was a term for the gently swirling clouds of insects I often saw in the backyard twilight or along forest paths. In the field, gnats are vampires that can immediately pinpoint your weak spots, almost imperceptibly take their blood meals, and then flit around your face and ears as if they are trying to drive you mad. Applying bug spray almost seems to encourage them, as if you’re challenging them to a fight. A mosquito may buzz away from the scent of DEET. A gnat will want to bathe in it.

Allosaurus femora found during this year's excavations. Photo by Brian Switek.
Allosaurus femora found during this year’s excavations. Photo by Brian Switek.

Mercifully, a stiff and persistent breeze kept the gnats at bay for most of my time in the quarry. A different kind of annoyance came from the building next door. The undergrads blasted dubstep and death metal in their private excavation. Fair enough for them, but the muffled music was just distracting enough to become almost as irritating as the occasional visits from gnats. Peterson, who was working at my feet, suggested that we crank up our own soundtrack by putting an iPhone inside a metal bucket amplifier. His choice: The Doors. Whenever someone in one of his quarries played The Doors, Peterson cheerfully explained, someone found something good.

The Lizard King’s band was about halfway through the hypnotic jam of “L.A. Woman” when a flick of my awl turned up something shiny in the grey grit of the ancient sandstone. I knew that the black sheen could only be part of a dinosaur’s dental toolkit. “Huh, I think I’ve got a tooth”, I said, and handed the fossil into Peterson’s outstreched hand before even cleaning it off. From the size and little dimples along the edge, I suspected that I had found nothing more than a broken bit of an Allosaurus tooth. Not a bad find, I thought, but not so impressive as the fossils everyone was finding around me.

“This is weird”, Peterson said, turning over the tooth in his hands. I hadn’t found part of an Allosaurus tooth. The shape was all wrong, and the serrations I thought I saw were enamel wrinkles along a squared-off and tapering crown. The anatomy was totally wrong for a carnivore, and didn’t fit any of the sauropods, either. Peterson and I exchanged ideas. Could the tooth be from a Stegosaurus? Or a bipedal, beaked dinosaur called Camptosaurus? What if it’s something new? Peterson had never seen someone uncover such a tooth before from the quarry. Who did the mystery fossil belong to?

Peterson ran up to the visitors center to compare the tooth with the casts of Stegosaurus and Camptosaurus on display. The petrified remnant didn’t seem to match either, he reported back. For one thing, the tooth was way too big – the tooth crowns of Stegosaurus and Camptosaurus were about the size of the rounded head of a fabric pin, while the Jurassic piece I’d discovered was bigger than my thumbnail. If the tooth was from either of these two candidates, the individual would have been a giant.

The puzzling tooth I found at the CLDQ. Photo by Brian Switek.
The puzzling tooth I found at the CLDQ. Photo by Brian Switek.

After snapping a photo of the tooth with my phone, I trudged uphill to the visitor’s center myself. Peterson was right. The tooth didn’t exactly match the casts, and was far too large to fit in the jaws of either skull replica. But who else could the tooth be from? The Morrison Formation dinosaurs in eastern Utah are well-documented. If there was some other giant herbivorous dinosaur in Cleveland-Lloyd with such teeth, surely paleontologists would have already found the monster’s bones.

I walked over to where I parked my rental car, one of the few spots with fair cell service, and slowly browsed the web for images of dinosaur teeth for comparison. The fossil I uncovered matched the anatomy of fresh Camptosaurus teeth. The dentition of the cast inside the visitor’s center was replicated as worn-down and didn’t contain all the delicate details of real fossils. But compared to close-ups of other specimens, my tooth fit the pattern. Yet the size of the freshly-uncovered tooth was still strange – might the tooth have been from an especially big Camptosaurus? That question awaits future comparison with fossils already found.

A reconstruction of Camptosaurus at the Brigham Young University paleontology museum. Photo by Brian Switek.
A reconstruction of Camptosaurus at the Brigham Young University paleontology museum. Photo by Brian Switek.

The rest of the day lazily drifted by beneath the quarry building. I didn’t find anything else of interest or importance, despite my goal of at least starting to uncover a truly spectacular fossil. (Earlier in the day, Peterson had jokingly encouraged me to find the Allosaurus hips that he just knew had to be right under my quarry spot. No luck.) After about nine hours in the quarry, everyone was ready to close up the buildings and dig into the dinner that a few volunteers had left to start just a bit earlier. For me, though, this was the end of my Jurassic journey. My rental car was due back in Salt Lake City, and I couldn’t put off the pile of freelance assignments I had left to ferment in my inbox much longer. After having one of Peterson’s Jurassic Park-themed homebrews and trying to avoid the flying bowls of salsa launched by windy gusts funneled by the outcrops through the camp, I packed my tent and started for home. Next year, when Peterson returns to Cleveland-Lloyd and the warm weather brings out the gnats, I’ll renew my pursuit of Allosaurus.

[Many thanks to Joseph Peterson and Mike Leschin for inviting me to join the Cleveland-Lloyd Dinosaur Quarry excavations this year. Next season, I’ll set aside more time to help.]

Dinosaurs on Mars

I’ve never been to Mars, but I’ve been close. From my Salt Lake City home, the journey takes a relatively scant four and a half hours – through the smoggy sprawl of the valley and over lonely highways pocked here and there by small Utah farming towns before reaching the tourist-dependent outpost of Hanksville. I wonder how many people speed along the main drag, on their way to see the imposing geology of Capitol Reef National Park or make the spirit of Edward Abbey cringe by boating over Lake Powell, without ever realizing what lies up a unremarkable dirt road just a few miles outside of town.

Known as Cow Dung Road to the locals, the graded track snakes into hills banded in maroon, gray, and tan, set off in contrast by grey formations further beyond that ominously loom like the Black Gate. And plunked down in this landscape of strangely-shaded slopes and draws is a gleaming white structure just a quick left off the road – the Mars Desert Research Station.

The otherworldly geology of Utah’s San Rafael Swell may be the closest we get to Mars on Earth. Hollywood concurs. When Disney made their fumbling attempt at bringing Edgar Rice Burroughs’ Barsoom series to the screen, they selected a locale not so very far away to be a stand-in for the Red Planet.

As I bumped my rental car along the Bureau of Land Management road in the early June heat, part of a daily commute I traveled for almost a week, the tinges of Mars were only of passing interest. The scenery outside Hanksville is otherworldly, absolutely, but where many see Mars I envision spectacles that are more planetarily parochial yet just as strange. As the crew of John Carter found when they kicked up some stony scraps on their set, and as Hanksville locals have known for decades, the richly-colored badlands are permeated with what remains of dinosaurs that lived and perished over 148 million years ago. This is the closest we’ll ever get to an alien dinosaur, and the fossils were not an isolated lucky break. A quarry replete with the bones of Jurassic celebrities, not the Martian vistas, was what drew me out into the surreal outcrops.

No one knows who first discovered what is now known as the Hanksville-Burpee Quarry. (The site was going to be dubbed the Cow Dung Quarry after the road, but the humorless BLM requested a more dignified title. A shame.) Townsfolk and passers-by regularly found fragments of black and white bone as they wandered over the sun-baked sandstone around where the dig site is now established. A handful of paleontologists even took a passing interest in the locality, noting a rich accumulation of bones outside Hanksville in their letters and notes, but no one seemed particularly inspired to start sifting through what was out there.

Paleontologist Scott Williams gives a tour of what has already been uncovered at the quarry. Photo by Brian Switek.
Paleontologist Scott Williams gives a tour of what was already been uncovered at the quarry when I arrived. Photo by Brian Switek.

By the time the Jurassic bonebed came to the attention of professional dinosaur experts, many major museums had already discovered, cataloged, and described much of the classic Morrison Formation fauna. Apatosaurus, Allosaurus, Barosaurus, Camarasaurus, Camptosaurus, Ceratosaurus, Diplodocus, Stegosaurus, and more – these dinosaurs were celebrities already well-known from famed graveyards such as those preserved at Bone Cabin Quarry, Wyoming and Dinosaur National Monument, Utah, many of which yielded their secrets during the “Second Jurassic Dinosaur Rush” of the early 20th century. For paleontologists and curators seeking new species to name and spectacular specimens to mount, yet another jumble of bones seemed rather mundane. The species encompassed in the stone outside Hanksville were probably all already known, and the prospect of spending years pulling out the remains of familiar Jurassic giants didn’t appeal to many museums.

But the Burpee Museum of Natural History, based out of Rockford, Illinois, wasn’t a venerable institution that already had stores overfull with Jurassic dinosaurs. A little more than six years ago, the institution started looking for sites that might yield suitably imposing dinosaurs for their exhibits. The Utah BLM directed them to the neglected Hanksville bonebed, where Burpee paleontologist Scott Williams and colleagues were instantly taken with the richness and expansiveness of the boneyard. The site could yield just the sort of charismatic dinosaurs they were hoping to excavate. In 2007, the Burpee Museum of Natural History started pulling the dinosaurs from the rock.

I had visited the site once before, in 2010, just to chat with Williams, sauropod expert Matt Bonnan, and their crew. But I returned this summer with every intention of getting my hands dirty. Once spring begins to creep into Utah, when snow is relegated to the high peaks around my valley home, I itch to go dig up dinosaurs. This year, I had nothing planned for June and worried that I wouldn’t have a chance to pick through the Mesozoic until much later in the summer. I needed dinosaurs, and soon. So I asked Williams, who I know runs his operation in Hanksville in early June, if he needed an extra hand. Fortunately for my Apatosaurus addiction, he agreed to let me get my fossil fix.

By fieldwork standards, the Burpee crew rolled in luxury. The experience was a sharp contrast with another excursion I took earlier this year. A few weeks before my journey to Hanksville, I got the unexpected chance to excavate dinosaurs in geologically younger rocks in Utah’s Grand Staircase-Escalante National Monument, further to the south. The situation is pack-in, pack-out: from food and shelter to plaster for making jackets and baby wipes (essential given the lack of showers in the backcountry), you must bring in everything you need and account for every scrap going out. Every few days, the crew might take the long ride into the nearest town to buy groceries and show respect to the close quarters in the quarries by taking showers at a KOA, but otherwise the camp has to be self-contained. But at Hanksville, some of the crew stayed in a trailer and others in the local motels. On the night I arrived, I pitched my tent near the laundry of the local campground – a facility with hot showers and a stone’s throw from the John Wayne-themed Slickrock Steakhouse. This was the height of luxury.

Actual quarry work was similarly cushy. Generators and air compressors squatted and thrummed on the exposed tufts of the quarry, creating constant white noise as they powered the vibrating microjacks – a hammering tool that looks like an insidiously oversized piece of dental equipment – that the volunteers and paleontologists pressed into the rock to free bone from sandstone. The crew had even set up shade – shade! – for heat-addled workers to take breaks and sip chilled Gatorade whenever they needed to. A field volunteer could easily get spoiled in conditions like this.

I never made use of the microjacks, though. As I quickly learned, my work was a little too delicate for such potentially destructive tools.

The Burpee crew had already been working the Hanksville quarry for a week by the time I arrived. Most choice spots were already taken. But, knowing that I have an affinity for menacing Jurassic carnivores, Scott Williams directed me to the sloping knob of the quarry where his crew has previously extricated the articulated vertebrae of a theropod dinosaur. Williams and colleague Josh Williams told me they suspected Allosaurus – a common Jurassic predator that could reach lengths in excess of 39 feet, armed with three-clawed hands and an airy skull full of serrated teeth – but the tri-horned, long-fanged Ceratosaurus was also a possibility. They were sure there had to be more of the predator on the side of the hill, so Williams told me to pick up a tool I’ve never used before in the field – a pushbroom.

The tools required to free a dinosaur from ancient sediment differ from site to site. At the last Utah excavation I blistered my hands assisting, field expert Mike Getty busted through concrete-tough swaths of sandstone with a jackhammer while the other crew members and I attacked the slightly softer rock with picks and shovels until we got down to the bone layer. At Hanksville, I accidentally started uncovering bone with the plastic broom. After pushing all the loose sediment off the side of the hill, making a suitably clean space to work, I looked down to see an oddly-shaped discoloration on the surface. The strange chunk had the texture of rotten wood. On my hands and knees, I could see more clearly – bone.

Freshly-exposed dinosaur bone usually isn’t very pretty. Limb bones that once supported the bulk of young sauropods – Camarasaurus? Apatosaurus? No one yet knew – exposed to the sun just to the right of my spot were mostly intact, but still split and cracked. My scrap was even worse off. The punky surface seemed to be run through with tiny rifts, making the fossil especially fragile. I needed vinac, and lots of it.

The first bone of the season, with a 4-inch awl for comparison. Photo by Brian Switek.
The first bone of the season, with a 4-inch awl for comparison. Photo by Brian Switek.

A little brushing was enough to know that I had struck bone, but I had to stabilize the petrified mess before going any further. A mixture of acetone and polyvinyl acetate beads, vinac is an adhesive that penetrates bone and, after the acetone evaporates, leaves the plastic behind to hold the fossil together. I had mixed mine in a little jar earlier in the day, and had a little brush to apply the sticky stuff, but I didn’t even want to touch the bone lest bits of dinosaur come off on the hairs of the brush. Dribbling was the best I could do, trying to flick away some of the loose sandstone soon after so that the stone didn’t stick to the bone.

When visitors look over my shoulder in quarries or museums, many mention how tedious the work looks. Getting a fossil out of the ground or prettied up in the lab involves hours upon hours of separating prehistoric creatures from their encasing matrix. And while I suppose the repetitive task doesn’t look the most thrilling to an outsider, the joy of working on a dinosaur is that every piece of rock removed brings you a little closer to solving the conundrum of what you’re working on and where that piece fit in the skeletal puzzle of the living animal. As I carefully scratched the sandstone to see more of the bone I’d lucked across, the fossil thinned and ran back towards where I had been standing, pushing away sand, just a few minutes before. Through the process of scrape, brush, vinac, repeat, the fossil started to come into view.

I didn’t want to take the whole bone out. In the field, the goal is to find the extent of the bone or skeleton without fully preparing the specimen – that comes later, with more delicate tools, in the lab. And even though the odd shard was fragile, the fossil was small enough that I was hoping to dig a little trench around both sides, make a cap of wet paper towels and plaster-infused bandages, flip the bone over, and take the fossil out by the end of the day.

No such luck. The Hanksville-Burpee quarry is so dense that I struck more bone as I started to excavate around the first. Fair enough. I’d tackle the new bone first. Scrape, brush, vinac, scrape, brush, vinac, BONE. Again. Now I was beginning to feel conflicted. The first sign of a dinosaur in the rough always sends a rush of endorphins to my brain. But in such a tangled mass of bone, friable pieces laying under and around other bones quickly became the inspiration of enough frustration that the first word I repeatedly said upon striking them was not “Hooray!” but an expletive that I’m not allowed to print on this blog.

I spent four days going through this cycle. (I only took one day off to do some dinosaur sightseeing and replace my tent, which had irreparably collapsed during a midday wind gust.) During breaks, Williams would ask me how my “weirdness” was, to which I replied that I don’t have the health care coverage to afford mental therapy to alleviate my personality defects, and that the confusing muddle of fossils wasn’t helping. While other crew members were uncovering limb bones, pretty rib fragments, and even the back of a skull, I was left to toil with my mystery mess.

Chipping through stone on my stomach, side, knees, and an assortment of contortions required to keep my nose to the stone bones, I had plenty of time to think about what the fossils were and how they got there. The delicate pieces had the look of cervical ribs – the thin processes that jut out from neck vertebrae. But even if I was right, what species could they be from? And how could such delicate fragments survive the rough treatment of their deposition? The sandstone I scratched at more times that I could count was speckled with large pebbles from a prehistoric streambed where the quarry’s dinosaurs came to rest in a rotting heap. Such prominent stones were a hint of swift transport by fast-moving water.

What exactly happened at Hanksville-Burpee is only just beginning to be researched, but, as paleontologist Josh Matthews explained to me one especially hot morning, the deposit seems to be the remnant of a shallow channel where dinosaur bones were washed in by water flows of varying intensity over a period of who knows how many years. Perhaps, as was the case at other sites of Jurassic catastrophe, annual droughts killed parched animals and the bones of the dehydrated dinosaurs were all washed together when rains returned to the floodplains.

The question is why the Hanksville-Burpee quarry seems to be dominated by relatively young individuals of the long-necked, heavy bodied sauropod dinosaurs. There are some big bones in the quarry – the posterior part of a respectably-sized Allosaurus, limb elements from big sauropods – but many of the bones appear to be from juvenile and young subadult sauropod dinosaurs. After surveying the exposed fossils in the quarry during a morning visit, paleontologist and Jurassic expert ReBecca Hunt-Foster exclaimed “Your bones are so small!”

There’s still much to be found, but, as far as has yet been discovered, the site preserves an overwhelming abundance of dinosaurs that died especially young. Maybe this particular area was favored by young sauropods that traveled together – after all, the nutritional needs of young sauropods were different from those of adults and herding together might have made them less vulnerable to formidable carnivores of their era – but this is only speculative. The puzzle tickled and teased my mind as I went about extricating just a little bit more of a past I’ll never see myself.

Bone, or not bone? The author at the Hanksville-Burpee quarry. Photo by May Blueotter.
Bone, or not bone? The author at the Hanksville-Burpee quarry. Photo by May Blueotter.

I left my weirdness in the Jurassic. There was no conceivable way to safely remove any of the pieces before I had to leave for my next Jurassic stop, and I was finding new signs of bone until the very last minute. The dinosaur tidbits I had uncovered had waited over 148 million years in the rock. Waiting one more year cradled in sandstone won’t hurt them.

[I’m indebted to Scott Williams, Josh Matthews, Katie Tremaine, and the rest of the Burpee Museum of Natural History crew for letting me lend a hand during this year’s excavation. I’ll be back next year to finish what I started. Promise.]