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Archive for the ‘CT scanning’ 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 actual 1861, two-paragraph article with the single, controversial sentence pulled out that names Archaeopteryx lithographica.

It was 150 years ago today, on 30 September 1861, that Hermann von Meyer gave the name Archaeopteryx lithographica to the feathered animal that fluttered over the Solnhofen lagoon in Late Jurassic Bavaria. At right is the entire published article…a scant two paragraphs, only one of which is devoted to Archaeopteryx. In that one paragraph he announced the discovery of a feathered skeleton, to go along with the isolated feather that he had announced six weeks earlier. For decades later, scholars argued over his key statement: “For the denomination of the animal I consider the term Archaeopteryx lithographica as appropriate” (the original German sentence is pulled out in the illustration). He named the animal, but not a specimen. Modern rules dictate the designation of a “holotype” specimen that officially bears the name. Should it be the feather, the skeleton, or neither? I discussed this debate a little in my first Archaeopteryx sesquicentennial post, but the result has been that the skeleton—now known as the London Specimen (BMNH 37001)—is the holotype. Happy 150th Birthday, Archaeopteryx! To celebrate, WitmerLab is launching today a website with five sets of interactive 3D PDFs of skull or skull parts of three Archaeopteryx specimens, including the one von Meyer announced 150 years ago today. It’s all open access and freely downloadable!

The skull of the Eichstätt Archaeopteryx (JM 2257), based on microCT scanning of a high-resolution cast made by Peter Wellnhofer for Witmer.

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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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WitmerLab members are like many paleontologists in having their teaching responsibility in the medical gross anatomy lab. Here Witmer and grad student William Porter work with OU-HCOM med students.

August is vacation time at most universities. For members of our research lab, however, summer is the busy season. We’re completely consumed by teaching a comprehensive medical gross anatomy course at our academic home, the Ohio University Heritage College of Osteopathic Medicine (OU-HCOM). “Wait…what? I thought you were dinosaur guys…paleontologists, not medical people.” I get that all the time. We’re both, and it’s not as crazy as it sounds, nor as unusual as you might think.

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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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Alligators are everywhere. They’re team mascots, Transformer toys, actors in Lubriderm commercials (and CSI: Miami), unwanted golfing partners, and even expensive cowboy boots. What might be a surprise is that they’re also “model animals” for scientists, meaning that there are dozens, if not hundreds, of published technical articles on all things gatorly. They’re also commonly used in K-12 and undergraduate classrooms. WitmerLab has been working on American alligators for years, because crocodilians are one of just two living groups (birds are the other) of that great tribe known as archosaurs that includes dinosaurs and pterosaurs. Now, we’re joining with Casey Holliday’s lab at the University of Missouri to present the 3D Alligator, two parallel, complementary, and growing websites that present alligator anatomy in all its 3D digital glory. In both cases, we’re starting with the skull, although we include a few soft-tissue systems that are active areas of research for us (brain, inner ear, sinuses, etc.). Casey’s team presents an adult skull, and we present a wee gatorling, a “day-0” hatchling that was stillborn on its birthday. Sad perhaps, but this little guy is now immortal, because we’re releasing him to the tubes of the interwebz. We also present some of our 3D alligator work on an adult done “way back” in 2008. Check out the WitmerLab 3D Alligator site and the Holliday Lab 3D Alligator site. (more…)

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