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A line-drawing of the Triceratops known as "Raymond." From Fujiwara, 2009.

If you asked me right now what my favorite dinosaur is, I wouldn’t have an answer for you. There are so many fascinating species that I wouldn’t be able to pick just one. If you asked me the same question when I was about 10 years old, though, I would have immediately shot back “Triceratops!” Ol’ three-horned-face was the dinosaur I loved most—not least because you have to respect a dinosaur capable of skewering a Tyrannosaurus. Actually, I still have a soft spot for that most iconic of Late Cretaceous herbivores, and that’s why I was frustrated by Animal Review’s recent assessment of Triceratops.

Animal Review gave Triceratops a grade of B+. That didn’t give me much to complain about. What bugged me was the fact that they perpetuated the common myth that paleontologists don’t know very much at all about this dinosaur other than the fact that it had three horns:

Little is really known about Triceratops. As always, that’s caused no hesitation in wild speculation on the part of paleontologists. For instance, it is now argued that while Triceratops was once believed to live a solitary life, they actually lived in herds. The fossil record is used here, one assumes, despite the fact that a complete Triceratops skeleton has never been found. This is why nobody has ever seen fit to consult paleontologists about anything that might actually matter.

This is what you get when “research” equals skimming Wikipedia. The Wikipedia page for Triceratops says that “a complete skeleton representing a single individual has eluded fossil hunters,” but the citation for that statement comes from 1993′s The Ultimate Dinosaur Book. Not exactly an up-to-date resource, especially since an exquisite, articulated Triceratops skeleton nicknamed “Raymond” was found in 1994. Only the right side of this individual dinosaur was preserved, but since the left side of a dinosaur was the mirror image of the right, Raymond has provided paleontologists with a near-complete look at Triceratops. It’s also worth noting that paleontologist Shin-Ichi Fujiwara recently studied this specimen to get a better idea of how all the bones of the Triceratops forelimb actually fit together.

Raymond is one of the more complete Triceratops, but partial skeletons of this horned dinosaur have been known to paleontologists for a very long time. In 1904 the institution that would become the Smithsonian National Museum of Natural History mounted the first skeleton of Triceratops anywhere. This skeleton was created from the remains of several individuals excavated in Wyoming, paleontologist Charles Schuchert explained in an American Journal of Science notice, and the specimens had previously been used by Othniel Charles Marsh’s scientific team to create an illustrated reconstruction of the dinosaur’s skeleton.

The American Museum of Natural History followed suit with its own Triceratops in 1933. Like the Smithsonian dinosaur, the AMNH mount was also a composite of real fossils and plaster casts, and part of the basis for the reconstruction was an incomplete skeleton recovered from Montana by fossil hunter Barnum Brown in 1902. Even though both the Smithsonian and the AMNH skeletons were composites, paleontologists were still able to assemble a complete view of the Triceratops skeleton on the basis of various partial skeletons found in the American West.

I asked horned-dinosaur expert Andy Farke about other complete or near-complete Triceratops to make sure I was not missing any significant finds. In addition to mentioning the composite skeleton at the Science Museum of Minnesota, Farke noted, “The skeleton with ‘Kelsey‘ at the Indianapolis Children’s Museum is also quite nice, and just of a single individual.” He also said that the Natural History Museum of Los Angeles “will also have a nice skeleton on display at its upcoming opening this summer—and I think it’s only a composite of two or three individuals (including a nearly complete leg).”

But a complete skeleton isn’t everything. Paleontologists rejoice when they find near-complete dinosaur skeletons, but partial skeletons and isolated bones make up most of what we know about many dinosaurs. In the case of Triceratops, especially, the skull is arguably the most informative part of the skeleton in terms of the animal’s biology and behavior, and paleontologists have recently been turning to the imposing heads of these dinosaurs to learn more about their lives. In 2009, for example, Farke published a paper on the evidence for Triceratops vs. Triceratops combat with co-authors Ewan Wolff and Darren Tanke. Tell-tale patterns of damage on the skulls of the dinosaurs indicated that they truly were locking horns. Then there’s the recent “Toroceratops” controversy over whether the horned dinosaur called Torosaurus represents the adult growth stage of Triceratops. This debate relies upon the skulls of these dinosaurs and the significant changes the animals underwent as they grew up, and is a representative case of how paleontologists are using multiple lines of evidence to investigate the paleobiology of dinosaurs.

Collections of incomplete skeletons can tell us more about Triceratops lives. Another 2009 paper reported on the discovery of several young Triceratops preserved in the same bonebed. This discovery threw support to the idea that juvenile dinosaurs might have hung out together during a vulnerable time in their lives.

Complete, reconstructed skeletons in museums are very impressive, but partial skeletons and isolated bones are the bread-and-butter of dinosaur research. That’s because a collection of skulls or partial skeletons can act as a fossil database that allows paleontologists to investigate questions that cannot be approached by studying a single, complete skeleton. In this respect, Triceratops is an excellent study animal due to the sheer number of specimens that have been collected, and I have no doubt that future investigations will continue to flesh out what this dinosaur was like in life. To me, Triceratops is still an A+ dinosaur.

References:

Brown, B. 1906. New notes on the osteology of Triceratops. Bulletin of the American Museum of Natural History, 22 (17), 297-300

Farke AA, Wolff ED, & Tanke DH (2009). Evidence of combat in triceratops. PloS one, 4 (1) PMID: 19172995

Fujiwara, S. (2009). A reevaluation of the manus structure in Triceratops (Ceratopsia: Ceratopsidae) Journal of Vertebrate Paleontology, 29 (4), 1136-1147 DOI: 10.1671/039.029.0406

Osborn, H.F. 1933. Mounted skeleton of Triceratops elatus. American Museum Novitates, 654, 1-14

Schuchert, C. 1904. The mounted skeleton of Triceratops prorsus in the U.S. National Museum. The American Journal of Science, 4 (20), 458-459

Dinosaurs and other prehistoric creatures have spent plenty of time in IMAX theaters lately. Dinosaurs Alive, Sea Rex, Dinosaurs: Giants of Patagonia and more—the giant screens seem like the perfect venue for resurrecting enormous, Mesozoic monsters. The Tyrannosaurus affectionately known as Sue, arguably the most famous fossil celebrity, even has her own big-screen, 3D spectacle, and I had a chance to catch it during a visit to Utah’s Museum of Ancient Life last week. (A 2D version of the film is now playing at Smithsonian’s National Museum of Natural History.)

Called Waking the T. Rex, the short Sue biography is a combination docudrama and behind-the-scenes peek at paleontology. Visions of Sue brought back to life are interspersed with appearances by Chicago Field Museum paleontologists Lindsay Zanno, Bill Simpson and Peter Makovicky, all of whom share some insight into the science behind the impressive tyrannosaur. While Zanno explains the basics of field work, for instance, Makovicky interprets microscopic sections of Sue’s bones and points out some of the injuries that left their mark on the dinosaur’s skeleton. This combined approach—matching paleo-vignettes of Sue’s world with comments from scientists—informs as well as entertains, and I was glad to see that the film showcased some of the new techniques paleontologists are using to investigate the details of dinosaur lives. High-powered microscopes and CT scanners are allowing scientists to view fossils in ways never before possible.

As for the computer-generated dinosaurs, they trundle across the screen in the stereotyped manner of all big screen dinosaurs. In other words, they don’t act very much like real animals. Sue announces her attacks by roaring; the Triceratops is ornery but relatively easily subdued, and a group of threatened Edmontosaurus discourage the attacking Tyrannosaurus by bellowing and waving their arms about. That aside, I was pleased to see that the filmmakers did not make a young version of Sue look like a miniature adult. Young Sue is long-legged, shallow-snouted, covered in a fuzzy coat of feathers and, appropriately, looks like an awkward teenager. A gaggle of feather-covered dromaeosaurs also makes a cameo in the film, and, in this respect, the movie was up-to-date. We have all seen enough naked dinosaurs.

Die-hard paleo-buffs might not see anything new in Waking the T. Rex, but I thought the film was a solid, accessible introduction that used Sue to introduce viewers to the elements of paleontology. Sometimes it’s good to go back to basics and explain the ways in which scientists investigate prehistoric life. In that regard, Waking the T. Rex is a good film for enthusiastic dinosaur fans who want to know more about how dinosaur bones go from the their rocky graves to museum halls.

One of the Copper Ridge theropod tracks. The front of the foot - indicated by the three toe impressions - is towards the top of the picture. Photo by author.

Even when you know what to look for, dinosaur tracks can be easy to miss. I learned this the hard way on a recent visit to one small tracksite in eastern Utah.

Although Moab, Utah is best known for Arches National Park, uranium mines and various sorts of outdoor recreation, there are traces of dinosaurs in the area, too. Among the fossil sites is a short set of the only known sauropod tracks in Utah. About 23 miles north of Moab on State Road 191 is an inconspicuous, unmarked turnoff around mile marker 148.7. The unpaved road crosses a set of railroad tracks and disappears in the low, dusty hills, and after bumping along for about two miles in our small car, my wife and I arrived at the trailhead.

We spent about 15 minutes looking for the tracks. Neither of us could quite figure out where they were hiding, and the interpretive sign at the top of the trail gave no indication of where they might be. We had no idea that we had walked right over them until my wife spotted one of the large theropod tracks. Right at the top of the trail, there were at least three kinds of footprints set in the rippled, reddish rock, tracks that had persisted for about 150 million years. A fresh coating of dried mud gave some of the tracks a more recent look—as if the dinosaurs had walked by just last week—and partially obscured them from view.

The tracks were not all made at the same time. The sauropod footprints—attributed to Camarasaurus by the sign—were crossed by tracks left by a small theropod dinosaur moving in a different direction. The overlay of the smaller tracks meant that they were made after the big sauropod had passed. Footprints made by a larger predator were left just a few feet away. Several impressions recorded the movement of an Allosaurus-sized theropod, but the tracks had a curious pattern. Rather than indicating an even stride, the tracks alternated between long and short steps. Perhaps this individual had an injury that caused it to limp or take an irregular gait. Thanks to Allosaurus specimens like “Big Al,” we know that these dinosaurs did suffer foot injuries and infections that would have affected their ability to walk, and the Copper Ridge tracks might record the painful footsteps of one such dinosaur.

A hump-backed Spinosaurus, restored by R.E. Johnson and from Bailey 1997.

Spinosaurus and Ouranosaurus were among the most prominently ornamented of all dinosaurs. Both dinosaurs—a carnivore and herbivore, respectively—had elongated neural spines sticking out of many vertebrate along their backbones, which created prominent skeletal sails. In life, these structures are thought to have been covered by a thin layer of flesh, but in 1997 paleontologist Jack Bowman Bailey proposed an alternative idea. These dinosaurs were not sail-backed, Bowman hypothesized. They were hump-backed.

Superficially, the high-spined dinosaurs appeared to be analogues of two other strange prehistoric creatures. The carnivorous Dimetrodon and the herbivorous Edaphosaurus were synapsids, our own distant cousins, that lived between approximately 280 million and 265 million years ago. Both had the skeletal rigging for prominent sails on their backs and lived in a dry, arid landscape roughly similar to the kind of habitat Spinosaurus and Ouranosaurus inhabited much later. But Bailey argued that paleontologists had selected the wrong set of analogues. Bison were a better choice.

Bailey used basic anatomical comparison to set the stage for his idea. Illustrating the skeletons of Ouranosaurus, Dimetrodon and a bison side by side, Bailey noted that the back spines of the dinosaur were most similar to the thick, flattened spines near the shoulder region of the bison and were generally unlike the spindly backbone spires of Dimetrodon. (The elongated neural spines of the bison were so high, in fact, that Bailey wondered, “If bison had become extinct prior to the emergence of our own species, would they be interpreted today as sailbacked mammals?”) The resemblance led Baily to propose that the sails were sites for the attachments of powerful ligaments and large muscles.

Bison-backed dinosaurs would have been obligated to take up a different posture to handle all that extra bulk. If Spinosaurus had a thick hump, Bailey hypothesized, then it probably walked on all fours instead of balancing on two legs like other large theropods. “Thus, it seems unlikely that Spinosaurus was an agile cat-like sprinter like many short-spined theropods (e.g., Allosaurus),” he wrote, “but perhaps used the huge mass of its bear-like body to overpower young or weak prey, or perhaps to steal the kills of smaller more agile predators.” Restored by R. E. Johnson in one of the paper’s illustrations, Bailey’s vision of Spinosaurus looks like an enormous, hunch-backed crocodile.

Spinosaurus and Ouranosaurus were not the only dinosaurs Bailey thought might have humps. Bailey also viewed the elongated neural spines of dinosaurs such as the large theropod Acrocanthosaurus, the ceratopsian Protoceratops, the plate-backed Stegosaurus and others to infer the presence of large and small humps among many dinosaurs. These structures might have allowed dinosaurs to store up large amounts of energy in harsh environments, or maybe they allowed dinosaurs to maintain high, constant body temperatures (something that Bailey did not think dinosaurs were capable of without some specialized anatomical equipment, like a hump). The idea seemed plausible to some. A few months later, in a news report printed in Science, paleontologist Paul Barrett was cited as being in favor of Bailey’s notion. More recently, a 2007 National Geographic feature on “Extreme Dinosaurs” also counted Hans-Dieter Sues as supporting the idea, and a sketch by paleontologist Jason Poole showed a typical, sail-backed Spinosaurus standing next to a hump-backed one.

Beyond these notes, however, the idea that dinosaurs were bison-backed has not caught on. Spinosaurus, Ouranosaurus, and other dinosaurs Bailey cited are most often depicted with sails or other relatively thin structures, such as the fin-like projection at the hips of the recently-described predator Concavenator. There are a few reasons for this.

At the time Bailey wrote his paper, Ouranosaurus and Spinosaurus were thought to have lived in hot, dry, arid habitats where big sails would have caused them to overheat in the hot sun. A hump, in Bailey’s alternative view, would have acted as a “heat shield” in the Cretaceous environments. But paleontologists now know that these dinosaurs lived in lush, swampy environments and probably did not require protection from the desert-like environment Bailey based his ideas on. This also means that the dinosaurs would not have needed humps to store extra energy to make it through harsh dry seasons, thereby undermining the idea that Spinosaurus and Ouranosaurus were like desert lizards that store resources for tough times. (Additionally, if Spinosaurus and Ouranosaurus really did have heat-shield humps, then it is strange that other dinosaurs from the same ancient environments did not share the same adaptation.)

The dinosaurs were also relatively unique in the shape of their elongated spine rows. In terms of maximum spine height compared to the rest of the body, the dinosaurs considered in the study had sail or hump heights intermediate between those of Dimetrodon and bison, and the long spines of Spinosaurus and Ouranosaurus jutted up over a greater length of the back than in the mammals. Whereas the elongated spines of bison typically peaked between the shoulderblades and quickly became reduced in size, the highest points of the dinosaur backs were set further back along the spine and had a more gradual slope to them. This is probably because the elongated spines of bison are sites for muscle and ligament attachments that connect to the neck and head, whereas there is no indication that Ouranosaurus, Spinosaurus, or the other sail-backs needed extra support and power in the neck region. (If this were the case, and dinosaur humps contained muscles to support the head and give the neck more power, then it is odd that huge-headed dinosaurs like Tyrannosaurus did not have a similar adaptation.) Nor is there any indication that Spinosaurus had a body adapted to walking on all fours, although Ouranosaurus likely shared the ability of its hadrosauroid relatives in being able to switch between two- and four-legged locomotion.

Why Spinosaurus and Ouranosaurus had long rows of elongated spines is unknown. The structures supported fleshy banners that almost certainly played roles in display and species recognition—these dinosaurs practically carried billboards on their backs—but beyond that, it is difficult to say. Reconstructing soft tissues on extinct animals is very difficult, and doubly so when there are no solid modern analogues for the structures in question. Though Bailey pointed to the humps of mammals, for example, the elongated spines of bison, mammoths, prehistoric deer and other creatures were related to providing support for the head and strength to the neck, which was apparently not the case with Spinosaurus and Ouranosaurus. Desert lizards with fat tails don’t appear to be good analogues, either. Spinosaurus and Ouranosaurus were fundamentally different, and they remain among the most bizarre dinosaurs yet discovered.

References:

Anonymous (1998). Dino Fins More Like Humps? Science, 279 (5354), 1139-1139 DOI: 10.1126/science.279.5354.1139d

Bailey, J.B. (1997). Neural Spine Elongation in Dinosaurs: Sailbacks or Buffalo-Backs? Journal of Paleontology, 71 (6), 1124-1146

The Mamenchisaurus centerpiece in the "World's Largest Dinosaurs" exhibit. Photo by Flickr user gsz.

The sauropod at the center of the American Museum of Natural History’s “World’s Largest Dinosaurs” exhibit goes by a few different names. Her scientific name is Mamenchisaurus, but she tweets under the name Giant_Dino (mostly about food—as the exhibit explains, she has a big appetite!). Now the AMNH is asking visitors to help give this dinosaur a nickname.

After narrowing down the possibilities to Brook, Neckita, Mei Mei, Tiny, or Mame, the museum has opened up voting on what the sauropod’s name should be. The poll remains open until June 5. Whatever you call this hungry, hungry dinosaur, though, just don’t call her late for dinner.