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Fw: Physiological Adaptations of the Dinosauria (long)



Abbreviations that I could decipher so far (thanks to help from the list):

AFAIK = as far as I know
IMHO = in my humble opinion
IIRC = if I recall correctly
BTW = by the way
PDW = Gregory S. Paul: Predatory Dinosaurs of the World, Simon & Schuster
1988; its author = GSPaul or GSP
HP = Honoured Person (standard way to refer to list members)

What is OOC?

----- Original Message -----
From: "David Marjanovic" <David.Marjanovic@gmx.at>
To: "Waylon Rowley" <hot__male60@hotmail.com>
Sent: Monday, January 29, 2001 10:43 AM
Subject: Re: Physiological Adaptations of the Dinosauria (long)

> > >To shortly summarize the discussions -- Nonsense. Crocodiles,
> > >prolacertiforms etc. don't have respiratory turbinates "either".
> >
> > I was merely referring to what Ruben had said in a press release.
>
> Of course. I didn't say that this "nonsense" was your idea. :-)
>
> > Well, I wouldn't go far as to say that insulations completely impedes
> > thermoregulation in an ectotherm. A hypothetical cold-blooded
> > Sinosauropteryx could compress its...errr..."filaments" close to the
body,
> > allowing greater heat transfer with the environment, then fluff itself
up
> to
> > trap it.
>
> Hm. Possible, though improbable. But I think if *Sinosauropteryx* would
> compress its...errr...protofeathers close to the body, this would still
> allow quite little heat exchange. The "downy covering" was quite dense. So
> I'd still say, if protofeathers aren't direct confirmation for endothermy,
> they come very, very close.
>
> > I've heard the term "heterothermy" used in the context of sauropods,
where
> > young would be endothermic and progressively become gigantothermic as
they
> > grew into adulthood.
>
> Oh! Seems like Ruben uses a different definition :-/ . Horner has
suggested
> that hadrosaurs used the mode you describe and has called this
> "mesothermic". However, he thinks that only really big adult dinosaurs
were
> gigantothermic.
>
> Of course, the surface/volume ratio is used for insulation by modern
> endotherms. That's why elephants, rhinos etc. hardly have hairs, and why
> elephants can survive winters in German zoos.
>
> > Forgive my rampant speculation, but maybe the iguana-like spines on
> > sauropods also allowed cooling?
>
> If they were sufficiently vascularized (which I don't know), yes.
Stegosaur
> plates were surely good for this purpose.
>
> > I'm not saying that sauropods were
> > endothermic throughout their entire lives,
>
> I do, based on the article I cited yesterday (or today, depending on where
> you are...), which says that a heart that can sustain a sauropod has alone
a
> greater energy demand than a hypothetical ectotherm of sauropod size, and
on
> Bakker's "Heresies", where the argument is raised that a rainy season
would
> have completely chilled out all gigantotherms -- they would have needed
> _months_ to get their temperature back by basking. (The old calculation
that
> a 10-tonne dinosaur would have needed to bask for _86 hours_ to raise its
> body temperature by _1_ °C is still quite interesting in this regard.)
>
> > but younger individuals could
> > have benefitted from a higher metabolism.
>
> True.
>
> Forgive my ignorance on sauropod spines -- does this have something to do
> with them?
>
> > Maybe archosaurs are plesiomorphically endothermic, with crocodilians
> > reversing the condition, but I'm sure there's a good reason why I'm
> probably
> > wrong about that....
>
> This argument has been raised quite often, and the only counterargument is
> that this has never happened elsewhere... Well, I think the plesiomorphy
for
> archosaurs or at least crurotarsans is the liver-pumped lung that Ruben
> imagines for dinosaurs (LOL) which allows greater activity for ectotherms.
I
> don't think one can explain the success of big runners (some of them
> probably bipedal or semibipedal) like ornithosuchids, rauisuchians
(however
> paraphyletic they may be) and early crocodilomorphs if they all were
> normally cold-blooded.
>
> Indeed, crocs can gallop, and I've even read that if you manage to scare a
> croc, it may run away on its hindlimbs!
>
> > >Why do you mention *"Dilophosaurus" sinensis*?
> >
> > Because (to my knowledge) ?D. sinensis has the largest nasolacrimal
crest
> > among coelophysoids (with the possible exception of D. wetherilli)
> > which when acting as a radiator panel for the superior nasal artery,
would
> > give it a higher condensation rate than, say, a similarly-sized E.
> baldwini.
> > If you took a measurement of the istopic ratio for the crest itself and
> the
> > base of the antorbital fossa, it should indicate how much heat was being
> > lost, and whether condensation was really possible in this animal.
>
> Oh!
>
> > >Well, there were several temperature fluctuations in the Mesozoic; in
> >the
> > >Maastrichtian (not at its end) average temperatures rose by 3 °C
(forgot
> > >the ref :-( ), what seemingly didn't affect dinosaurs, and then >the
> > >meteorite came. Mantra time: Could a rise in temperature (or its
>cause,
> or
> > >its effects, or whatever) explain THE WHOLE K-T extinction?
> >
> > Ok, i'm wrong about the gradual increase. How about the meteor itself
> > though? Could a thin iridium/ash/vaporized rock cloud act as an
insulation
> > to cover the earth and turn it into a (temporary) toaster-oven?
>
> Yes. At first it became terribly cold and dark for some months, and later,
> when sunlight got through again, temperatures rose by 10 °C for 100 or
1000
> years because the rock at the impact site (as well as the global forest
> fires) gives lots of carbon dioxide when vaporized. Of course, the
scenario
> is more complicated, e. g. it involves terrible acid rain...
>
> > >While reptiles are (and birds can at least withstand higher air
> > > >temperatures because their body temperatures are tremendous), mammals
> > > >get into real trouble when their surroundings are warmer than them.
> (I'm
> > >not talking of sauna conditions, where e. g. you can't lose water >and
> the
> > >time is limited.)
> >
> > What about the small subterranian mammals? They could simply hole-up in
> > their little dens until the crisis ended- like a kangaroo rat.
>
> I don't know whether there is a way at present to check if the
K-T-surviving
> mammals were all burrowers. Anyway, burrows are excellent to survive acid
> rain, cold... and I really don't think the birds that survived were
> burrowers!
>
> > As for reptiles, you said:
> >
> > >For a short time. Then they'd desperately look for a cool place.
> >
> > Reptiles also have the ability to burrow, or in the case of crocodilians
> to
> > submerge themselves in cool water.
>
> Unfortunately, I don't have J. David Archibald's book on the K-T
extinction
> at hand. This book lists victims and survivors.
>
> > And on bird RT's:
> >
> > >Hm. They would probably, but they have no cooling effect...
> >
> > Well, the birds would've pulled through nicely because, as you said,
they
> > have much higher body temperatures (the highest i've heard of reached
40º
> > C), and the fact that they could cool themselves by flying.
>
> Flying rather heats, because it is such a demanding exercise.
> BTW, I've heard of 42 °C, and probably even more.
>
> > Many dinosaurs from the southern hemisphere (e.g. Amargasaurus
> > cazui, Spinosaurus aegyptiacus, Ouranosaurus nigeriensis) have dorsal
> > sails.
> >
> > >All from equatorial regions (which is actually irrelevant to your
> > > >argument.
> >
> > The point is that these animals boosted their body temperature with the
> > sails *beyond* (for food energy conservation) that of their normal
> metabolic
> > rate to facilitate condensation.
>
> Oh! I misunderstood that because the standard interpretation (apart from
> display) is that they were for cooling...
>
> > Besides, we may be wildly off when it comes to the continents exact
> > position, as is hinted at by gondwanan fauna.
>
> You mean the similar faunas of South America and Madagascar? Well, SA and
> Antarctica were connected until the end of the Eocene, and people now say
> there may have been a volcanic land bridge between Antarctica and India,
of
> which the Kerguélen islands remain. And India and Madagascar hadn't yet
> separated. However, I'm not sure whether Madagascar and Africa had already
> drifted apart at the time.
>
> > >AFAIK, there was no significant increase in temperature, and the K-T
> > >extinction was (mantra) NOT gradual!
> >
> > I think that remains to be seen. And as for the more gradual decline of
> > dinosaurs during the LK, hmmmmm....I thought that was a given.
>
> Lots of new books and papers show that this is a myth based on poor
> statistics (the Signor-Lipps effect). Recently, someone found a
> *Triceratops* skull 1.8 m below the K-T boundary, and hadrosaur footprints
> have long been known from 37 _cm_ below the boundary, so the 3-m-gap is
> closed.
>