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.
Hey I live in Southern California and there are many bush fires...you should see what a burn area looks like a year or two after a fire...better than before.
Just watched a show on Science Channel this past weekend.
The Planets were all formed by a disk of dust that kept getting bigger. Then the big parts kept getting bigger, then gravity of the big ones made them bigger.
According to the Scientists on the subject Pluto and Venus Proved this theory.
Yet when it comes to Uranas and Neptune the quote is:
"No matter how many times we tired we could get no computer model to create these two planets. It just didn't work. We put in all the data and still came to nothing. I think the science is not yet perfect."
And as to the big extinction, there is one "respected archeologist, he looks like a hippie wears a hat all the time, (name escapes me) He said that there is a little tree frog in S. America and if you change his surrounding temp by a degree it DIES. He does not believe in the Asteroid but says what killed the Dinos was the little critters, Disease.
Land bridges afforded at time migration and some had immmunities others did not. ???
If Science was always right then scienctist would always agree. Either evidence says planets were formed one way or another. But then 2 PLanets do not fit into the mix at all.
As Stephen Hawking said, "The big bang happened, but can we say that a supreme being did not use that method to "create" the universe?" It is something that must not be left out.
There are two ways to figure a probability: Calculate it or estimate it. I think the "once every 100 million years" assessment falls into the latter category -- though we do have a much better idea what's out there nowadays than even 20 years ago and can do a better job calculating these probabilities. You're definitely correct, though, I was only referring to the "unconditional" probability of a 6+ mile bolide clobbering us.
I think it's just based on the physics of the situation; e.g., what is the kinetic energy of Mt. Everest approaching Earth at ~30 miles/sec?
Why would good,fast carbonized horsemen be a factor?
Sorry,couldn't resist. ;)
Bush did it. Dan Rather said so.
;)
Can one (or some) coming from God only know where (no disrespect meant), sling around some star(s), planet(s), moon(s) and end up traveling at google speeds?
Thus arriving at their ultimate destination sooner than anyone might expect?
Hmmm . . . Have to ask the resident astronomers here for a complete explanation, but all asteroids definitely do not travel at the same speed relative to Earth, though I think there are correlations between their speeds and their origin. For instance, asteroids coming in from the asteroid belt between Mars and Jupiter come in relatively slowly (though God help us if a big one ever smacks into us!), whereas asteroids and comets coming in from further out in the solar system, or even interstellar space, tend to be moving quite a bit faster.
Actually, there would be lots of cooked food everywhere...
I think that there is much discussion that could be had on this topic.
I'm not a physicist, astronomer or rocket scientist...but this subject as both intrigued and concerned me for years.
Aren't "falling stars" after all, just asteroids and comets on near misses of Earth?
I think the Earth's speed as it orbits the Sun is in the neighborhood of 60,000 MPH. Fast enough for a large floating chunk of space rock to do major damage as it slams into us!
Yeah, for a decade. Sure....
Falling stars are meteors, usually not much larger than a grain of sand. They enter Earth's atmosphere at several miles per second and burn up.
It's always amazed me that we could even see something as small as that burning up when it's so darned far away from us (what, five, ten or even twenty miles over our heads?). So, they miss Earth in the sense that they do not make it to the ground, but they definitely hit Earth's upper atmosphere (and that's no miss in my book!).
Astronomers don't call them asteroids or comets, reserving those designations for larger stuff.
BTW, I'm not an astronomer/physicist either, just a guy who's had a couple of astronomy courses. :-)
At any rate, if all the dinosaurs died then, how do they explain Helen Thomas?
Seriously, interesting article.
They know what happened 65 milion years ago?
I can't even find my keys...
Lots of people still laugh when there is talk of setting up an asteroid defence system. The chances of a big hit are small but there's always that chance, the planets have swept up most of the rocks flying round the solar system but there will always be rocks out there.
Sure, and the animals that burrowed underground or sheltered in water survived how? By eating what?
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.