More Evidence Supports Massive Asteroid Strike

InnerPeace Volunteers writes "From a BBC Sci/Tech article: The idea is that a giant asteroid about 10 kilometres wide, travelling at 90,000 km/hour slammed into the Earth at the southern margin of North America. This was a case of global devastation rather than North American catastrophe. The asteroid devastated pretty much everything."

Comments

gulf of mexico

[Anonymous Coward]

Didn't anyone besides me think that this is why the gulf of mexico exists?

Re:gulf of mexico

[jc42]

Well, yeah; probably lots of people would guess at such a hypothesis. But it's not consistent with what is known about the 65-Million-year-old crater on the coast of Yucutan. You'd expect the crater to be near the middle of the Gulf, but it's not. And the crater itself is only maybe 1/10 the diameter f the Gulf.

Also, any geologist will probably tell you that the Gulf of Mexico is much older than that. It's really a very old feature of that part of the planet.

But this shouldn't be taken as a criticism of the idea. The scientific process isn't harmed by such wild guesses. They are often the start of interesting findings. The Gulf of Mexico does look like a "circular feature". It could be an impact crater. But apparently it isn't.

For that matter, the Pacific Ocian is also roughly circular. There has been lots of hypothesizing about this, including the idea that it's the scar left from when the moon was torn from the Earth by the impact of another planet. The scientific jury is still out on this one. After 4.5 billion years, there's not a whole lot of fossil evidence left ...

Re:gulf of mexico

[mmol_6453]

I wasn't aware that there was material that could be made into fossils 4.5 billion years ago...

Re:gulf of mexico

[Hektor_Troy]

Of course not ... people from back then are very secretive about it ... just look at Scientology.

Re:gulf of mexico

[Anonymous Coward]

Of course in order for the Pacific Ocean to look like a crater you kind of have to throw out all of plate tectonics, considering that >200My ago there wasn't a Pacific Ocean...

david

Re:gulf of mexico

[jc42]

That's part of the problem.

Of course, in many scientific circles, "fossil" is routinely used to refer to any distinct objects or materials found in rocks. The term doesn't just mean remains of once-living organisms. Thus one reads of bits of "fossil gases" entrapped in cracks or bubbles in rocks or ice; these are used to learn about ancient atmospheric conditions. Sedimentary strata contain "fossil rock" as tiny inclusions. And so on.

But still, 4.5 billion years ago, the Earth didn't have much in the way of solid crust, and most of that has long-since been subducted and melted. So we may never have many details from back then. This makes it a bit difficult to find data for or against the "colliding planets" hypothesis. The best argument so far isn't fossil at all. It comes from physicists' attempts to explain how a pair of planets so closely matched as the Earth and its moon can end up in the orbits that we see today. Orbital mechanics seem to preclude this, except as the outcome of a grazing collision between two planet-sized objects.

As a separate subject, though, geologists do say that even if this collision happened, it probably has little if anything to do with the formation of the Pacific Ocean. From what has been learned of plate tectonics in the past decades, it seems that oceans and continents have come and gone many times. The presence of such a large, circular ocean at this time is somewhat of an accident, and wasn't really true at several times in the past billion years.

Gotta go ...

Re:gulf of mexico

[fjordboy]

the whole thing reminds me of a bbc article from about 2 days ago about that mars "fossil" that was found a couple years back. A team of scientists determined that there was no fossils in the rock, it was just magnetite crystals. Sort of interesting, the whole article is located here at bbc.co.uk

Re:gulf of mexico

[Mr. Slippery]

A team of scientists determined that there was no fossils in the rock, it was just magnetite crystals.

"Determined" is much too strong a word. The nature of the magnetic grains has been disputed from the start, and the question is still very much open.

Re:gulf of mexico

[Cheese Metal Rulez!!]

What he obviously meant is that the big blob of land that was on the other side of the planet at that time is the scar (more like a scab really).
The scab just split up and is slowly moving into the pacific.

Re:gulf of mexico

[SectoidRandom]

I remember back in primary school thinking that, and argueing that point to my teacher when they talked about the 'ice age'..

But there is an error in that, although they have found 'evidence' now of a meteorid strike in the gulf of mexico, as i remember the evidence showed a 10 or so kilometer creator, which is obviously MUCH smaller than the gulf of mexico!

I would think an impact causing a creator the size of the gulf of mexico, would be the kind that gives us a second moon! (Or there abouts) :)

Re:gulf of mexico

[SectoidRandom]

Oops little correction, I was reffering to the Chicxulub crater, 100miles 10k's same thing. :)

Re:gulf of mexico

[Arjuna]

The scab just split up and is slowly moving into the pacific.
Um.. isn't the pacific growing?
To come close on this one we'd have to look at roughly where the continents were when the supposed impact happened. Maybe 'pangea' the supercontinent was a relic of the moon-genesis impact, kindof like the tharsis bulge that was probably caused by the impact which created the hellas basin on the opposite side of mars.
Note - this is rambling speculation. I love thinking about cataclysms.

Yellow journalism

[tercero]

I used to have this book that speculated what would happen to the earth if that big of an asteroid hit. One of the things mentioned was a colossal crater (as in more than 1000mi in dia.) that so far is no where visible on Earth.

So they say they found a bunch of bones that suggest "major disturbances in climate that led to the death of most trees and flowering plants." Why does that sort of stuff always lead toward an asteroid that there is no _direct_ evidence of?

This is what I call yellow journalism. It is there opinions and beliefs that are reported and taken as truth.

News flash: It's good for you health to eat saturated fatty foods. The large fat globules travel through the blood vessels and break up smaller globs stuck to the insides of vessels.

BTW: What does this have to do with nerd news? Are there some archeological nerds out there that go to /. for their news?

Re:Yellow journalism

[Mannerism]

Actually, the evidence for the asteroid is pretty compelling IMO. There's a good article about it here.

Re:Yellow journalism

[mmol_6453]

Historically, whenever there was a missing piece of evidence that seemed necessary for a theory to be true, either it was found eventually or its absence was explained by some insightful fellow.

It could still go either way.

Re:Yellow journalism

[rudedog]

Umm, why exactly do you think that they keep mentioning the Yucatan Peninsula? It's because that is where they found the Chicxulub crater, mostly covered with water and estimated to be at least 100 miles across. I would bet any money that this book you had was one of those creation "science" books, right?

Re:Yellow journalism

[rve]

Thing with craters on the earth's surface is that they weather. Water, wind, ice, chemicals and life erode the features.

As a result, a crater on earth doesn't look like one on for example Mars: a hole, with a ring around it and an elevation in the middle. The crater on Yukatan for instance, is completely covered with sediment, and can only be recognised with detailed geological research.

Re:Yellow journalism

[jc42]

If this were the only evidence, you'd be right. When the impact hypothesis was first fielded, most scientists just said "Interesting; where's your evidence?" But over a couple of decades, geologists and paleontologists have done lots and lots of testing on strata around the world of that age. They keep turning up more and more data that is "consistent with" the impact hypothesis, and nothing that convincingly debunks it. By now, the evidence is overwhelming, so what was a weak hypothesis has elevated to a mostly-accepted theory.

Nowadays, if the face of so much consistent evidence, you'd have to have some really spectacular counter-evidence to be taken seriously. There are still scientists out there trying to debunk the idea, of course, but mostly they just keep turning up more evidence in favor of the impact. That's what this story was. One more of a chain of hundreds of findings that support the general idea of a major impact 65 million years ago.

Has anyone found strata anywhere that is well-dated and continuous across the 65-million-year age that doesn't show a thin anomalous layer and a radical change of fossils?

(Yes, there are continuous strata of around that age that can't be firmly dated. There are also strata that straddle the date but can't be shown to be continuous. None of these is evidence pro or con the impact.)

What does it have to do with nerd news? Well one thing that a few people have been pushing is funding for equipment and people to do a thorough study and census of small objects in the solar system. There could be such an object aimed to hit us Real Soon Now. We don't know. The sooner we can spot such things, the sooner we can do something to deflect them. If we don't, well, one of them will hit the Earth eventually. Maybe it'll hit next week; maybe it'll hit 30 million years from now.

There are roughly a thousand objects now known of km-size or greater that cross the Earth's orbit. None of the known objects will hit the Earth within a century or so. But we have no idea how many more may be out there.

We nerds are just the ones to find them. And knowledge of earlier disasters is one of the best ways to pry funding out of governments agencies.

Re:Yellow journalism

[Joe Decker]

Have some crater pix. Of course these aren't surface artifacts, those would have worn away in the intervening hundreds of millions of years... but the rock densities live on.

I call this direct evidence. Your mileage may vary.

Re:Yellow journalism

[tercero]

You're on. It is not a "creation science" book.

Re:Yellow journalism

[bujoojoo]

Take a look at Hudson Bay (Canada). Kinda round, wouldn't you say?

Re:Yellow journalism

[Antity-H]

Why should the crater have to be on earth surface? Since most of earth is covered with water AFAIK, an asteroid would most probably fall in an ocean. Nom I remember my geology courses well enough, the ocean floor is "replaced" (subduction...) much faster than earth surface. Added to that the energy released into the crust would be much reduced thanks to the water absorbing a good deal of it.

Re:Yellow journalism

[Anonymous Coward]

I've read years ago that there is some slight, tentative basis for suspecting the pacific ocean may be the location of the 1000+ mile crater you're looking for, or in fact may mostly be the crater itself (assuming a larger asteroid than usually mentioned, I'd guess).

Re:Yellow journalism

[athlon02]

Ok, the talk in this thread so far seems to be about the fact that there are "supposed" 100 mile or 1000 mile, etc. craters on the earth that would support such a theory as a "global killer" (from one of those asteroid movies I saw)...

For one, we already know that there's glaciers, volcanoes and other natural phenomena ON EARTH that can rip out or blow up huge sections of land leaving huge holes. So then how do we KNOW these "supposed" craters are really craters?

Secondly, my question is not just "are these really craters?" My big question is WHERE IS(ARE) THE ASTEROID(S) THAT SUPPOSEDLY HIT EARTH?

And you can't just say "They burned up in earth's atmosphere" because then they wouldn't have had the life killing impact that is proposed by Godless scientists.

Sorry, but all that article sounds like to me is flamebait by so-called scientists who refuse to believe in God because then they'd have to deal with the consequences of willfully ignoring the Bible.

Re:Yellow journalism

[Anonymous Coward]

So *why* do you believe in a literal interpretation of the Bible?

The only logically consistent position you can take is that your belief is based on faith - *despite* any evidence you might be exposed to.

You are predisposed to ignoring evidence at best, and at worst engage in ad hominem attacks on anyone who doesn't agree with you (e.g. "flamebait").

P.S. - if you want to know how we *know*, go get a Ph.D. in geology.

P.P.S. - Do you *know* how a computer works at the quantum mechanical level? If not, how can they exist?

Re:Yellow journalism

[Anonymous Coward]

I suspect this is a troll, but I'll respond seriously nonetheless.

>Ok, the talk in this thread so far seems to be about the fact that there are "supposed" 100 mile or 1000 mile, etc.
>craters on the earth that would support such a theory as a "global killer" (from one of those asteroid movies I saw)...

I'd hesitate to take anything, even something as simple as a title of an event, provided by Hollywood with a grain of
salt. To quote a friend more acquainted with the industry, even "based on a true story" is more accurately translated
as "big fat f**king lie".

>For one, we already know that there's glaciers, volcanoes and other natural phenomena ON EARTH that can rip
>out or blow up huge sections of land leaving huge holes. So then how do we KNOW these "supposed" craters are
>really craters?

this is not my area of research, but i have a passing familiarity with it.

Size is an issue; even large volcanoes (earthquakes generally don't cause this effect, unless they trigger said
volcanoes) don't cause this kind of devastation. Krakatoa is one of the larger volcanic eruptions in recent times,
and yet it didn't have global cataclysmic consquences (AFAIK). Impacts work well in this regard, and as someone
above mentioned, even those trying to debunk the impact idea seem to have provided more info to support it.

>Secondly, my question is not just "are these really craters?" My big question is WHERE IS(ARE) THE
>ASTEROID(S) THAT SUPPOSEDLY HIT EARTH?

That's fairly easy. A similar question was asked about the meteor crater in Arizona; where was the meteorite?
That feature is pretty/fairly obviously an actual impact... and yet, no nice big space rock down below. There
was quite a bit of digging back in the early 20th century looking for it, before they figured out it just splintered
and left no nice big chunks. The bigger meteors should do this; Arizona was hit by something the size of a car,
if I remember correctly. Something multi-km across, even barring the idea that it likely punched through the
crust and into the mantle, would never survive the strike.

>And you can't just say "They burned up in earth's atmosphere" because then they wouldn't have had the life killing
>impact that is proposed by Godless scientists.

Unlikely something over the size of a basketball would burn up. It would depend on what the rock is made of - iron
meteors last longer than stony, which last longer than comets - but there's still an upper limit on what can't make
it to the surface.

>Sorry, but all that article sounds like to me is flamebait by so-called scientists who refuse to believe in God because
>then they'd have to deal with the consequences of willfully ignoring the Bible.

The nature of the origins of the bible is not a can of worms to be opened here, but a comment:

I've found quite a few researchers who are quite religious. When they study things like this, they are in
tremendous awe at the wonder of the universe. Some have reported that whereas they once were agnostic/atheistic,
looking into the enormity of it all changed them & woke up the faith in them. One has a comment on your post -
from which I'll remove the derogatory comments - that he believes in a God, a great God, for whom no impact crater,
discovered dinosaur bones or fossil record holds any threat to. If anything, these things show how incredible He
really is - look at the wonder of a world He chooses to show to you, a gift from Him to us, his children, which
tantalizes the senses and imagination. In this case, he's given to us what any loving parent would give a young,
intelligent child - a puzzle, a mind-bender to help us begin to understand the enormity of His works.

Re:Yellow journalism

[Anonymous Coward]

"Secondly, my question is not just "are these really craters?" My big question is WHERE IS(ARE) THE ASTEROID(S) THAT SUPPOSEDLY HIT EARTH?"

Well, if they were big enough to cause that scale of crater, the remaining unvaporized, unejected pieces would likely punch thru the crust of the earth and be melted and drifting down to the core with the mantle circulation.

Even if not, remaining pieces would be very deep, and like the studies have shown, be miles under all those deposits made in those 60 odd millions of years since..

But, that much energy of motion, tens of thousands of megatons... it's more likely that nearly the entire object would blown out of the resulting crater.. and rain down as dust around the planet.

Which is what they found... at the KT boundary, all over the planet, a very thin layer with a unnaturally high amount of Iridium, with an isotope mix that is NOT found in rocks on earth. But IS characteristiclly found, in meteoric nickel-iron...

So, actually, they found the asteroid first, and then went searching for the crater..

You should read the actual information on the subject, rather than that badly written short bit that was linked to.

What you say?

[Man of E]

The asteroid devastated pretty much everything.

I dunno, last time I checked, most of the Earth was still around after the impact. Or did the mice rebuild it?

Re:What you say?

[Mannerism]

No, the mice are merely hell-bent on its conquest.

Re:What you say?

[Alien54]

Or did the mice rebuild it? Basically, more or less, yes. Considering that the Impact was 65,000,000 years ago. Plus, evolution is faster when you have a clean slate to play with.

This actually was a big thing a few years ago. Thus you have goodies like the Sky and Telescope Impact Hazards website, along with this nifty cosmic impact calulator.

To be fair, there is this article about a scientist that thinks mass extinctions are a myth. ( I am skeptical of this.

And not that a ten mile wide asteroid would make a mess, but that an asteroid needed to wipe out and actually destroy the earth would likely be much much large, maybe 1,000 miles across or more.

10 miles across is like a bug on the windshield. Note that humans are living on the outside of the windshield.

So it sounds like you get to have fun researching impact craters on google, etc.

Re:What you say?

[Cro Magnon]

Yup! I've seen pictures of the primitive mammals that survived the dinosaur era, and they didn't look that much different from mice.

Re:What you say?

[Anonymous Coward]

To Earthlings, the thin skin of their biosphere pretty much counts as "everything" when speaking in terms of the survival of a native species.

A barren chunk of rock isn't much good for supporting Earthling life-forms.

-- just a guy from outer space...

Re:What you say?

[rossdee]

"did the mice rebuild it?"

No, the Magratheans rebuilt it, the mice merely paid the bill...

Re:What you say?

[Lips]

Lets see...

10k wide, 90,000 km/hour

kinetic energy = 1/2 * m * v^2
mass (kg), velocity(m/s), energy(joules)

Asteroid Otawara is 5.5 k across and has an estimated mass of .2*10^15 kg

1/2 * 200,000,000,000,000 * (90,000 * 3600)^2 =10,497,600,000,000,000,000,000,000,000,000 joules
This is the equivalent of 166,628,571,428,571,000 Hiroshima bombs. Thats a big mess :(

http://www.imsa.edu/edu/geophysics/asteroid/energy .html has great info.

Re:What you say?

[Alien54]

10k wide, 90,000 km/hour
kinetic energy = 1/2 * m * v^2 ,br> mass (kg), velocity(m/s), energy(joules)
Asteroid Otawara is 5.5 k across and has an estimated mass of .2*10^15 kg
1/2 * 200,000,000,000,000 * (90,000 * 3600)^2 =10,497,600,000,000,000,000,000,000,000,000 joules This is the equivalent of 166,628,571,428,571,000 Hiroshima bombs. Thats a big mess :(

hmmmmm, I think there may be a mis calculation

According to the Impact Calculator, based on your initial parameters.

Projectile = Iron Asteroid
Diameter = 10.0 kilometer(s)
Velocity = 25.0 km/s
Target = Earth

Yeilds these results:

Energy Released = 305 million MT (MegaTons of TNT)
(The Dinosaur Killer: 100 million MT)
QUAKE!! Magnitude 11.3 (largest recorded Earthquake: 9.5)
Crater Diameter: 209.0 km
Crater Depth: 1.5 km
A collision this large occurs roughly once every 240 million years.

[insert picture of Marivin the Martian here]

http://janus.astro.umd.edu/gifdir/marvin.jpg

Ohh! Look at all the dust in Earth's atmosphere! It's going to block the sunlight and make it very very cold there for many years. There will be another wave of mass extinctions. You humans will not survive.

What would Buck Turgidson say?

[Anonymous Coward]

Hey, we gotta get us one of those asteroids. We can't let there be an asteroid gap!

Re:What would Buck Turgidson say?

[Joe Decker]

Wasn't that the goodly Dr. Strangelove?

Re:What would Buck Turgidson say?

[Anonymous Coward]

Hi COLMAN!

Gee, I wish we had a beowulf cluster o' them doomsday asteroid machines, eh Stains?

If they want to strike, let 'em

[Anonymous Coward]

Look, Asteroids have been members of Dockworkers Union Local 3223 for what?, one or two hundred million years? If they want to strike, that is their right. They obviously have some grievences with working conditions in our solar system and earth in particular.

Two words I like to say in sentences: Uranus and Asteroids

Thomas Dz.

Everything but the frogs

[corvi42]

Yes, it destroyed everything but the frogs, salamanders, and other very precarious fragile life forms which have existed pretty much unchanged for millions of years before this impact. That is just one of the many problems with this giant space-rock theory.

Now I'm not saying that this theory isn't very convincing, but its going to be a long time before we truly understand the nature of what happened during this massive impact. I'm not doubting that a massive metor / asteroid hit the earth and caused catastrophic environmental fallout, but the facts are far from convincing.

Frogs and salamanders and other small amphibians like these are very delicate fragile creatures which are very easily affected by even small changes in their habitats. They breathe and drink through their skin, and so absorb pretty much anything thats in the air and water. They are also very sensitive to light & heat conditions. If a massive environmental disaster occured that was so devastating that it wiped out thousands of species, including very large robust reptiles like dinosaurs, why did it not wipe out the many frog & reptile populations that have continued pretty much unchanged since that time.

Understanding the consequences of a massive explosion / impact of this sort is very important to us. We should understand thoroughly the consequences and the survival strategies that are important in a post-nuclear / post-asteroid fallout situation. The dillemma of the frogs is just one of the massively understated holes in our knowledge about such disasters, and the verdict on what really did kill the dinosaurs is far from conclusive at this point - despite what the popular media likes to portray.

Giant space rocks hitting the earth and causing massive fallout is a great story, and the media loves to play it up. It satisfies our thirst for biblical-type plague stories and apocalyptic premonitions, but as far as the science goes, its anything but conclusive. Certainly this meteor impact did happen at the same time as the beginning of the end of the dinosaurs, but we must remember that despite what you may remember seeing in Disney's Fantasia, they didn't all just drop dead in a matter of one symphony movement. Their extinction happened over a long period ( although geologically it might look quick ), and we are very far from understanding the ecological and environmental changes that came out of it.

Re:Everything but the frogs

[Anonymous DWord]

Maybe the salamanders were hiding in caves in Afghanistan when the asteroids hit. Those suckers are pretty safe.

Re:Everything but the frogs

[nels_tomlinson]

Many frogs are able to hibernate. I have seen frogs in the swamps in Fairbanks, Alaska, where the ground is permanently frozen. During the summer the top few feet thaw, and this eems to be enough for these frogs, or their eggs, to survive from year to year.

Re:Everything but the frogs

[rve]

Frogs and salamanders and other small amphibians like these are very delicate fragile creatures which are very easily affected by even small changes in their habitats. They breathe and drink through their skin, and so absorb pretty much anything thats in the air and water. They are also very sensitive to light & heat conditions. If a massive environmental disaster occured that was so devastating that it wiped out thousands of species, including very large robust reptiles like dinosaurs, why did it not wipe out the many frog & reptile populations that have continued pretty much unchanged since that time.

You cant take amphibians alone as counter evidence. There are for example several species of toads and frogs that live in the desert, and lie buried under ground, sometimes for many years, waiting for the conditions to become just right to come to the surface and reproduce.

When food is suddenly very scarce, a huge dinosaur suddenly loses its robustness and starves, while small creatures, or species that can lie dormant for some time (seed bearing plants for instance) gain in robustness...

Re:Everything but the frogs

[Anonymous Coward]

Frogs are not fragile. Consider that they survive just fine in subarctic Canada as well as the desert.

When it starts getting cold and/or dry, they hibernate. They bury themselves and basically shut down completely until warmth/water returns. They can survive for years in that state. Ditto for salamanders.

If anything, the prevalence of hibernating reptilians and amphibians today is good evidence for mass extinction via asteroid strike.

Re:Everything but the frogs

[fobbman]

Unlikely. They were actually pets of Keith Richards.

Re:Everything but the frogs

[Anonymous DWord]

Pets? I didn't think he was THAT old. I mean, he looks that old, but...

Re:Everything but the frogs

[Anonymous Coward]

You are making a basic false assumption that the current variety of amphibians present today are the same as those before 65 million year ago. If a particular species exists today and could not have survived even a minor environmental change (much less the global fallout winter following a large meteor strike), then that ONLY means any similar species would not have survived the meteor strike* at the end of the Cretaceous Period.

*The evidence for this is more than compelling to me (more available through http://search.npr.org/cf/cmn/cmnpd01fm.cfm?PrgDate =11%2F23%2F2001&PrgID=3 [remove any spaces] and look for 'Dinosaur Deaths.' Note that this is based on a Science magazine article). If you choose to ignore or discount the same (which is too numerous and requires too much background to summarize), sorry.

"Suddenly disappeared..."

[Philippe]

I want to point out that the dinosaurs did not disappear "suddenly", 65MY ago. The decline of dinosaurs began millions of years before that fateful iridium trace in the geological record (aka the cretaceous-tertiary or K-T boundary), and dinosaurs were found in the fossil record on top of that boundary. It's not like they disappeared in one, ten or a hundred years. It took millions of years (tens of thousands of generations) for the dinosaurs to disappear.

Philippe

This is akin to the "Cambrian explosion" theory where at the beginning of the Cambrian, there was suddenly (here's that word again) "exponential" increase in diversity of form (see the Burgess shale for an example). But if you look at it in linear time, and not in compressed (geological) time, the exponential curve looks more and more linear. An explosion that takes hundreds of millions of years to occur is not really an explosion, wouldn't you say?

Re:"Suddenly disappeared..."

[mmol_6453]

An explosion that takes hundreds of millions of years to occur is not really an explosion, wouldn't you say?

Depends on your scale.

I can graph y1=x^2 on my graphing calculator, and it looks fine. If I change my y axis tic mark spacing so that each mark represents, say, 4, then suddenly my graph looks like y1=4x^2 to the uninformed eye.

Re:"Suddenly disappeared..."

[jc42]

Actually, dinosaurs didn't all disappear. At least six species survived, according to recent DNA studies. By whatever coincidence, they were all in the suborder that we call "birds".

The hypothesis that birds are dinosaurs was actually proposed early in the 1800's. The reaction of lots of scientists was the usual "That's an intriguing idea; where's your evidence?" It took more than a century for people to stumble onto convincing evidence. Most of the best evidence has been found in the last 30 years or so. Birds don't fossilize too well. Also, it seems that most of the few good bird fossils are in China, and political problems prevented much serious paleontological work there for a long time.

Also, it wasn't just frogs and salamanders that survived. Several species of mammals managed to hang on until things got better. This included a small tree-shrew-like proto-primate.

Re:"Suddenly disappeared..."

[RollingThunder]

As I understand it (from the Science of Diskworld, quite a great read, and about real science despite the title) the problem with the "it was gradual" argument is this.

Fossils are rare. Damn rare to create, even harder to find. Up until Jurassic Park came out, there were all of THREE T-Rex fossils found. They've since found more.

This means that you may find only four or five fossils of a given species. The last one you -happen- to find may be a million years before the K-T boundary, but that's only because you haven't found any newer ones yet.

What is significant, though, is that there is a time when 99.99% of the fossils stop appearing past. There's also evidence of massive dieoffs in the area of the crater of much more common things - I think ammonites were the significant ones, but I don't have the book handy.

Now, this is all thirdhand data (studies, paraphrased by the book, [mis]remembered by me). But it does help explain why you may seem to see species slowly drifting off, when they really all stuck around until that fateful year.

Crater Size Calculator

[T-Punkt]

Well, that's funny. Just this morning I found this link:

http://www.lpl.arizona.edu/tekton/crater.html

Which let's you calculate the estimated diameter of the crater a body of a given size, given density, given speed and given impact angle will make on different targets. (Or reverse that and estimate the diameter of a body that creates a crater of a given size).

Accoring to this a 10km body with the density 3t/m, speed of 25km/sec (=90000 km/h) will create a crater with a diameter of ~216km when it hits Earth in an area of "compent rock or saturated soil" (target density 3t/m).

Re:Crater Size Calculator

[Yazeran]

Competent rocks are rocks like granite or gneiss that does not deform under it's own weight like soil or ice.
When i say does not deform under it's own weight i mean at ordinary pressures and temperatures. Even granite will deform under high stresses and temperatures, and this is the main reason for the creation of mountain ranges like Rocky Mountains.

Yours Yazeran

Plan: To go to Mars one day with a hammer.

what about a dinosaur BinLaden with suitcase nukes

[dario_moreno]

or some offensive action by an alien civilisation,
like the asteroids with an altered trajectory
in "starship troopers" ?

This could cause the same phenomena...

Temperate versus tropical climates

[Mike Greaves]

Falling temperatures and declining sunlight levels would be the main pressures on plant and animal populations in this kind of scenario. Breathing through your skin has nothing to do with these kinds of stresses.

The creatures which you describe could survive the cold in tropical areas. The dinosaurs were living in temperate areas, which would get far too cold. The reason they evolved so big was to survive in cooler areas due to the cube-square law and it's ramifications for body-heat retention.

When the hard times came, that size proved a disadvantage. Lean times are harder on big critters than little ones - the food supply problem becomes impossible for them. Remember, modern-day elephants descended from rat-sized mammals.

Old news!

[sofar]

Well, it was 65 million years ago people!

Seriously, this has been accepted widely already in geology. I as a geology student was pleasantly surprised about 4 years ago when my teacher Dr. Jan Smit from the Free University of Amsterdam (a sedimentologist) gave us an introduction in the extinction of the dinosaurs. And even then this was already not *the latest*.

For the non-geologists: J. Smit discovered after some fieldwork and years of research all around the world measuring the K-T boundary (the boundary of strata of where the creteaucious rocks and the tertiary rocks have contact, which is, of course at 65 million years age), that at the Yucatan peninsula there has been an impact crater with a huge diameter (~240km). From this crater ejecta had travelled as far as the great plains...

The story posted here is just one of *many* researches going on right now to verify this theory.

The major point being discussed now is not why did the dinosaurs die, but how did they die when the asteroid hit. The most discussion goes about nuclear winters and climate changes, or even thermal heating due to infall of debris (think 'big eruption'), because it has not really been identified how long the period of extinction was. (at least, as far as I know, comment, anyone?)

I guess the world has some time to accept this story as true, funny how a sometimes dusty science area as geology can already be ahead of the media by far.

Re:Old news!

[DrSpin]

Its no mystery -American Football was invented, and they died out of boredom.

Seriously, how can people what a game which even the promoters know is so boring that you need semi-naked women bouncing their breasts around to retain interest in it for more than a few minutes?

Math BS

[melquiades]

But if you look at it in linear time, and not in compressed (geological) time, the exponential curve looks more and more linear.

That doesn't make any sense at all. If you compress time linearly, it's still an exponential curve, no matter how flat it looks. (Any differentiable function locally resembles a line, but that doesn't mean it's linear.)

The whole point of geological time is that evolution happens very slowly by the standard of a human lifetime. The Cambrian explosion was, in fact, pretty fast. You expected, maybe, something like the New Kids on the Block Explosion?

!@#^$% math abuse...

Re:Math BS

[Philippe]

That doesn't make any sense at all. If you compress time linearly, it's still an exponential curve, no matter how flat it looks. (Any differentiable function locally resembles a line, but that doesn't mean it's linear.)

Sorry, I should have explained further. Of course an exponential curve will still "look" exponential if your scale is linear, no matter what resolution you're looking at. But the exponential "curve" of the Cambrian explosion is just a list of species (i.e., real data) to which an experimental curve was fitted. The experimental curve that best fit the data was exponential, hence the term "Cambrian explosion". But look at the data in more detail, at the 100,000 or million-year interval, and the fitted curve is no longer exponential. *That's* what I meant :-)

Until real evidence show up...

[Anonymous Coward]

I still stand by my 'invisibly thin line stretched between two trees' theory...

human ingenuity

[aratuk]

It's amazing to think that something with such enormous and horrible consequences could pretty easily have been caused to happen again just 25 years ago. The effects of the earth being struck by a 10 kilometer wide asteroid sound very similar to the effects of the activation of a nuclear device only about six meters wide, nuclear winter.
Anyone can visit the airforce base in Albuquerque, New Mexico and go to the nuclear weapons museum and see a demilled 20 megaton nuclear bomb, sitting there looking very much like an innocent septic tank, but once, not too long ago, having been capable of the type of devastation described in this article. It's a very unique experience to see something so small that could have undiscriminatingly killed you and all your friends and all the members of your species and most of the other species on the planet.

On an unrelated note, I wonder if there would be anything left of that asteroid or if it would have been completely destroyed in its collision with the earth. Does anyone know if any scientific groups have looked or are looking for pieces of it off the coast of the Yucatan? It seems like it wouldn't be too difficult to figure out what it was composed of, by analyzing layers of what would have been topsoil at the time, and then one would know what sort of rocks to look for under the sea. A lot could be learned by knowing more about that asteroid, probably.

Re:human ingenuity

[Anonymous Coward]

Your scale is a bit off. While a 20 megaton nuclear device going off certainly would be bad, it alone wouldn't cause a fallout winter. The energy involved in the dino-killer asteroid was in the GIGAton range.

Argh, we're all gunna die!

[Anonymous Coward]

a giant asteroid about 10 kilometres wide, travelling at 90,000 km/hour slammed into the Earth at the southern margin of North America.

HOLY SCHMOLY!! We only have hours left to live! Damn terrorists.

This asteroid crash could have been averted!

[Sonicboom]

Hell, didn't they know about the HYPERSPACE key?

It saved my little space ship so many times in the arcade.

Re:hurt prost

[Guy Innagorillasuit]

That's funny, there's no mention of him here.

Re:This is ridiculous

[tercero]

What flood are you talking about? BTW, why should I listen to someone who won't even reveal who (s)he is?

I agree with your first statement, but it sounds like you got on a soapbox and started blathering. Care to expound upon your claims?

if you want to read about old news...

[supernova87a]

phillipe and sofar are correct -- the Chixulub crater impact has been known about for several years ago as the "cause" or associated event with the K-T boundary. If you want to read more about it, I suggest an entertaining scientific chronicle of the discovery called "T. rex and the Crater of Doom", a book by one of the famous father-son teams in paleogeology -- Walter and Luis Alvarez. An interesting thing to note is how they actually discovered the crater site -- it was by working with scientists from oil companies! Turns out that oil companies have significant geologic mapping efforts (in order to discover more oil of course) all over the world, and in this case, they (eventually) decided to help these geologists by sharing some of their information. I find the topic of asteroid/near-Earth object *discovery* to be even more interesting. This is going to take a very intensive effort which combines observations (telescopes) and computing, because if you want to discover these things, you've got to work with automated systems that can log astronomical object movement in an automated fashion.

Re:if you want to read about old news...

[jmlowes]

I also suggest reading "T. Rex and the Crater of Doom". It is well written so even a non geologist like me could read it.

Theres another possibility thats always ruled out

[Anonymous Coward]

Theres one other thing that could cause such destruction, and thats a planetary nuclear bomb. Of course scientists instantly rule that out :P

Did I miss something?

[Mockery]

"...a giant asteroid about 10 kilometres wide, travelling at 90,000 km/hour slammed into the Earth at the southern margin of North America. This was a case of global devastation rather than North American catastrophe. The asteroid devastated pretty much everything."

Either they forgot to give an appropriate chronological frame of reference, or I need to get out more...

We need an ASTEROID defense system not MISSILE!

[Anonymous Coward]

Instead of wasting 100 of billions of dollars on Missile shield we should develop an ASTEROID DEFENSE SYSTEM AFAIK!

This is a much better way to spend the Money.

Re:We need an ASTEROID defense system not MISSILE!

[Moonshadow]

We already have one! Just take anyone that's ever played "Missle Command" and put them in charge of our nukes.

On the other hand, maybe that's NOT such a great idea.

Re:This is ridiculous

[mgv]

The idea can be valid irrespective of its source.

Michael

Discovery Channel

[jpostel]

Why did I see a show on this on the discovery channel a couple of months ago?

Compent rock??

[Anonymous Coward]

Durned if I can figure out that one.

Rubber reality cheque: support for many ideas

[leonbrooks]

Nowadays, if the face of so much consistent evidence, you'd have to have some really spectacular counter-evidence to be taken seriously. There are still scientists out there trying to debunk the idea, of course, but mostly they just keep turning up more evidence in favor of the impact.

Unfortunately, the evidence is consistent with a lot of things, including a strong episode of vulcanism, most of what Immanuel Velikovsky's had to say, and the idea of rapid worldwide flooding which so neatly explains many other things (-: a theory so popular on bone-dry Mars, but anathema here on our own soggy globe :-).

What seems to be happening is the same thing, over and over, as when geologist Harlan Bretz fought tooth and nail for four decades before geology accepted his theory for the Spokane badlands. A theory becomes dogma (generally without much real proof) and then all new evidence is seen as conforming to the dogma until finally the explanations become so stretched as to become indefensible, then everyone hurries to been seen as having allowed for the new idea in their old prognostications.

There are a couple of big showstoppers for the meteor-strike-kills-dinosaur idea, including the observation that a lot of dinosaurs did not perish at the end of the Cretaceous, and a lot of creatures which should logically have perished as readily, didn't. Perhaps the most damning is the occasional multiple or conspicuously absent Ir layer, features which are often masked, overlooked or rationalised away during reporting. [pro multi strike] [ con vulcanism] [con flood, many references esp in the linked PDF] [con egg-stinction, but he's wrong, eg non-stealthy birds survived]

Has anyone found strata anywhere that is well-dated and continuous across the 65-million-year age that doesn't show a thin anomalous layer and a radical change of fossils?

I recommend using names, rather than specific ages, or you'll see still more debate about the length of the periods involved, rather than a focus on more ``core'' ideas like seqences of events. And yes, many such have been found; there are less than 200 sites worldwide that do show Ir anomalies, and many of those either show multiple anomalies, or anomalies at depths other than the top of the Cretaceous. Do your own searching. (-:

250,000+ species, millions of tonnes of fossils

[leonbrooks]

...and that was a decade or so ago.

Up until Jurassic Park came out, there were all of THREE T-Rex fossils found.

I think you'll find that this was three complete Rex skeletons, which is quite a different matter.

Flying species like the bird, Archeopteryx, or delicate species like jellyfish don't meet the conditions for fossilisation as easily, so there are only a handful of those. Marine creatures like trilobites and turtles, on the other hand, we have running out of our ears - so in a way Terry Pratchett's Discworld model is actually right, it's turtles at least some of the way down. (-:

The true mystery

[jackcaj]

Remeber, some dinosaurs were small, even very small, and dinosaurs filled every ecological niche an animal could fill. Of the major animal types: reptiles, amphibians, mamals and dinosaurs (not to mention insects and fish and whatnot)- ONLY the dinosaurs were COMPLETELY wiped out. Go figure.