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RE: feathered ornithopods?




-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
Dann Pigdon
Sent: Saturday, July 20, 2002 2:15 PM
To: DML
Subject: Re: feathered ornithopods?


"Tracy L. Ford" wrote:
>
> We do not know this for sure. This is an assumation due to modern times
and
> we can in no way know whether or not it actually did get frosty. We happen
> to be at different ends of this.

Lets look at the evidence:<<

Ok.

>>- Cryoturbational geological structures, associated with both permafrost
and "hummocking". Mean annual temperature (MAT) estimated at between -6°
and 3° celsius based on these.<<

I was talking to someone about this recently and he said that this geologic
evidance may be due to some other kind of geology. I'm waiting to hear from
him again on this.

>>- Iceberg/glacial dropstones in the ocean that covered much of the state
of South Australia.<<

Whats the published papers on this? I'd be interested to read them.

>>- O-18 isotope studies suggesting an MAT of -2° +/- 5° celsius.
- The Koonwarra insect community suggesting a similar make up to that of
modern alpine insect communities.<<

Ok, but are all alpine forest's have a snow period? I haven't a clue if they
have to have one or not.


See http://www.alphalink.com.au/~dannj/ecenvir.htm<<

Nice link. So can all those plants you listed live in a climate that freezes
over? Do any of them do that today?

> So can crocodilians (in Florida and Lousiania). But labyrinthodons had
> scales (which may or may not work for or against a cold climate) not like
> modern amphibians.

There are labyrinthodont remains dating to 120 MYA, but no crocs. Things
warm up a tad by about 115 MYA - you find croc remains, but no more
labyrinthodonts. This suggests that crocs outcompeted the labys, the
prevailing theory for the rest of the world as well, and that labys
survived in this area to the Early Cretaceous because crocs were kept
out, probably by cold temperatures.

See http://www.alphalink.com.au/~dannj/non-rept.htm#amphibians

> Right and I just wanted to qualify my point. There are animals that
weren't
> marine and that is the point I'm tyring to make.

It is indeed a "tyring" point... :)<<

Fine, let me 'try' again. What about the Antarctic Cretaceous dinosaurs?
Hadrosaurs and ankylosaurs? Where they covered in integument to survive the
supposed frosty winters? No way IMHO. What about the Freamouv Formation?
Would that have had a 'frosty' time? Procolophonids, labyrinthodontis,
prolacertaforms..

The day's were shorter back then and so was the seasons. Whether or not this
would play into a 'frosty' winter or just be a shorter winter is beyond me
right now.

>>Plesiosaurs in Australia and other parts of the world (ie. Antarctica,
New Zealand) seem to have prefered breeding in colder climates (perhaps
due to lack of predators?). There are more juvenile marine reptile
remains known from South Australia than those of adults (a ratio of
about 19:1). This is the same South Australia with the dropstones.<<

Well, this is a theory. Pretty good one...So, what's the paper/s on this?
Just so I'm up to date on this.

See http://www.alphalink.com.au/~dannj/addyman.htm

>>Hypsilophodontids may have also chosen the polar areas to breed in.<<

Don't know that for sure. Have there been any eggs/eggshells found yet?

>>There are lots of juvenile remains found in Victoria and South
Australia. One specimen, probably a Leaellynasaura, was found with an
advanced osteomyelitic infection of the tibia.<<

I have this specimen listed as Hypsilophodonid gen sp indet. If you know
otherwise I'd like to know and I'll change that in my lists.

>> The other tibia grew
another 27 mm, indicating the animal lived for quite a while with the
condition. None of the bones show signs of scavenging. So, you've got an
animal that lived for a while without being able to run, and wasn't
scavenged when it finally died. This suggests to me that predators were
pretty thin on the ground, perhaps why the hypsies chose this area to
breed in (like a modern version of Arctic geese).<<

Don't know that for sure. Theropods are outnumbered what 10 to 1. Different
than other areas...

See http://www.alphalink.com.au/~dannj/hypsilof.htm

> Hows about Lightning Ridge? [sauropod remains]

>>Not as far south as southern Victoria. They may have moved to the
central parts of the continent seasonally (seas barriers permitting),
travelling north to breed (hence the sauropod "herds" moving along the
coast of Broome - migration?). Much like a land-bound whale. Tom Rich
has argued that sauropods will never be found in southern Victoria. So
far he's been right.<<

So far. Like no sauropods from the Lance? Their coming...



Tracy L. Ford
P. O. Box 1171
Poway Ca  92074