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Re: pterosaurs, bats, flying theropods



But, Jaime, pterosaurs surely must have flocked and
swarmed and pestered the hell out of megaherbivores
(and, perhaps, graduate students?).  And: while the
literature is extensive on the relationality of
teeth/mouths, I have seen a bear eat berries, a cat
eat an apple, a wild pig eat meat, etc. etc. When
hungry in environmentally stressed regions, taxa will
eat what they can consume, ignoring hominid
classifiers. Your citing of the various feeding guilds
of pterosaurs is familiar to me -- but one should not
attempt to "carve into stone" what the pterosaurs may
have eaten when necessary just because you do not
think they were capable of it. In the main -- and here
I agree with your supposition -- one can, of course,
determine probable diets on the basis of teeth and
oral cavities: insectivores have been observed eating
nectar, piscivores eating shrimp, etc. Living
behaviour is, often, more complex that restrictive
classifications.
*******************************************************
--- "Jaime A. Headden" <qilongia@yahoo.com> wrote:
> Stephan Pickering (stefanpickering2002@yahoo.com)
> wrote:
> 
> <... [A]nd, reading the comments below carefully, I
> fail to see their
> applicability. I believe the pterosaurs were driven
> into extinction by
> flying dinosaurs, and am cognizant of the diversity
> of the pterosaurs by
> the end of the Cretaceous. Moreover, for you to
> state there were no
> possible parallel specializations between pterosaur
> and theropod diets is
> something I do not agree with: snout shape and teeth
> differences do not
> obviate the possibility similar prey may have been
> pursued by both flying
> theropods and pterosaurs.>
> 
>   Snout shape and teeth is what lends us to infer
> the ability to feed, and
> if you followed the ecology papers you cite into a
> more direct
> morphological level you will find there is often a
> direct correlation to
> type of food and type of oral anatomy, and that this
> has been used by
> mammalogists such as MacFadden and Janis to relate
> to ungalte feeding
> strategies, between rodent teeth and foods, etc. I
> have an extensive
> literature on the relation and evolution of teeth to
> food and can provide
> numerous citations and pdfs of many of these if
> required. Such relation of
> teeth and food in pterosaurs has led to the
> provincialization of guilds in
> feeding strategies in the Solnhofen pterosaurs, and
> the small Solnhofen
> volume by Barthel, Swinburne, and Conway Morris is a
> good place to start
> on a well-studied, if not _the best_ studied,
> paleo-ecosystem. Piscivores,
> insectivores, fructivores, necterivores, etc. are
> all easily separable
> feeding types that have distinct jaw and tooth
> morphologies, as are
> durphages and faunivores which feed from object
> larger than their jaws
> (producing crushing platforms and bladed teeth,
> respectively). That only
> one pterosaur in the Solnhofen has carinate, bladed
> teeth compared to the
> others (*Pterodactylus kochi*) and some have finely
> pectinate sets of
> teeth shows that there were carnivores and strainers
> among this group as,
> compared to say, a bird with fine, widely-spaced,
> recurved conical teeth,
> occuring in insectivores. This data has been
> presented before elsewhere,
> as in Bennett's work on the age-classes of
> *Pterodactylus*/*Cteochasma* or
> the various Wellnhofer pterosaur or *Archaeopteryx*
> papers, the latter
> also involving work by Elzanowski both in
> collaboration and by himself.
> 
> <Nor did I anywhere state there were Cretaceous bats
> --> >
> 
> This is what is implied herein, without appropriate
> separation of clauses:
> 
>   "...[D]uring the end Cretaceous, when the flying
> dinosaurs out-competed,
> as it were, the pterosaurs, diversification of bats
> may have been well
> underway."
> 
>   Note use of the word "during." The implication in
> the post I originally
> cited was that all three were implied to co-exist,
> without separation
> based on the fossil record of the only two
> co-occurences in time, pre- and
> post-K/T boundary time. Thus the impression (note,
> not _implication_)
> along the line of the post in bat/pterosaur/bird
> complex ecology.
> Otherwise, bats serve no effective purpose in being
> illustrated but to
> lead into the citation of a forthcoming book, which
> is good for
> chiroptologists and those studying complex social
> behaviors among
> non-primate archontans, but the thrust of the book
> is a modern ecology and
> behavioral synthesis, and has nothing to do with the
> reflection of this
> data in the fossil record and is of questionable
> relevance, in my opinion.
> If, however, it presented phylogenentic information,
> this has in the past
> led to discussions of fruitful endeavour with
> respect to various students
> of phylogeny and bats such as the absent Matt
> Troutman, Darren Naish (not
> absent), or the late, great Betty Cunningham [who is
> still remembered].
> 
> <Moreover, the flying theropods are far more diverse
> in morphology than
> bats, but this does not mean bats do not display
> diversity within their
> limitations.>
> 
>   What limitations? And what level of diversity do
> you measure? I see just
> as much diversity in other aspects of their
> morphology such as which birds
> do not elaborate on. The syrinx is developed _once_
> in birds, but most of
> the internal anatomy stays the same. Feathers change
> count, but there are
> still essential types that are followed. Birds
> elaborate color,
> decoration, and wing shape the most, as well as
> plumage coverage, and one
> or three muscles in the leg/tail musculature but not
> to the degree that
> bats change their facial anatomy or muscular design
> or even physiology.
> This shows a level of relative lack of knowledge in
> bat anatomy on
> Pickering's part, sad as it may seem, and I would
> love to be proven
> otherwise.
> 
> <I believe, as I wrote, that bat ecomorphologies, as
> represented in this
> magnificent volume, will shed light on the cluttered
> skies at the end of
> the Cretaceous, when pterosaurs and flying dinosaurs
> may have been using
> some of the skills bats would later display.>
> 
>   Yet bats and birds and pterosaurs have markedly
> different wing designs
> and locomotor methods of involving powered flight;
> while birds use their
> major finger to anchor feathers, and pterosaurs one
> outstretched finger to
> hold a membrane, bats expand the "sail" between the
> fingers; the wrists
> are entirely different, whgere pterosaurs and birds
> have a semilunate
> swivel action and bast have more ape-style
> pronatatory structure that
> permits a sphere of action birds can only
> approximate with different parts
> of their limb; this permits bast, aside from
> wing-specialized birds like
> hummingbirds, to hover irrespective of wing or body
> size. Unlike birds and
> pterosaurs, bats lack a large sternal keel and in
> fact lack a broad
> sternum entirely; they have a much shorter neck and
> consequently the
> sternocranial muscles are coupled to the flight
> apparatus unlike in birds.
> Consistently the bat hindlimb is involved to the
> forlimb in the "deep
> wing" design which is being refuted for in
> pterosaurs, and the method of
> terrestrial locomotion and static resting behavior
> and anatomy is so
> different as to be incomparable. Birds do not perch
> upside down, or even
> rest that way, and parrots and some similar birds
> can do so only during
> excercise, breeding, or feeding, and do not stay in
> this position at all.
> Bats use this position for nearly every thing when
> not feeding, and as
> such they has developed a level of anatomy and
> constraint that makes them
> unique and relatively incomparable creatures.
> 
> <I believe that pterosaurs may have been more
> bat-like than dinosaurs at
> the end-Cretaceous, and may have had a similar
> fascinating array of
> behaviour strategies as do bats today.>
> 
>   I fear belief is a very bad thing to have. I have
> little, for the simple
> fact that to become so involved in a belief one
> fails to look away from
> it. It is easy to delude yourself if one believes in
> something, however
> 
=== message truncated ===


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