Dinosaur impact theory changed

Scientists have cast doubt on the well-established theory that a single, massive asteroid strike killed off the dinosaurs 65 million years ago.

New data suggests the Chixculub crater in Mexico, supposedly created by the collision, predates the extinction of the dinosaurs by about 300,000yrs.

Dinosaurs

This is really quite interesting as due to the fact that for many many years now people have believed this crater to be the impact zone...they find something that puts all there theories to hell.

I think there is gonna be a TV programme about this on BBC2 in the next week or so...i'll keep u updated.

Just curious here...whats ur theory on how the dinosaurs were wiped out?

At the moment mine is that an astroid did hit the earth but it caused a severe change in the planet and something happened to make them all die out..possibly due to gases in the air..or even plant life dying out?




Here is a wee pic of where the crater is btw...just incase ur geography isnt upto scratch.

cheers
Gryff

I subscribe to the theory that increases in the volcanic activity on Earth filled the skies with soot and this is what killed them off. The soot blocked sunlight, causing algae and plant levels to drop, which killed off the largest species.

This has been suggested for years, but was mostly overshadowed by the big impact theory.


[Edited on 2-3-2004 by Zzub]

What about the iridium layer? Is this still dated in the right time? That's really the big question. If so, then we're still looking for an impact crater... I'd always felt they jumped the gun when looking for the impact site...

We're still talking about one of only a few mass extinctions in Earth's history, so I think it had to be a major event, maybe even over a span of time...but the iridium suggests an asteroid still...

I agree, the iridium layer does suggest a large impact which affected the whole world.

However, as I understand it, the point of current thinking is that by the time this happened, the dinosaurs were already, for the most part, extinct.


[Edited on 2-3-2004 by Zzub]

take it u guys are on about this???




Another theory could be that the Iridium leaked into the food and water supply and poisoned them all?

is Iridium radioactive or not? Corrosive??

u guys seem to know what ur on about so i am guessing that u know somerthing about this already?

Not sure, but then the question becomes...the Mexican impact was larger, yet no big mass extinction...

Why the difference?

Maybe it's a one two punch.... The first one started the chain, and the trend down...but the last one simply sealed the deal, and quickly, by accelerating the volcanic activity, caused by two such impacts over a relatively short period of time (geologically speaking)...

Here is another interesting theory on the extinction of the dinosaurs from an articale in Discover mag. called "20,000 Microbes Under the Sea".

"Scientists have discovered that nearly a third of all the life on this planet consists of microbes living under the seafloor in a dark world without oxygen. Many of these tiny creatures make so much methane gas that if even a small proportion of it is released, we might be overwhelmed by huge tsunamis, runaway global warming, and extinctions."

www.discover.com...

That still presents the problem though, of why relatively nothing major happened at the time of the Mexico impact......???

Intriguing, to be sure... How sure are they about the dating discrepancy of the crater? I guess that's probably a better question....

This was something interesting...

In addition, debris thrown out by this collision gets thicker the closer you get to Chicxulub like a trail pointing to the impact site.

Perhaps the act of impact, etc. throws off the age analysis....as the physical evidence, seems to suggest that the KT boundary is a result of that impact....

[Edited on 2-3-2004 by Gazrok]

from what i can make out of the chart is:

when the astroid hit Chicxulub it cause some major climate changes..probably raised the sea temp a few degrees, increased volcanic activity and the after effects of this caused the smaller life forms and plant life to begin to die off very slowly...

then comes another hit and wipes the poor buggers out!!

does that make sense??

good theories thou guys

Yep the one two punch....

Only one problem...you'd need a SECOND impact site, and iridium layer, etc. UNLESS the second impact occured at the same location (unlikely to say the least)....

I remember hearing about another massive crator site i think it was in america somewhere and there was scuttlebug about that being a possiblity for the astroid site?

i canna remember the name of the place but i am sure it was in somewhere like Arizona???

Maybe i am wrong???

I dont think it was an astroid that killed them, it was what the astroid did to the planet. The planet was covered in massive clouds that blacked out almost all sunlight. In turn, large plants died from lack of sunlight, the animals who ate the plants died and so in turn the carnivourse died because there was no animals to eat.
So all the big animals died and only small animals like mammels and birds lived.
The were small and could survive off anything.

A second IMPACT
??the 2nd 'impacting' event might not have been a sizeable asteroid.

I may well have been volcanism (which also spews out
irridium from the earths' primevel magmas)

2 recurring sites for monumental volcanism & potentials
for the exploding-gasses event of a volcano-->>

are Hawaii and the Oceania Area of the S. China Sea.
the Sundra Straight = Krakatau

i'm no scientist but this Krakatau thing should get more study...not as a replacement of a KT/Impact Theory...
but as an Adjunct to the Chicxulub theory

*do not dismiss the Krakatau...because of the recent
explosion 1889-9?? or mix up the possible eruption that made the Sundra Straight some 32,000 YA...

see: volcano.und.nodak.edu...

][you might have to repeat, as linking seems out of phase today...or try again later, this is the 1st time the ERROR default has happened while trying to access this page][...sorry

or, a neighboring super-nova? you know we are in a tunnel of debris from the last SN circa 2.5MYA??

"New evidence from geoscientists, published Monday in the Proceedings of the National Academy of Sciences, suggests a much more complex hypothesis of hostile conditions spread over many years.

"Dinosaurs are very popular, and the asteroid theory is sexy, it's a perfect story, and in the past few years it's all you've read in the popular press," said Princeton University professor Gerta Keller, the paleontologist who wrote the study.

Keller said that while her theory may not be as riveting as a massive space object hitting Earth, it answers a lot of questions that she said don't seem to fit in the "wipeout" theory that's been publicized since the early 1980s."

www.cnn.com...

Found this website that gives a lot of geological data on Chicxulub and its minerals and stones that it creates.

Just tryin to really read up on this as its got me hooked to it.

If anyone understands Geophysics or that...can u help us out a wee bit!!

MIAC

This looks really cool:

The big problem, as I see it, is this..

We have an impact site, in which the irridium is clearly spread from (ie it's thicker the closer you get to the crater). But.....the layer is dated as being about .3 million years later than the crater....

Thats a problem...no matter how you cut it....

A combination of things (not triggered by a single catastrophe), doesn't cover how it (the mass extinction) happened so quickly (geologically speaking)....

And it isn't the first ELE (Extinction Level Event) to occur, and likely won't be the last...

I once heard that the asteroid hit an area of some kind of rock (limestone i think but dont quote me on it) that cause acid rain.

i think that u can make acid out of limestone but u need to charge it first with energy.

good input thou....u never know..they may have been melted!!!!!

did anyone actually understand that Geophysics then??

did anyone actually understand that Geophysics then??

Yes, but I didn't see anything there except to substantiate the impact site...which we are already accepting....

What if you had an impact in a thin crust regone
say like yellowstone
would'nt you have a lot of volcanism to