Dave Hone: T-Rex, Dinosaurs, Extinction, Evolution, and Jurassic Park | Lex Fridman Podcast #480

Dave Hone walks Lex Fridman through the biology of T. rex, from its colossal size and tennis-ball-sized eyes to its bone-crushing bite, efficient bird-like feet, and tiny arms. He explains how paleontologists reconstruct behavior, ecology, and even sex from fragmentary evidence like bite marks, taphonomy, and population data, while debunking myths such as T. rex's blindness to motion and confident claims of pack hunting. The conversation ranges across dinosaur evolution, sexual selection and feathers, intelligence, the asteroid extinction event, and why birds are living dinosaurs. Hone also critiques the accuracy of the Jurassic Park franchise and argues that ordinary animals like Protoceratops, with large population samples, teach us more than rare superlative specimens.

• Hone suspects large tyrannosaurs were primarily nocturnal, since their gigantic eyeballs likely gave them excellent low-light vision and a three-to-four-meter-tall animal can't hide in open daylight.
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• T. rex is uniquely weird because it was by far the largest carnivore in its ecosystem with essentially no big-predator competition, like a world where lions are followed in size only by weasels.
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• Hone half-jokingly argues all science funding should go to paleontology because fossils erode away and disappear forever, whereas other sciences can be studied any time.
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• The evidence for pack hunting in any dinosaur is almost nonexistent; the famous Deinonychus-Tenontosaurus site is better explained by predator traps or toxin events than coordinated hunting.
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• T. rex cannibalism is essentially confirmed by a T. rex foot bone bearing distinctive T. rex feeding traces, identifiable because no other large carnivore existed in its ecosystem.
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• A claim that T. rex had primate-level intelligence was rebutted by other researchers who revised its neuron count down from about three billion to roughly 250 million to 1.7 billion, comparable to crocodiles.
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• Birds literally are dinosaurs, descended from something very close to a small Velociraptor, the same way humans are apes.
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• Hone argues Protoceratops is the single most scientifically valuable dinosaur because over 100 specimens from one place and a narrow time window let researchers study it as a real population.
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• T. rex was roughly 12 meters long and about seven metric tons, described by colleague Tom Holtz as an orca on land.
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• The most detailed recent estimate puts T. rex's top speed around 25 mph (40 kph); it power-walked with one foot always on the ground rather than truly running.
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• The origin of cinema traces to Eadweard Muybridge's photographic experiment settling a bet over whether a galloping horse ever has all four feet off the ground.
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• Carnivores typically eat prey only about 5 to 20 percent of their own mass, so an adult T. rex might not even consider a human worth hunting.
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• The famous T. rex skeleton Stan, dug up by the Black Hills Institute, sold at auction for $31.8 million, later revealed to be bought by Abu Dhabi's Department of Culture and Tourism.
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• Tyrannosaurs have fused nasal bones that make the snout a single solid, rigid structure able to withstand their powerful bite forces.
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• Paleontologists can identify a female dinosaur only if it has medullary bone, a calcium-rich tissue grown by laying females, so they can detect a laying female but not distinguish males from non-laying females.
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• The dinosaurs were killed by an asteroid roughly the size of Mount Everest hitting off the Yucatan at about ten times the speed of sound, triggering a near-instant nuclear winter.
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• Feathers far predate birds: Middle Jurassic tyrannosaurs about 165 million years old already had simple hair-like feathers, around 100 million years before the extinction.
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• The ocean sunfish (Mola mola) can release up to roughly 300 million eggs in a single spawning event, illustrating evolution as a numbers game.
  03:09:24