Sunday, November 13, 2011

SVP Part 2: Water Launching Pterosaurs

I gave a second presentation at SVP this year, as well, in the form of a poster on pterosaur water launch.  Specifically, I presented a model that Jim Cunningham and I have worked out for a plausible water launch strategy in Anhanguera.  If you want to see what this might have looked like, turn your cursors here to Mark Witton's website.  The relevant illustration is on the far right.

I will not give too much detail on this presentation at the moment, as it is shortly bound for PLoS ONE.  However, here are some of the highlights:

- A bipedal water launch model appears to fail for Anhanguera (and other pterosaurs), just as the bipedal model fails for their terrestrial launch.

- A quadrupedal water launch model, in which the wings are the primary mechanism used to free the animal from the surface and to push along the surface to reach launch velocity, seems to check out for all of the parameters we can currently estimate with any confidence.

- Anhanguerids probably took multiple hops across the water surface to launch, but our calculations suggest that most of the actual energy expenditure was spent escaping the surface tension.

- Our model makes testable predictions about comparative anatomy of pterosaurs, which is important when building these kinds of models from fluid theory.  Our model predicts that water launching pterosaurs should have features such as: warped deltopectoral crests or dp crests with flared distal ends, enlarged scapulae, extreme disparity between forelimb and hindlimb lengths, and reinforced scapulo-notarial joints.  We have a more extensive list of features that can be shared a later date, but the primary note here is that these predicted features do indeed seem to show up mostly in marine pterosaurs, and less so in terrestrial taxa, so there is a least a loose, pattern-matching form of validation that can be applied to our hypothesis.

We hope to have animations and a full paper out on the topic of pterosaur water launch in the near future (next few months) so stay tuned!


  1. - A bipedal water launch model appears to fail for Anhanguera (and other pterosaurs), just as the bipedal model fails for their terrestrial launch.

  2. The relevant illustration is on the far right.

  3. It is a stretch to even make the assumption that these pterosaurs, reptiles, could float on the water rather than simply drowning. The reasons that large waterfowl can take off from the water is because their unique respiratory system already floats about three fourths of their bodies above the water, by flapping their wings they lift themselves even higher, and their web feet give them an effective pushing surface for propelling them forward until they exceed their stall speed so as to achieve flight.

    So in your mind you have a plausible water launch strategy for pterosaurs? Bigfoot, loch ness monster, mermaids, Santa Clause, and the Easter Bunny are all possibly plausible ideas. However, as open minded as we want to be, your water launch strategy is not plausible. Your reasoning ability appears to be stuck at a first grader’s level.

    Can you swim? Never mind it’s not important. Why don’t you try proving your hypothesis by jumping into a deep lake and then throw yourself back onto the shore by slapping at the water with your arms and legs as hard as you can just like you described in your hypothesis?