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.
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.