Dino's out prior to meteor?

[Fishteacher73]

I was watching an old show on PBS today that was speaking about the extinction of the dino's at the end of the cretaceous.. The model that was pushed up until the end was meteor impact and the evidence at the K-T boundry. There does seem to be evidence of a meteor impact. The question was just brought up near the end of the show, why so many other types of animals survived (frogs were one example, which are EXCEDINGLY prone to ecological problems) and others did not.

 

IMO it seems that the meteor impact was not as devistating as thought, but just the final nail into a group that wason its last legs anyways (As a whole.. there were very advanced dinos's at the end. But one could look at primates. While there has been much greater diversity in the past, there is little now, but here are humans).

 

There are a few things that seemed to be going on....

 

1) Climate change.

2) Dominant plant life shifting from gymnosperms to angiosperms.

3) Massive migratory paterns into new areas (transmission of indigenous disseases)

 

Any ideas...comments?

I'm just trying to look a little deeper into an event that seems to be blamed on one cause, but it doesn't really describe the outcome that we have...

[Eclogite]

I think a few points that can be agreed upon:

1. There was a massive die off.

2. The earth was struck by a large bolide with devastating results

3. The eruption of the lavas of the Deccan traps caused major changes in the Earth's climate.

4. We still do not have enough detailed data across the KT boundary to decide whether or not 2. or 3. or some combination caused the extinction event.

 

I don't have a problem with the frogs. I would expect the survivors to include small creatures, especially those with a watery refuge.

 

I also wonder if the Chicxulub impact may have triggered the Deccan traps eruptions. Shock waves from the impact would have converged in the general area of the eruptions. (Using general in a very general sense.)

[damocles]

Considering that the meteor impact involved a size discriminator component(a kinetic shock wave spreading from the impact site that could kill large soft-tissued animals above the size of a chicken in the atmosphere and yet have little or no effect on small water-borne animals) and that gas venting and induced vulcanism would magnify the environmental effects of a large localized meteor impact to at least continental/hemispheric proportions, I can well accept that the K-T boundary is a little more than a coincidental confluence of the fossil evidence of a Dino die-off and a meteor strike.

 

I agree that we can debate whether Mister Dino was already on the way out due to a change in the herbivore food supply or alternatively the usual temperature fluctuations in the Sun. I suggest, though, that there is sufficiently strong evidence

 

http://www.lpl.arizona.edu/SIC/impact_cratering/Chicxulub/Chicx_title.html

 

to show that the Chicxulub impact site gives us a sufficiently massive enough event kinetically to fulfill the requirements laid forth in paragraph one. I also argue that if the dinos were on their way to losing the natural selection ball game, then that the Chixilub meteor was the last cosmic strike hurled over the plate in their last inning at bat.....*

 

* Ramdom chance event not connected to any intelligent intervention. I append this clarification to dispel the notion that there is anything but humor involved in my describing the meteor impact as part of an evolutionary sporting event-i.e. applied gaming theory as a real factor in the biological game of survival. D.

[Fishteacher73]

I don't have a problem with the frogs. I would expect the survivors to include small creatures, especially those with a watery refuge.

The dino's aren't the only thing that died out though, a vast majority of the marine life suffered as well. Everything from ammonites to forams have a massive if not complete extinction of the families. Yet there are others that should have been more vulnerable if the scenerio is as currently accepted. :eek2: