December 13, 2012
Dinosaurs are much more than real monsters that fire our imaginations, but, let’s face it, part of their persistent appeal is that many were enormous prehistoric oddities. And it’s just that aspect of dinosaurian nature that is raising ire in a historically-rich California town and on an Australian golf course.
San Juan Capistrano, California is famous for the local cliff swallows and the historic Spanish architecture, but the town has recently been in the news because of an unwelcome dinosaur. According to the LA Times, a huge sauropod statue erected in the town’s petting zoo has drawn the ire of those who seek to retain some semblance of southern California’s past. Where kids and the zoo’s owner sees the dinosaur as a fanciful distraction, local historians argue that the dinosaur is totally out of place with the rest of the town’s decor. The dinosaur is staying put for now, but may yet be removed if the city decides that there’s just no place for a dinosaur in a place where Californian history and modern life already mix.
A different dinosaur is frustrating Australia’s professional golfers. The wealthy owner of the Palmer Coolum Resort has installed a 26 foot long, animatronic Tyrannosaurus rex in the middle of the course. Along with other recent installations, ESPN reports, the dinosaur is expected to adversely affect the games of Australian PGA Championship golfers set to play there. With the resort’s owner promising more dinosaurs on the way, the sports group has decided to move the tournament elsewhere after this year. Whether a sauropod looks out of place is one thing–having a T. rex get in the way of your shot is another.
Not everyone is so bothered by giant dinosaurs, though. A Best Western hotel in Colorado is taking on an entirely prehistoric theme, including fossil casts and dinosaur sculptures. In addition to attracting tourists, the hotel’s owner says he wants to draw attention to Colorado’s exceptional fossil sites, such as the nearby track site at Dinosaur Ridge. Dinosaur sculptures are frustrating eyesores to some and paleo-vacation essentials to others.
October 26, 2012
For a dinosaur so terrifyingly powerful as Tyrannosaurus, there was no greater rival than Triceratops. Each was the acme of their respective lineage–one a hypercarnivorous bone-crusher, the other an immense three-horned herbivore. No wonder that artists, paleontologists, filmmakers and children on playgrounds have been pitting these dinosaurs against each other for over a century. Yet, despite how much we love to revel in the Cretaceous gore of such scenarios, we don’t really know whether Tyrannosaurus and Triceratops ever fought each other.
Earlier this week, Nature News reported on a delightfully gruesome Cretaceous vignette presented at the 72nd Society of Vertebrate Paleontology conference. After examining tooth marks on Triceratops frills, paleontologist Denver Fowler of the Museum of the Rockies in Bozeman, Montana, reconstructed how Tyrannosaurus could have torn the head off the great three-horned dinosaur to gain access to the herbivore’s succulent neck meat. There wouldn’t have been much flesh on the frill of Triceratops, Fowler pointed out, so it’s more likely that hungry tyrannosaurs used the bony collars for leverage to wrench the skull of the ceratopsid away from its body. Fowler also notes that he’s still studying these trace fossils and that a paper spilling the full details is in progress.
But the preliminary research only shows how Tyrannosaurus dined on Triceratops. Despite sensational ledes about the study that play up the “immortal battle” between the dinosaurs, the work doesn’t tell us anything about whether the enormous tyrant was capable of killing old three-horned face. Bitten bones and even fossil feces can help us fill out what was on the Maastrichtian menu for Tyrannosaurus, but they can’t tell us how our favorite Cretaceous carnivore acquired that meat.
Consider a damaged Triceratops pelvis described by Gregory Erickson and Kenneth Olson in 1996. The fossil was dotted with at least 58 punctures that were mostly likely created by an adult Tyrannosaurus. These were not injuries caused during predation, but they record the feeding behavior of a tyrannosaur as it ripped the hips off the Triceratops and defleshed that mass of meat and bone as best it could. That’s as far as the evidence goes. Tracing those punctures back to the Cretaceous scene, the Tyrannosaurus is already standing over the felled Triceratops. What killed the Triceratops in the first place is a mystery.
So far, no one has found direct evidence of a Tyrannosaurus versus Triceratops battle. A healed bite wound on a Triceratops skeleton or an injured Tyrannosaurus bone corresponding to damage that could have only been made by a horn would provide paleontologists with a sign that these dinosaurs actually fought. After all, paleontologist Andrew Farke and colleagues recently found that tussling Triceratops wounded each other, so there’s at least a possibility that Triceratops horns might have left tell-tale signs in the bones of an attacking Tyrannosaurus. For now, though, we are left with more indirect clues that will undoubtedly disappoint some dinosaur fans.
Tyrannosaurus was undoubtedly both a hunter and a scavenger. There is no longer any reasonable debate on that point. But, despite the dinosaur’s fearsome reputation, there’s no reason to think that Tyrannosaurus ate whatever it wanted. Tackling an adult Triceratops would have been a dangerous proposition, because of both the ceratopsid’s horns and bulk, so Tyrannosaurus might have avoided such risky encounters. Instead, as David Hone and Oliver Rauhut have pointed out, Tyrannosaurus and other large, carnivorous theropods may have preferentially hunted younger, less-imposing individuals, as well as the old and infirm. And there’s no reason to think that Tyrannosaurus would have passed up Triceratops carrion when the opportunity arose.
The ornaments of Triceratops don’t do much to help the predator-prey scenario, either. Although this dinosaur’s horns and frill have been characterized as weapons, the only direct evidence known of combat is for fights between adult Triceratops. Likewise, even though ceratopsids lived alongside tyrannosaurs for tens of millions of years, predator defense doesn’t seem to have anything to do with horn evolution. If horned dinosaurs developed horns to ward off attacks by big theropods, we would expect there to be an optimal form for defense, or at least severe constraints on the shapes of horns and frills so that they would still be effective. Instead, paleontologists have recorded a confounding array of different horn arrangements among ceratopsids, and the adornments appear to have more to do with communication within their species than defense against others. This is just as true for Triceratops as other horned dinosaurs. While some horns are better than none when confronted by a tyrannosaur, there’s no indication that the ornaments evolved as a predator defense strategy.
We need to reimagine what a confrontation between Tyrannosaurus and Triceratops would have looked like. Instead of two equally matched dinosaurs squaring off against each other, adult Tyrannosaurus probably ambushed young, unwary Triceratops or picked off sick individuals too weak to put up much of a fight. Tyrannosaurus had no sense of honor to uphold–the tyrant was an apex predator that had to maximize its chances of acquiring flesh, and the only safe adult Triceratops was a dead one. Perhaps, someday, a lucky researcher will stumble across evidence of our favorite Hell Creek scene at a field site or in a museum drawer. For now, though, we need to consider the magnificent Tyrannosaurus and Triceratops as real animals and not slavering monsters made to gore each other for our delight.
Erickson, G., Olson, K. 1996. Bite marks attributable to Tyrannosaurus rex: Preliminary description and implications, Journal of Vertebrate Paleontology, 16:1, 175-178 DOI: 10.1080/02724634.1996.10011297
Farke, A., Wolff, E., Tanke, D. 2009. Evidence of Combat in Triceratops. PLOS ONE 4(1): e4252. doi:10.1371/journal.pone.0004252
Fowler, D., Scannella, J., Goodwin, M., Horner, J. 2012. How to eat a Triceratops: Large sample of toothmarks provides new insight into the feeding behavior of Tyrannosaurus. Society of Vertebrate Paleontology 72 poster.
Holtz, T. 2008. A Critical Reappraisal of the Obligate Scavenging Hypothesis for Tyrannosaurus rex and Other Tyrant Dinosaurs, pp. 370-396 in Larson, P. and Carpenter, K. (eds) Tyrannosaurus rex: The Tyrant King. Bloomington: Indiana University Press.
Hone, D., Rauhut, O. 2009. Feeding behaviour and bone utilization by theropod dinosaurs. Lethaia 43.2 (2009): 232-244.
October 23, 2012
The annual Society of Vertebrate Paleontology meeting is a test of endurance. The science comes fast and furious in presentations, posters, hallway conversations and shouted exchanges over the din of the bar, with no consideration for how dehydrated, weary or hungover you might be. (Paleontologists study hard and party harder.) By the last day, my brain ached with details of flying Microraptor, bounding crocodiles, marsupial bone microstructure and dozens of other topics. When my friends at the conference asked “What did you like best?” after the technical sessions finally concluded, I was only capable of grunts and indelicate gestures.
I’ve had a day to settle down and process what I saw. And I know this–at SVP, dinosaurs rule. This isn’t to say that the conference is all about the Mesozoic celebrities. I saw many excellent talks on prehistoric fish, mammals, amphibians and other forms of ancient life. But, for a dinosaur fan, SVP offers a glut of dinosaur science from new discoveries about the beloved Tyrannosaurus rex to brand-new species that have only just come out of the ground. Since this blog is called Dinosaur Tracking, I’m going to focus on some of the stand-out dinosaur science I saw during the meeting.
Montana State University graduate student Jade Simon’s presentation focused on giant Cretaceous dinosaur eggs found in Idaho, but the implications of the discovery were what really grabbed by attention. According to Simon and her collaborators, the pair of elongated, oblong eggs most closely match those found in the nests of oviraptorosaurs–beaked, feathered theropods like Citipati and eponymous Oviraptor. Yet the two eggs were so large that they suggested a dinosaur of prodigious size, on the scale of the 25-foot-long Gigantoraptor recently found in China. If Simon and coauthors are correct, then an enormous, as-yet-undiscovered oviraptorosaur strutted around Idaho around 100 million years ago. The next step–finding this fantastic creature’s bones.
Simon wasn’t the only researcher showing off dinosaur eggs. Just prior to her presentation, meeting attendees were treated to a pair of talks about dinosaur embryos found in the Late Jurassic rock of Portugal. These deposits are similar in age to those of the famous Morrison Formation of the American west and share many of the same types of dinosaurs. An embryo studied by Ricardo Araújo and coauthors appears to be a nascent Torvosaurus–a giant Jurassic carnivore that topped Allosaurus in bulk–and paleontologist Octávio Mateus followed with a skeletal embryo of Lourinhanosaurus, a mid-size theropod dinosaur found in the same formation. The embryo described by Mateus stood out because it was found by his parents–amateur paleontologists–in a nest of 100 eggs, including crocodile eggs mixed in with those of dinosaurs. Was this nest a communal site used by many mothers? The embryo and the nest it was found in will definitely help us better understand how some baby dinosaurs entered the world.
The SVP crowd also got treated to previews of various dinosaurs that are slowly making their way to press. Researcher Corwin Sullivan presented some scrappy evidence that a second giant tyrannosaur might have lived alongside the recently named Zhuchengtyrannus, and Nathan Smith showed off some new material from what may be two new species of sauropodomorph dinosaurs collected from Antarctica. Oliver Rauhut added to the list with a new theropod from Argentina that looks like a more archaic version of Allosaurus, and visitors to the poster session got to check out what might be a new species of Diabloceratops that Eric Lund and his colleagues have been working on. Most of the new dinosaur presentations followed the same format–where the fossils were found, how much of the skeleton was found, what sort of dinosaur the species is–but, in time, we should get fuller details of these dinosaurs in progress.
But not all the presentations at the conference were on new field discoveries. Increasingly, paleontologists are scanning, slicing and otherwise studying fossils in new ways, drawing ever more data about dinosaur biology from old bones. The first talk I walked into, by Eric Snively, reconstructed the neck musculature of Allosaurus for insights into the feeding behavior of this Jurassic hypercarnivore. As it turned out, Allosaurus probably had quite a strong neck and used this power to stabilized its flexed head while ripping flesh from prey–think of a giant, toothy falcon. In another session, Jason Bourke created virtual models to examine whether sauropod dinosaurs such as Camarasaurus and Diplodocus had their nasal openings on the tops of their heads–as was shown when I was a kid–or had nostrils further down the snout. The airflow models better fit the nose-at-end-of-snout model, although, as Bourke pointed out, there’s still quite a bit we don’t know about sauropod soft tissues.
Unsurprisingly, Tyrannosaurus got some love, too. Sara Burch reexamined the shoulders and forelimbs of old T. rex in an attempt to reconstruct the dinosaur’s musculature. Among other things, Burch found that the dinosaur’s arms underwent significant functional changes over time. The arms of the tyrant weren’t fading away, but modified for different uses than that of earlier relatives. What exactly the dinosaur was doing with its infamously small arms, though, we still don’t know.
Within the various new areas of research, though, dinosaur histology has been providing paleontologists with some of the most tantalizing details of prehistoric biology. My friend Carolyn Levitt presented her new research on the microstructure of Kosmoceratops and Utahceratops bones. These horned dinosaurs didn’t show any lines of arrested growth (LAGs) in their bones–rings thought to mark annual slowdowns in bone growth and often used to roughly age dinosaurs–while previously studied dinosaurs from more northern sites in North America do show these markers. This might mean that, like mammals, dinosaurs maintained high-running metabolisms but their growth was still influenced by environmental pressures, such as cold or dry seasons, in their surrounding environment. In a time of scarce resources, dinosaurs in highly seasonal habitats probably slowed their growth while those in lusher environments did not face the same pressures. Indeed, the dinosaurs with the most LAGs were the northernmost, while Utahceratops and Kosmoceratops were the southernmost sampled.
In a similar vein, a poster by Julie Reizner looked at the histology of the horned dinosaur Einiosaurus and what the microstructure details might say about the ceratopsid’s biology. The sampled dinosaurs, found in a rich bonebed, suggest that growth in Einiosaurus slowed at about three to five years of age, which might mean that these dinosaurs made a dash for reproductive maturity before their growth slowed. The fact that Reizner’s animals were predominately young and perished long before full skeletal maturity–or, in other words, still had some growing to do–is consistent with the idea that dinosaurs generally lived fast and died young.
And I would be remiss if I didn’t mention that there was an entire session devoted to Appalachia–a Late Cretaceous subcontinent formed when a shallow sea split North America in two, of which my former New Jersey home was a part. Paleontologists have made fascinating discoveries on the sister continent, Laramidia, but Appalachia has often been ignored given that we as yet knew little of the dinosaurs that lived there. Still, there is much to be learned by going back to the fragmentary and rare dinosaurs of that early eastern landmass. In addition to featuring Dryptosaurus, New Jersey’s fearsome tyrannosauroid, Stephen Brusatte reexamined the few remains of “Ornithomimus” antiquus. This ostrich-like dinosaur probably belonged to a different genus and was not as primitive as previously thought. Shortly after Brusatte’s talk, Matthew Vavrek spoke about dinosaurs found in the high Arctic of Appalachia. Hadrosaurs, deinonychosaurs, tyrannosaurs and others lived along the northwestern coast of the continent and may help use better understand the differences between Appalachia and Laramidia. The most frustrating aspect of all of this is that the eastern dinosaurs are so poorly known–we need more dinosaurs.
The findings I mention here are just a scattered sampling of SVP, based upon the talks and posters I personally encountered. With three sessions going at the same time, it was utterly impossible to see everything. (Please chime in about your own favorite presentations in the comments.) Nevertheless, it was amazing to see paleontologists showing off new finds and going back to fossil collections for new information. We’re learning more, at a faster rate, than ever before. As multiple experts said to me during this conference, it’s a great time to be a paleontologist. The SVP dinosaur sessions left no doubt of that, and I can hardly wait for next year.
Thankfully, many other paleontologists have been sharing their thoughts about the conference through the #2012SVP Twitter hashtag and on their blogs. For an outsider’s perspective on the conference, see Bora Zivkovic’s rundown of the meeting, as well as Victoria Arbour’s summary of SVP silliness. Out of everything, though, I think this year’s attendees will all remember the conference center’s whoopee cushion chairs–caught on video by Casey Holliday’s lab. I hope that next year’s conference in Los Angeles is just as exhausting, and just as fun.
October 3, 2012
Recently I was leading friend and fellow-writer Seth Mnookin through the Natural History Museum of Utah’s prehistoric exhibits when he asked a question that has popped up in my own mind from time to time–why is Tyrannosaurus rex so popular? There were stranger carnivores, and journalists love to delight in the announcements that slightly bigger theropods have dethroned the tyrant king. Yet T. rex remains the quintessential dinosaur.
Part of the secret, I think, is cultural inertia. Paleontologist Henry Fairfield Osborn named Tyrannosaurus rex in 1906, during a time when paleontologists were still dealing with a bare bones outline of what dinosaurs were like. Very few species were known from partial skeletons, much less complete ones, but Osborn’s field man Barnum Brown discovered two exquisite T. rex skeletons in rapid succession. The massive carnivore burst onto the scene as the largest carnivorous dinosaur ever found, and the second, more complete skeleton Brown discovered was quickly turned into an iconic mount that inspired many generations of paleontologists.
T. rex remained unchallenged until the mid-1990s. After nearly a century at the top, it was impossible to knock down the heavyweight. No museum display was complete with at least a T. rex tooth, if not a cast of a skeleton, and films such as King Kong and Jurassic Park underscored the savage power of the dinosaur. From the time of its discovery, we have celebrated T. rex as the acme of destructive dinosaurian power. The dinosaur so dominated the cultural landscape that it overshadows all others.
But, as Seth pointed out while I laid out this hypothesis, the dinosaur’s reputation is fully deserved. Some giant carnivores might have been a little longer or heavier–we don’t really know, since they’re not known as completely as T. rex–but there is no question that T. rex was among the top four gargantuan dinosaur predators and the biggest meat-eater in its Late Cretaceous ecosystem. Even though our general image of the tyrant has changed, from changes in posture to the addition of fuzz, T. rex has remained the biggest and baddest dinosaur from America’s badlands. The reputation of T. rex has not been diminished. To the contrary, the more we learn about the paleobiology of the theropod, the more fearsome T. rex becomes. And to that, I say “Long live the king!”
October 1, 2012
Last month, we asked readers to vote for their favorite entry from all the weird and wonderful Dinosaur Sightings we’ve cataloged over the past few years. Naturally, though, there are even more roadside monsters out there. Readers quickly responded with a significant omission from our list–Tampa, Florida’s Recyclosaurus.
Reader Wyrmwren sent in this snapshot, writing “With so much to see and all the traffic, we almost missed him and had to go back for a closer look.” But this dinosaurian monument to recycling isn’t looking as good as it did when it was constructed in 1992. The mass of steel beams, plastic fencing and aluminum cans needs some touch-ups, and there’s a campaign to save the Recyclosaurus from extinction.