[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: What do we know about dinosaurs?



>What facts do we know about dinosaurs?
>
>1)   There are no (non-avian) dinosaurs known today.
>2)   There are no known dinosaur fossils more recent than approx 65Mya.
>3)   Dinosaur fossils include petrified bones, nests, eggs, footprints, skin
>impressions and dino-doo-doo (coprolites).
>
>On a macro level, those are the facts... everything else - EVERYTHING ELSE -
>is speculation and supposition!  Educated, informed, highly-probable
>speculation in many cases; but supposition nonetheless!
>
>Even such seemingly obvious hypotheses as that theropods were carnivorous
>(because they SEEM to be adapted to a carnivorous lifestyle) are based on
>interpretation, and analogies to living creatures.  We DON'T know FOR A FACT
>that T. rex was a carnivore, do we?  Has anyone actually seen one eat?

I think you are missing the point here. "Speculations and suppositions"
about the behaviour and life of dinosaurs can still be made within a
scientific framework. We can suggest a model (eg Theropods are carnivores)
then test that by correlating features (sharp teeth, sharp claws etc) and
comparing those to similar structures in modern animals (eg varanids) and
see how they use them. This is within science: a model is proposed, tested
and cannot be rejected on the available evidence and so is accepted.

By this technique, more than one model can be proposed for the life of a
dinosaur and parsimony allows us to choose the simpler model as being more
correct. The creationist model that T. rex is actually a melon-eater is a
competing model for T. rex dietary preferences. It cannot be rejected by
direct observation (no one has seen a T. rex not eating melons) but it can
be rejected as less parsimonious than the carnivore model because the
melon-eater model requires a more convoluted understanding of tooth and
claw morphology of the beast than the explanation that these features were
used for a carnivorous diet (just like similar structures in varanids).

Some people step outside of science largely on the rules of parsimony. My
favourite is the stegosaur plate flappers. It has been suggested that stegosaurs
could flap their plates to scare off predators (I always thought that this
would make a great cartoon; 2 ceratorsaurs approach a stegosaur; stegosaur
flaps plates; ceratosaurs pounce and kill the stegosaur anyway; after
dinner one ceratosaur turns to the other and says "Those flapping plates
sure scared the shit out of me!"). Anyway, back to my point. While
stegosaur plates have no modern analogues to compare with, flapping them
would require a completely new set of muscles that other tetrapods do not
have. So, for this model to be correct, we need to create a new set of
muscles for stegosaurs. An opposing model is that the plates were used as
heating surfaces for solar heating. This would require a reasonably minor
rerouting of the cutaneous blood supply. The second model is simpler than
the first and so that model should be rejected. (Note this does not mean
that stegosaurs were using their plates as heat-transfer surfaces or that
other models for their use are not more parsimonious than this one; lets
not get into that chestnut again).

This way (and a few other ways) is where what some people do is out side of
science while what most of the rest of the community do is as good a
science as any biochemist or astrophysist does (probably better in many
cases!). So don't
try the fools gambit of "He is just another speculator like the rest of
you". It just ain't so.

Cheers, Paul

pwillis@ozemail.com.au