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The reconstructed skull of Eotriceratops. The actual specimen is not complete, but, based on the recovered elements and the dinosaur’s relationships, we know the dinosaur would have looked similar to Triceratops. Photo by Roland Tanglao, image from Wikipedia.

Triceratops is among the most cherished of dinosaurs. Even that might be a bit of an understatement. Fossil fans threw a conniption when they mistakenly believed that paleontologists were taking the classic “three-horned face” away, after all. But where did the charismatic chasmosaurine come from? Triceratops didn’t simply spring from the earth fully formed–the ceratopsid was the descendant of a long tail of evolutionary forerunners. And in 2007, paleontologist Xiao-chun Wu and collaborators described a 68-million-year-old dinosaur that might represent what one of the close ancestors of Triceratops was like–Eotriceratops.

In 2001, while on an expedition to search the Horseshoe Canyon Formation around the Dry Island Buffalo Jump Provincial Park in Alberta, Canada, Glen Guthrie discovered the partial skeleton of a huge ceratopsid dinosaur. This was the first identifiable dinosaur skeleton found in the top quarter of the formation, and, as Wu and coauthors later argued, the bones represented a new species. They called the animal Eotriceratops xerinsularis.

Paleontological devotees know that “eo” translates to “dawn.” The tiny mammal Eohippus was the “dawn horse” (which Victorian anatomist Thomas Henry Huxley famously characterized for the steed of a tiny “Eohomo“), and there are plenty of dawn dinosaurs such as Eoraptor, Eodromaeus, Eobrontosaurus and Eolambia. The prefix is a kind of honorific, used to indicate the hypothesized beginning of a major lineage or significant change. In the case of Eotriceratops, Wu and colleagues found that the dinosaur was the oldest known member of the evolutionary ceratopsid club containing Triceratops, Torosaurus and Nedoceratops (which, depending on who you ask, may or may not be the same dinosaur).

The individual Guthrie found had fallen apart between death and burial. Aside from some vertebrae, ribs and ossified tendons, the scattered specimen was primarily represented by a dis-articulated skull. When reconstructed, though, the head of Eotriceratops stretched almost ten feet long–about a foot longer than the largest-known Triceratops skull. And while different in some characteristics, Eotriceratops had the same three-horned look of its later relatives Triceratops and Torosaurus.

This isn’t to say that Eotriceratops was directly ancestral to Triceratops, Torosaurus, Nedoceratops or whatever combination of the three paleontologists ultimately settle on. Eotriceratops could be the closest relative of Triceratops to the exclusion of Torosaurus, which would support the idea that those later dinosaurs were separate genera.  Then again, Wu and coauthors pointed out that Eotriceratops might be the most basal member of the subgroup, which would make sense given that it was older than the other three genera. In either case, Eotriceratops can give us a rough idea of the Triceratops and Torosaurus prototype, but we lack the resolution to know if Eotriceratops was ancestral to any later dinosaur. Eotriceratops undoubtedly had some significance in the evolution of the last three-horned dinosaurs, but we need many more fossils to know this little-known dinosaur’s role in the story. Every dinosaur paleontologists find comes with a handful of answers and a myriad of new mysteries.

This post is the latest in the Dinosaur Alphabet series.

Reference:

Wu, X., Brinkman, D., Eberth, D., Braman. 2007. A new ceratopsid dinosaur (Ornithischia) from the uppermost Horseshoe Canyon Formation (upper Maastrichtian), Alberta, Canada. Canadian Journal of Earth Sciences 44: 1243-1265

What could be better than seeing a living Triceratops? Riding one, of course. Doctor Who showed us that much.

Sadly, old “three horned face” is long gone. I wouldn’t count on the dinosaur to be brought back to us by way of genetic experiments or alien arks filled with dinosaurs. But don’t despair, Triceratops fans. An art group called Wreckage International combined Triceratops with a Jeep to create “Adrianne,” a working autosaurus. You can hear about how Adrianne was created here. No word yet on whether the next model will resemble Torosaurus.

[Hat-tip to Texas Triffid Ranch]

A sculpture of Torosaurus—or, according to some, a mature Triceratops—outside Yale's Peabody Museum of Natural History. Photo by the author.

I wish I could take dinosaurs away from the media for a while. Someone certainly should. Lazy journalists and unscrupulous documentary creators have amply demonstrated that they just can’t play nice with Tyrannosaurus, Triceratops and kin.

In the past month and a half, we’ve seen aquatic dinosaur nonsense resurface in shoddy news reports, a brief media invasion of hyperintelligent alien dinosaurs and stinky stories about dinosaur farts, not to mention the bizarre creationist/extraterrestrial conspiracy-theory mashup on Ancient Aliens. I’m almost surprised that this glut of utter dreck wasn’t followed by reports of dinosaurs who used their noxious flatulence to propel themselves through space. To paraphrase the immortal words of Ozzy Osbourne, it would seem that dinosaur news has gone off the rails on a crazy train.

And the distortions keep coming. The sci-fi and science news aggregator io9 just drew on a ceratopsid misunderstanding I thought had been left behind two years ago. Yesterday afternoon Ed Grabianowski posted an article titled “Everything you need to know about the scientific controversy that could destroy Triceratops.” The article was meant as a quick survey of recent, and quite controversial, research about whether the horned dinosaurs called Torosaurus and Nedoceratops are really more mature forms of ol’ three-horned face, Triceratops. The general idea is that the solid, rounded frill of Triceratops changed shape and developed two large holes, called parietal fenestrae, relatively late in life, when the dinosaur hit skeletal maturity. What were previously considered to be three different dinosaurs might actually just be three growth stages of the same genus.

Whether this was truly the case is a matter of debate. And while Grabianowski produced a fair review of the research, the post repeated the hyped—and entirely wrong—idea that paleontologists might soon be sinking Triceratops. “If you cried over the sick Triceratops in Jurassic Park, or just loved this horned dinosaur as a kid,” Grabianowski wrote, “there’s one scientific controversy you need to understand right now—it’s the one that may wind up demonstrating that Triceratops never existed.”

Here’s the thing. Triceratops is totally safe. It’s only the dinosaur die-hards who adore Torosaurus and Nedoceratops who have anything to worry about. I covered this two years ago, when the publication of the first paper in this ongoing debate kicked off a wave of ill-informed hysteria. (Although I must say that the Triceratops-Pluto shirt design was pretty cool.)

If—and I emphasize if—Triceratops, Nedoceratops and Torosaurus turn out to be growth stages of a single dinosaur, then the name Triceratops has priority. Paleontologist O.C. Marsh named Triceratops in 1889, and he followed that with the first description of Torosaurus in 1891. Nedoceratops is a newcomer name for a single skull that has been given many monikers over the past century; A.S. Ukrainsky coined the name in 2007. Given the taxonomic arcana that govern the proper scientific names for organisms, Triceratops would remain the proper name for the dinosaur since it was established first.

(“Brontosaurus” was put to bed for the similar reasons. Brontosaurus is a synonym for a dinosaur O.C. Marsh named earlier—Apatosaurus—and paleontologist Elmer Riggs recognized this state of affairs more than a century ago. But Brontosaurus still has a great deal of cultural cachet because museums, books, documentaries, writers and paleontologists keep reminding everyone of the name change. Brontosaurus still lives because we keep reminding people that it didn’t really exist.)

No matter what happens, Triceratops isn’t going anywhere. What we think we know about the dinosaur’s biology might change, but the classic name will stay. I pointed this out on Twitter shortly after the io9 post appeared, and, to io9′s credit, science editor Analee Newitz quickly changed the headline and introduction. I appreciated the speedy edit. The body of the post was a good summary of the argument as it presently stands, but it was painful to see the same “ZOMG, THEY’RE TAKING AWAY TRICERATOPS!” myth used to frame the article.

I’m thrilled that dinosaurs are so popular. Discoveries are coming so fast and furious that it is almost impossible to keep up, and a new wave of cultural dinomania seems to be swelling. That’s why I get so frustrated by misrepresentations of what we’re actually learning about dinosaur lives. We don’t need embellishment—whether it’s teasing us with the false threat of a beloved dinosaur’s disappearance or the idea that sauropods farted themselves into extinction. The wonderful resolution we’re gaining into dinosaur biology and evolution is best communicated simply, directly, and without having to find some snarky or inaccurately comedic hook that ends up distorting what we actually know. And I would be remiss if I didn’t point out that scientists sometimes play this game, too. Chemist Ronald Breslow tried to use armchair speculation of space dinosaurs to give an otherwise mundane paper a little spice—a ham-fisted and ill-executed grab for attention that I sadly saw some other writers agree with. There’s no such thing as bad publicity, right?

Of course, I realize that simply shaking my fist in the air and frustratedly growling “Do better!” isn’t going to fix the problem. There are seemingly innumerable internet news outlets, and never enough professional science writers, so it’s all too easy for dumbed-down churnalism and other misconstrued reports to richochet around the web. Maybe we’ve seen the last of dinosaur farts and space tyrannosaurs, at least for a while, but places like the Daily Mail, FOX News, and the various outlets that pass off barely modified press releases as news will undoubtedly come up with another headache-inducing hook in the not-too-distant future. If it’s not too much to ask, though, I’d like it if the usual suspects gave it a rest. Dinosaurs are amazing enough without the sensationalism.

A restoration of Yutyrannus, with the therizinosaurs Beipiaosaurus in the foreground, by Brian Choo. Caption added by the author.

When I first heard the news that paleontologists had discovered a giant, fuzzy tyrannosaur, I was giddy with excitement. The dinosaur, dubbed Yutyrannus, was a confirmation of an idea that researchers and artists had been cautiously exploring for years. While most of the feathered dinosaurs discovered so far have been very small and often quite bird-like animals, Yutyrannus was a roughly 30-foot-long bruiser which showed that even huge predators might have sported fluffy plumage. And if an imposing predator like Yutyrannus sported a fuzzy coat, the same might be true for the theropod’s notorious cousin, Tyrannosaurus rex. The tyrant king may not have been the wholly scaly monstrosity I grew up knowing, but an apex predator decorated by patches of simple protofeathers.

Not everyone shared my enthusiasm. “Tyrannosaurs were supposed to be scaly,” came the cantankerous cry from die-hard fans of more reptilian dinosaurs. Why are paleontologists so committed to destroying the fantastic imagery Jurassic Park embedded in our cultural landscape? Across the web, tyrannosaur traditionalists registered their displeasure. “Oh, how the mighty have fallen!” mourned one WIRED commenter, and elsewhere, Yutyrannus was presented as a “fuzzball” and “chicken from hell.” And while the outrage was not as great as when people mistakenly believed that paleontologists were trying to kill Triceratops, at least some dinosaur fans lamented the increasingly avian aspect of tyrannosaurs.

Paleo blogger Mark Wildman recently jumped in with a post titled “In Defence of Scaly Dinosaurs.” He was sad to see yet another proud dinosaurian lineage turn fluffy. “Those of us who like our dinosaurs scaly appear to be frowned upon,” Wildman wrote, “as if we don’t know what we are talking about and that we really ought to ‘get with it’ and rejoice that the dinosaurs are covered in fuzz and feathers. Well that isn’t going to happen—certainly not by me and, I am sure, not for many others.” And to dapple Tyrannosaurus with feathers would be the ultimate indignity. Citing the awesomeness of Tyrannosaurus in Dinosaur Revolution, and how silly the feathery Gigantoraptor looked, Wildman challenged readers: “Do you really want the ultimate theropods, the megastars of the dinosaurian world—the tyrannosaurs—displaying colourful yet gaudy feathers and dancing like a demented turkey cock?”

I actually wouldn’t mind a strutting tyrannosaur, even though I admit that Dinosaur Revolution‘s Gigantoraptor sequence was a little over the top. And none of this is to say that Wildman objects to the evidence of feathered dinosaurs. He makes it quite clear that he’s entirely on board with the science. All the same, his post and other comments about how Yutyrannus has somehow ruined tyrannosaurs made me wonder about why it is so fashionable to register cranky displeasure with the way dinosaurs have changed. Some people just don’t like feathery dinosaurs, many wept and wailed at the false assertion of journalists that Triceratops might disappear, and “Brontosaurus” still stirs up strong feelings among those who grew up with the thunder lizard. It’s cool to show contempt for new discoveries in favor of the dinosaurs we grew up with. Before I knew the extent of the evidence, even I felt a little sad that so many of the scabrous, ugly dinosaurs I met as a kid were turned into pretty peacocks.

I can’t explain why this is so any more than I can explain why we adore dinosaurs in the first place. I don’t think anyone has successfully articulated why we’re so enthralled by these creatures. But I think Mike Brown identified one important thread in his book How I Killed Pluto and Why it Had it Coming. When Pluto was officially demoted from planet to dwarf planet, many people objected to the loss of one of our solar system’s icons. Brown recalled:

In the days that followed, I would hear from many people who were sad about Pluto. And I understood. Pluto was part of their mental landscape, the one they had constructed to organize their thinking about the solar system and their own place within it. Pluto seemed like the edge of existence. Ripping Pluto out of that landscape caused what felt like an inconceivably empty hole.

Of course, Pluto didn’t actually go anywhere. Its title simply changed. But the alteration virtually obliterated the cosmic body in people’s minds. Might the same be true for dinosaurs? For those of us who grew up with scaly, swamp-dwelling dinosaurs, the new images of fuzzy dinosaurs are conflicting with the Mesozoic world as we think it should be. A Tyrannosaurus with feathers isn’t really a Tyrannosaurus, but a different sort of creature that doesn’t quite fit what we had in mind for so long. This tension is inevitable. There is so much that remains unknown that any vision of the past is certainly going to change. I have no doubt that, a few decades from now, children who grew up with feathery dinosaurs will lament how future generations of paleontologists are altering the picture of dinosaur lives.

Triceratops (left) and Torosaurus (right). Art by Nicholas Longrich.

More than 120 years ago, the Yale paleontologist Othniel Charles Marsh described two of the most spectacular horned dinosaurs of all time. The first, named Triceratops in 1889, had three impressive horns jutting out of its face and a solid, curved frill. Two years later, Marsh named Torosaurus, another great, three-horned dinosaur, but with a longer frill perforated by two round holes. Although the two overlapped in space and time, they seemed distinct enough that paleontologists considered them to be separate dinosaur genera. That is, until Museum of the Rockies paleontologists John Scannella and Jack Horner suggested that these two dinosaurs were really one in the same.

Scannella and Horner presented their “Toroceratops” hypothesis at the 2009 Society of Vertebrate Paleontology meeting in Bristol, England, and the following summer their paper came out. Based on skull anatomy, bone microstructure and other lines of evidence, the paleontologists proposed that Marsh’s Torosaurus was really the skeletally mature form of Triceratops. As Triceratops grew, the dinosaur’s frill would have changed size and shape, and those trademark Torosaurus holes would have opened up. An enigmatic fossil named Nedoceratops seemed to show this intermediate anatomy and was cited by Scannella and Horner as a dinosaur caught in the act of changing. Poor reporting on the research sent the public into a tizzy—Triceratops fans wept, wailed and gnashed their teeth at the suggestion that paleontologists were taking away one of their favorite dinosaurs, but only those with an affinity for Torosaurus had anything to fear. Since Triceratops was named first, the name had priority and Torosaurus would therefore be sunk. (No one seemed to care a whit that poor, neglected Nedoceratops would suffer the same fate.)

But should we sink Torosaurus? In the two years since Scannella and Horner’s paper came out, paleontologists have gone back and forth about whether such a radical, late-life transformation in Triceratops was even possible. Early last year, ceratopsian expert Andrew Farke of the Raymond M. Alf Museum of Paleontology criticized the Triceratops transformation hypothesis and pointed out that Nedoceratops did not actually fit neatly into the sequence of changes Scannella and Horner had proposed. Naturally, the Museum of the Rockies paleontologists disagreed, and in a response published in December of 2011, Scannella and Horner reaffirmed the relevance of Nedoceratops to the extreme changes Triceratops might have undergone as it grew up.

Now another set of challengers has appeared. In a paper published last night in PLoS One, Yale University paleontologists Nicholas Longrich and Daniel Field concluded that Triceratops and Torosaurus truly were distinct dinosaurs, after all.

Most of what we know about Triceratops and Torosaurus has been extracted from skulls. Post-cranial skeletons are rare and, in the case of Torosaurus, incompletely known, and so the current argument is centered on how the skulls of these horned dinosaurs changed. In the new study, Longrich and Field coded twenty four different characteristics—relating to bone surface texture, fusion between skull bones, and other features—in a swath of Triceratops and Torosaurus skulls. The paleontologists then used this data to sort the different specimens into growth stages based on their cranial development. If Torosaurus truly represented the mature form of Triceratops, then all the Torosaurus should have come out as adults.

The skulls of Torosaurus YPM 1831 and Triceratops YPM 1822 compared. Image courtesy Nicholas Longrich.

Of the six Torosaurus examined, five fell into a range between young and old adults. But there was one particularly large individual that seemed to be significantly younger. When Andrew Farke issued his critique of the “Toroceratops” hypothesis last year, he noted that a skull designated YPM 1831 was a possible candidate for a young Torosaurus. The paper by Longrich and Field supported this idea—YPM 1831 grouped with the subadult dinosaurs. “It’s a little surprising considering how damn big the skull is—probably about nine feet long—but it’s not fully mature,” Longrich said. “It’s like a teenager,” he noted, “a physically big animal but not all that mature yet.” The development of ornaments on the skull, the fact that some bones are not fused, and a bone texture associated with rapidly growing bone are possible signs that this dinosaur was not yet an adult.

If YPM 1831 really was a subadult Torosaurus, then it is probable that Triceratops and Torosaurus were distinct dinosaurs. Indeed, if Torosaurus truly was the fully mature form of Triceratops, then we should not find any juvenile or subadult Torosaurus specimens. “[B]oth Torosaurus and Triceratops,” Longrich and Field concluded, “span a range of ontogenetic stages,” and the features which distinguished each dinosaur appear to have developed before full maturity.

But Scannella disagrees. “Nothing in this paper falsifies the synonymy of ‘Torosaurus‘ and Triceratops,” he says. In particular, Scannella notes that the new study relies on comparative anatomical techniques, but does not employ studies of dinosaur bone microstructure which shows how individual skull bones were changing. Scannella explained:

Comparative morphology is useful in examining dinosaur ontogeny, however it shouldn’t be considered in a vacuum. There are other factors which provide a wealth of information on dinosaur growth. For example, by examining histology, the microstructure of the bones, we can actually see how the thick, solid frill of Triceratops expanded, became thinner, and developed the characteristic holes of the ‘Torosaurus‘ morph. You can look at a Triceratops squamosal under a microscope and see how it was transforming. We are also finding that the stratigraphic position of specimens is critical to understanding morphological trends.

Other subtle skull modifications are also in contention, such as how fusion between bones in the skull relates to maturity. Among other features, Longrich and Field looked at the fusion of skull bones to help determine which age bracket particular specimens fell within. “We think that what the fusions are telling you is that growth has slowed,” Longrich explained, “because you can no longer deposit new bone between those bones. This seems to be a fairly reliable indicator of maturity in relatively fast-growing animals like lizards, mammals, and birds.” In the case of Triceratops and Torosaurus, skull fusion seemed to occur in a particular sequence. “First the skull roof is fused, next the hornlets on the frill and cheeks fuse, then the beak and the nose fuse on. It’s a very regular pattern which suggests we can use this as a reliable way of getting at roughly where the animals fit in the developmental series,” Longrich said.

Yet Scannella and Horner have previously argued that the timing and degree of skull bone fusion aren’t as clear. Recently discovered specimens are contributing to the picture of how variable skull fusion might be. “The Museum of the Rockies has collected over a hundred new Triceratops from the Hell Creek Formation of Montana in the last decade,” Scannella said, and these specimens indicate that the details of skull fusion varies between individuals. “We have some huge, fairly mature Triceratops in which much of the skeleton is unfused; and there are also smaller, less mature specimens with many skeletal elements fused,” Scannella explained.

How the skulls of dinosaurs like Triceratops fused is not yet entirely clear, but, according to Andrew Farke, the degree of fusion between skull bones might be reliable for getting a general idea of how old an animal was. “There is little argument that the individual bones of the braincase tend to be unfused in young animals, and fused in old animals,” Farke pointed out, and further explained that “The same goes for the hornlets (epinasals and epijugals) on the face of ceratopsian dinosaurs,” he said, since “young animals tend to have unfused hornlets and old animals have fused hornlets.” Such features are what made the YPM 1831 Torosaurus stand out as a possible subadult to Farke’s eye.

Exactly which dinosaur YPM 1831 represents remains uncertain. The skull is the best candidate so far for a teenage Torosaurus, but this ambiguous specimen alone cannot end the debate. In fact, we have so much left to learn about Triceratops and Torosaurus—particularly about how their post-cranial skeletons changed as they aged—that a great deal of exploration and description remains to be done before this debate can be resolved. And this isn’t the only dinosaur name game in progress. The tiny tyrant “Raptorex” may have been a juvenile Tarbosaurus, the huge Anatotitan likely represents a mature Edmontosaurus, Titanoceratops was probably a big Pentaceratops, and the thick-skulled Dracorex and Stygimoloch might represent early growth stages of Pachycephalosaurus. Some of these changes sting—both Torosaurus and Anatotitan were childhood favorites of mine, and I’d hate to see them go—but, ultimately, these debates will help us better understand how dinosaurs grew up.

References:

Longrich, N., & Field, D. (2012). Torosaurus Is Not Triceratops: Ontogeny in Chasmosaurine Ceratopsids as a Case Study in Dinosaur Taxonomy PLoS ONE, 7 (2) DOI: 10.1371/journal.pone.0032623