From one piece Dave Hone: T-Rex, Dinosaurs, Extinction, Evolution, and Jurassic Park | Lex Fridman Podcast #480 24 beliefs, in the piece's order there
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Their words
Why don't Chinese dragons look like Mexican dragons or equivalent thunderbirds or whatever? Well, because it probably wasn't influencing them. If they were all seeing the same skeleton, they'd probably all produce the same kind of mythical animals.
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korrents.com
The papers claiming Spinosaurus was a diver or a strong swimmer rest on very weak evidence at best.Their words
So Spinosaurus is a super weird and exaggerated version of what was already a kind of super weird group of theropods. So Spinosaurus is properly strange. And then, as you kind of hinted at, super controversial as well, because various papers have claimed it's a diver or a really good swimmer, and I think the evidence for that is very weak at best.
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Their words
But fossils are in places that erode, and if we don't dig them up, they're gone. So we should dig all the fossils up now, and then we've got forever to study them.
+ 21 more
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Because actually, however cool these new things are, genuinely if you want to know what dinosaurs are and how they worked, another hundred Protoceratops will actually probably tell us a lot more than 50 new species, however cool 50 new species might be.
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So the instant assumption is, okay, so you can tell female from male. No, we can tell laying female from everything else. So males won't have medullary bone. Young females won't have them. Females outside of the breeding season won't have it.
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I think people think evolution is, like, perfecting things in some way. And they're not. They're bodge jobs, you know? That's why we have a blind spot in our eye, but things like squid don't.
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Their words
But I'm being obviously overly facetious, but if ultimately part of your scaling is how big is the animal versus how big is its brain, that's most of a T-Rex brain. It's a fraction of the size of a chimp brain, and chimps don't weigh seven tons.
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Their words
So birds did not appear as a result of the dinosaurs going extinct. Birds lived alongside the dinosaurs for 100 million years. The birds were not new on the scene, and it's not like, "Oh, the dinosaurs died, and from the ashes rose the birds." No, they've been knocking around forever.
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Yes, it's what ultimately killed the dinosaurs, but I'd be amazed if there wasn't some equivalent of Hawaii or New Zealand or some other tucked away island or valley where actually dinosaurs were fine for anything from a few hundred thousand to a couple of million years.
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But yeah, there's been a back and forth about whether dinosaurs were already on their way out or were they a bit limited by the very end of the Cretaceous. I think the more recent analyses have shown that's probably not the case, because in other words, they were basically doing fine right up to the extinction event. And so yeah, if the asteroid hadn't hit, there's no reason to think that they were on some kind of terminal decline.
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korrents.com
All five mass extinctions were ultimately climate change — the climate shifting faster than life could adapt to it.Their words
There are five recognized mass extinctions in the history of life on Earth, and all of them are ultimately some form of climate change. Whether it's volcanic eruptions or hyper-oxygenation, or an ice age or whatever, it's climate changing too quickly for things to adapt to.
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Their words
You're dominant in contests, particularly with conspecifics. If you're trying to win a territory or win mating rights, bigger things usually beat up smaller things. So there's going to be selection favoring them. But then big things don't usually do well in extinction events, so that tends to reset the clock by killing off the big stuff, and then smaller stuff does better again.
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korrents.com
T. rex was not an apex predator: an apex predator eats other predators, and T. rex ate herbivores.Their words
I have a problem with the term apex predator because ecologically, apex predators are generally defined as things that eat other predators. So a great white shark is, because it's eating stuff like tuna and sea lions, which are themselves predators, so it's a predator of predators. Whereas people love saying lions are apex predators, and they love saying T-Rex is an apex predator. They're eating herbivores.
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Their words
And that's the thing, it's the pool of data, and I think that's what people miss. We as paleontologists get caught up on single superlative specimens and then try and treat them as a silver bullet almost.
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Their words
There are various canids that all hunt in groups, but then you've got things like maned wolves, which are effectively solitary. The hyenas. Spotted hyenas are, yeah, these super social animals, but the brown hyena, the striped hyena, and the aardwolf are solitary. So you just can't do group versus solitary off close relatives or anything like that.
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Their words
The evidence for pack hunting in any dinosaur at all is almost nonexistent. It basically doesn't exist. And that's going exactly back to, again, that stuff we were talking about, bite marks and taphonomy and the history of specimens and how you interpret stuff.
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korrents.com
The scavenger-versus-hunter argument about T. rex is over: the bite marks show it did both.Their words
They're obviously both. A, because we've got things like the bite marks I just described, which is pretty much definitive scavenging, and then we've got the healed bite marks with T-rex teeth buried in bones, which is pretty much definitive active predation. So we've got evidence of it doing both.
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Their words
They're relatively efficient compared to a lot of other things, and particularly compared to the herbivores, so that means they're probably looking at long distance rather than speed.
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korrents.com
T. rex never ran in the biomechanical sense — it was a power walker that always kept one foot on the ground.Their words
And yeah, big theropods, T-rex, is going to be a power walker. It's not going to run in the conventional biomechanical sense where both feet are off the ground at once.
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Their words
So, giant eyeballs, they can either see very well, they can see a very long way in daylight, or they can see very well at night. And my suspicion is it's the latter. I think they're probably primarily nocturnal when they get that size.
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So, I think it's just straight fiction. It works for the book and it works for the movie, but it's... as far as I can tell, it's straight fiction, and Crichton just made it up. If it's buried in some bit of literature, he's done better finding it than I have, and I've had a really good look, and I know how to look.
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Their words
But this is the absolute rule of thumb for how foraging and growth and predation operate across everything from fish to starfish, praying mantises, all the way up to things like big cats via stuff like crocodiles. It's how it works. So it'd be very weird if it didn't also operate for dinosaurs. And then, as I say, we've actually got the direct evidence for this from bite marks and stomach contents. They're taking small stuff.
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Their words
These are weird and rare outcomes. These don't usually happen. The vast majority of active predation is on stuff much, much, much smaller than you.
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korrents.com
T. rex is a genuine ecological oddity: nothing else in its ecosystem came anywhere near its size as a carnivore.Their words
But fundamentally, T-Rex is definitely weird, even compared to all the other giant tyrannosaurs that are very closely related to it, because it is by far, ludicrously by far, the largest carnivore in its ecosystem.