Dinosaurs Died Within Hours of Asteroid Impact, says New Study 862
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.'"
Re:Broil? (Score:3, Informative)
Article title (Score:4, Informative)
According to the article, the dinos were cooked by super-heated air. That would mean they were broiled, not fried
Re:2 Marks from.... (Score:5, Informative)
Gas Mark is a Fahrenheit scale.
From this chart [godecookery.com] it is possible to infer that Gas Mark 0 is 250 Fahrenheit, and each increment of 1 Gas Mark is equal to 25 Fahrenheit degrees.
So at what Gas Mark setting did they bake/flambe the dinosaurs?
As an exercise for the interested reader, using spectroscopic data, estimate the surface temperature of Zubenelgenubi in Gas Mark.
Re:Facts? (Score:5, Informative)
Re:Correct me if I'm wrong. (Score:3, Informative)
It is widely accepted that an asteroid fell down around 65 million years ago and that this approximately coincided with the end of the dinosaurs (except for birds). You will not find a single serious scientist who disagrees with this.
What is more controversial is how quickly they died off and if it was only because of the asteroid or if other factors were involved as well. This latest claim is that it was quick; we will see how well it will be received in the scientific community.
Tor
"Alvarez Hypothesis" (Score:5, Informative)
Re:Facts? (Score:5, Informative)
So, Racer X, the scientific community would appear to have two consensuses (consenses? WTF?), one on each of the two issues.
Mass extinctions are a fairly regular event in the Earth's geologic history. There are at least two more, besides the Permian and Cretaceous catastrophes, with which I'm familiar. Most people only get taught about the Cretaceous one in high school, though, so they never hear about the others.
Kind of like the Ice Age. Up until I was 16, I only thought there was one. Turns out there were a shitload of them.
Not really. (Score:3, Informative)
But as the article point out, this theory does not explain the water extinction of the animals.
Re:Facts? (Score:4, Informative)
Re:Correct me if I'm wrong. (Score:2, Informative)
Re:Correct me if I'm wrong. (Score:2, Informative)
Well. Not much I can do. But I will say this, You will believe two, 5 milliseconds after you die. Mark my words, and remember them well. They will come back to haunt you at the end of time. Whether you want to believe it or not, is irrelevant.
You think dinosaurs are older than bees? (Score:2, Informative)
Look at this link http://www.pubmedcentral.nih.gov/articlerender.fc
and this one created by honey bee farmers
http://www.angus.co.uk/bibba/bibborig.html
Bees are almost as old as flowering trees which are much older than dinosaurs.
Re:kill all the plants too (Score:4, Informative)
Some points from the Journal article (Score:5, Informative)
Unfortunately the linked article is available in the Online Journal which you can either subscribe to or go to you neareast Uni Library and check it out.
A Thermal heat pulse and the ejecta from the impact could travel around the world because of gravity dragging the ejecta back towards the earth. Upon reentry, the ejecta emitted IR radiation, brightening the sky globally. This means no night and no shadows (as the heat sources were distributed across the sky compared with the single-source solar IR radiation). This means there was nowhere to hide unless you were underground. Even rock crevices were no shelter. Subsequent fires igniting simultaenously [the suggest that there are isotopically uniform charcoal deposits at the boundary] would have added to the carnage. These fires were not significant compared to the intensity of the IR radiation. Normal solar flux ~1.4kW.m^-2, this event was calucated by Melosh in a previous paoer in 1990 to product ~10kW.m^-2. Note that ambient air temerature would have only rise ~10 K.
As for survivors, those burrowers > 10cm below the soil surface would survive. Sheltering and semi-aquatic birds are posited to be survivors.
The important thing is that this paper presents no specific fossil evidence. It does offer some phylogenetic evidence to support the bird survival hypothesis. It presents one model that can be further refined and/or refuted with evidence. It is not necessarily true or false but it can be falsified. They suggest checking Gondwanan sites for evidence of spherules (proof of ejecta reentering) and their distribution. That is the nature of science which the majority of posters thus far need to grasp. Think of science in terms of mathematical functions that approach a limit/converge as evidence and models accumulate.
Re:Broil? (Score:4, Informative)
Hmm, considering there's a dish called "London Broil", it just makes me wonder if that's not actually British, but yet another American bastardization...
Re:kill all the plants too (Score:5, Informative)
This doesn't at all take into the account the fact that the starting temperature of the air is higher than that of the water. The average temperature of water in the oceans is just a bit above freezing in the pole areas and is about 17C(62F) on average (max 36C). The average temperature of air is much higher due to being over landmasses. Thus heating all of the air is MUCH easier than water.
Re:The important question... (Score:1, Informative)
Wired News article: A Fiery Death for Dinosaurs? (Score:2, Informative)
Re:kill all the plants too (Score:5, Informative)
Re:Broil? (Score:2, Informative)
Re:Correct me if I'm wrong. (Score:3, Informative)
Re:kill all the plants too (Score:2, Informative)
having huge oceans is really why we can exist without dying. they act as a massive heatsink that stabilizes the temperature of the rest of the planet, keeping the days from cooking us and the nights from freezing us.
You can watch them die in this video ;) (Score:2, Informative)
http://sushi-x.com/gallery/4d/chicxulub.zip
Re:Survival (Score:2, Informative)
Survival? Realize the magnitude of an impact that could produce a crater that size.
Massive global earthquakes, volcanic eruptions, a shock wave many times the speed of sound and essentially a wall of fire incinerating everything in it's path for many miles, absolute disruption of global weather patterns, fallout, etc... etc...
Use one of the asteroid simulators. Even if you were on the other side of the planet you'd get 10+ magnitude earthquake along with a hefty shockwave more than strong enough to rip apart any remaining structures still standing. I'm not talking about crumbling. I'm talking about steel girders being smashed into splinters.
We could unleash all nuclear weapons at the same time in one spot and we wouldn't even get close to the energy an impact like this would unleash.
No, an impact like that would pretty much scour the surface of the planet. Maybe through sheer luck some very small number of humans would survive. They would be the unlucky ones, as there would be nothing left.
Life would survive and evolve out of this as it always does, but humans would become extinct along with a large number of other life forms.
Re:Correct me if I'm wrong. (Score:2, Informative)
Re:thats really not funny. /I'll bite [T] (Score:3, Informative)
Domestication is a form of evolution. By man learning and practicing husbandry of animals and selecting desirable traits he (he in the generic sense) exerted specific pressures on large based familial lines. Thus was eventually born our concept of breeds. The blue heeler was bred for herding ability, the greyhound for running, the poodle as a dare (?). nearly every trait that a modern dog has is genetically coded in his ancestor the wolf it is only the frequency of expression which sets them apart. That information is part of the reason that the smithsonian (who is responsible for taxonomy) reclassified the dog from C. familiaris to C. lupus familiaris.
Back in a time before you can imagine (Score:3, Informative)
Viruses mediate the exchange of genetic material.
The development pathway that unites all animals includes a stage in which a viable (usually fertilised) egg cell (zygote) divides a number of times to form a ball of cells (morula, blastula) gradually differentiating because of (dorsal/ventral etc.) gradients in (HOX) gene expression.
Sponges (porifera) are a likely candidate for the oldest surviving animal lineage, potentially dating from the recently annointed Ediacaran Epoch [slashdot.org] through the Cambrian explosion, so called because the basic developmental forms of animals diversified wildly in a (geologically) short time.
Hermaphroditic sponges produce sperm and eggs [berkeley.edu] at different times, obviating themselves, and thus the last common ancestor of all sexually reproducing animals, from any requirement for different male and female phenotypes.
Sexual dimorphism came later and very differently in different taxa.
Such "all or nothing" questions are a standard intellectual trap for people who cannot see the overwhelming evidence for the fact of evolution, a fact that various theories strive to account for without ever needing to overturn the core Darwinian insight that everything alive today is the product of a very long history of variation and selection from multitudinous common ancestors.
Re:And the chicken-sized dinosaurs still exist... (Score:3, Informative)
True - but the dinosaur ancestors of birds displayed none of the attributes that this paper specifies as enabling them to escape this instant extinction story. So that hurts rather than helps their case.
Mammals 65 million years ago were tiny (mice sized) and most likely nocturnal
There were larger [abc.net.au] ones.
And this leaves out all the animals that survived and were much larger than many of the dinosaurs that went extinct. Crocodiles, for example. They weren't small, and couldn't burrow - so this bit of speculation falls straight over.
Then, of course, there's all the animals that lived in the sea that died out right along side similar-sized animals that didn't.
No, I think simplistic explanations just aren't going to cut it. Clearly there was something more complex going on - but it's unlikely we'll ever know for sure at this point, short of inventing a time machine. Certainly the fact that population sizes and diversification had already been decreasing for quite a long time tell us that there were other factors at work.
Re:But so much survived (Score:2, Informative)
Large carnivores need large prey. See next paragraph.
Large herbivores need large vegitation. An impact like this would also create an ice age, even a large volcano can effect the climate for years. The heat pulse then climate change would kill off most of the large vegitation.
Re:Back in a time before you can imagine (Score:2, Informative)
Re:*YOU* don't know?!?!? (Score:4, Informative)
What you call broiling we call grilling. What you call grilling we call frying. What you call frying we call deep frying.
Re:Broil? (Score:3, Informative)
When we say grill, we mean what you call broiling.
Re:Broil? (Score:1, Informative)
No, roasting is cooking in an oven in fat. If there's no fat, you're baking, not roasting.
At least, that's how it is in Britain... doubtless you Americans use the names the other way round or something.
Grill (Score:3, Informative)
Regarding London Broil, I've seen tins of stuff called "London Grill" which appears to be beans and bacon bits and sausages and black pudding and bits of kidney all mixed together in tomato sauce. Which sounds pretty grim, but grim in a particularly English way.
Re:The important question... (Score:3, Informative)
Nope, the the pangea breakup was around 150 million years earlier. A guesstimate off by a factor of 3 or so ain't so bad when your talking about geological timescales
Here's a rough map of the Earth 65 million years ago. [kaibab.org]
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Re:The important question... (Score:2, Informative)
Apatosaurus (not a new name at all) tracks have been found on definitely non-swampy terrains in numbers indicating herds. Also, their nests were not in swamps.
You really need to read more.
Um, Indricotheres were much bigger than elephants? (Score:3, Informative)
Indricotheres [yahoo.com] were considerably bigger than elephants -- around twice the mass. They're mammals, the closest living relations being rhinos. Dinosaur-sized mammals, easily. Think giraffe height with the mass of a rhino.
Re:The important question... (Score:3, Informative)
The catch: they were most likely very slow. E.g., assuming a reasonable distribution of its muscles (and not, say, 90% of the body weight concentrated into the leg muscles), you could easily outrun a Tiranosaurus Rex.
That was one of the faster dinosaurs for its size, btw. A herbivore was a lot slower. It only had to walk very slowly from tree to tree.
Standing up is not just a questions of muscles, it's also one of bones. Try just standing up without moving. You don't have to work your muscles too hard to do that, do you? In fact you could be almost completely relaxed and still remain standing. Most of the weight is supported by the bones, not the muscles.
Even with the disparity in the exponent between muscle force and body weight, you could probably be 10 times taller and still have no problems.
For a four legged animal -- such as all the largest dinosaurs -- it's even easier. For that kind of animal, you don't have to use the muscles to keep the back straight. It's basically a suspended bridge between the hind legs and the fore legs.
I.e., to just stand at that size, the dinosaurs mostly needed good bones. Which they had. The larger dinosaurs had _massive_ bones to support their weight.
Now walking or running is another exercise. Then you actually have to move that mass around. For that you need muscles.
Fortunately, up to a point you can get away with just moving slower. You _can_ design an animal much larger than an elephant, but the catch is that it will run much slower than an elephant.
Which again, is what the dinosaurs most likely did.
Re:The important question... (Score:3, Informative)
Can you possibly double the muscle/bone stresses on an elephant like that? Circus elephants have been trained to go from a sitting position to standing on just their rear legs (front legs in the air through the whole process). So it is clearly within the stregth limits of ordinary muscle and bone to double the load (and thus scale) in an ordinary elephant.
Of course nature does NOT use naive designs. If you were to double the scale of an elephant (and 8 times the mass) over tens of millions of years, evolution leads to redesign and major optimizations. An animal 8 times the mass does not need need 8 times as much skin mass or brain matter or heart or liver or kidneys etc etc etc. Such an animal could easily have 10 or 11 times as much raw bone and muscle muscle mass. Bone density can increase. Structure can change. Manuverability/strength/safety margins in some areas can be traded off for bone and muscle mass in other areas. For example there are also signifigant advantages to be had by sacrificing abilities such as running - and even elephants can run. Such redesign may increase kneww and other joint leverage by a factor of 2 or so. With such optimizations it is certainly possible to more than double the scale of an elephant.
And while raw strength of muscle and bone suffer from square-cube issues, it turns out that stamina / work / power for walking around actually improves with increasing scale.
If you were to naively stretch a human neck to many feet in length it would instantly snap. Obviously with evolutionary redesign giraffes have no trouble with necks many feet long. It is also "impossible" for any mammal to pump blood to the altitude of a giraffe brain - or at least it seems obviously and mathematically imposible until you look at the specific structure redesigns in a giraffe. When you redesign a structure the limits fundamentally change.
P.S.
About your sig and Metanet. While I support the idea, there are just way too many security flaws. For example it would fail to a blind traffic analysis attack and it ingores the fact than an attacker can set up an arbitrarily large chain of nodes under his own control. Arbitrary trusted nodes may fall under attacker control through related or even unrelated leagal action. There is also an international treaty floating around to deal with exactly that sort of situation. I can also think of a few more sophisticated attacks. It's really tough to get a solid level of security.
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