From one piece Dave Hone: T-Rex, Dinosaurs, Extinction, Evolution, and Jurassic Park | Lex Fridman Podcast #480 15 beliefs · youtube.com
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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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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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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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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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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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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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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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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.