How scientists actually measured the bite force
You can't strap a bite-force sensor onto a living T. rex, so in 2017 Florida State University's Gregory Erickson and Oklahoma State University's Paul Gignac built their estimate a different way: they started with living crocodiles, lassoing individual animals and getting them to bite down on a modified scale to measure real bite force directly. From there, they used what's known about crocodilian jaw muscle architecture to build a detailed 3D computer model scaled up to T. rex's skull.
The result, published in Scientific Reports, put T. rex's bite at roughly 8,000 pounds of force (about 34,522 newtons at the back teeth), more than double the bite of the largest crocodiles alive today. Erickson described the scale of it plainly in an interview with NPR: "What we came up with were bite forces of around 8,000 pounds. That's like setting three small cars on top of the jaws of a T. rex, that's basically what was pushing down." The long, conical teeth concentrated that force into an estimated 431,000 pounds per square inch of pressure at the tooth tip, enough to crush bone rather than just cut through flesh, a feeding style researchers call extreme osteophagy.
Predator or scavenger? The bite mark that settled it
For years this was a real, serious scientific argument, not a fringe theory. In 1994, paleontologist Jack Horner published the case that T. rex was primarily a scavenger, not an active hunter, pointing to its keen sense of smell (useful for finding carcasses from a distance), its bone-crushing jaw shape (more useful for cracking open scavenged remains than for a clean kill), and the risk a 40-foot animal ran by sprinting after live prey. National Geographic's account of the debate is a good record of how seriously paleontologists took the idea at the time.
The evidence that resolved it came from a single fossil. In 2013, researchers reported a broken T. rex tooth crown embedded between two tail vertebrae of a hadrosaur (a duck-billed plant-eater), and the bone around that tooth showed new growth, meaning the wound had begun healing. That only happens if the animal survives the bite. A T. rex had attacked a living hadrosaur, missed a killing blow, and the hadrosaur got away and lived long enough afterward for the bone to start repairing itself. Horner eventually conceded, in peer review, that T. rex was both a hunter and an opportunistic scavenger, which is the position paleontologists hold today: an active predator that, like most living predators, wouldn't turn down a free meal either.
Did it actually have feathers?
This one is genuinely unsettled, and the honest answer is more interesting than a flat yes or no. A 2017 study in Biology Letters examined skin impressions from the neck, pelvis, and tail of multiple adult T. rex specimens, comparing them against skin patches from related tyrannosaurs like Albertosaurus and Gorgosaurus. The finding: scaly skin in every one of those examined regions, with no feather impressions turning up in any of them.
That doesn't fully settle the juvenile question, though, and it doesn't rule out feathers on parts of the adult body that haven't been found as fossil impressions yet either. Hatchling and young T. rex weighed only a few kilograms, small enough to face the same heat-loss problem that smaller feathered theropods dealt with, which makes an insulating juvenile coat biologically plausible. But no well-preserved juvenile T. rex skin has ever been found, so that idea remains an informed guess rather than a confirmed fact. The scaly-adult finding, for the body regions actually examined, is solid; the feathered-juvenile idea is a reasonable hypothesis waiting on fossil evidence that may never turn up.
The timeline that breaks most people's intuition
Popular culture tends to lump "dinosaurs" into one blurry era, which makes this fact land harder than it should: Stegosaurus lived in the late Jurassic period, roughly 150 million years ago. T. rex showed up in the late Cretaceous, around 66 to 68 million years ago. That's an 83-million-year gap between the two, according to Smithsonian Magazine's rundown of the timeline.
Compare that to the roughly 66 million years separating T. rex's extinction from today. T. rex is closer in time to you reading this than it was to Stegosaurus. If Stegosaurus could have watched T. rex evolve, T. rex would have seen Stegosaurus the way we see it now: as an impossibly ancient relic from a different age entirely.