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Origins (was: Re: Sharovipteryx)

George Olshevsky <Dinogeorge@aol.com> wrote:

> Two mutually exclusive scenarios currently compete to explain the
> origin of birds and avian flight.

This and what followed represent a false summary of the actual
discussions occurring among those trying to understand what are really
two separate issues here (although admittedly the proposed dichotomy
is inappropriately used by some of the debaters).  Question 1: what
extinct animals were the closest relatives of living birds?  Question
2: what ecological factors lead to the development of flight in the
ancestors of modern birds?  More succinctly, it is unhelpful to
conflate the origin of birds with the origin of avian flight.

Question 1 is currently receiving the most attention in part because
it is the easier question to address scientifically.  Toward that end
I should point out that this:

> As far as I know, there is no skeletal feature or combination of
> skeletal features that is unique to arboreality among vertebrates;

essentially takes that facet of the answer to question 2 outside the
realm of scientific investigation.  Perhaps when we build machines
that allow us to go back in time to place thermometers in dinosaurs so
that we can settle once and for all the questions about their
thermoregulatory physiology, we should make sure that some of the
temperature takers also make note of the percentage of time the
animals spend in trees.  Beyond that, insisting that an animal was or
wasn't arboreal is about as useful as insisting exactly 5 angels fit
on the head of a pin.  If it makes you feel happy to assert that one
or another dinosaur was arboreal then go ahead and assert it.
However, recognize that in making such an assertion you're probably
not using the scientific method and your assertion should be treated

The essence of science is not the telling of stories that make sense;
it is the testing of ideas with empirical observations.  If no
observations can recognizably be used to test an idea then the idea is
not scientific.  And the purpose of this list is to provide a forum
for the discussion of dinosaur *science*.

Mickey Rowe     (rowe@psych.ucsb.edu)