Richard W Travsky | 3 Jun 17:09 2002
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Pics Of Dino Trackway

Not very good pictures but I haven't noted any others yet...

 http://dsc.discovery.com/news/reu/20020527/dinos.html

Williams, Tim | 3 Jun 18:14 2002

RE:


> You'd also have to consider the fact that something that would affect 
> some dinosaurs would have no effect on others (similar to modern 
> diseases in various populations of animals today). The Black Plague 
> doesn't seem to do much to rats that carry the fleas...

Actually, not true.  Rats are also killed by the plague-causing bacterium
_Yersinia pestis_.  During the Black Plague, the urban rat population of
Europe was being killed off at a rapid rate due to _Yersinia_ infection.
It's only because its natural host was declining that the rat flea resorted
to biting other mammals - including humans - and therefore passed the
bacteria on to them.  Rats are not the natural host for the palgue
bacterium; they were victims too (though it's hard to feel sorry for them.)
If rats didn't succumb to the bacteria, then we may not have had the Black
Death.  

Jura wrote:

> The most popular non-dinosaurian reptiles to go extinct were the marine 
> reptiles: the plesiosaurs and the mosasaurs. 

And which were the most *unpopular* non-dinosaurian reptiles?   :-)

> In the air, pterosaurs were another large group to disappear. On an 
> interesting (if not entirely arguable) note, crocodilians, lizards, 
> snakes, turtles, mammals and birds seemed to have come through the 
> extinction pretty well.

I don't think 'pretty well' is entirely accurate.  These groups certainly
survived, and placentals/eutherians seem to have been much less affected
(Continue reading)

James R. Cunningham | 3 Jun 20:29 2002
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Re: Hell Creek (long)


David Marjanovic wrote:

> Gigantic amounts of sulphur (dioxide) must indeed have been injected into at
> least the stratosphere and have led to cooling sulphuric acid droplets and
> then acid rain, but because of the anhydrite (waterless gypsum -- calcium
> sulphate) at the impact site, not because of the dolomite (mixed
> calcium/magnesium carbonate). :-) The latter yields carbon dioxide when
> vaporized, though -- greenhouse effect and acid rain, too.

I'm not entirely sure that the in-situ molecular compounds at the immediate
impact site would be as important as the overall element ratios.  The reason
being that the energy in the vicinity of the impact site would likely have been
sufficient not only to break all molecular bonds (thereby destroying most of the
in-situ compounds), but also to strip the outer electrons from the atoms,
leaving an elemental plasma which after cooling would reaquire the free
electrons and form new and different compounds from the individual particles
that had contributed to the plasma.  There's a lot of talk about the water vapor
kicked off, but one should keep in mind that in the immediate vicinity of the
impact there was not much water vapor left.  There were a lot of protons, free
electrons, and some oxygen nuclei.  Little proximate salt either.  A lot of
sodium, chlorine, calcium, and sulpher available to form whatever after the
initial temperatures declined sufficiently.  Further away from the impact,
outside the area of plasma formation, one could expect in-situ compounds to be
more directly related to the final product.

> > Also the Chixculub bolide hit in (admittedly shallow) salt water. This
> > means that large amounts of water vapour and _salt_ must have gone into
> the  stratosphere.

(Continue reading)

Danvarner | 3 Jun 19:38 2002
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New Cretoxyrhina Specimen

       This spring, Mike Everhart has discovered and collected an exceptional 
specimen of the shark, Cretoxyrhina, the constant nemesis of Tylosaurus in 
the Kansas sea. It's a monster with some verts approaching 4 inches in 
diameter. 
       For the full story go to: http://www.oceansofkansas.com/BigShark.html

       DV

Daniel Bensen | 3 Jun 19:51 2002
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How the ammonites? (was why the ammonites)


David Marjanovic wrote:

> >>Interesting. What I've read (forgot where) is that ammonites had planktonic
> larvae (do we know that, actually?)<<

This raises an interesting question: how do we know anything about ammonites at
all?  (aside from the shape of their shells, I mean).  Have any soft-body
impressions ever been found?

Dan

longrich | 3 Jun 20:28 2002
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Re: Hell Creek (long)


On Monday, June 3, 2002, at 05:22 AM, John Bois wrote:

>
>
> On Sun, 2 Jun 2002, Allan Edels wrote:
>
>> I want to remind everyone that nearly ALL THE ANIMALS THAT WEIGHED MORE
>> THAN 30 KG DISAPPEARED!  I'm not sure of the numbers of small
>> (non-avian) dinosaurs that existed in the late Maastrictian, perhaps
>> someone can supply this info.  My current understanding is that 
>> dinosaur
>> genera had reduced drastically prior to K-T - mostly the larger sized
>> animals (_T. rex_, _Triceratops_, etc.).  It seems like all the small
>> dinosaurs were birds!
>
> If true, this is a startling fact!  Why, since species don't just
> _surrender_ niche space, would there be fewer small non-avian
> dinosaurs?  This is a smoking gun of sorts.  Were birds
> outcompeting/preying on small non-avian dinosaurs?
>   Did birds do the same
> thing to pterosaurs?

	We apparently get a change in species-level diversity change 
between Hell Creek and some other formations. I'm not sure that this 
means anything, in that we would expect dinosaur diversity to be lower 
or higher variously at various points through their history, and there's 
no evidence that this is part of a larger pattern rather than just 
something that is typical of Hell Creek's ecology or depositional 
patterns. The question "is X different from Y" (yes) is a lot less 
(Continue reading)

frogfoot | 3 Jun 21:20 2002

Stegosaurs: why did most of the species die out before the end?

Hi all
 
This question has been bugging me for a long time actually.  The first few dinosaur books I ever got were still of the days when Stegosaurs had these plates for armor protection.  I guess that its well established that they used them for regulating body temperature now, or differentiating between species?
 
The only Stegosaur I know that was around til the end of the Cretaceous is Dravidosaurus.  Only a handful of others made it into that same era.  So what happened to them, climatic change, different predators/food?
 
Regards
 
Gavin
Josh Smith | 3 Jun 21:25 2002

Re: The Lost Dinosaurs Of Egypt

Quoting Julia Heathcote <astrodon <at> hotmail.com>:

> For any fellow Brits on the list, this programme is on tonight
> that might be of some interest.  I believe Josh is on the list, right?
> 
>    Date: Monday 03 June  Time: 8:30pm to 10:00pm
> 
>    German palaeontologist Ernst StromerÂ’s
>    legendary "lost" dinosaurs were four new species that
>    he unearthed in the remote western desert of Egypt in
>    the early 1900s, but were destroyed in the bombing of
>    Munich in the Second World War. Two years ago Josh
>    Smith and a US team returned to Egypt and, during a
>    six-week dig, recovered nearly 6,000lb of dinosaur
>    bones and fossils. They also found a "new" dinosaur,
>    which at 80 tons is the second biggest ever discovered.
>    This feature-length film follows the remarkable quest.
> 
> Julia Heathcote
> 
Wow.  It is June already?  I guess it is.  It was actually a US AND 
Egyptian team (University of Pennsylvania and Egyptian Geological 
Museum), but the press never remembers that.  The last version I saw 
(maybe three weeks ago), the music and the narration were still TEMP 
and they were terrible.  I suspect that has improved by now, though...
-j

----
Josh Smith
Department of Anthropology
Harvard University
18 Traymore Street
Cambridge, MA 02140
Office: 617.495.1966
Project Director, Bahariya Dinosaur Project
http://www.egyptdinos.org

Williams, Tim | 3 Jun 21:42 2002

RE: Hell Creek and stegosaurs


Nick Longrich wrote:

> We apparently get a change in species-level diversity change 
> between Hell Creek and some other formations. I'm not sure that this
>  means anything, in that we would expect dinosaur diversity to be
lower 
> or higher variously at various points through their history, 

I completely agree.  As I said in a previous post, dinosaur diversity
most likely had its 'ups and downs' within each period.  The apparent
decline in dino species diversity in the final few million years of the
Cretaceous of North America cannot be taken as representative (or
indicative) of a global decline.

>And if you look at the family level everything's still there right 
> up to the end of the Cretaceous. 

Also true.  Sure, there was less *species* of ceratopsians, hadrosaurids
and tyrannosaurids than earlier strata; but the groups themselves were
still in existence - and doing quite well.  The fact that, at the very
end, N. American terrestrial environments were dominated by a smaller
number of dino species than previously may reflect local environmental
factors.  

Gavin "Frogfoot" wrote:

> This question has been bugging me for a long time actually.  The first
> few dinosaur books I ever got were still of the days when Stegosaurs
had
> these plates for armor protection.  I guess that its well established
> that they used them for regulating body temperature now, or 
> differentiating between species?

I had thought that all of the above theories were currently regarded as
possible.  Still, the big triangular osteoderms of _Stegosaurus_ seem
poorly adapted for defense (or offense), and were perhaps better
utilized as thermoregulatory devices or in threat displays.  

> The only Stegosaur I know that was around til the end of the
Cretaceous
> is Dravidosaurus.  

_Dravidosaurus_ is probably not a stegosaur - or even a dinosaur.  I
have heard that the scrappy material from southern India named
_Dravidosaurus_ actually comes from a sea reptile (plesiosaur?)

> Only a handful of others made it into that same era. So what happened 
> to them, climatic change, different predators/food?

One theory is that stegosaurs, with their relatively unprotected flanks,
were vulnerable to the new 'breed' of maniraptoran killers - especially
deinonychosaurs.

Tim

----------------------------------------------------------- 

Timothy J. Williams, Ph.D. 

USDA-ARS Researcher 
Agronomy Hall 
Iowa State University 
Ames IA 50014 

Phone: 515 294 9233 
Fax:   515 294 9359 

David Marjanovic | 3 Jun 22:00 2002
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Re: Hell Creek and stegosaurs

----- Original Message -----
From: "Williams, Tim" <TiJaWi <at> agron.iastate.edu>
Sent: Monday, June 03, 2002 9:42 PM

> The fact that, at the very
> end, N. American terrestrial environments were dominated by a smaller
> number of dino species than previously may reflect local environmental
> factors.

And maybe the Manson impact 8 Ma before?

> _Dravidosaurus_ is probably not a stegosaur - or even a dinosaur.  I
> have heard that the scrappy material from southern India named
> _Dravidosaurus_ actually comes from a sea reptile (plesiosaur?)

Yes, it's a plesiosaur according to Glut's Encyclopedia, Supplement 2.

> > Only a handful of others made it into that same era.

Do you mean the Cretaceous?

> > So what happened
> > to them, climatic change, different predators/food?
>
> One theory is that stegosaurs, with their relatively unprotected flanks,
> were vulnerable to the new 'breed' of maniraptoran killers - especially
> deinonychosaurs.

That speculation is certainly wrong -- said killers were nothing new,
stegosaur tails should provide enough protection, and *Wuerhosaurus* lived
rather late in the EK. When exactly? Could I maybe blame the little
Aptian-Albian mass extinction? Or the Cenomanian-Turonian one (would imply
some ghost lineage)? :-) -- With the few known stegosaurs it's of course
rather improbable that we'll find out anytime soon why they died out before
the K-T, and when.


Gmane