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.

Paleontologists Discover a Hidden Dinosaur

There’s more than one way to make a significant dinosaur discovery. You can fill up water bottles, slather on sunscreen, and strike out across exposed stone in the hope that luck and a sharp eye will lead you to bones no one has ever seen before. That’s the traditional way. But museums have become metaboneyards where dinosaurs hide within plaster jackets and newspaper-lined drawers, forgotten until a lucky fossil hunter discovers them anew. This alternate sort of fossil hunting is what led paleontologists Michael Hanson and Peter Makovicky to uncover additional remains of a rare Jurassic carnivore.

During more than a century of discovery and research, paleontologists have identified at least three enormous carnivorous dinosaurs that roamed the lands of the American west around 150 million years ago. Allosaurus is the most abundant and most famous, challenged in pop culture notoriety by the gnarly and rare Ceratosaurus. But just as big and frightening is a little-known megalosaurid dubbed Torvosaurus.

Often found in the same quarries as Allosaurus, albeit in lesser numbers, Torvosaurus had long, deep skulls set with elongated teeth that they presumably put to work on the hides of sauropods. And that’s not to mention their short, stout forelimbs which bore a set of three wicked, recurved claws. No complete specimen has yet been found, but the bones discovered so far indicate this thirty-foot long predator prowled the Jurassic floodplains of Colorado, Utah, Wyoming, and, as recently realized, Portugal.

Despite the size and apparent rapacity of Torvosaurus, though, the dinosaur never gained the popularity of Allosaurus and Ceratosaurus. Perhaps that’s because the theropod was only named in 1979 – the classic Jurassic neighbors of Torvosaurus were named much earlier and had more time to gain iconic status. Maybe Torvosaurus could have joined them if earlier researchers knew what they had found.

The specimens that Peter Galton and Brooks Britt used to officially describe the dinosaur actually were not the first to be found. A very large Jurassic tooth collected in 1879 and not figured until a 1927 study, Galton and Britt proposed, may have been the first piece of Torvosaurus ever discovered by scientists. And now Hanson and Makovicky have identified another case of a Torvosaurus before its time.

Between 1899 and 1901, the Field Museum paleontologist Elmer Riggs led a crew on several expeditions to discover dinosaurs among the Freezeout Hills of southeast Wyoming. Riggs had been tipped off to the area by colleague Samuel Wendell Williston, and most of the sites Riggs’ team opened contained only one genus of dinosaur in each. Quarry 6 was different. This site was strewn with the fossils of “miscellaneous dinosaurs”, Riggs recorded in his notebook, including what appeared to be the sauropod Camarasaurus, the spiky-tailed Stegosaurus, and Allosaurus.

A Torvosaurus chases Othnielosaurus at the Museum of Ancient Life. Photo by Brian Switek.
A Torvosaurus chases Othnielosaurus at the Museum of Ancient Life. Photo by Brian Switek.

Not everything the team collected was opened or studied upon arrival at the Field, however. One particular jacket collected dust for over a century until a 2005 inventory of the museum’s collections turned up the historic specimen. When the fossils inside were finally exposed and cleaned, they were not the  Allosaurus Riggs had suspected. By 1901, nearly eight decades before the animal would be named, Riggs’ team had found Torvosaurus.

The jacket didn’t contain much of the elusive dinosaur. Hanson and Makovicky report that the jacket included the left metatarsus – or long bones of the foot – a toe bone, a finger bone, and broken pieces of the dinosaur’s belly ribs. Still, the anatomy, size, and robust nature of the foot bones show that this was indeed Torvosaurus, which had a heftier build than the Allosaurus and Ceratosaurus the carnivore likely competed with for food. So far as is presently known, this was the first set of non-skull elements from the dinosaur to be excavated.

The belated discovery of Riggs’ Torvosaurus brings up a tantalizing possibility. Paleontologists have been collecting fossils from the Morrison Formation – in which Torvosaurus is found – since the late 19th century. And given that paleontologists often collect more than they ever get a chance to study themselves, there are probably unopened jackets that may contain more of Torvosaurus, not to mention the possibility of misidentified bones that rightly belong to this dinosaur. Paleontologists may have more of the dinosaur than they know. There’s even the chance that paleontologists have already found some pieces of young Torvosaurus.

Not only is Torvosaurus rare, but all the specimens known to date are from large-bodied, adult or near-adult individuals. As Hanson and Makovicky point out, this may because Torvosaurus is often recognized by the large, robust nature of the dinosaur’s bones. Yet dinosaurs changed dramatically as they aged, and young individuals of a species are sometimes confused as members of another. Perhaps elements of young Torvosaurus have already been found and mislabeled, especially since this dinosaur is more often found in multi-species bonebeds were isolated bones, rather than articulated skeletons, dominate.

The romance of paleontology is of discovery. To wonder about vanished lives that have been stripped down to the bone. Bringing dinosaurs out of the field is the first step in this ongoing quest, but as museums stores pile up, bonebeds kept on shelves and in drawers brim with mysteries and clues to rival sun-baked field sites.


Hanson, M., Makovicky, P. 2013. A new specimen of Torvosaurus tanneri originally collected by Elmer Riggs. Historical Biology.

New Exhibit Explores Idaho’s Buzzsaw Jaws

When I think of Idaho, ratfish are not what immediately come to mind. Spuds and the ghastly belt of agricultural reek that keeps me holding my breath whenever I speed past Idaho Falls on the interstate, sure, but not strange cartilaginous fish. A new exhibit at the the Idaho Museum of Natural History is aiming to change that.

Over 270 million years ago, the area that eventually would be called Pocatello, Idaho was an ancient sea that hosted an exceptionally enigmatic fish whose mystery has only just started to truly unravel. These archaic ratfish are known almost entirely from their jaws – whorls of teardrop-shaped teeth first described from finds in Russia, but later discovered in abundance among the spoil piles of eastern Idaho’s phosphate mines. Experts knew these spirals by the name Helicoprion, and there were seemingly as many opinions about what these toothy coils were as paleontologists who studied them.

Virtually everyone agreed that the fossils were part of some sort of ancient fish. Where the whorls fit on those fish, however, was a matter of constant contention. Some placed the spiky circles on the backs or tails of ancient sharks, while others believed that the peculiar structures must have been part of the jaw. Even within this latter hypothesis, paleontologists disagreed over whether the spirals freely hung below the jaw, were enclosed within the mandible, or had a matching set of upper teeth. With only a swirl of teeth to work with, the rest of the animal was a blank that paleontologists could restore in almost any way they chose.

A gallery of Helicoprion hypotheses. Artwork © Ray Troll 2013.
A gallery of Helicoprion hypotheses. Artwork © Ray Troll 2013.

But, as displayed in the new Idaho Museum of Natural History exhibit, we now have a much clearer idea of who Helicoprion actually was. Thanks to the persistent questions of student Jesse Pruitt, the technical expertise of paleontologist Leif Tapanila and colleagues, and, most of all, the obsession of artist Ray Troll, the whorl-toothed “shark” has turned out to be a sleek, buzzsaw-jawed ratfish that sliced through ancient cephalopods with a single blade of enamel-covered spikes.

Preserved remnants of cartilage – long-known, but only recently seen through high-resolution imagery – was the key to finally restoring Helicoprion. The fragments revealed enough of the skull to show how the teeth sat in the jaw and, unexpectedly, brought the fish into a closer relationship with ratfish than with sharks, as had traditionally been thought. (Helicoprion is still often referred to as a shark, though. To bastardize a classic movie line: “You yell ‘ratfish’, people say ‘Huh? What?’ You say ‘shark’, you’ve got a hit exhibit.”) The resulting image is an alien creature – the familiar fusiform, shark-like body with a bizarre, bug-eyed head sporting those characteristic teeth.

The Idaho museum’s exhibit inundates visitors with this new imagery from the second they step foot into the shadowy hall. Alongside displays of actual Helicoprion jaws – including the very specimen that solved the Permian puzzle – gorgeously-detailed artistic depictions of the ratfish by Troll hang from wallpaper also designed by the fossil’s biggest fan. Sculpted versions of Helicoprion by artist Gary Staab and a working set of Helicoprion jaws bring the fish to life in a way never seen before, and the brief tour ends in a little lounge complete with a couch specially-upholstered in tooth whorl fabric. When I spoke to Pruitt, Tapanila, and Troll at the exhibit’s opening, I begged them to make the line of Helicoprion home furnishings available for purchase to fellow paleo nerds.

A new look for the ratfish relative Helicoprion. Artwork © Ray Troll 2013.
A new look for the ratfish relative Helicoprion. Artwork © Ray Troll 2013.

Thanks to the artistic abilities of Staab and Troll (who has been chasing in the wake of the whorl-tooth for decades), the Helicoprion exhibit is totally entrancing. Walking through the exhibit feels like a stroll through Troll’s mind, complete with the lighthearted weirdness that makes his artwork so wonderful. On a portrait of a scissor-toothed fish known as Edestus giganteus, for one, Troll paired his scientifically-rigorous restoration with lines such as “‘Ed’ the Shred Head”, “The Ripper!”, and “Slice and dice, I’d say” scrawled onto the illustration. And if you visit the displays, try to count all the cheeseburgers hidden within the art and exhibits.

The joy of the Helicoprion celebration is in the visuals. This isn’t to say that the displays shy away from science, but rather that the accompanying text is minimal and to-the-point. That’s a good thing. The approach allows visitors to engage with the displays at whatever level they desire. You can walk through the hall and simply enjoy Troll’s odes to Helicoprion, or you can dig into some details of strange fish called eugeneodontids – the varied family of Helicroprion that included scissor, whorl, and pavement-toothed monstrosities, including a nightmarish form called Edestus newtoni, with spiky, outward-curving jaws that look as if they’re sinisterly inviting prey for a deadly kiss.

The techniques that Pruitt, Tapanila, Troll, and collaborators used to envision Helicoprion will help reveal the nature of some of these other weird fish. But Helicoprion will always be the star in the family. Few petrified puzzles have been more famous, and the Idaho Museum of Natural History exhibit is a loving tribute to Helicoprion created by those who have found their imaginations permanently snagged on those spiral jaws.