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Re: pterosaurs, bats, flying theropods



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
this may be (I am not talking about spiritualism, but if you want, you can
watch *Dogma* to see what I think may be the perfect description of this
paradigm ... belief is _bad_, because they cannot change with new data,
they are resistant). _Inferring_ anything of pterosaurs from bats requires
a set of data that you have not presented; if it is mentioned to the list,
but refused for elaboration, then what point is there to mentioning it?
This list appreciates discussion and _data_; after all, this list is about
_Dinosaur Science_, not _Dinosaur "What Say I"-ism_.

  I try, often to my frustration I guess, to get others to practice
practical science. I am sure others got tired when I would continue to
press for it during times of discussion with those who would only go so
far as to say "I said so" or "I beleive". But how I still try. Science is
not a matter of proof, its never been about finding or making proof; this
is not a reason to step away from proof, though, for science is about
refuting hypotheses, and that which becomes universal (like gravity) is
that which cannot be refuted by any present datum; gravity has today only
failed to be refuted, as in plate tectonics, and there is plenty to
support it, but nothing proves either. That which is most reasonable to
exist compared to other data is more likely to be true. I am tired of
arguing against people who ignore data for their own theory, or believe
things to the neglect of data. As is their wont; but that is when science
is not served and their statements are no longer valuable. I seek to make
them valuable, so I keep trying.

<No proof, to be sure, but one can use available ongoing processes to
infer the might-have-been.>

  Only by ignoring the rules of inferrence, possibly. Fish school, bats
swarm, therefore pterosaurs must have "flocked". There is no data here.

  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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