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Fwd: The birds vs. the pterosaurs



This is my reply to Dave Edward's reply to me personally. Treat
the text as if "you wrote" is Dave. People are welcome to
correct me, as well. Thanks,

-------------------------Forwarded-------------------------------
> 
>   Just so you know, I've more experience in work on ecology
> (the
> bulk of my study, or mechanics, really) than general
> concepts
> of biology [well, that too, but not as much as I'd like]; I'm
leaving that (now) for the specialists.
> Similarly, I am not a professional, but an amateur as well,
> still studying, so student is a better term for me. I will
> admit
> to when I am wrong.
> 
>   You wrote:
> 
> <Granted, aircraft design and vertebrate evolution aren't
> really
> similar, but it's just an analogy, and most analogies are
> faulted in some way.>
> 
>   In your example, well-drafted in my opinion, there is a
> distinct niche partitioning between the F-22, the C-17, and a
> MiG, that suggests that their specialties, not their relative
> performances, owes to them being varied. I am not familiar
> with
> aircraft, however, but I have been working slightly on flight
> dynamics in pterosaurs and early bird evolution to study the
> mechanical ability to evolve wings and feathers, and those
> wings
> of a pterosaur by the Late Jurassic were miles ahead of that
> of
> birds. This was true by the time of the Late Cretaceous, as
> well. We get pterosaur-like birds (soaring, high-load bearing,
> heavy performance dynamics) in only stork and vulture and
> eagle
> lineages. Only eagles and hawks can at any point carry double
> their weight and still retain flight performance;
> maneuverability is lost, thus an unburdened hawk is much like
> an
> F-22 in this respect, a well-fed hawk a C-17. Perhaps a
> burdened
> vulture is better in this case, due to the degree of mechanics
> developed for locked-soaring flight, which eagles are at an
> effort to assume and retain.
> 
>   There are mechanics that suggest that the largest known
> pterosaur, at 200 kilos, could bear on its wings _well_ twice
> that value. This is similar to the design in vultures, and for
> this reason, without consideration of their relative
> physiologies, which we cannot begin to assume (I believe,
> anyway, some ethologist-bent biologists can have their go),
> they
> are comparable. Birds just survived the K/T, inexplicably.
> Champsosaurs outperformed the crocs in the sea, but were gone
> by
> the Eocene extinctions, but crocs did not take to the seas,
> but
> rather stayed near the shores in their global transgressions,
> which is to say champsosaurs did not directly outcompete
> crocs,
> but that there was a distinct niche partition that crocs did
> not
> cross, but for all their adaptability, they survived (not one,
> but three global extinctions) and even _diversified_
> terrestrially in the absence of some land predators (big
> predator birds, carnivoran mammals, presumably also
> dinosaurs).
> 
>   Thanks, by the way, for the analogy.
> 
> ------
> 
>   Did you mean to send this to the list? If so, I've saved
> your
> message. I think it might be a discussion best continued where
> my merits may also be questioned. I'm not a professional,
> after
> all.
> 
> ------
> 
>   Jaime A. Headden
> 
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