Skip to comments.Study: Dinosaurs Died Within Hours After Asteroid Hit
Posted on 07/08/2004 12:29:19 AM PDT by LibWhacker
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.
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.
A paper on the subject was published by Robertson in the May-June issue of the Bulletin of the Geological Society of America. Co-authors include CU-Boulder Professor Owen Toon, University of Wyoming Professors Malcolm McKenna and Jason Lillegraven and California Academy of Sciences Researcher Sylvia Hope.
"The kinetic energy of the ejected matter would have dissipated as heat in the upper atmosphere during re-entry, enough heat to make the normally blue sky turn red-hot for hours," said Robertson. Scientists have speculated for more than a decade that the entire surface of the Earth below would have been baked by the equivalent of a global oven set on broil.
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.
A nearly worldwide clay layer laced with soot and extra-terrestrial iridium also records the impact and global firestorm that followed the impact.
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. 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.
Terrestrial vertebrates that survived also were exposed to the secondary effects of a radically altered, inhospitable environment. "Future studies of early Paleocene events on land may be illuminated by this new view of the KT catastrophe," said Robertson.
Sure, and the animals that burrowed underground or sheltered in water survived how? By eating what?
It's all true...it's science. I read it in a book.
(I, too, observed this same thing 65 million yrs ago)
Burnt and rotting plant and animal matter, each other, etc. They survived it so obviously there was some food for them.
It looks like VELIKOVSKY's "Worlds In Collision" is being revisited!
There are two kinds of college students: science students and liberal arts imbeciles who can't make the grade.
And wouldn't that have killed every land plant?
No, we don't need Velikovsky to see there are comets and asteroids out there.
You'd think so, but not necessarily.
Hmmmmm...I wanna see their model for this.
RA, you'd have a better grasp of the physics behind this...what do you think? Locally, yes, I can accept this hypothesis, but globally? Musta been one h*lluva bolide, and I'm not convinced that smaller biota would have survived even in well-protected niches...availability of free atmospheric oxygen being a major factor.
Permian, maybe...K/T? Call me very skeptical.
Perhaps deep roots survived, and I'm sure seeds did. And, other animals were carrying around seeds. Those would produce new, adapted plants and underground plant matter and insects would provide food and water.
Velikovsky was a dolt.
Must have been a lot of rain after that much evaporation.
Probably, but not all their seeds.
I'd also think that creatures and plants nearer the poles would have had an advantage.
If I recall correctly, species that were exclusively shallow-water-dwelling had a hard time pulling through as well.
Earth may be a small target, but it has been traveling in a repetitive pattern for billions of years; in the field of trajectory of billions of astronomical projectiles...what are the odds of a hit?
Yes, and the mineral content of the astroid may have been very beneficial to plant growth and animal development.
A big hit like that one? I've heard something like once every 100 million years or so.
Fast destruction and everything set for a quick rebirth?of life.
If they do...it must be one heck of a mathematical computation to figure out the probablity...then of course there's the differences of consequences of a direct hit, a negative rotation hit or a positive rotation hit...is it in the Northern Hemisphere during which season or the Southern?
I bought a Lotto ticket today...odds 41,600,000 to one...hundreds of people have "beat the odds."