Re: Climate Changes Mid-late Dinosaur era.

["David Marjanovic" <david.marjanovic@gmx.at>]

> Okay, well, maybe I'm just ill informed (most of my infomation comes from
> Discovery Channel and the Newspaper.)
>
> Anyway, I'll lay it out;
>
> What possibilities would there be of an "Ice Age" (or several of them)
> during the course of the Jurassic and Cretacious?

Less than that of several huge meteorites bumping down during that time.

We'd expect some evidence for ice ages, such as evidence for globally low
sea levels (on the contrary, they were crazily high most of the time),
evidence for glaciers ("polished" rocks and tillites = the rock debris that
glaciers transport and deposit somewhere) and evidence for low sea
temperatures (on the contrary, the seas were all warm down to great depths,
and at least sometimes the Canadian Arctic were nearly tropical).

> It just strikes me as odd
> that landbound creatures would develope feathers for the purpose of
> handling their body temperatures (since they probably weren't using them
to
> fly) when scales would suffice (assuming it was continually warm.)

There are other ideas, such as feathers originating as a disposal site for
excess sulfur-rich protein... though I won't start that discussion again
before I know what taurocholin exactly is and whether birds can produce it.
Check the archives of IIRC March 2001 for "Feathers for S excretion" if
you're interested.

> The other thing that bothers me is this Bering Strait. In more recent
times,
> the only time North America and Asia have been connected was during an ice
> age; now, while it's equally likely that there was a large rock formation
> between the two continents, that would basically mean that there was a
> constant flow of migrations between the two continents (which we don't
seem
> to see that frequently either.)

The paleogeography of that area is largely unknown. What is known is that
there are several microcontinents involved, as well as lots of stuff scraped
off the Pacific floor, and that it must have been quite chaotic.

> Some other things I was thinking was an Ice Age could explain the rise of
> the gigantic sauropods. Think about it; if you're going to have large
> quantities of creatures ranging from 30-90 ft in length, you are going to
> need a HUGE expanse of land,

Well... wasn't there enough land?

> and imagine a 20 ton Sauropod trying to cool
> off on a hot day?

That's one reason they had AIR SACS. More air than bone in the vertebrae of
especially the big forms.

> The last thing that bothers me is the migration patterns of the
Hadrosaurs.
> It seems they were migrating (or spread out, at least) between Australia,
> Antartica, North and South America, and probably Asia (I'm not sure if any
> have been found in Asia.) Now, it would make more sense that these intense
> migrations were possible due to the land bridges that would be above sea
> level due to expanding ice caps.

They were surely capable of swimming... island-hopping, I mean.
Hadrosaurs in Australia are totally news to me. On the other hand, several
have been found in Asia (?*Saurolophus*, *Barsboldia*, *Tanius*,
*Tsintaosaurus*, *Charonosaurus*... check out http://dinosauricon.com for
more.)
No evidence for routine migrations between continents -- the species at
least are all known from only one continent.