Tuesday, August 16, 2011

CT Scans of Bennettazhia

Back in 2008, I had CT scans done of the humerus of Bennettazhia oregonensis.  I have one of the slice videos here, which I have previously only shown in talks (though they did make an appearance in two television programs).  The outer, bright layer is the cortical bone (very thin).  The grey areas are matrix.  You can see some of the "trabecular" struts running through the matrix.

Originally described as “Pteranodon” oregonensis by C. W. Gilmore in 1928, Bennettazhia oregonensis consists of a single well-preserved and uncrushed humerus, and two associated dorsal vertebrae.  Nessov (1991) erected a new genus name for the specimen, and reclassified the specimen as an azhdarchid in agreement with Bennett (1989).  The humerus retains a deltopectoral crest with a primitive, unwarped orientation.  The crest is highly elongated, and curves anteroventrally, which is consistent with the humeral morphology of azharchoids.  The specimen is currently housed at the Smithsonian's National Museum of Natural History in Washington, DC.  (USNM 11925)

Tuesday, August 9, 2011

Drag Isn't so Bad (Paleontology Myths Part 2)

One comment that I encounter relatively frequently at scientific conferences is that the limbs of aquatic marine reptiles were "paddles" (such as our friend from the LACM photographed above by yours truly). The same is sometimes suggested of the fins and flippers of living animals.  Ironically, I also regularly encounter the idea that drag is "bad" and always costly.  This is an ironic situation because a true paddle is a drag-based propulsion structure.  This came up again recently, so I thought perhaps a quick post on the subject might be a good idea.  We see both lift-based and drag-based swimming in nature today, but the roles of each are pretty different...

Saturday, August 6, 2011

BBC Science Weekly interview

The BBC radio interview I did a couple of weeks ago on the Los Angeles County Museum of Natural History dinosaur hall just ran on BBC Science Weekly. Check it out at http://www.bbc.co.uk/iplayer/c​onsole/p00j5w1k

The section with me starts at 11:45. I didn't do the sound reconstruction, we got that from Tom Williamson and the New Mexico Museum of Natural History (major thanks to them for letting us use it). I re-modeled the airway with more modern software so we could do a 3D visualization of the passage to go with the sound.

Wednesday, August 3, 2011

Return from Los Angeles

Deinonychus © John Conway

We just finished a very productive week of work at the Los Angeles County Museum of Natural History (e.g. the LACM). I am back in Pittsburgh, and working over the final details of a paper we have put together for a top peer-reviewed journal. We cannot disclose the details at this time, except to say that the paper involves feathered dinosaurs (such as the wonderful Deinonychus above by John Conway of Ontograph Studios). The realization that many theropod dinosaurs were feathered really started to solidify in the 1990's. The number of known specimens with feathers continues to grow steadily, and these extremely bird-like animals have greatly changed our understanding of bird origins and the systematics of dinosaurs. However, there has been relatively fewer rigorous biomechanical investigations. As you might expect, we have gone and done exactly that for one species of note. With any luck, we will be posting a followup about this research when it's accepted for print!

We also worked on our analysis of mosasaur swimming. Mosasaurs were marine reptiles of the Cretaceous, found to be closely related to modern snakes and monitor lizards. The group included some real aquatic giants, the sort of animals you probably would not want to go swimming with...