Dinosaur extinction?

Question

If dinosaurs perished because of the meteor that created the KT boundary, why does the fossil record show that the mass extinction was over a very long period of time (tens of thousands of years) rather than tens of years?

Answer 1

It is actually very difficult to pin down the extinction period other than to say it was geologically speaking very rapid. Not everyone is convinced of the meteorite theory, at least not a stand-alone explanation; massive volcanism from the Deccan region of India also coincides. And if it was a bolide (meteorite), several geologists have argued that Chicxulub is perhaps several hundred thousand years before the end of the Cretaceous, and is not the cause of the Iridium rich layer that marks the end of the Period.

To further complicate matters, there are claims of dinosaur fossils, albeit poorly preserved, from the Palaeocene epoch, after the Cretaceous period (others counter that these are actually fossils washed out of Cretaceous deposits and re-deposited in the younger sediments).

But I'm inclined to agree: if the meteorite was the culprit, whether it was the Chicxulub event or another one, any species that survived the first hundred to a thousand years after the event would likely have bounced back.

Answer 2

In geologic time, that is practically instantaneous. At any rate, not everything died instantly because the climatic effects were not complete and instantaneous.

For example, it takes time for the dust in the atmosphere to reduce the air temperature appreciably so that the dinosaurs would have only gradually succumbed to the changes in temperature, precipitation, vegetative changes, etc.

Those that moved to follow the changes were more likely to survive longer. What was the lifespan of a healthy dinosaur? Who knows? A young healthy dinosaur may have lived for years in isolation to have only died from old age and was never successful in finding a mate. Or egg-laying dinosaurs may have died out because the eggs were not maturing fast enough to keep pace with the weather changes.

Not all dinosaurs died out at the same exact time, either. Smaller more mobile, more adaptable one may have lasted longer. Some who were truly isolated may have lasted well beyond the mass extinction and remnants may still be around -- for example, the kioto dragons, or some of the strange creatures in the sea. Or John Mark Karr.

Answer 3

The reasons for the mass extinction that occured 65 mya are still not properly understood, there are many theories as to the cause of it. Such as Alvarez hypothesis, Chicxulub crater, Deccan traps, Multiple impact event, Supernova hypothesis. Studies of the diversity and population of species have shown that the dinosaurs were in decline for a period of about 10 million years before the asteroid hit. Also the fossil record in not a complete record. Check out http://en.wikipedia.org/wiki/Kt_boundary#Further_skepticism for a better account

Answer 4

After the inital impact the earth was punged into a nucleur winter that lasted for thousands of years The temperature fell gradually over the eons causing a slow extinction of cold blooded dinosaurs. Warm bloodied mammals survived.

Answer 5

The impact would have created a comlex sequence of events, that would cause death to move up the food chain. The impact was lilekly to raise a cloud of dust and ash that would have coverd the sun for many months (if not years). That would cause the plants to die (and indeed, the biggest victims of the end-cretacious mass extinsion were plants, about 90% of all plant species), which in turn brought on the death of plant eating animals and then carnivours. The effect would have been most aperant on large animals. All these events take a long time to play out.

Answer 6

The fossil record shows periodic mass extinctions. One of these was already well underway when the meteor hit.

Answer 7

The majority of dinosaurs were killed near the collision area but the main factor was probably the climatic and environmental changes caused by the meteor collision. Dinosaurs' habitats and ecosystems would have been altered/destroyed . they did not have time to adapt to these changes.

Answer 8

probably because the dinosaurs were on the planet for tens of thousands of years and died naturally quite a lot, the meteor just killed the rest off pretty quickly.

Answer 9

Maybe because it took a long time to affect the entire food chain.

Answer 10

Ok look at it this way could you pin point say 50years in a stratigraphic column of 65Ma?