Controversial new theory for what killed the dinosaurs: *two* asteroidsand maybe some volcanos too!

The matter about what killed off the dinosaurs is still far from settled
yet. As far as I'm concerned, a single asteroid impact coinciding with
an extinction event is far too convenient of an excuse -- and lazy.
There is still no convincing reason for why certain animals died off
while others didn't. If small animals like mammals survived, while large
dinosaurs died, then why didn't small dinosaurs survive?

Yousuf Khan

Here's a couple of links:

SPACE.com -- New Dino-destroying Theory Fuels Hot Debate
"Paleontologist Sankar Chatterjee of Texas Tech University says a giant
basin in India called Shiva could also be an impact crater from the time
of the dinosaurs' demise, and the crash that created it may have been
the cause of the mass extinction scientists call the KT
(Cretaceous–Tertiary) event, which killed off more than half the Earth's
species along with the dinos. This argument runs counter to the
widely-held wisdom that the Chicxulub impact on the Yucatan Peninsula
off Mexico was behind the cataclysm."
http://www.space.com/scienceastronom...ur-crater.html

India Asteroid Killed Dinosaurs, Made Largest Crater?
"A six-mile-wide (ten-kilometer-wide) asteroid is thought to have carved
out the Chicxulub crater off Mexico's Yucatán Peninsula, triggering
worldwide climate changes that led to the mass extinction.

But the controversial new theory says the dinosaurs were actually
finished off by another 25-mile-wide (40-kilometer-wide) asteroid. That
space rock slammed into the planet off the western coast of India about
300,000 years after Chicxulub, experts say. "
http://news.nationalgeographic.com/n...dinosaurs.html

Dear Yousuf Khan:

On Oct 20, 8:40*pm, Yousuf Khan wrote:
The matter about what killed off the dinosaurs is
still far from settled yet. As far as I'm concerned,
a single asteroid impact coinciding with an
extinction event is far too convenient of an excuse --
and lazy.

I don't see how this claim can be valid. Would you imagine a Theia
encounter to allow any survivors? And only one impact. (Had there
been any life at that time.)

There is still no convincing reason for why certain
animals died off while others didn't.

You mean other than the warm-blooded vs. cold-blooded thing?

If small animals like mammals survived, while large
dinosaurs died, then why didn't small dinosaurs
survive?

Like crocodiles, alligators, Komodo dragons, birds, and such?

"Nuclear winter" goes a long way towards terminating those life forms
that cannot regulate their body temperatures without direct sunlight.
Kills their food, decreases the surface water, which makes them less
able to travel, and "inordinately large" for the environment.

I think you'd be better off just to watch this particular battle
proceed on... from the sidelines.

David A. Smith

In article
,
dlzc wrote:

Dear Yousuf Khan:

On Oct 20, 8:40*pm, Yousuf Khan wrote:

[Cretaceous-Tertiary extinction]

There is still no convincing reason for why certain
animals died off while others didn't.

You mean other than the warm-blooded vs. cold-blooded thing?

If small animals like mammals survived, while large
dinosaurs died, then why didn't small dinosaurs
survive?

Like crocodiles, alligators, Komodo dragons, birds, and such?

"Nuclear winter" goes a long way towards terminating those life forms
that cannot regulate their body temperatures without direct sunlight.
Kills their food, decreases the surface water, which makes them less
able to travel, and "inordinately large" for the environment.

There are lines of evidence that point to dinosaurs, at least some of
them, having been warm-blooded. Of your list of survivors (to which we
could add the turtles -- and taking Komodo dragons, which have been
around for only a few million years, to stand for the ancestral scaly
reptiles), all are cold-blooded except for the birds. Not only
land-based life was affected: none of the marine archosauria made it
past the K-T boundary, among other oceanic animals (e.g. ammonites) and
plants that were wiped out. OTOH the fishes and amphibians appear to
have suffered relatively few losses.

--
Odysseus

dlzc wrote:
Dear Yousuf Khan:

On Oct 20, 8:40 pm, Yousuf Khan wrote:
The matter about what killed off the dinosaurs is
still far from settled yet. As far as I'm concerned,
a single asteroid impact coinciding with an
extinction event is far too convenient of an excuse --
and lazy.

I don't see how this claim can be valid. Would you imagine a Theia
encounter to allow any survivors? And only one impact. (Had there
been any life at that time.)

Theia was hardly an asteroid, it was a planet. But yes, that does go to
my point: a larger body would have more destructive potential. It just
doesn't seem plausible that a single asteroid of a mere 6 miles wide can
cause that kind of global catastrophe. However, a 25 mile wide one seems
more likely to do so.

There is still no convincing reason for why certain
animals died off while others didn't.

You mean other than the warm-blooded vs. cold-blooded thing?

There is a growing body of evidence that dinosaurs were warm-blooded
too. One school of thought says that at least the large dinos were warm
blooded, simply due to their mass. Another school of thought believes
that many of the small dinos were feathered too, just like birds, so
they too could preserve body heat.

If small animals like mammals survived, while large
dinosaurs died, then why didn't small dinosaurs
survive?

Like crocodiles, alligators, Komodo dragons, birds, and such?

"Nuclear winter" goes a long way towards terminating those life forms
that cannot regulate their body temperatures without direct sunlight.
Kills their food, decreases the surface water, which makes them less
able to travel, and "inordinately large" for the environment.

Many cold blooded animals survived too, such as the aforementioned
crocs, gators, and lizards. Many of them were fairly large, as large as
dinos.


Yousuf Khan

Dear Yousuf Khan:

On Oct 21, 10:01*pm, Yousuf Khan wrote:
dlzc wrote:
Dear Yousuf Khan:

On Oct 20, 8:40 pm, Yousuf Khan wrote:
The matter about what killed off the dinosaurs is
still far from settled yet. As far as I'm concerned,
a single asteroid impact coinciding with an
extinction event is far too convenient of an excuse --
and lazy.

I don't see how this claim can be valid. *Would
you imagine a Theia encounter to allow any
survivors? *And only one impact. *(Had there
been any life at that time.)

Theia was hardly an asteroid, it was a planet.
But yes, that does go to my point: a larger body
would have more destructive potential. It just
doesn't seem plausible that a single asteroid of
a mere 6 miles wide can cause that kind of global
catastrophe. However, a 25 mile wide one seems
more likely to do so.

When the lifeforms we are discussing thrive in/near low-lying
wetlands, and hundreds of thousands of humans die when a tsunami
thousands of time less energetic occurs, I am less than certain the
"numeric" size required to accomplish the feat.

As to two asteroid-sized impacts, perhaps it was a Shoemaker-Levy type
of affair. A once solid body encounters Earth, is gravitationally
shattered, and bombards Earth over succeeding aeons.

There is still no convincing reason for why certain
animals died off while others didn't.

You mean other than the warm-blooded vs.
cold-blooded thing?

There is a growing body of evidence that dinosaurs
were warm-blooded too. One school of thought says
that at least the large dinos were warm blooded,
simply due to their mass. Another school of thought
believes that many of the small dinos were feathered
too, just like birds, so they too could preserve body
heat.

Which indicates that glaciation was probably occurring even back
then. Feathers don't evolve "systemwide", unless they provide some
benefit.

If small animals like mammals survived, while large
dinosaurs died, then why didn't small dinosaurs
survive?

Like crocodiles, alligators, Komodo dragons, birds,
and such?

"Nuclear winter" goes a long way towards
terminating those life forms that cannot regulate
their body temperatures without direct sunlight.
Kills their food, decreases the surface water,
which makes them less able to travel, and
"inordinately large" for the environment.

Many cold blooded animals survived too, such as
the aforementioned crocs, gators, and lizards. Many
of them were fairly large, as large as dinos.

I think the dinosaurs were as likely to have passed due to a case of
"reptilian ebola". The organisms that survived that age had
significantly different "skin types" that what we figure the dinos had
at the time. (Speaking from my personal ignorance again, I'm sure.
Turtle skin seems similar to dinos, but they are not in general
carnivores, and they have a shell to prevent flesh-to-flesh incidental
transmission.)

Which isn't to say that *any* single cause did it, but that too many
cards were stacked against them.

David A. Smith

On Oct 20, 10:40*pm, Yousuf Khan wrote:
The matter about what killed off the dinosaurs is still far from settled
yet. As far as I'm concerned, a single asteroid impact coinciding with
an extinction event is far too convenient of an excuse -- and lazy.
There is still no convincing reason for why certain animals died off
while others didn't. If small animals like mammals survived, while large
dinosaurs died, then why didn't small dinosaurs survive?

* * * * Yousuf Khan

Here's a couple of links:

SPACE.com -- New Dino-destroying Theory Fuels Hot Debate
"Paleontologist Sankar Chatterjee of Texas Tech University says a giant
basin in India called Shiva could also be an impact crater from the time
of the dinosaurs' demise, and the crash that created it may have been
the cause of the mass extinction scientists call the KT
(Cretaceous–Tertiary) event, which killed off more than half the Earth's
species along with the dinos. This argument runs counter to the
widely-held wisdom that the Chicxulub impact on the Yucatan Peninsula
off Mexico was behind the cataclysm."http://www.space.com/scienceastronomy/091018-dinosaur-crater.html

India Asteroid Killed Dinosaurs, Made Largest Crater?
"A six-mile-wide (ten-kilometer-wide) asteroid is thought to have carved
out the Chicxulub crater off Mexico's Yucatán Peninsula, triggering
worldwide climate changes that led to the mass extinction.

But the controversial new theory says the dinosaurs were actually
finished off by another 25-mile-wide (40-kilometer-wide) asteroid. That
space rock slammed into the planet off the western coast of India about
300,000 years after Chicxulub, experts say. "http://news.nationalgeographic.com/news/2009/10/091016-asteroid-impac...

No man, smoking killed the dinosaurs.

dlzc wrote:
When the lifeforms we are discussing thrive in/near low-lying
wetlands, and hundreds of thousands of humans die when a tsunami
thousands of time less energetic occurs, I am less than certain the
"numeric" size required to accomplish the feat.

The direct effects of any disaster kill every lifeform in its path of
destruction, not just selective ones. However, the indirect effects may
selectively kill lifeforms, but the selection criteria in this case are
weird. For example, why did dinosaurs die out, but not birds, their
direct descendants? Why did certain sea reptiles like turtles survive,
but not Ichthyosaurs & Plesiosaurs?

The selectiveness of the disaster more resembles that of a disease,
rather than an impact explosion. In fact there is evidence that the
dinosaurs were starting to die off even millions of years before the
impact.

By contrast, the biggest extinction event of all, the Permian-Triassic
extinction from 250 million years ago from before the age of the
dinosaurs, aka "The Great Dying", was much more understandable. It
killed off 96% of all marine species, 70% of land species. Not much
selectiveness there, just killing & killing.

As to two asteroid-sized impacts, perhaps it was a Shoemaker-Levy type
of affair. A once solid body encounters Earth, is gravitationally
shattered, and bombards Earth over succeeding aeons.

The only difference is that Shoemaker-Levy hit Jupiter over succeeding
hours, if not minutes. In this case it seems as if a body actually
entered into unstable orbit around the Earth and a small 6-mile piece of
it hit the Earth first, and then the remaining may have come down
hundreds of thousands of years later as the orbit decayed. It would
explain why the second 25-mile piece hit at an angle rather than
straight down to create an elliptical crater.

The body would have had to enter into orbit millions of years earlier
and then break apart as its orbit decayed. It probably entered into
elliptical orbit in the opposite direction of the Moon, thus it lost
momentum in its orbit. This might even explain why the dinosaurs were
dying off millions of years before the final impact, the body in orbit
might have been raising unusual tides on Earth.

There is a growing body of evidence that dinosaurs
were warm-blooded too. One school of thought says
that at least the large dinos were warm blooded,
simply due to their mass. Another school of thought
believes that many of the small dinos were feathered
too, just like birds, so they too could preserve body
heat.

Which indicates that glaciation was probably occurring even back
then. Feathers don't evolve "systemwide", unless they provide some
benefit.

Feathers and fur also helps to protect against hot weather.

But yes, glaciation probably occurred well before the age of the
dinosaurs too, if one can believe the Snowball Earth Theory. In fact,
that would be glaciation at a level not seen today. Antarctica wasn't at
its present position during the age of the dinosaurs, it was closer to
Australia now. Once it took up residence over the South Pole, it
probably cooled down the Earth considerably. But if dinosaurs were
warm-blooded, and some feathery, then many of them should have survived
that climate change.

Many cold blooded animals survived too, such as
the aforementioned crocs, gators, and lizards. Many
of them were fairly large, as large as dinos.

I think the dinosaurs were as likely to have passed due to a case of
"reptilian ebola". The organisms that survived that age had
significantly different "skin types" that what we figure the dinos had
at the time. (Speaking from my personal ignorance again, I'm sure.
Turtle skin seems similar to dinos, but they are not in general
carnivores, and they have a shell to prevent flesh-to-flesh incidental
transmission.)

Yeah, as I said, it almost seems like the disaster was disease, like a
virus. However, it occurred in the water as well as land. If a large
asteroid was in orbit about the Earth for millions of years, with its
apogee skimming very close to the surface, there might have been all
kinds of implications all over the Earth for millions of years.


Yousuf Khan

Dear Yousuf Khan:

On Oct 23, 12:52*pm, Yousuf Khan wrote:
dlzc wrote:
....
Many cold blooded animals survived too, such as
the aforementioned crocs, gators, and lizards. Many
of them were fairly large, as large as dinos.

I think the dinosaurs were as likely to have passed
due to a case of "reptilian ebola". *The organisms
that survived that age had significantly different "skin
types" that what we figure the dinos had at the time.
(Speaking from my personal ignorance again, I'm sure.
Turtle skin seems similar to dinos, but they are not in
general carnivores, and they have a shell to prevent
flesh-to-flesh incidental transmission.)

Yeah, as I said, it almost seems like the disaster was
disease, like a virus. However, it occurred in the water
as well as land.

Plenty of viruses and disease transmission in aquatic ecosystems.
Which is why ozone is used there too. ;)

If a large asteroid was in orbit about the Earth for
millions of years, with its apogee skimming very close to
the surface, there might have been all kinds of implications
all over the Earth for millions of years.

There was a short bit on National Public Radio today. Seems like
there is evidence for an overgrowth of toxic algae at the time of the
die-off too.

http://www.npr.org/templates/story/s...ryId=114081479

David A. Smith

Dear Gordon Stangler:

On Oct 23, 12:23*pm, Gordon Stangler
wrote:
....
No man, smoking killed the dinosaurs.

I figured they developed lawyers... or insurance (aka. "protection
money").

David A. Smith