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Re: pterosaurs, bats, flying theropods



Stephan Pickering (stefanpickering2002@yahoo.com) wrote:

<[P]terosaurs surely must have flocked and swarmed and pestered the hell
out of megaherbivores (and, perhaps, graduate students?).>

  Surely they must have how? I see no evidence to support this. Indeed,
most often pterosaurs are never found in association with one another,
disproving this common idea of groups of pterosaurs. This is
preservational, and 

<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.>

  Actually, this is supported by the dentition, and I can describe for you
the odd things any herbivore would eat for purposes of nutrition
(geophagous elephants for minerals, deer eating squirrels for protein),
wheras pigs, like bear and humans, have bunodont molars that are
quadrangular with distinct conical cusps that are useful in tearing and
pulverizing. This is why both pigs and bears are called omnivores. And my
cat eats pasta, so this isn't much of a wierd thing anyway. It is not her
staple diet (meat) and this constrains how much of anything she can eat
aside from meat. Both dogs and cats will eat grass, but they cut then
swallow, and when they regurgitate it, it is whole (this is cleaning
purposes only). Insectivores have coupled pulverizers and many piercing
cusps or crowns, and piscivores have interlocking conical crowns for
piercing and tearing, but cannot slice or dice their prey and thus cannot
"chew" but must swallow their food, much as birds do, with the exception
of the hooked bill in parrots and raptors which permits tearing coupled
with the foot.

<When hungry in environmentally stressed regions, taxa will eat what they
can consume, ignoring hominid classifiers.>

  Animals (taxa are classificatory structures, not organisms themselves)
will eat what they can eat. An herbivorous animal will not start stalking
prey to eat, and a cat does not start eating wood like deer, because its
available. This is how animals starve in the wild.

<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.>

  _I_ do not think this, contrary to the above. Forgive "reading into what
I wrote" as Pickering himself ascribed to me. I gave reasons for
constraints. Give me data that points to the contrary, and I would easily
adapt the work.

<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.>

  Give me some examples, but otherwise this is in agreement with that I
have already written. Faunivores such as humpbacks eat both krill and
fish, but they do not swallow sharks or the like; there _are_ constraints,
and "piscivore" does not mean "eats teleosteans," but eats slippery,
aquatic prey by grasping and swallowing. If one were to follow the
literature on the subject of feeding guilds, this would become apparent. I
have seen necterivores, similarly, will eat insects, but it is never the
other way around: this is because the adaptation to nectarivory imposes a
morphology for feeding in flowers to the rostrum, wether bird or mammal,
(hui'a, hummingbird, bat, colugos, etc.) and insects are then used to
supplement this. Similarly, there is no general rule but there are animals
that eat nothing but a particular item, as in koala and panda. And the
rule holds true in principle as long as one does not conceive of narrow,
literalist definitions; this is not a cop out, and I strongly urge
Pickering or anyone interested to follow the adaptational literature in
regards to feeding; at least one such guild, durophages, have a strict
constraint that provides an inability to eat some things, as do
"hypercarnivores" towards any form of plant matter as a nutritional
supplement in any way.

  Cheers,

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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