Re: Study: Dinosaurs Died Within Hours After Asteroid Hit Earth 65 Million Years Ago

From: deowll (deowll_at_bellsouth.net)
Date: 06/28/04 

Date: Sun, 27 Jun 2004 21:48:13 -0500

"Eric" <notValid@comcast.net> wrote in message
news:FksDc.116244$eu.1815@attbi_s02...
> R.Schenck wrote:
>
> > baalke@earthlink.net (Ron) wrote in message
> > news:<d5786437.0405251103.1ce85240@posting.google.com>...
> >> http://www.colorado.edu/news/releases/2004/168.html
> >>
> >> Study: Dinosaurs Died Within Hours After Asteroid Hit Earth 65 Million
> >> Years Ago University of Colorado at Boulder
> >> May 24, 2004
> >>
> >> According to new research led by a University of Colorado at Boulder
> >> geophysicist, a giant asteroid that hit the coast of Mexico 65 million
> >> years ago probably incinerated all the large dinosaurs that were alive
at
> >> the time in only a few hours, and only those organisms already
sheltered
> >> in burrows or in water were left alive.
> >
> > Ah, so thats why nessie is still around.
> >>
> >> The six-mile-in-diameter asteroid is thought to have hit Chicxulub in
the
> >> Yucatan, striking with the energy of 100 million megatons of TNT, said
> >> chief author and Researcher Doug Robertson of the department of
> >> geological sciences and the Cooperative Institute for Research in
> >> Environmental Sciences. The "heat pulse" caused by re-entering ejected
> >> matter would have reached around the globe, igniting fires and burning
up
> >> all terrestrial organisms not sheltered in burrows or in water, he
said.
> >
> > I guess the crown group of birds must've had a fossorial ancestor.
> >
> > snip
> >
> >> The evidence of terrestrial ruin is compelling, said Robertson, noting
> >> that tiny spheres of melted rock are found in the Cretaceous-Tertiary,
or
> >> KT, boundary around the globe. The spheres in the clay are remnants of
> >> the rocky masses that were vaporized and ejected into sub-orbital
> >> trajectories by the impact.
> >
> > Shocked quartz no? But this is not an artefact of re-entry is it?
> >>
> >> A nearly worldwide clay layer laced with soot and extra-terrestrial
> >> iridium also records the impact and global firestorm that followed the
> >> impact.
> >
> > But that's not evidence of re-entry either. They're both evidence of
> > global dispersal, which may be a result of orbit followed by re-entry
> > tho. But the shocked quartz isn't shocked by the re-entry process.
> > And the iridium is evidence of an impact, but hasn't got anything to
> > do with 'global firestorms'.
> >
> >>
> >> The spheres, the heat pulse and the soot all have been known for some
> >> time, but their implications for survival of organisms on land have not
> >> been explained well, said Robertson.
> >
> > Did they have some minimum estimate for the amount of material
> > re-entering, based on estimates of whats actually preserved?
> >
> >
> >> Many scientists have been curious
> >> about how any animal species such as primitive birds, mammals and
> >> amphibians managed to survive the global disaster that killed off all
the
> >> existing dinosaurs.
> >>
> >> Robertson and colleagues have provided a new hypothesis for the
> >> differential pattern of survival among land vertebrates at the end of
the
> >> Cretaceous. They have focused on the question of which groups of
> >> vertebrates were likely to have been sheltered underground or
underwater
> >> at the time of the impact.
> >>
> >> Their answer closely matches the observed patterns of survival.
> >> Pterosaurs and non-avian dinosaurs had no obvious adaptations for
> >> burrowing or swimming and became extinct. In contrast, the vertebrates
> >> that could burrow in holes or shelter in water -- mammals, birds,
> >> crocodilians, snakes, lizards, turtles and amphibians -- for the most
> >> part survived.
> >
> > Birds? In nest's made out of kindling or inside trees? If a dinosaur
> > is roasted by this heat, then a tree certainly is. And what about
> > things like mircoraptor?
> >
> > Well, at least they said they restricted the study to a consideration
> > of land animals and didn't want to get into what happened in the seas.
> > I would think tho that anything baking the continents must've had a
> > dramatic effect on creatures living near the surface of the oceans.
> > Especially planktons and forams and the like.
>
> If the "heat pulse" which lasted hours and caused temperatures to rise
like
> an oven on broil then surely living under a rock wouldn't help you nor
> would living in a borrow. In fact shallow water bodies would probably have
> evaporated and all the insects and plants would have died. Nope, if what
> they say was true then its doubtful any of the earths "non-aquatic" life
> would have recovered. They need to think it through again.
> Eric
>

You find evidence for that kind of kill fairly close to the impact in the
south western part of north america in the fern spike that followed. All the
flowering plants seem to have vanished for a time before the region
recovered. The region nearest the crater is harder to study because most of
it is deep under rock. In other parts of the world you would have most
likely gotten a rain of hot debris from the impact that was fairly scattered
and didn't last long.

What most of them would have had is a nasty earthqauke maybe 13 or so. Major
tidal waves all over the place. A shower of hot rock that would start fires
if fuel was handy, heavy dust layer in the upper air for a year or three
that would have badly cooled the place off until it settled out, acid rain
from the sulfer, then once the dust settled and the sky cleared the co2
would have caused abnormallly high temps until it got soaked up. Some of the
co2 would surely have been soaked up by the oceans during the cool stage and
might have slightly off set it.

Peace of cake of course there may have been some other things we don't know
about yet. Oh yes the bleeping basalt flows were occuring before and after
this time frame.

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