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Re: Sauropod inferences



Stephan Pickering (stefanpickering2002@yahoo.com) wrote:

<With all due courtesy, I wish to point out to you that your statement
"all we really have at our disposal are fossils" is -- how can I put it?
-- not quite on my wavelength. All we have are 9000+ species of living
theropods (in time, I am sure, the vast majority of these species and
genera will be collapsed into scientifically accurate reflexions vs.
colour-based taxonomies).>

  It seems hard, but inferring the behavior of a ten tonne animal on the
basis of something like woodpecker breeding or mammals is putting the
cranium before the notochord, if you get my meaning. You cannot get to
point D by jumping over both B and C, which involves the degrees of
inference the  sheer fact that behavior does not fossilize; trackways,
nearly our only true guess at what an animal _did_ at a specific point in
time, gives us only pitiful insight, and Farlow and Thomas even disagreed
about the conclusions of a joint paper on the evidence of behavior in the
famous Paluxy Trackway sequence. Behaviorologists do not say because a
person is sleeping one way it is therefore indicated of some hidding
meaning that is true for any sleeping one way, and certainly the thing
about psychology noting body posture as evidence of mind depends on the
society and things we cannot, everm guess at for animals dead sixty-five
million years ago. No matter the relatedness. Very similar birds,
including the many bower birds, have very different behaviors for mate
attraction, including some that do not pick pretty items or build bowers.
It is a horrendously teppid swamp to walk in when dealing with "why"
something "may" occur in _dead_ animals for which no corrollary can be
drawn when closely related or distantly related animals have different
behaviors. Pack strategies in different carnivores, including marine and
aerial, are vastly different from one another, and not Cape dog or hyaena
or humpback whale or Harris' hawk have convergent styles of behavior when
dealing with other members of the group, much less the prey.

  Bones are bones, they do not have signs saying this or that happened
when they died, and they do not carry signs about what they did last
month, the year before, or how they consumed the bolus in the gut.

  Inferrences are inferrences, but there is no way to relate an extinct
form beyond speculation to any living behavior. Preening, parental care,
bite strategy, all can carry some inference that can be assessed by
current fossils, but this ends at some point. Vocalization, struting,
etc., do not carry any fossil record, and not all animals do it. The
basenji is a dog famous for its lack of voice, and so is the nearly silent
giraffe (it does have a voice, but does not use it as often as, say, the
elephant, despite subvocalization).

<...all giving the dinosaur scholar insights into analogous econiches.>

  A stable element to our particular philosophy, brought up because you
used "scholar", is the nature of the scientific formulation, which
requires data, and testing. Your "data" can only be applied to living
forms, not to fossils, and this cannot be tested. Econiches? What
econiches wuld you talk about? Herds? Currie argues that herding and
gregarious behavior in his own fossils is a tenuous conclusion, and is
wary about people picking up on oit as if it were "truth"! Pack hunting?
Suggested because of population construction by ontogeny (Currie's
albertosaurs) or an fluviatile system of corpse collection (Maxwell and
Ostrom's dromies and a tenontosaur), and not much else. People have seized
on the beautiful idea of pack hunting, but the critics, including Currie,
and placed this at the feet of an unknowable with some supportive data
(structure at time of death, variable dental morphology through ontogeny);
the Maxwell and Ostrom work depends a lot on the association of fossils in
a system that is structured as many questionable assemblages, many
multi-taxa, such as the Cleveland-Lloyd Quarry fossil mud pit, or "flash
mud-flood" Ghost Ranch Quarry. But many associations occur in such a
manner, and include multiple taxa, such as the last two, and this must be
doubted in relation to "packing." I cannot stress this enough.

<Take, e.g., biomechanics: with computer simulations, after having scanned
AMNH 5027, it has been possible to visually recreate how a tyrannosaur
walked, how its jaws operated with a nut-cracker bite (Ralph Molnar's
dissertation on the taxon is still quite cogent), etc.>

  You need to read Hutchinson and Garcia again, and take some advice from
Steve Gatesy: they estimated muscle mass and positions, and Steve warns
that walking sequences, or wing sequences, requires knowledge of muscle
ennervation and firing of the nerves, as well as live models. It is
possible to deduct speed and general posture, but not a walking sequence,
and the argument goes on about suspension phases in bipedal animals,
which, typically by definition, do not occur in such graviportal animals
such as sauropods and humans. Hopping is a different modus locomotus, and
the suspension phase generated is developed from a system different than
running, in both kangaroos and man.

<Phil Tippett and Stephen Czerkas have animated dinosaurs (and, of course,
so have FrameStore) one can use as visualizations of inferences.>

  What was done for Jurassic Park is still speculation, and does not
involve any reasoning of fossil data aside from what makes a movie monster
do what they want it to do. Garcia has commented (I think it was him) on
how the running sequence in the first movie was very like his work on
computer generated models of postions of legs in sequence using the
anatomy, mass and math of Hutchinson and Garcia's work, but the jeep, for
all it's being gas-powered, never got above 30 miles an hour and in todays
world, that's slow.... This was based on some work of Bakker's, I beleive,
and his theory on track-speed in purported tyrant tracks.

<From this, and knowing something of its ecosystems,>

  What ecosystem? Have you knowledge of the trophic web and behavioral
interactions that have starved the likes of Horner, Russell and Currie for
decades? An ecology is more than what kinds of animals are in a given
locality/formation. Time is unknown between depositions of commitant
fossils, so even distributed associations are questionable. There are not
bonebeds of *Triceratops* in a single layer as there are for
*Centrosaurus*, *Styracosaurus*, *Edmontosaurus*, and *Pachyrhinosaurus*
in Canada.

<one can reasonably assume the animal was a successful predator.>

  Knowing who predated who, and how, is another thing we do not know, or
the full repertoire of tyrants and carnosaurs and megalosaurs, and
ceratosaurs around the world for prey-choice, all of what a spinosaur
would eat, interaction between Gadoufaoua or Nemegtian fauna (let's not
get stuck in the Hell Creek), and so forth.

<The search for understanding why, 65 million years later, dinosaurs
thrive and survive (albeit in smaller form, with some econiches "ruled" by
bats in the night skies,>

  And day skies, don't get stuck in Neararctic zones with
microchiropterans, tropical megachiropterans are massive competitors to
fruit and insect prey, as well as a small mammal foods. There are
relatively less large active avian predators in the equatorial belt than
there are polar to it.

  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.

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