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A composite reconstruction of Torosaurus utahensis, based upon the skull found by Gilmore, bones found in the Texas bonebed, and the form of Pentaceratops. From Hunt and Lehman, 2008.

What is Torosaurus? The answer depends on who you ask. While it is certain that the dinosaur was one of the biggest and most impressive horned dinosaurs of the Late Cretaceous, paleontologists are now actively debating whether Torosaurus was a distinct genus of dinosaur or the fully mature growth stage of the more famous Triceratops. Anatomy, bone microstructure and the geological context of the two dinosaurs make up part of the ongoing discussion, but there is one key bit of evidence that has remained in the background: a little-known species from Utah.

When paleontologists John Scannella and Jack Horner proposed that Torosaurus was really a grown-up Triceratops in the Journal of Vertebrate Paleontology last year, the immediate public reaction was one of despair that scientists were taking away another beloved dinosaur. This was not actually the case—Triceratops was named first and so its name would have priority if the hypothesis of Scannella and Horner is confirmed—but, frustratingly, the myth that paleontologists are trying to toss Triceratops remains. The confusion over the dinosaur name game has obscured some of important details of the “Toroceratops” hypothesis. The debate has been discussed in the context of dinosaur genera, for instance. But within each genus, Triceratops and Torosaurus, are two species, and all four species are relevant to the fate of Torosaurus.

In last year’s paper, Scannella and Horner proposed that the species Torosaurus latus was synonymous with Triceratops. It wasn’t clear which individual Torosaurus latus specimens should be referred to which Triceratops species: Triceratops horridus or Triceratops prorsus. But the overlap of Torosaurus latus with both Triceratops species in time and space was used as a supporting argument for why Torosaurus should be synonymized with Triceratops.

The paleontologists also briefly mentioned a second, southern species of Torosaurus. Fragmentary fossils of the dinosaur Torosaurus utahensis have been found in Utah, New Mexico and Texas from sites where no Triceratops remains have ever been found. If this geographic separation is real, and Torosaurus utahensis really is a valid species of Torosaurus, then this little-known dinosaur will have an important role to play in the wider argument over whether paleontologists have named too many dinosaurs.

While Torosaurus latus and both species of Triceratops were found and described by paleontologist O. C. Marsh during the great “Bone Wars” of the late 19th century, Torosaurus utahensis was a more recent discovery. In 1946, a monograph on the “Reptilian Fauna of the North Horn Formation of Central Utah” was published by Charles W. Gilmore. (Though this was a posthumous publication likely completed by a colleague; Gilmore had passed away the previous year.) The formation that was the focus of Gilmore’s attention represents the latest Cretaceous—a finding supported by the more recent discovery of Tyrannosaurus rex within it—and is about the same age as the northern formations that have yielded Triceratops and Torosaurus latus. At the time that Gilmore was working, though, the dinosaurs of the North Horn Formation were little known, and among the enigmatic specimens were remains from up to 11 individuals of an unknown horned dinosaur. The bones were so fragmentary that it was difficult to tell whether they were something entirely new or should be assigned to an already existing dinosaur, so Gilmore tentatively presented the remains as a new species of an already known dinosaur genus: Arrhinoceratops? utahensis.

Three decades later, paleontologist Douglas Lawson reassigned Gilmore’s dinosaur to Torosaurus utahensis on the basis of several skull characteristics, with one of the main differences from the northern Torosaurus latus being a proportionally shorter squamosal bone (the broad bones that make up the borders of the dinosaur’s big frill). The trouble is that many specimens assigned to Torosaurus utahensis are so fragmentary that it is nearly impossible to confirm whether they belong to this dinosaur or to another. Many are only identifiable as chasmosaurines, the horned dinosaur subgroup to which Torosaurus, Triceratops and others belong. Since the most distinctive parts of Torosaurus specimens are their frills, specimens lacking these parts can be infuriatingly difficult to assign. (In a 2005 reassessment of the original material found by Gilmore and specimens assigned to Torosaurus utahensis, Robert Sullivan and colleagues concluded that the species was only definitively known from the type specimen from Utah’s North Horn Formation. The other proposed specimens could not be confirmed.) Perhaps the difficulties could be mitigated by the discovery of a complete or near-complete specimen of Torosaurus utahensis, but at the moment, there are a number of specimens which may or may not be referable to this dinosaur.

Torosaurus utahensis is obviously a problematic dinosaur, but this doesn’t mean that it is irrelevant to arguments over the growth stages of Triceratops. Depending on whether the dinosaur is confirmed as valid or is synonymized with a different genus or species, the horned dinosaur may help resolve the great Toroceratops debate. A few clues were reported by ReBecca Hunt-Foster and Thomas Lehman in 2008. The paleontologists described a bonebed of horned dinosaurs found in the Javelina Formation of Texas. Thirty-seven identifiable skeleton elements were found from at least three individual animals, hypothesized to be one juvenile and two adults.

Based on Gilmore’s original specimen and the new elements found in Texas, Hunt-Foster and Lehman proposed that Torosaurus utahensis is distinguishable from Torosaurus latus in exhibiting a thickened bar of bone on the squamosal bone along the suture with the neighboring parietal bone (which makes up the middle part of the frill and is the bone containing the large holes that help distinguish Torosaurus from Triceratops) and a small bone called the epiparietal at the midline of the frill. Perhaps these features will be enough to distinguish the two Torosaurus species, or perhaps the more recently named species will be lumped into Torosaurus latus, but the existence of Torosaurus in a place where Triceratops is absent may help affirm the unique nature of Torosaurus.

The case that the dinosaurs we have called Torosaurus are simply fully mature Triceratops relies on the hypothesis that we are not going to find juvenile, sub-adult or young adult Torosaurus. If definitive juvenile specimens of Torosaurus are found then the large-frilled form cannot be considered the fully-grown stage of Triceratops. Paleontologist Andrew Farke recently pointed out one possible specimen of a subadult Torosaurus latus in the collections at Yale, and some of the bones described by Hunt-Foster and Lehman may belong to juvenile or sub-adult Torosaurus utahensis. The Yale skull requires further study, and the bones from Texas are too fragmentary to resolve the issue (near-complete skulls, or at least well-preserved frills, are needed), but they hint that young Torosaurus specimens may already rest in museum collections or might still await discovery in the field.

Perhaps, now that paleontologists are looking, Torosaurus may become known from its own growth series. Such a collection would allow paleontologists to compare how both Triceratops and Torosaurus grew up and visualize when the prominent adult traits of  each species became established. Then again, perhaps Torosaurus utahensis will turn out to be a different genus of dinosaur, and maybe Torosaurus latus will be sunk into Triceratops. There are a number of ways that the debate could be resolved. Further study is needed, and we could certainly use better specimens of Torosaurus utahensis. Until we really know what Gilmore’s enigmatic horned dinosaur truly is, those of us waiting to learn the fate of Torosaurus will be left in suspense.

References:

Farke, A. 2007. Cranial osteology and phylogenetic relationships of the Chasmosaurine Ceratopsid Torosaurus latus. In Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs. Bloomington: Indiana University Press. pp 235-257

Gilmore, C.W. 1946. Reptilian Fauna of the North Horn Formation of Central Utah. United States Geological Survey Professional Paper, 210-C, 53 p.

Hunt, R., & Lehman, T. (2008). Attributes of the Ceratopsian Dinosaur Torosaurus, and New Material from the Javelina Formation (Maastrichtian) of Texas Journal of Paleontology, 82 (6), 1127-1138 DOI: 10.1666/06-107.1

Sampson, S., & Loewen, M. (2005). Tyrannosaurus rex from the Upper Cretaceous (Maastrichtian) North Horn Formation of Utah: biogeographic and paleoecologic implications
Journal of Vertebrate Paleontology, 25 (2), 469-472 DOI: 10.1671/0272-4634(2005)025[0469:TRFTUC]2.0.CO;2

Scannella, J., & Horner, J. (2010). Torosaurus Marsh, 1891, is Triceratops Marsh, 1889 (Ceratopsidae: Chasmosaurinae): synonymy through ontogeny Journal of Vertebrate Paleontology, 30 (4), 1157-1168 DOI: 10.1080/02724634.2010.483632

SULLIVAN, R., BOERE, A., & LUCAS, S. (2005). REDESCRIPTION OF THE CERATOPSID DINOSAUR TOROSAURUS UTAHENSIS (GILMORE, 1946) AND A REVISION OF THE GENUS Journal of Paleontology, 79 (3), 564-582 DOI: 10.1666/0022-3360(2005)0792.0.CO;2

Soldiers and dinosaurs are an excellent match. Any kid with a bucket of plastic army figures, a horde of dinosaur toys and a sandbox knows this well, as do many grown-up dinosaur fans. In addition to the many, many comics that have pitted packs of dinosaurs against platoons of soldiers, a strange Virginia theme park features Civil War-era theropods and this summer saw the release of the online, multi-player WWII shooter Dino D-Day. It’s only a matter of time before someone creates an alternate history in which George Washington rode a Torosaurus into battle. And the latest addition to the growing list of historical dinosaur fiction? A new survival horror game called “1916: Der Unbekannte Krieg (The War You Never Knew).”

Set behind German lines during WWI, the new dinosaur-haunted game is a claustrophobic experience. The player must navigate through the dark, damp trenches in search of a way out, because it is better to face the horrors of the battlefield than be torn apart by the sickle-clawed dinosaurs that might be hiding right around the next corner. There are no machine guns, rocket launchers, or other heavy firepower here. Your only chance is to distract the dinosaurs with flares and, in a macabre game element, the body parts of your fallen companions long enough to escape. If you would rather gun down scores of raptors and have a shot at blowing up a Tyrannosaurus, you’ll just have to wait for Primal Carnage to come out.

“The War You Never Knew” is a tough game. I quickly got lost in the trenches and more than once found myself hopelessly stuck in a narrow corridor between two approaching dromaeosaurids. I managed to get a little further with each run-through, but the game is one of strategy and memory. You don’t want to try to escape a dinosaur by running down a pathway that leads directly into that pocket of mustard gas you passed by. Which brings up one of my complaints about the game—the predatory dinosaurs seem to be exceptionally resistant to the poison gas in the air. I understand that the point of the game is to avoid the dinosaurs rather than gun them down, but I don’t think the raptors should be nearly invincible, either!

Another small problem for English-speaking users: As you sneak through the trenches, you will stumble across letters which contain background information and clues. These letters are in German. You can still play the game without the information, and the first letter has a handy illustration of a solider distracting a raptor with another man’s hand tossed into the air (a clue as to what you will soon have to do yourself), but I imagine that the other letters probably contain some useful information.

Nevertheless, I quite like the idea of a second, unknown conflict taking place during the chaos of WWI, and the dark, shadowy design of the game sets the perfect mood. I have yet to find the ladder and climb out of the dinosaur-infested trenches, but with some more practice, I just might make it.

When I was a young dinosaur fan, Spinosaurus was one of my most favorite dinosaurs. What could be more fantastic than a giant predatory dinosaur equipped with a bizarre sail? But Spinosaurus as I knew it during the 1980s—imagine a fin-backed Allosaurus—looked significantly different from the dinosaur as we know it today. The reason for the big change is largely attributable to the discovery of a different, related dinosaur in England.

In 1986, Alan Charig and Angela Milner described a very strange, crocodile-snouted dinosaur they called Baryonyx. The Cretaceous creature turned out to be the key to identifying what is now one of the most famous dinosaur groups, the spinosaurs. Paleontologists had been finding pieces of spinosaurs for over a century, but often the teeth of these dinosaurs were confused for those of crocodiles, and the original Spinosaurus fossils were destroyed during Allied bombing of Germany in WWII. When Baryonyx was discovered, however, paleontologists began to recognize the similarities between it, older discoveries and similar dinosaurs that were soon found in South America, Africa, Asia and Australia. Some, such as Suchomimus and Spinosaurus from Africa, had sails, while others—including Baryonyx—did not, but the initial discovery formed the basis for the great spinosaur makeover. (Even before new Spinosaurus material was found, the relationship between it and other spinosaurs like Baryonyx was used to restore the predator with heavy-clawed hands and an elongated snout.) In the above video, created by London’s Natural History Museum, paleontologist Angela Milner explains how the dinosaur was discovered and why Baryonyx is so peculiar compared to other predatory dinosaurs.

The 11th skeleton of Archaeopteryx. Photo by Helmut Tischlinger.

For Archaeopteryx, 2011 has been a year of ups and downs. Paleontologists celebrated the 150th anniversary of when the iconic feathered dinosaur was named. But shortly afterwards, a controversial paper in Nature in July proposed that the creature—widely hailed as the first bird—was further removed from avian ancestry than previously thought. Now Archaeopteryx is back on the upswing. According to a press release circulated by the New Munich Trade Fair Centre in Germany, paleontologists now have an 11th specimen of the famous fossil creature to study.

Until this week, ten Archaeopteryx skeletons were known to paleontologists, not including the fossil feather the German paleontologist Hermann von Meyer used to give the animal its name. Peter Wellnhofer, the world’s foremost expert on the “urvogel,” detailed the backstory of each fossil in his comprehensive book Archaeopteryx: The Icon of Evolution. The London specimen and the Berlin specimen are the best known—particularly the latter, arguably one of the most visually stunning fossils ever found—but there’s also the busted-up Maxberg specimen, another that was initially confused for a pterosaur (the Haarlem specimen) and a slab known as the Solnhofen specimen that was originally thought to contain the skeleton of the small coelurosaurian dinosaur Compsognathus.

As far as I am aware, the new specimen does not have a name and has yet to be described in the literature, but this Archaeopteryx appears to be one of the more complete and well preserved of the lot. In fact, the preservation and position of the bones are reminiscent of the Thermopolis specimen I saw in Wyoming this past year, although this new Archaeopteryx is missing one forelimb and the skull. Don’t be fooled by the fact that, at first glance, the fossil looks a little jumbled up. If you start by following the tip of the tail (on the right), the articulated vertebral column leads to the hips and splayed legs before curving up and back in the classic dinosaur death pose. The arm is displaced below the hips but remains articulated.

We will have to wait for the descriptive paper to learn the important characteristics of this new find, as well as where the slab came from. But if you happen to be in the vicinity of the New Munich Trade Fair Centre in Germany, you can see the 11th Archaeopteryx for a limited engagement at “The Munich Show” from October 28-30.

Two-horned face: a reconstruction of Zuniceratops at the Arizona Museum of Natural History. Photo by the author.

On Sunday, I drove two and a half hours to meet a dinosaur. My journey was part of a trend this year. As I have traveled around the west, from Montana to New Mexico, I have sought out dinosaurs that I have never seen before, and while at this year’s National Association of Science Writers conference in Flagstaff, I found out that the Arizona Museum of Natural History in Mesa has a mount of a unique horned dinosaur called Zuniceratops. That was all I needed to know before getting on the southbound highway.

Though unfamiliar, Zuniceratops is not a brand new dinosaur. The creature was initially described by paleontologists Douglas Wolfe and Jim Kirkland in 1998, and even got a few minutes of relative fame in 2001′s When Dinosaurs Roamed America. Not too shabby for a relative newcomer, but what horned dinosaur can compete with the celebrity of Triceratops and ridiculously well-ornamented genera such as Styracosaurus? Zuniceratops was relatively small, had only two brow horns, and doesn’t look quite as imposing as its later Cretaceous relatives, but those characteristics are part of why this dinosaur is significant to paleontologists looking at the big picture of horned dinosaur evolution.

The bones of Zuniceratops were found in the roughly 89-million to 93-million-year-old rock of western New Mexico’s Zuni Basin. This makes the dinosaur one of the oldest known ceratopsians found in North America, and, as described by Wolfe and Kirkland, the remains of Zuniceratops exhibit a mosaic of features shared with both earlier ceratopsians (such as Protoceratops) and the later, more familiar ceratopsids (such as Triceratops). While the body of Zuniceratops appeared to retain a more archaic, lightly built form, the prominent brow horns, the arrangement of the teeth (set up like a pair of scissors to shear vertically through food), a curved part of the hip called the ischium, and other characteristics underlined a close relationship to the ceratopsid dinosaurs that would eventually become so common on the continent.

But Zuniceratops was not a “missing link” or an ancestor to any of the ceratopsid dinosaurs. Instead, it is a peculiar dinosaur with a suite of features that may help us understand the transition between the more archaic ceratopsians and the early ceratopsids. The arrangement of anatomical characters in Zuniceratops gives us a general picture of what was happening among the horned dinosaurs at the time. After all, the grand pattern of evolution is a wildly branching tree of life, and in technical terms, Zuniceratops falls on a branch just outside the ceratopsid group—a relatively close cousin—but it did not share some of the telltale characteristics of the famous dinosaur group. Hopefully, as more dinosaurs like Zuniceratops are found, paleontologists will gain a clearer picture of how the greatest of the horned dinosaurs evolved.

References:

Farke, A., Sampson, S., Forster, C., & Loewen, M. (2009). Turanoceratops tardabilis—sister taxon, but not a ceratopsid Naturwissenschaften, 96 (7), 869-870 DOI: 10.1007/s00114-009-0543-8

Wolfe, D.G. & Kirkland, J.I. (1998). “Zuniceratops christopheri n. gen. & n. sp., a ceratopsian dinosaur from the Moreno Hill Formation (Cretaceous, Turonian) of west-central New Mexico”. Lower and Middle Cretaceous Terrestrial Ecosystems, New Mexico Museum of Natural History and Science Bulletin 24: 307–317.

Wolfe, D. G. (2000). New information on the skull of Zuniceratops christopheri, a neoceratopsian dinosaur from the Cretaceous Moreno Hill Formation, New Mexico. pp. 93–94, in S. G. Lucas and A. B. Heckert, eds. Dinosaurs of New Mexico. New Mexico Museum of Natural History and Science Bulletin No. 17.