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A reconstruction of Acrocanthosaurus at the North Carolina Museum of Natural Sciences in Raleigh, North Carolina, where this year’s SVP reception was held. Photo by Famille Wielosz-Caron, image from Wikipedia.

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.

The tyrannosaur Gorgosaurus in a classic death pose (although note that the tail is almost entirely missing and speculatively reconstructed). Image from Diller and Brown, 1923.

After a week packed with presentations, posters and lots of paleo-goodness, the 71st annual Society of Vertebrate Paleontology meeting is over. There’s not much to be sad about, though. If the conference is any indication, we’re going to be seeing lots of fascinating dinosaur stories in the coming weeks, months and years.

There were far too many dinosaur presentations to attend them all, but the big-picture trend is that paleontologists are able to pull ever-more information about dinosaurs out of their bones and geological context. Last week I wrote about the meeting’s Laramidia session, in which paleontologists pondered the distribution and evolution of horned dinosaurs, hadrosaurs, tyrannosaurs and other Late Cretaceous celebrities up and down the western subcontinent. These discussions consequently fed into the ongoing debate about how diverse dinosaurs were and whether we have named too many species. In a poster presented on the last day of the conference, Museum of the Rockies paleontologist Denver Fowler proposed that some horned dinosaurs such as Mojoceratops, Titanoceratops and Kosmoceratops are really different stages of previously named dinosaurs such as Chasmosaurus and Pentaceratops. There was quite a bit of discussion and arguments about this proposal—just as with the idea that Torosaurus is really a grown-up Triceratops—but that’s not a bad thing. By combining anatomy, histology, biogeography and other lines of argument, paleontologists may be able to get some better resolution about how dinosaurs actually lived and the big patterns of their evolution. Yes, there are going to be controversies and debates, but that is a positive thing that speaks to the current vibrancy in the field of study.

The strange oviraptorid dinosaur, on display at the Carnegie Museum of Natural History, mentioned by Matt Lamanna at this year's SVP meeting. Photo by the author.

Attendees also got an early look at previously unknown and little-studied dinosaurs. On Saturday morning Max Langer from the Universidade de São Paulo presented a report on an early sauropodomorph dinosaur found in the Late Triassic Santa Maria Formation of Brazil. The skull was vaguely reminiscent of Eoraptor—a dinosaur hypothesized to be a sauropodomorph and not a theropod in a paper published early this year—and this new dinosaur was apparently close to the origins of the varied and successful group of dinosaurs which would eventually contain giants such as Apatosaurus and Giraffatitan. But not all the undescribed dinosaurs mentioned at the session were new. At the SVP reception held at the Carnegie Museum of Natural History last year, I saw the reconstructed skeleton of a strange oviraptorid dinosaur from North America. This toothless, crested creature is known from several partial skeletons but has been little studied until now. That’s why I was glad to see a presentation by Carnegie Museum of Natural History paleontogist Matt Lamanna, which presented the animal as the best-known oviraptorid dinosaur from our continent. Even though ovirpatorids remains have been found in North America before, they were so scrappy that their counterparts in Asia filled in most of what we know about these dinosaurs. The yet-unnamed oviraptorid Lammana described will help fix this problem, and will provide another way for paleontologists to investigate the trade of different dinosaur lineages between North America and Asia during the Late Cretaceous.

New technologies and sophisticated methods are also being used to fill out our understanding of dinosaur biology. Paleontologists are agreed that dinosaurs were active, dynamic and fast-growing animals, but how they achieved this lifestyle is still a matter of investigation. In a talk in the theropod dinosaur session, paleontologist Mark Goodwin from the University of California Museum of Paleontology in Berkeley presented results that tested the conclusions of an earlier study about the physiology of Tyrannosaurus rex. The earlier study had used oxygen isotopes—chemical signals locked in bones and teeth that can be compared to determine things like temperature—to determine that Tyrannosaurus was probably a homeothermic endotherm, that is, it generated heat internally and maintained a constant body temperature. But when Goodwin took a greater sample of chemical isotopes from Tyrannosaurus bones, he found that the body temperature of the animal probably fluctuated. This would mean that Tyrannosaurus, like some birds, was an endothermic heterotherm—the dinosaur generated heat internally but had a body temperature that varied on a regular basis. Thinking of dinosaurs as “hot-blooded” or “cold-blooded” doesn’t do justice to the variety of physiological characteristics biologists know about.

The terminal end of dinosaur lives also got some attention in a presentation by Alicia Cutler of Brigham Young University on why the classic head-back, tail-up death pose is so common in dinosaurs. Cutler used fresh and frozen chickens to see how immersion in water affected the posture of the dead birds. Although not all her videos of the experiments worked, those that did showed that the necks of the chickens arched back almost immediately upon becoming immersed in water. The pose was not the result of drawn-out periods of dessication as some paleontologists had thought. In addition to previously proposed hypotheses, such as the idea that the pose could be created during the death throes of the animals, the experiments may help fill in our understanding of how particular dinosaurs died and became preserved.

Obviously, I have left out many studies. I can’t possibly do justice to the entire meeting, and I undoubtedly missed some intriguing presentations and posters. (Although, on the other hand, if I absorbed everything my brain probably would have exploded from paleo-overload.) There were many previews of soon-to-be-published work and ongoing research, and the smattering I was able to see underscored the point that our understanding of dinosaurs is constantly in flux and growing ever deeper. I can hardly wait for next year’s meeting in North Carolina, where I may even be able to present something about a research project I am just now embarking on. Stay tuned.

The skull of Utahceratops, one of the unusual dinosaurs from southern Utah. From Sampson et al., 2010.

Southern Utah sure has changed from how it was during the Late Cretaceous. Today the area known as Grand Staircase-Escalante National Monument is a dry, rocky place where plants are few and far between. But during a swath of time between 90 and 70 million years ago, the area was a lush, swampy habitat near the great interior seaway that cleaved North America in two. Giant crocs and weird dinosaurs lived in this coastal environment, itself just one part of a vast island continent which was once isolated from other parts of the world. This isolation undoubtedly influenced dinosaur evolution. And it’s possible that distinct pockets within the continent itself caused dinosaur evolution in the north and south to play out very differently. During a specialized technical session yesterday at the annual Society of Vertebrate Paleontology meeting, paleontologists gathered to present the fauna of North America’s lost western continent, called Laramidia.

I did not attend the entire session, but I did catch all the talks in the latter half. Together they created a rough picture of just how different the world once was. For one thing, southern Utah was home to some strange and imposing crocs. Paleontologist Randall Irmis from the University of Utah and the Natural History Museum of Utah reviewed the array of prehistoric crocodyliforms found in Grand Staircase-Esclanate National Monument, including the huge, dinosaur-eating “terror croc” Deinosuchus. There are still some mysteries waiting to be resolved, and discoveries are still being prepped out in the lab, but many of the ambush predators found in the area were alligatoroids—creatures more closely related to modern day alligators than to living gharials or crocodiles.

Damaged bones indicate that one of those long-lost crocs once sunk its teeth into a small dinosaur. In fact, the attacking croc even left part of its tooth behind. In the following talk, University of Iowa paleontologist Stephanie Drumheller highlighted bite marks found on the skeleton of a small, bipedal, unnamed herbivorous dinosaur found in the Kaiparowits Formation of southern Utah. Using high-resolution visualization techniques and comparisons with damage to bones created by modern crocodylians when they feed, Dumheller was able to narrow down the list of possible suspects to a roughly three-foot-long crocodyliform. There is more than one potential candidate among animals of this size, but Drumheller’s work showed that some dinosaurs had as much to fear from relatively small crocs as from huge predators such as Deinosuchus.

Of course, there were large, predatory dinosaurs running around in the same area during this time. Natural History Museum of Utah paleontologist Mark Loewen delivered an overview of theropod dinosaurs found in the Late Cretaceous rock of Grand Staircase-Escalante National Monument with a focus on the weird tyrannosaurs found there. These predators, such as the recently named Teratophoneus, had relatively short, deep skulls set with impressive teeth that set them apart for their cousins living during the same time in the northern part of Laramidia. Exactly why these dinosaurs evolved this way is unknown, but the distinct nature of the tyrants and other dinosaurs from the same deposits have led paleontologists to wonder if there was some sort of physical barrier which isolated them and caused them to undergo distinctive changes. As strange as they might look, though, at least one might provide some resolution as to where the ever-popular Tyrannosaurus rex came from. Drawing on a talk on the animal he gave last year, Loewen suggested that a yet-undescribed tyrannosaur from southern Utah’s Wahweap Formation may represent the form of the long-sought Tyrannosaurus ancestor.

But some of the most spectacular dinosaurs of all were the horned dinosaurs of Laramidia. Andrew Farke from the Raymond M. Alf Museum of Paleontology highlighted the rapid rate of discovery in the southwestern United States that is altering our understanding of ceratopsid evolution. While dinosaurs such as Zuniceratops appear to indicate that the earliest ceratopsid dinosaurs—the lineage including horned dinosaurs such as Styracosaurus and Utahceratops—evolved in North America, the exact time and place of their origin is unknown. Furthermore, the relationships among the various ceratopsid dinosaurs discovered in Laramidia to date is mysterious—better resolution is needed to understand how the dinosaurs evolved in space and time. Though we’re quickly adding new ceratopsid genera thanks to some great new fossil finds, we are going to have to wait for future fossil finds and revised analyses to really understand the big evolutionary picture for this group.

The several talks that followed, by paleontologists Caleb Brown of the University of Toronto, David Evans from the same institution, and Terry Gates of the Field Museum, respectively, highlighted other evolutionary and geographical patterns within other dinosaurs and smaller animals in Laramidia. During his talk on hadrosaurs found in the northern part of Laramidia, for example, Evans pointed out that there was at least some interchange between the northern and southern parts of the continent. The recently named hadrosaur Acristavus has been found in both the northern and southern parts, so perhaps barriers between the two areas were not so impenetrable to dinosaurs after all. Likewise, Gates pointed out that we require a much finer picture of what the ancient environments of Laramidia were like and a clearer understanding of which slices of rock correspond in the northern and southern parts of the continent. Better constraints on these issues will allow paleontologists to make the more exact comparisons needed to draw out evolutionary patterns.

The final talk was delivered by Natural History Museum of Utah paleontologist Scott Sampson. He  noted that paleontologists had previously thought that many major dinosaur groups of the Late Cretaceous—the hadrosaurids, the ceratopsids and the tyrannosaurids, among others—had evolved in Asia and later invaded North America. Sampson argued the opposite. New evidence may indicate that these groups emerged within Laramidia and then dispersed to Asia after about 70 million years ago (though some groups of dinosaurs that evolved in Asia likely came into North America, too). There may have been a great dinosaur interchange between what is now Alaska and Russia. Though a number of the talks in the session emphasized the need for additional information before we can draw out the patterns, Sampson did make the case that Laramidia was an important center of dinosaur evolution. As discoveries accumulate, and as paleontologists find new ways to analyze the fossil data, the major evolutionary story will come into focus.

Top image from:

Sampson SD, Loewen MA, Farke AA, Roberts EM, Forster CA, et al. (2010) New Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur Endemism. PLoS ONE 5(9): e12292. doi:10.1371/journal.pone.0012292.g003

A Protoceratops nest containing up to 15 baby dinosaurs. From Fastovsky et al., 2011.

“The fossil record is incredible when it preserves things,” paleontologist Jack Horner said during his talk about dinosaurs and evolution the other night, “but it’s not a complete record.” Many of the sessions and posters I have seen at the annual Society of Vertebrate Paleontology meeting so far are a testament to that truth, either in a positive or negative sense.

In one of the most talked-about presentations delivered so far, McMaster University masters student Ben Novak brought up some substantial obstacles that he and his co-authors have discovered to the hypothesis that remnants of dinosaur soft tissues and proteins have been found in the fossil record. The evidence for long-lived Tyrannosaurus goo may not be as good as previously thought, Novak explained, and the record of proposed dinosaur soft tissue remnants accumulated so far should be reexamined. The fossil record may not be as kind to us with dinosaur remnants as we would like.

Then again, there were notices of some exquisite finds which will provide researchers with a way to better understand dinosaur lives. A poster created by paleontologists Jingmai O’Connor, Zhou Zhonghe and Xu Xing from Beijing’s Institute of Vertebrate Paleontology and Paleoanthropology presented fossil evidence for a Cretaceous turducken. Inside the gut contents of the non-avian, feathered dinosaur Microraptor were the partial remains of a prehistoric bird, and the fact that the bird probably lived in the trees may provide some supporting evidence for the notion that Microraptor may have also been an arboreal animal. Like anything presented at the conference, these findings will be further researched, scrutinized and hopefully published, but such preliminary announcements illustrate the difficulties and the wonders of the fossil record.

But not all the cool announcements are exclusive to SVP. Significant new discoveries pop up regularly in journals, and one that caught my eye is the first description of a Protoceratops nest by University of Rhode Island paleontologist David Fastovsky and colleagues in the Journal of Paleontology. This discovery has been a long time coming.

During the 1920s, American Museum of Natural History expeditions to Mongolia brought back, among other things, dinosaur eggs that they attributed to the horned dinosaur Protoceratops. The researchers were so confident in this assignment that the remains of a small theropod dinosaur found in the same deposits as the supposed Protoceratops eggs was named Oviraptor: “egg thief.” Restorations of Protoceratops parents guarding their nests from Oviraptor hungry from an omelet proliferated through dinosaur books. But reexamination of those eggs during the 1990s showed that paleontologists had the story wrong. Developing dinosaurs preserved inside some eggs were actually oviraptorid dinosaurs—the “egg thief” was more likely a parent! Good thing for us Oviraptor can’t sure for defamation of character.

How Protoceratops nested once again became a mystery, as paleontologists continued to amass more evidence of oviraptorid nests. The closest thing to a Protoceratops nest was an aggregation of small, juvenile dinosaurs found in China and attributable to an evolutionary cousin known as Psittacosaurus. But the new paper by Fastovsky and colleagues documents a rare discovery than can give us some insight into how Protoceratops reproduced and grew up.

The nest in question was found in the roughly 84- to 75-million-year-old strata of the Upper Cretaceous Djadokhta Formation in central Asia. Rather than being a nest full of eggs, though, this Protoceratops nest is packed with baby dinosaurs. Fastovsky and co-authors count as many as 15 juvenile animals inside the nest, but these were not newborns. The degree of skeletal development among the little dinosaurs and a lack of eggshells within the nest indicates that they had already been in the nest for some time. Sadly, these little dinosaurs were buried alive, probably by a sandstorm.

What this discovery indicates about parental care in Protoceratops is uncertain. No adult dinosaur was found in association with the babies. Perhaps the adult continued to care for the little dinosaurs while they remained in the nest, or perhaps they left the nest and the baby dinosaurs remained together in the nest area. With any luck, future discoveries will provide more insight into these points. Nevertheless, the new find adds to the growing body of evidence that many dinosaurs stuck together as juveniles. Their tragedy is a boon for paleontologists hoping to understand dinosaur lives.

References:

Fastovsky, D., Weishampel, D., Watabe, M., Barsbold, R., Tsogtbaatar, K., & Narmandakh, P. (2011). A Nest of Protoceratops andrewsi (Dinosauria, Ornithischia) Journal of Paleontology, 85 (6), 1035-1041 DOI: 10.1666/11-008.1