New Theory Suggests Dinosaurs Were Already Dying When Asteroid Hit (phys.org) 167
The new "biotic revenge hypothesis" suggests that dinosaurs were killed off by toxic plants. (And an inability to recognize the taste of a toxic plant.) the gmr summarizes a new paper reported at Phys.org:
The dinosaur population had been drastically decreasing before the asteroid impact, [and] the appearance of the first flowering plants -- angiosperms -- in the fossil record coincides with the gradual disappearance of the dinosaurs... The scientists concluded that though the asteroid played a role in the extinction of dinosaurs, the "plants had already placed severe strain on the species."
Crocodiles (believed to be descended from dinosaurs) also can't recognize the taste of toxic plants -- the researchers tested 10 different species. And they point out that not only did dinosaurs start to disappear before the asteroid impact -- they continued to "gradually disappear for millions of years afterward."
Crocodiles (believed to be descended from dinosaurs) also can't recognize the taste of toxic plants -- the researchers tested 10 different species. And they point out that not only did dinosaurs start to disappear before the asteroid impact -- they continued to "gradually disappear for millions of years afterward."
We all are, (Score:1)
aren't we?
Crocodiles are dinosaurs - since when? (Score:5, Insightful)
A quick quote from Wikipedia [wikipedia.org],
As such, birds were the only dinosaur lineage to survive the Cretaceous–Paleogene extinction event 66 million years ago.
Crocodiles are not decedents of dinosaurs - they are reptiles. If this paper can not even see this then I can not put much weight into their theory.
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Even if we gave them the benefit of the doubt and said "yes, gators and crocs and caiman and ... are all modern versions of dinosaurs, the result of evolution"... *why* would an animal that is totally carnivorous be able to identify (in any way...) a plant that will do Nasty Things to it if eaten?
Now if we stretch the gators and such to include iguanas, and they did a study on them (or any other vegitarian/omnivor reptile or perhaps amphibian type beast) then they may have half a flicker of a half baked ide
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It won't. But it will simply starve to death when their food source gets removed from the ecosystem. If all the big herbivores die off, then sometime later the carnivores too will have a mass extinction. Or so the idea goes.
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As a counterpoint to their crocodile argument, turtles which first arose in the Jurassic period, and are largely herbivorous can recognise and deal with toxic plants (and coral and much other poisonous sea life) and are about as closely related to dinos as crocs are.
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Crocodiles are not decedents of dinosaurs - they are reptiles.
Eh?
Dinosaurs are a diverse group of reptiles [wikipedia.org]
You're right that they're not descendants of dinosaurs, but it's not because dinosaurs aren't reptiles.
Re:Crocodiles are dinosaurs - since when? (Score:4, Insightful)
Pro tip: don't believe everything you read in Wikipedia.
That's a vast oversimplification -- sure, trace a cladogram back far enough and you'll see something called Reptilia as the ancestor of both dinosaurs (and birds) and things ancestral to turtles, snakes and crocodilians. Dinosaurs are as much reptiles as birds are (indeed, birds are considered avian dinosaurs.)
Trace mammals back far enough and you come to synapsids aka "mammal-like reptiles" -- which aren't reptiles either.
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Pro tip: don't believe everything you read in Wikipedia.
Okay, how about "pretty much every dictionary definition of the word 'dinosaur' I could find"? Plus the guy who proposed the name in the first place.
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That sounds like a good point, until you think about how science advances and such and realize that the guy who proposed the name in the first place had VERY little to go on compared to an armchair palaeontologist today.
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Dinosaur means "Terrible lizard", not "Terrible reptile"
Lizards are reptiles.
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New genome research suggests birds and reptiles are descendants of dinosaurs, with crocodilians [arizona.edu] being the reptile most closely related to birds.
It's certainly plausible the asteroid impact was not the absolute end for many of the dinosaurs, but merely a Toba-event bottleneck they could not outlast.
Re:Crocodiles are dinosaurs - since when? (Score:5, Informative)
Crocodiles are not descended from dinosaurs. They are related, as part of a group called archosaurs. Birds and crocodilians are (by the definition of Archosauria) the two surviving groups of archosaurs.
The reptiles most closely related to birds were the non-avian dinosaurs, but they are all dead. The most recent common ancestor of birds and crocodilians probably lived about 250 million years ago, so they are not that closely related.
If this paper can not even see this ... (Score:2)
... then I can not put much weight into their theory.
Ahhh, c'mon. The Dinos are all dead, SOMETHING killed them. Asteroids, meteors, tar magnets, poisonous plants, global warming, SOMETHING. It's a heavy subject. So what if they got a few supporting things wrong? It's almost like you doubt their conclusions or something. If it feels right, it IS right -- right?
After all, everyone knows THIS [google.com] is what actually happened.,
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Umm, no. They're not. There's a nest of avian dinosaurs living in my greenhouse. And my dino-feeder is very popular with the local wood-pecking dinos (Downy, Red-headed, and Red-bellied, at least one pair of each in the back yard)....
Re:Crocodiles are dinosaurs - since when? (Score:4, Informative)
This is once again an example of Slashdot summary disease.
Summary says: "Crocodiles (believed to be descended from dinosaurs) also can't recognize the taste of toxic plants " etc
Except that the actual paper does not say that crocodiles descended from dinosaurs. This is what the paper says:
Since crocodilians are descendent from the same creatures that gave rise to dinosaurs, this creates the opportunity to evaluate the tenability of the proposition that dinosaurs went extinct due to an inherent inability to learn to avoid eating toxic plants
The funny thing about crocodiles is that they are evolutionarily less like lizards and are evolutionarily the closest living relative to birds and non-avian dinosaurs. Crocodilians evolved in the Triassic as part of the Archosaur group which is crocodiles, non-avian dinosaurs, birds.
So it's not completely ridiculous to use crocodiles in their experiment.
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Apart from the fact that crocodiles, being carnivores are likely to avoid toxic plants on the grounds of them being plants.
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If you bothered to RTFA you would see it says "Crocodilians are descendent from the precursors to...dinosaurs".
So... (Score:2, Troll)
Can birds taste the toxins? (Score:3)
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My thought exactly. Crocodiles are NOT descended from dinosaurs, they pre-date them. Other reptiles had split off from the evolutionary branch that led to dinosaurs a bit sooner, but not dramatically so. Birds are pretty much the only living species that are descended from dinosaurs. (hadn't heard about the bottleneck before, I may have to investigate.)
Moreover, the last time I checked crocodiles are carnivores, and have been since before the dinosaurs arose - meaning that being able to taste plant toxins
Re: Can birds taste the toxins? (Score:2)
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Humans are one of the only animals that ARE adversely affected by poisonous plants they don't eat (e.g., Coca, Opium).
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I wonder if birds can taste the toxins then, since they're descended from dinosaurs and survived, though apparently at their worst they were down to a fairly small population on a remote island somewhere. (Can't remember where I read that...)
According to the summary at the link, no:
Gallup and Frederick examined whether or not birds (considered to be a descendant of dinosaurs) and crocodilians (also considered to be descended from dinosaurs) could develop taste aversions. They found that the birds, rather than forming aversions to taste, developed aversions to the visual features of whatever made them sick. Still, they knew what they shouldn't eat in order to survive.
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Last time I had a jalfrezi it was the other way round.
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Dinosaurs are not extinct (Score:1)
Dinosaurs are not extinct. Over the past few decades, research showed that birds are closely related to dinosaurs. They are directly descended from theropods and are now classified as dinosaurs. Scientists now classify birds as feathered dinosaurs and, as a result, that means dinosaurs never went extinct. It's certainly reasonable that the populations of many dinosaurs were already declining prior to the asteroid impact, and it's plausible that toxic plants may have contributed to this. It is somewhat remar
Crocodiles can't recognize toxic plants (Score:2)
"Crocodiles (believed to be descended from dinosaurs) also can't recognize the taste of toxic plants..."
Are you fucking kidding me!!!???
They are strict carnivores! Why in hell they would give a damn about a plant, toxic or otherwise!?
Ooooh! but they tested (so they say) about crocodillian ability to discern toxic food (not only plants)... Crocodillians come from a lineage about 200M year old -they haven't find ANY damn thing that makes them real sick so, why they should bother!?
Stuff that matter, they say..
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Yep, bad science all around. Including the fact that crocodiles are NOT descended from dinosaurs - they split off from that evolutionary branch only slightly later than the other reptiles, long before anything normally recognized as a dinosaur evolved.
Lots of predators eat fruits & Veg sometimes (Score:3)
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see here [sciencedaily.com]. Haven't you ever seen a dog eat grass?
Dogs have evolved to be omnivores.
Theory (Score:2)
I'll wait for experimental conformation of this theory's predictions.
Headline is wrong (Score:2)
Bunch of baloney (Score:2)
All the birds we see today are the descendants of the dinosaurs.
Ammonites? (Score:4, Interesting)
This may (although it doesn't, really) explain the decline of dinosaurs, but it says nothing about why thousands of other species (including all the ammonites) went extinct at the same time.
And the theory that dinosaurs were already dying off before the K/Pg boundary is hardly new. Part of that is an artifact of how fossils are formed and found. A species could have lasted several million years after its latest-known fossil, it just didn't happen to leave any fossils that have yet been found. (Conversely, the last surviving member of a species could have been fossilized. Unlikely though, except in the case of a mass extinction event.)
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Guess that is the cue to mention the coelacanth
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Also, pretty sure that not being able to detect poisonous plants doesn't explain why say, Spinosaurus, would go extinct. After all, they supposedly ate fish, not plants...
Re: Ammonites? (Score:2)
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It is also a little strange to posit that plants became very toxic when being slightly toxic in the first place does not at all save you from being eaten by voracious herbivores. I am not dismissing the idea out of hand, but there are significant missing pieces from this tale, like why those plants who invested precious metabolic activity in toxins outcompeted existing ubiquitous plants that did not.
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Some kind of food chain collapse I would guess. Given how we routinely fail to comprehend modern ecosystems I would honestly be very surprised if we ever figured out such ancient systems with much certainty.
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This may (although it doesn't, really) explain the decline of dinosaurs, but it says nothing about why thousands of other species (including all the ammonites) went extinct at the same time.
And the theory that dinosaurs were already dying off before the K/Pg boundary is hardly new. Part of that is an artifact of how fossils are formed and found. A species could have lasted several million years after its latest-known fossil, it just didn't happen to leave any fossils that have yet been found. (Conversely, the last surviving member of a species could have been fossilized. Unlikely though, except in the case of a mass extinction event.)
I think the summary is a bit of a misdirect, the paper isn't trying to claim that the asteroid didn't wipe out the dinosaurs, nor invent the idea that the dinosaurs were already in trouble. The papers is trying to come up with the reason they were already in trouble, which was the emergence of plant toxicity.
It seems quite plausible, at least for the larger herbivores, even if they could evolve fast enough to learn to avoid toxic plants they might not have been able to find enough non-toxic food, and when t
Cool (Score:5, Funny)
Anyone know if florists will deliver to Congress?
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Just be sure to wear your tinfoil hat when you microwave them afterwards.
Rubbish, I know what happend. (Score:4, Informative)
First the Earth cooled. And then the dinosaurs came, but they got too big and fat, so they all died and they turned into oil. And then the Arabs came and they bought Mercedes Benzes. [McCroskey walks off] And Prince Charles started wearing all of Lady Di's clothes. I couldn't believe it- [Jacobs turns and starts to walk away, continuing to speak, trailing off as he gets further from the camera] he took her best summer dress and he put it on and went to town...
SOME species of dinosaur were already in decline (Score:2)
This is a case where it's difficult to be specific, because the evidence is scant. If you're only getting one good fossil per thousand years, detecting a decline is dubious. But it does seem that some species of dinosaur were already in decline. And others weren't. A few appear to have been flourishing.
OTOH, accepted theory as of a few years ago is that birds are not descended from dinosaurs, they descend from a line that branched off before the dinosaurs separated from the rest of the reptiles. The or
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You seem to have run into some confusion.
It is true that birds are not descended from ornithischian dinosaurs. But birds are descended from dinosaurs. The birds are descendants of the theropods, traditionally classed as one of the major divisions of saurischians.
(There is a recent suggestion that a reclassification is necessary, that most theropods are actually closer-related to the ornithischians than the rest of the saurischians. But either way, birds are descended from theropod dinosaurs while not bei
Re: SOME species of dinosaur were already in decli (Score:2)
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You sure about that? When I studied it (well, informally) birds were said to have branched off before the dinosaurs were a separate group. Sort of like the Pterosaurs, which also branched off before the dinosaurs had separated.
OTOH, all these recent fossils with feathers may have caused people to reorganize things.
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Well duh (Score:2)
Given that the vast majority of dinosaurs were already extinct by that period, I'd say there's a good chance the effects of that asteroid are somewhat over-stated.
MOST dinosaurs were feathered to begin with (Score:3)
This includes 1.5 tonne monstrosities like Yutyrannus Huali, (related to Tyranosaurous Rex) https://news.nationalgeographi... [nationalgeographic.com]
Discoveries and detailed analysis of recent dinosaur fossils indicate that they were covered with feathers long before flight evolved. And they are now believed to have been warm-blooded. this is confirmed by CT scans of well-preserved fossils (e.g. 600 pound herbivore) showing a 4-chambered heart with *ONE* aorta http://contenidopatrocinado.cn... [cnn.com] This is a physiological sign of a warm blooded animal.
So dinosaurs had feathers and were warm blooded. Birds have feathers and are warm blooded. Birds are one group of dinosaurs that survived the asteroid. This was probably due to small size and being able to scavenge scarce food right after the impact.
Once Upon A Time (Score:2)
Once upon a time, there was all the time in the world.
The human race rested comfortably for millennia in warm nests of tales that the world had been created especially for us, and later science stepped in to supplant this quaint notion with immeasurable expanses of geologic time in which a rich compost of academic theory might take root and prosper. Everything that had come before us had made way for us, dinosaurs died so that we might live. Children calmed their nightmares with this simple idea after the
I'm not convinced (Score:2)
Crocs eat flowering plants ?!?! (Score:2)
Did not know that? Also how do they test to see if the crocs can recognize the taste of toxic flowering plants? Force feed them and see if they spit them out?
Just a weird thing to read ...
Riddle me this (Score:2)
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WOW! Someone made up more stupid RANDOM TRASH
Indeed. The paper is published by a psychologist, who is trying to psychoanalyse dinosaurs that lived 70 million years ago, when there is little evidence that psychoanalysis even works on living humans.
TFA contains some serious scientific illiteracy:
1. Dinosaurs are not "a species".
2. Crocodiles did not "descend from dinosaurs"
3. Plants would have no reason to evolve tasteless toxins, and there is no evidence whatsoever that they did.
Also, dinosaurs didn't go extinct. Some species died out, but other s
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Well what good would that do? If you taste nasty it chews a few leaves and then fucks off leaving you mostly intact. If you taste OK but are secretly poisonous it dies after it's already eaten you.
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The herbivore won't be back to eat the plants siblings, who share a lot of the same genes.
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I did think of that. Then it occurred to me that herbivores have siblings too.
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True, evolution is complex when it comes to the groups survival with humans being one example where sibling survival seems to be one of the driving forces behind our evolution.
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No, it's just that all the plants with tasteless poison got eaten leaving the ones with bad tasting poison behind to reproduce.
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It doesn't, but your comment proves that you don't.
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So what's the purpose of it? To deter something else? Or could it just be a coincidence? They do happen, and usually in pairs.
Re: A NEW THEORY! (Score:1)
It says "the species" not "a species", which could explain some of this confusion about singular or plural. "The species" can easily be plural.
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Where did he say otherwise? Perhaps you're confusing putting something in quotes with adding [sic] after it, in which case you're in no position to judge anyone's literacy.
P.S. They're not "a species". But if you can provide evidence of an Alllosaurus mating with a Diplodocus you can send me a postcard from Stockholm and I'll admit you're right.
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Perhaps he changed it because the definite article didn't make sense in context.
Like "he's a man" vs "he's the man".
In either case, dinosaurs aren't one.
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It could equally be interpreted the other way. At best, it's sloppy writing.
s/the species/them/ and it's unambiguous.
P.S. another gem (p48) "gastro-intestinal track". No doubt you'll find some convoluted way to justify that too.
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Re:A NEW THEORY! (Score:4, Informative)
First time I've heard anybody claim crocodiles are dinosaurs.
Because they are not. Dinosaurs and crocodiles are both archosaurs [wikipedia.org]. But to claim one group is descended from the other is incorrect in much the same way as I am not descended from my brother.
Crocodiles are also not lizards. Lizards split with archosaurs before dinosaurs and crocodiles split. So crocodiles are not lizards in the same way as I am not descended from my cousin.
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Indeed. Crocodilians are the closest living relatives to dinosaurs that are not themselves dinosaurs (the closest living relatives are, of course, the avian dinosaurs that are still around - a particularly cute variety of which is is currently trying to preen my fingers while I type ;) )
'scuse any typos - 13 fingers (Score:2)
For once, Alabama law agrees with science.
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Random mutations happen, some stick around, and a new equilibrium is established.
Toxins require energy to produce, and often are stressful for the plant, since they are ... toxic. So the genes for them aren't going to "stick around" unless they provide some countervailing benefit. If they are tasteless, they will not prevent consumption by herbivores, and will have no adaptive benefit.
It is possible that the toxin was directed at a different predator, such as insects, and just killed the dinosaurs as collateral damage. But that is just conjecture. There is no evidence that such toxi
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If they are tasteless, they will not prevent consumption by herbivores, and will have no adaptive benefit.
Their survival demonstrates their fittest-ness - whether it's apparent to you or not.
It is possible that the toxin was directed at a different predator,
This is a common mistake. There is no intelligence directing evolution, it's all random.
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There is no intelligence directing evolution
Nobody said there was. Something doesn't have be intelligent to having a reason for happening. If you drop a rock, it will fall. Reason: gravity. That doesn't mean rocks are smart. Polar bears evolved thick fur. Reason: The arctic is cold. That doesn't mean bears are smart either.
it's all random.
Nonsense. Mutations are random. Evolution (the survival of those mutations) is not.
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No it doesn't. It just demonstrates the absence of total crappiness. You don't have to be best to be good enough.
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Just bought a bag of squirrel prove dinosaur food. It is infused with cayenne that, while not actually poisonous to squirrels, sure discourages them from eating it. The dinosaurs in my yard are lacking in a sense (taste?) that gets triggered by cayenne and happily eat it. If cayenne was a deadly poison, mammals would avoid it and the dinosaurs would die.
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If cayenne was a deadly poison, mammals would avoid it and the dinosaurs would die.
If cayenne was poisonous, there would be intense pressure on dinosaurs/birds to evolve the ability to avoid it, either through taste or otherwise.
But cayenne is not poisonous, and it evolved to taste bad to mammals because birds (flying dinosaurs) are better at distributing seeds.
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I'm guessing that the problem here is something called "the gmr." That's the first link in the Slashdot article. It looks to be a badly garbled summary of the paper which is accessible as a pdf from the second link.
I'm not going to waste time deconstructing the gmr material. It's kind of a shambles.
What the paper actually says if one tracks it down is that dinosaurs MAY have been in decline at the end of the Cretaceous -- true, but hardly proven. The sampling is so non-random that it's hard to tell. T
Re:survived for millions of years after (Score:4, Informative)
And they point out that not only did dinosaurs start to disappear before the asteroid impact -- they continued to "gradually disappear for millions of years afterward."
If dinosaurs survived for millions of years after the asteroid impact, then very clearly the impact did not kill them. The asteroid didn't kill the dinosaurs any more than the Black Death killed humanity. No, Trump will kill humanity. Trump will kill us dead. Trump!
There's zero evidence that dinosaurs existed after the asteroid. The article referred to by Slashdot, the Biotic Revenge Hypotheses has this citation for their "continued to survive" claim:
Sakamoto, M., Benton, M.J., and C. Venditti. 2016. Dinosaurs in decline tens of millions of years before their final extinction. Proceedings of the National Academy of Sciences 113(18):5036–5040
But the Sakamoto article says this about that: "The fossil record shows that dinosaurs existed to the K-Pg boundary but did not survive into the Cenozoic"
So, bzzzzt wrong answer.
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Except there's this one. I had forgotten about it due to the thought that a single bone is more likely to be a re-buried bone, and also because I forget a lot of stuff lately. Decide for yourself.
http://palaeo-electronica.org/... [palaeo-electronica.org]
https://gsa.confex.com/gsa/201... [confex.com]
Re:survived for millions of years after (Score:5, Informative)
"There's zero evidence that dinosaurs existed after the asteroid"
Not zero. There's rather a lot of dinosaur material in early Paleocene strata in North America. The issue is whether it is (all) reworked from underlying cretaceous strata. In particular, a lot a folks think the saurian remains in the Ojo Alamo Formation in New Mexico are Paleocene . However, to my knowledge, no one has yet found an articulated Paleocene dinosaur skeleton. If articulated material is ever found, that'll probably settle the argument.
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Childeric says hello, and also he says you owe him $48.15 because you snuck out before the bar tab was closed.
I say kudos to you. I never got anything over on him.
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Well, that's one of the most entertainingly batshit ideas I've heard this week. Thanks!
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Um OK...
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Also, it would seem to better explain what we actually observed with the extinction event being discussed than the hypothesis put forward by the submitted article: All of the creatures far beyond a particular weight of around 20,000 lbs completely disappeared, and it would seem that of the creatures that did survive, they became considerably smaller. That's more-or-less precisely what one would expect if gravity was to suddenly change.
Extraordinary claims require extraordinary evidence. We know about gravit
Re: Galileo's Square-Cube Law (Score:2)
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Why not? Airplanes can. Even really big airplanes.
Oh, and pterosaurs weren't dinosaurs.
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Re:Galileo's Square-Cube Law (Score:4, Interesting)
<quote>Dinosaurs do not violate the square cube law.
Take the known strengths of bone and muscle, assume an animal shaped like the largest dinosaurs, apply the square cube law, and you get the maximum possible size and mass for an animal of that shape.
And, wait for it...
It turns out that maximum possible size and mass is just a tiny bit BIGGER than the biggest known dinosaurs!</quote>
Dinosaurs are a different shape to mammals.
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What I notice about the Quora claim is that the person did not include their algebra. He is making a claim about algebra, but fails to go through the math.
By contrast, others have indeed gone through the math, like here in the 2nd and 3rd bubbles [controvers...cience.com] and the answer of ~21,000 lbs would seem to be very far shy of the largest dinosaur weights. It seems very unlikely that fiddling with bone and muscle densities (etc) is going to make up the difference to the 176,000 pounds that the sauropod is claimed to have we
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Like Hungarian voters, you mean?
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You Jesus freaks make up all sorts of crap to fit your absurd worldview. Only 2018 years?!!?!? We know for a fact the world is 6000+ years old, and we have the tablets to prove it.
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Back then there were no tablets. Everyone used mainframes, or nothing at all.