Dinosaur Extinction

There are as many theories why the dinosaurs are no longer with us as there have been minutes since they departed this plane.

Two main ones:

  1. The Louis and Walter Alvarez study that indicated a possible extraterrestrial impact (asteroid or comet) causing what was effectively a nuclear winter, with plankton dieoff, carbonated oceans, frigid temperatures worldwide, etc. Supporting evidence indicates a possible 200-mile-diameter crater centered on Chicxulub, Yucatan, Mexico.

  2. Widespread volcanic eruptions causing similar phenomena. Supported by the eruption of the Deccan Traps, a multi-thousand-square-mile lava flow in peninsular India, dated to about this time.

Other hypotheses include ontogenesis (they evolved contrasurvival “adaptations” such as unwieldy size, a la Irish elk antlers, and died from them), loss of interest in sex, poisoning from alkaloids in angiosperms, racial senescence, etc. Then there are those that don’t believe they were killed off by anything catastrophic but were on their way out, and one of the above simply finished the last survivors off.

I’m inclined to believe a combination of the two main ones is responsible, but with inadequate evidence to support this view. Anybody got additional information? Any other WAGs that deserve posting?

One theory I heard long ago was that plants had evolved to something inedible for dinos (flowering plants, I believe).

Velikovsky! Velikovsky!
He’s my man!
If his dinosaur-extinction theories don’t do it for ya,
No one’s can!

Velikovsky! Velikovsky! Velikovsky!



New fall lineup on Channel 7?

Sorry, couldn’t resist.

Racial senescence. Dinosaurs as a species had become old, and it was time for them to go.

Frogs evolved before dinosaurs did, and they’re still here.

You forgot the third theory that dinosours didn’t die out. They carry on today and are called “birds.”

Sorry dinosaurs not dinosours. Oh well what are you gonna do? :slight_smile:

And I just noticed: “Dinosaurs as a species”?!?! Heck, Dinosauria was a whole order of vertibrates – that’s three rungs higher than the “species” level on the taxonomic ladder.

Dinosaurs were on the decline at the end of the Cretaceous, though. Why that was, I have no idea. That’s probably a bigger mystery than what eventually finished 'em off.

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Another theory I’ve heard is that mammals bread rapidly and found dinosaur eggs to be accessible and very nutritious. The first mammals are thought (by some, at least) to have been small semi-arboreal omnivores, difficult for dinosaurs to fight back against. I suppose this would make the first mammals somewhere between a tree shrew and a marmoset … perhaps evolved from a warm-blooded tree lizarnd?

Anyway, I like this theory because it implies a sort of David-and-Goliath struggle, with wily little rodents eating dino omelets while T. rex dashed around impotently. But I’m know I’m just reading too much into it.

Mammals bread rapidly? Sorry, I’ve got food on the brain today, even after two helping of cajun beans & rice.

I think Gary Larson showed the real reason, in a classic Far Side– they died from smoking.

Ok, ok, now that I got that out of my system.

Polycarp, I think that #1 is pretty much accepted as the cause. Yes, there are still some who hold on to #2, but they definitely don’t have consensus on their side, because the evidence has converted most everybody to #1.

Give me a break, tracer. :frowning: Other posters gave showed some levity, and you didn’t pick on them.

Levity? Levity? You dare call a reference to the greatest thinker of our century levity?

Why, Velikovsky’s observations are already being borne out by hee results coming back from hehe deep space probes. Not only that, but hehehe most of the so-called “debunkings” of hehehehehehe his work were poorly executed hehehehehehe hatchet jobs from so-called scientis… heheheheheheheheheheheh.

Damn. Almost made it.

Livin’ on Tums, Vitamin E and Rogaine

Personally, I like the Far Side cartoon about how the dinosaurs became extinct. :wink:

Actually, the crater wasn’t the tipoff that there had been a cataclysmic comet/asteroid impact; there was a lot of evidence before its discovery that led them to look for the crater. A couple of decades ago, some scientists noted, at the boundary marking the end of the Cretaceous (sp?) period (is that the K/T boundary?) the presence of a substantially increased concentration of a rare element (iridium? I can’t remember) found mainly in extraterestrial debris. Then other scientists found the same thing, at the same boundary, all over the world.

After that, a great deal of other supporting evidence was discovered to back up the asteroid theory. The crater was the smoking gun, so to speak. There’s obviously no way to be certain of anything that happened over 100 million years ago, but it’s a pretty safe bet that there was a cataclysmic impact of an object from outer space, at the end of the Cretaceous era, that was capable of causing a fairly major worldwide environmental impact all on its own.

Whether there were other cataclysms at the same time, and whether the effects of the impact were sufficient to snuff the dinosaurs all by themselves, I don’t know. If the dinosaurs were cold-blooded (they’re still arguing that one at great length), it seems pretty believable to me.

Larson almost had it right. Dinosaurs died out from a high-fat, high-protein, low carbohydrate diet, which was offered to them to solve their cronic trouble with being over-weight.

As for Velikovsky, his work, while interesting, fails to take into account that the Earth was flat and only started moving around the sun in the Middle Ages… :wink:

Sorry, RT, I hadn’t intended to suggest the crater was the proof, but that it bolstered the proof. Point taken, and thanks.

David, not to contradict you (which I do enough of elsewhere), but two fairly recent (i.e., post 1994) texts, one on vertebrate paleontology and the other on historical geology, give arguments for and against both and do not indicate that the matter is felt to be decided, though to be sure the ET theory is shown as being more supported.

Bolstering the vulcanism theory is the fact that the only extinction event more thorough than the K-T (exit dinosaur) one was at the end of the Permian, and was matched by the only vulcanism even more widespread than the Deccan Traps, i.e., the Siberian Traps. (Inconsequential question: why “traps” for these? Anybody know? No derivation in the books I’ve read.)

Being an old SF/catatrophist fan from way back, I’m inclined to like the Giant Asteroid Finishes Off Dinosaurs headline over some blah lava flows, but I’ve got to admit that there is some good evidence for the latter.

They were all burned at the stake by religious fundamentalists for existing when the Bible doesn’t mention them.

Actually, Velikovsky was a misunderstood visionary, Manhattan.

He would have been hailed as the Polka King of Wisconsin had it not been…

Oh, wait. Are you talking about that flake Immanuel, or the band leader?

Never mind.