Dinosaurs Died Within Hours of Asteroid Impact, says New Study

colonist writes "SPACE.com reports that most dinosaurs were incinerated within hours by the 'heat pulse' of an asteroid impact 65 million years ago. The study 'Survival in the first hours of the Cenozoic' presents a scenario where the only survivors were underground or were underwater in swamps or oceans. All unprotected creatures were 'baked by the equivalent of a global oven set on broil.'"

Comments

Re:Correct me if I'm wrong.

[Kenja]

Everything in science is a theory. The "asteroid impact" idea has a lot to back it up however since there are some realy big craters on this ball of mud we call home. Check out the 170 km one at the Yucatan Peninsula.

The Truth is so much cooler than Fiction

[GOD_ALMIGHTY]

The majority of the dinosaurs were instantly fried, like in a nuke blast that wrapped around the globe. I haven't seen a movie lately, that had those kind of cool FX. How about you?

Think about to all the meteor's crashing into earth movies there are, now think about all the FX. Nothing as impressive as ALL THE DINOSAURS getting fried as a heat wave travelled around the globe.

Why can't Hollywood just pay attention to history and science. It's way cooler than the drek they come up with.

But seriously folks, just think of all the Brontoburgers. I bet Fred and Barney boiled off the surface still salivating at the endless plains of dino ribs.

But so much survived

[DeadBugs]

So many things survived from that time other than the Dinosaurs. Large trees, many forms of reptiles and mammals that are virtually the same (based on fossil records) to this day.

Not too mention that the fossil records for Dinosaurs don't stop on 1 day.

It seems that the Doomsday theory gets more headlines than other theories suggesting, disease and climate change (a much slower, more boring process) were the cause. Even though the damage of a meteor strike would have been far more devastating and left the planet set back near square one as far as life.

If the earth was baked and then the sun was blocked by smoke and ash, how come so much survived?

*Note IANAS (I Am Not A Scientist), just wondering.

Plenty of evidence for this one.

[Ungrounded Lightning]

I read the article

Another wild hypothesis without a shred of verifyable evidence.

I couldn't read it THIS time (because the server is slashdotted). But I did read it - or another describing the same theory - when it first became newsworthy some years ago.

There's plenty of evidence for it.

First off, the prediction comes straight out of physical modeling of what happens when a big asteroid hits:

- A bunch of rocks are kicked every which way.
- If the asteroid is big enough a LOT of them go into space.
- A fraction of them have enough energy to get above the atmosphere but not achieve escape velocity.

Once you realize those three things, it's straightforward for a physicist to calculate, for various size impacts on various sites (land, shallow ocean, deep ocean), how MUCH mass goes up, how MUCH of it comes back down, WHERE it comes down, HOW FAST it comes down, and what the results are.

So they calculated that. And came to the conclusion that for impacts of a certain range of sizes the result would be several hours of a rain of sand, all over the Earth, at speeds of up to several miles per second (plus rains of rocks of varying density at different distances from the crater and its antipode). The sky becomes essentially solid meteor trails for hours.

And those are HOT! Hot enough to dry out most of the plants and set them afire. Hot enough to kill any animal life on the surface that can't get underground or under water right away and then stay there for hours.

So if the sky turned into a broiler oven over the whole Earth for several hours all at once, what does this predict? One hemisphere is day and the burrowing nocturnals survive, the other is night and the burrowing diurnals survive. (And in particular regions it got REALLY hot, or REALLY shocked by the primary impact or the secondary rain of rocks, and NOTHING survived).

So they looked at the fossil record and that's what they found. Prediction confirmed - very good evidence for the model. Further, they could now tell WHAT TIME OF DAY the impact occurred and roughly where.

Then they looked in the area where this model predicted the impact should have been and FOUND A CRATER of the correct size (along with plenty of other evidence that this PARTICULAR crater's impact coincided with the extinction event).

Looks solid to me. Unless something new comes up I consider the puzzle of the extinction events solved.

The only question I have is: Why is this news NOW?

Re:The important question...

[Ungrounded Lightning]

And just how much stronger could dino muscles have been than modern mammalian muscle? 140% stronger, 170%? That's really stretching it, and it still isn't nearly enough.

When doing comparisons be careful to avoid human muscle. Humans are cursorial hunters (jogging after their prey until it collapses from heat exhaustion.) Most of their muscles are set up to only use a few percent of their fibers at a time - and switch to another batch when the first run out.

That's why hysterical strength is so much greater: Under great stress you CAN use your whole muscle power for a few contractions - like a mother lifting a car off her kid (a rather common event, actually). But it comes at a cost: The bones, pads between them, and muscle attachments are NOT built to the necessary strength for this. Use of hysterical strength normally means some serious, often permanent, injury.

Most other animals (including even our close relatives the chimps) use a much higher fraction of their muscles all the time - or under only moderate provocation - and have the structure to support this use. (That's why they're so dangerous to people who handle them without having armor on and weapons handy.)

Land animals probably can't be much bigger than an elephant.

Not if they're going to be chased around by lion prides, packs of canids, and humans. (The square-cube law also applys to dumping heat.) You can build a workable animal MUCH bigger than an elephant. But now that there are warmbloods specializing in running things to collapse and eating them you can't keep a population of things that large viable in the wild.