The Colossal Predator: Unpacking the Biology, Biomechanics, and Ecology of Tyrannosaurus Rex with Dave Hone

This episode features paleontologist Dave Hone, who delves into the iconic Tyrannosaurus Rex, exploring its immense physical characteristics, biomechanics, and ecological role. Hone emphasizes T. rex's truly colossal size, describing it as an "orca on land" – larger and more massive than even a large African elephant, with a robust, boxy skull capable of swallowing a human whole. He details its massive, forward-facing, tennis ball-sized eyes, suggesting incredible visual acuity, possibly for nocturnal hunting, and highlights its uniquely thick, strong teeth that provided an uber-powerful crushing bite, distinguishing it even from other large tyrannosaurs. The discussion also covers its disproportionately small, two-fingered arms, which were largely non-functional for predation, and its short, bull neck designed to support its massive head.

Hone explains the complex biomechanics behind T. rex's bipedal movement, emphasizing the critical role of its gigantic, muscular tail, which anchored to the thigh bone and provided the primary propulsion for walking, similar to modern lizards and crocodiles. He describes a specialized foot adaptation, the arctometatarsalian foot, where the middle metatarsal bone is constricted, locking the foot for stability and energy efficiency during locomotion. Contrary to popular depictions, T. rex was a "power walker" rather than a runner, meaning one foot was always on the ground due to its immense mass, yet it could still achieve speeds of around 25 mph (40 kph) thanks to its long stride, making it a formidable pursuer.

The conversation shifts to T. rex's ecological niche and hunting strategies. As the largest carnivore in its ecosystem by a significant margin, it faced little competition. Hone argues that T. rex primarily preyed on juveniles of large herbivores like Triceratops and Edmontosaurus, rather than engaging in risky battles with full-grown adults. This strategy is supported by fossil evidence, including healed bite marks on juvenile bones, and aligns with universal predator-prey dynamics observed in modern carnivores, where prey typically constitutes 5-20% of the predator's mass. Juveniles are preferred targets because they are smaller, weaker, less experienced, lack adult defenses, and often forage in suboptimal, more exposed areas.

Finally, the episode addresses common misconceptions, particularly the "not moving" strategy from Jurassic Park, which Hone dismisses due to T. rex's excellent vision. He speculates on human survival strategies if encountering a T. rex, suggesting that humans might be too small or unfamiliar to be considered prey, or could potentially deter it with ranged attacks (throwing rocks) or by using agility around large obstacles like trees. The discussion also draws fascinating connections to other fields, such as the history of photography and cinema (Eadweard Muybridge's work on horse locomotion) and modern robotics (Boston Dynamics, Tesla Optimus) in their pursuit of efficient bipedal movement, underscoring the interdisciplinary nature of understanding prehistoric life.

- 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.

So I've got a copy of a T. rex skull in my downstairs from my office and yeah, I could fit comfortably through its mouth. So it would be just about capable of swallowing me whole, and I'm a pretty big guy.

So a colleague of mine, Tom Holtz, described them as an orca on land, but that's it. It is a killer whale-sized animal but on legs, on land.

And then you look at them that way on, and you realize it's a third of the width. So this isn't just massive, it's thick. And of course, being thick, it makes it strong. And with that giant head, with all that extra bone and then all the extra musculature attached to that giant head, they've got this uber-powerful bite and the ability to just chomp through basically anything it wants to.

T. rex is just massively bigger than basically any other big carnivore we know of.

But if you look at a lizard, particularly if you look at something like a crocodile, you see this massive, massive block of muscle sitting on the first third to half of the tail. And that's what dinosaurs are doing.

Power walking, so you're never... So, or running, there are moments in time when both feet are off the ground, and you're saying likely here one foot is always on the ground. - Yeah, pretty much has to be for loading.

The vast majority of active predation is on stuff much, much, much smaller than you.

Juveniles are relatively small and weak. They don't have the horns or frills or armor or shields and other stuff. They're naive.

Every record we have of basically any large carnivorous dinosaur where you have stomach contents, whether it's like consumed something or healed bite marks... They're, they're juveniles. They're relatively young animals.

The one thing, the one advantage humans have over almost anything else on Earth, there's a handful of exceptions, is we have range. I can pick up a rock and hurl it with reasonable accuracy.

And my suspicion is it's the latter. I think they're probably primarily nocturnal, when they get that size.