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Re: Chaoyangopteridae

I do not know if it would have sufficient muscle mass to generate the accelerations required, but if it did, the skeleton could withstand them.

Based on my launch model, which places 20%+ of the animal's total mass in overall forelimb musculature, and about 17-18% in the hind limb (including extrinsic muscles at the hip), the power should have been sufficient for the given accelerations. However, this assumes that 1) the forelimb muscle mass is highly anaerobic (expected for a large flyer, but obviously not known) and 2) there is some modest elastic storage in the forelimb tendons. In reality, my estimate here is a bit conservative, because I don't allow the animal much above 120% elastic storage. That may seem high, but dedicated jumpers (such as galagos and frogs) get 700%+ in combined elastic and counter-movement pre-load advantage. Given the length of the pterosaur forelimb, and several specific features of the osteology, I suspect that pterosaurs probably managed a fair bit of preload (better than I'm giving them).

I think Mike Habib prefers a somewhat lighter weight (about 80%) with about 3/4 as much wing area (in other words, the same wing loading). His scenario can get off the the ground without overloading.

Yes, that's indeed what I tend to use (note that Jim means 80% of the weight, not 80% lighter).

My methods are structured to give an average weight. I believe that both Darren's/Mark's and Mike's estimation techniques are structured to give maximum weights. (Guys, correct me if I'm wrong....)

You are correct again - my technique is definitely structured to give maximum weight; Darren/Mark's should do the same based on my understanding of their model. There are advantages to estimating maximums, but we also have to be careful with how they are used (and not assume that the animal flew near maximum weight all the time). I choose that approach in part because I am interested in mechanical limits, and this is obviously maxima oriented.


--Mike H.

Michael Habib, M.S. PhD. Candidate Center for Functional Anatomy and Evolution Johns Hopkins School of Medicine 1830 E. Monument Street Baltimore, MD 21205 (443) 280 0181 habib@jhmi.edu