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Archive for the ‘dinosaurs’ Category

Germany commemorated the 150th anniversary of Archaoepteryx with a 10-Euro silver coin, shown here on the WitmerLab cast of the Berlin specimen.

What a remarkable 150th birthday year it’s been for Archaeopteryx! Sesquicentennial celebrations, commemorative coins and stamps, historical articles, and special exhibits would have been enough, but Archaeopteryx made headlines when a prominent study in the venerable British journal Nature announced that it might not be a bird after all. That study was rebutted by another prominent study, which was in turn rebutted at a prominent conference. If that weren’t enough, an entirely new specimen of Archaeopteryx—only the 11th ever discovered—was announced. Let’s have a closer look at this very eventful year.
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The ankylosaurid armored dinosaur Euoplocephalus (AMNH 5405). A new article confirms the highly tortuous "crazy-straw" nasal passage coiled up within the snout..

In 2008, Ryan Ridgely and I published an article on dinosaur sinuses and nasal cavities in the Anatomical Record. One of our findings was unexpected to the point of seeming almost dubious. We found that, despite what had been stated in the literature, including my own published statements, armored dinosaurs (the plant-eating, tank-like ankylosaurs) didn’t have extensive paranasal air sinuses, but instead, long tortuous nasal airways. We looked at several skulls of both the ankylosaurid Euoplocephalus and the nodosaurid Panoplosaurus (or Edmontonia…someone needs to sort that out). According to our CT-scan-based analyses, the nasal passages took a long, twisting, looping course through the snout from the nostril to the throat. No one had ever suspected such a thing, and so we wondered what the community would think of our crazy crazy-straw hypothesis. Science is all about repeatability: if a claim is true, independent workers should be able to replicate results using the same or similar data. So, it was with no small amount of excitement/fear/anxiety that we greeted the news that an independent group consisting of respected researchers from the University of Alberta (Tetsuto Miyashita, ankylosaur specialist Victoria Arbour, and Philip Currie) were testing our hypothesis based on not only our own data but also data from additional specimens. Having others check our work was the reason we had freely released our original data to the community in 2008. That said, “promoting scientific repeatability” is a much more noble concept in the abstract (gulp!). Today, the results appear in an article in the Journal of Anatomy. (more…)

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The Berlin specimen of Archaeopteryx. (Photo of WitmerLab cast by Amy Martiny.)

I’m an unabashed archaeopterygophile. When I’m in the presence of these famous fossils, the sense of history and significance is palpable. So, when it occurred to me that 2011 marks the 150th anniversary of the discovery and naming of Archaeopteryx, I blogged here about sesquicentennial activities. Meanwhile, I was quietly reviewing an article for the venerable science weekly Nature that, if correct, would suggest that Archaeopteryx might not be a bird at all. Today, the article by Xu Xing and colleagues appears, and I was asked to write the News & Views commentary that appears in the same issue. Xu and colleagues report on the discovery of a new species from the Jurassic of Liaoning, China, named Xiaotingia zhengi. Their analysis suggests not only that Xiaotingia is an archaeopterygid, but that archaeopterygids are outside Avialae, the lineage of true birds. The bottom line: Archaeopteryx isn’t a bird! Really? How is that possible and what are the consequences?

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The Discovery Channels in the UK and the US recently have aired documentaries called “Dino Gangs” that follow dinosaur paleontologist Philip Currie around the globe (Alberta, Mongolia, Indonesia, South Africa, Great Britain), including little Athens, Ohio, the home of Ohio University. “Dino Gangs” addresses Currie’s theory that tyrannosaurs hunted as cooperative, social packs. Phil and the film crew from Atlantic Productions were here to talk with me about my work with Ryan Ridgely on tyrannosaur brains and sensory capabilities…basically whether tyrannosaurs had the mental wherewithal to pull off pack hunting. Phil Currie and his collaborators have published a few articles that have alluded to the possibility of coordinated, social, pack hunting, mostly notably his 1998 article in Gaia. My goal here is neither to evaluate the nuances of his arguments (e.g., the taphonomic issues) nor to address the media hoopla from the folks at Atlantic, the same folks who brought us Darwinius  and Predator X (check out Brian Switek’s thoughtful response). My goal is simply to relate what went on here in Athens and to clarify how I think tyrannosaur neuroanatomy fits into the argument.

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Cover of the issue of the Journal of Vertebrate Paleontology in which our Tarbosaurus research is the Featured Article. It's open access and freely downloadable!

Really young animals are always interesting to scientists, because they often shake up long-held notions based on the better-known attributes of adults. Youngsters are doubly interesting to paleontologists because they’re so rare. So, when the beautifully preserved, almost complete skull of a young Tarbosaurus came into the lab, we knew we had an important specimen. It was brought to the WitmerLab in early 2007 by Takanobu Tsuihiji, who had joined us as a postdoctoral fellow in 2006. Taka had participated in the joint expedition to the Gobi Desert of Mongolia led by the Hayashibara Museum of Natural Sciences and the Mongolian Paleontological Center. The first of our studies on this specimen just appeared as the open-access Featured Article in the May 2011 issue of The Journal of Vertebrate Paleontology. Others, such as Brian Switek and Jaime Headden, have also blogged about this article, and so I’ll try to focus on more of the back story from an inside perspective. We provide more resources on our university site, as well as a photo album on our WitmerLab Facebook page. (more…)

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Evolution in birds of the olfactory bulb, the part of the brain where smell information is processed, passing from a dinosaur (Bambiraptor) through early birds (Lithornis, Presbyornis) to a modern-day bird (pigeon).

Birds have a lousy sense of smell, right? That common perception may apply to some modern-day birds, but that wasn’t always the case. Early birds, frankly, smelled like dinosaurs, meaning that they inherited a pretty respectable sense of smell from their dinosaurian kin. The typical scenario had been that as birds evolved flight, the senses of vision and balance increased and the olfactory sense diminished. Darla Zelenitsky (University of Calgary) and François Therrien (Royal Tyrrell Museum) invited Ryan Ridgely and me to join forces in testing this scenario by studying the evolution of the olfactory bulb, the part of the brain receiving information on odors, across the transition from small theropod dinosaurs to birds. As our new article in Proceedings of the Royal Society B reveals, birds started out with a full sensory toolkit, including a pretty capable sniffer. And we also learned a thing or two about non-avian theropods along the way.
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Hadrosaur multimedia exhibit at "Dinosaurs Unearthed" at the Dallas Museum of Nature & Science. Photo courtesy of Rissa Westerfield, Texas Tech University.

The WitmerLab has an ongoing collaboration on the duckbilled hadrosaur dinosaurs with David Evans of the Royal Ontario Museum in Toronto. Recently, we’ve received word that some of that work has found its way into the “Dinosaurs Unearthed” exhibit that has been circulating through the US. First, Ohio University grad student Haley O’Brien texted me a photo of the exhibit at Union Station in Kansas City, and then Texas Tech grad student Rissa Westerfield posted a photo on Facebook of the exhibit at the Museum of Nature & Science in Dallas. Then just yesterday, WitmerLab alum Casey Holliday (now at Missouri) chimed in with his own sighting in KC. Presumably, it’s elsewhere, too. We’re thrilled to hear that the outcome of our research is reaching a broad audience!

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