I will be resuming the Dragon series on Aero Evo soon. I am currently at the annual American Society of Biomechanics conference (ASB 2012). Some good talks this morning; I was particularly intrigued by the experiments of T. Gross from Washington University showing that the primary trigger of bone loss following muscle paralysis is not the loss of mechanical loading. An endocrine or paracrine effect seems to be the primary influence. Very cool stuff.
Tomorrow I will give my presentation in the Comparative Session, entitled "Mesozoic Speed Demons: Flight Performance of Anurognathid Pterosaurs". If you happen to be at ASB, come on by.
Showing posts with label Anurognathids. Show all posts
Showing posts with label Anurognathids. Show all posts
Thursday, August 16, 2012
Sunday, May 20, 2012
Frogmouth Pterosaurs
I have (finally) some new material to post. In addition to the new stuff, I've decided to post some of my past abstracts that might not have been easily accessible to everyone. Here is my abstract from the GSA Northeast Conference in 2011. I gave a platform talk on the biomechanics of anurognathids (some of you will already know that Mark Witton and I have a manuscript nearing completion on the topic, as well).
Functional Morphology of Anurognathid Pterosaurs
Anurognathid fossils include several exceptionally well-preserved specimens, some of which include extensive soft tissue preservation. This exceptional amount of morphological information makes anurognathids prime candidates for functional biomechanical analysis. Furthermore, anurognathids displayed a suite of unusual characteristics that make them of particular interest for functional study. These traits included extensive pycnofiber coverings, fringed wing margins, shortened distal wings, shortened faces, and enlarged orbits. Prior authors have suggested that anurognathids were adapted to catching small insects on the wing. I present a quantitative analysis that supports this general behavioral inference, and provides details regarding probable anurognathid locomotion. Results indicate that anurognathids were exceptionally maneuverable animals.
Bone strength analysis in Anurognathus ammoni reveals that each proximal wing was capable of supporting nearly 22 body weights of force. The wing spar of A. ammoni was substantially stronger in bending than that of an average bird of the same size (residual of 0.72). The calculated relative bone strength overlaps significantly with that of living birds that capture prey on the wing (p>0.92) but differs significantly from all other avian morphogroups (p<0.04). Overall humeral robustness is similar between A. ammoni and megadermatid bats.
Anurognathid launch appears to have been particularly rapid and steep. Once airborne, anurognathid pterosaurs could likely generate high lift coefficients. Leading edge structure in Jeholopterus suggests that anurognathids were capable of generating a leading edge vortex (LEV) as observed in some living bats and swifts. Analysis of flapping efficiency suggests that the expansion of the proximal wing, coupled with reduction of the distal wing elements, would have increased flapping power at the cost of increased drag. The proportions of the wing and details of the shoulder may be indicative of the ability to hover for brief intervals; power analysis also supports this conclusion. These results are consistent with reconstructions of anurognathids as highly maneuverable flyers, preferentially foraging in cluttered habitats on small aerial prey.
Functional Morphology of Anurognathid Pterosaurs
Anurognathid fossils include several exceptionally well-preserved specimens, some of which include extensive soft tissue preservation. This exceptional amount of morphological information makes anurognathids prime candidates for functional biomechanical analysis. Furthermore, anurognathids displayed a suite of unusual characteristics that make them of particular interest for functional study. These traits included extensive pycnofiber coverings, fringed wing margins, shortened distal wings, shortened faces, and enlarged orbits. Prior authors have suggested that anurognathids were adapted to catching small insects on the wing. I present a quantitative analysis that supports this general behavioral inference, and provides details regarding probable anurognathid locomotion. Results indicate that anurognathids were exceptionally maneuverable animals.
Bone strength analysis in Anurognathus ammoni reveals that each proximal wing was capable of supporting nearly 22 body weights of force. The wing spar of A. ammoni was substantially stronger in bending than that of an average bird of the same size (residual of 0.72). The calculated relative bone strength overlaps significantly with that of living birds that capture prey on the wing (p>0.92) but differs significantly from all other avian morphogroups (p<0.04). Overall humeral robustness is similar between A. ammoni and megadermatid bats.
Anurognathid launch appears to have been particularly rapid and steep. Once airborne, anurognathid pterosaurs could likely generate high lift coefficients. Leading edge structure in Jeholopterus suggests that anurognathids were capable of generating a leading edge vortex (LEV) as observed in some living bats and swifts. Analysis of flapping efficiency suggests that the expansion of the proximal wing, coupled with reduction of the distal wing elements, would have increased flapping power at the cost of increased drag. The proportions of the wing and details of the shoulder may be indicative of the ability to hover for brief intervals; power analysis also supports this conclusion. These results are consistent with reconstructions of anurognathids as highly maneuverable flyers, preferentially foraging in cluttered habitats on small aerial prey.
Wednesday, April 4, 2012
Pterosaur Acrobatics
I received a fun message from David Hone of Archosaur Musings fame yesterday. Here's the relevant bit:
"A biology teacher in Ireland tweeted me to ask if I thought a pterosaur could pull off a loop-the-loop or victory roll or similar. My guess was 'probably' especially something like and ornithocherid, but I thought you'd love it as a thought problem..." -- David Hone
It's a fun idea to ponder. The precise maneuvers available to fossil animals are can be difficult to work out with much confidence, but there are a few things that can be said with confidence:
- The most maneuverable pterosaurs were probably anurognathids, and they could certainly pull off a loop-the-loop or just about anything else you could want from a flying animal. In fact, anurognathids were probably among the most agile flying animals of all time, right up there with living vesper bats, swifts, and the like. I talked a bit about their abilities at Pterosaur.net here. Mark Witton dealt with them more while debunking the vampire anurognathid concept here.
- For larger pterosaurs, things get a bit trickier, but the inertial problems would still be pretty minor. The real question becomes whether the animals could handle multiple extra body weights of force on the wings. Based on work I've done on pterosaur wing strength, as well as work by Colin Palmer, it seems that at least pterosaurs as large as Anhanguera (4-5 meter wingspan) could have handled major rolls or loops. I have yet to check the numbers for something bigger, like Quetzalcoatlus northropi, but I might have to give it a shot. I may post a more extensive conversation on it the idea at H2VP soon.
"A biology teacher in Ireland tweeted me to ask if I thought a pterosaur could pull off a loop-the-loop or victory roll or similar. My guess was 'probably' especially something like and ornithocherid, but I thought you'd love it as a thought problem..." -- David Hone
It's a fun idea to ponder. The precise maneuvers available to fossil animals are can be difficult to work out with much confidence, but there are a few things that can be said with confidence:
- The most maneuverable pterosaurs were probably anurognathids, and they could certainly pull off a loop-the-loop or just about anything else you could want from a flying animal. In fact, anurognathids were probably among the most agile flying animals of all time, right up there with living vesper bats, swifts, and the like. I talked a bit about their abilities at Pterosaur.net here. Mark Witton dealt with them more while debunking the vampire anurognathid concept here.
- For larger pterosaurs, things get a bit trickier, but the inertial problems would still be pretty minor. The real question becomes whether the animals could handle multiple extra body weights of force on the wings. Based on work I've done on pterosaur wing strength, as well as work by Colin Palmer, it seems that at least pterosaurs as large as Anhanguera (4-5 meter wingspan) could have handled major rolls or loops. I have yet to check the numbers for something bigger, like Quetzalcoatlus northropi, but I might have to give it a shot. I may post a more extensive conversation on it the idea at H2VP soon.
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