In our evolving understanding of dinosaurs, Tyrannosaurus rex has acquired a new persona in recent decades. It’s always been the imperious, curiously agile two-ton gargantua, personified as a gaunt, grizzle-faced gunfighter at the dark end of the bar, a soulless creature that lived to 30 and possessed a keen sense of smell, good eyesight, surprisingly pliable skin and banana-sized teeth. Add a taste for Triceratops, which it ate by pulling off the head then using its smaller front teeth to nip the soft flesh behind the frill.
Mark MacNamara | NAUTILUS
Its newer persona suggests a softer side, a demon looking creature but finally not a psychopath, merely a misunderstood everyman with feathers. Literally feathering on different parts of its body, mainly on its back, like a mane perhaps, wherever it was, an “extravagance” in evolutionary terms. Although still somewhat speculative for T. rex, feathers are definitively found in close relatives, including the 30-foot-long Zhuchengtyrannus, which lived in China. Paleontologists have found intact downy feathers of different colors, and speculate that while feathers obviously didn’t portend flight, or a show of intimidation to predators since there weren’t any for T. rex, the feathering may have been a display, a peacock affect, as though to say, “Hey, how sexy a gal or guy am I?” Incidentally, some of the biggest T. rexes ever found were female.
Chasing down prey is a dangerous business. It’s better to have a body that allows you to hunt like a casual forager.
And now, to add to this updated portrait, there is new insight into the physique of theropods like T. rex, distinguished by their hollow bones, three-toed limbs, and long hind legs. For small theropods, like the chicken-sized Comsognathus, from the Greek for “dainty,” lanky limbs helped it run like a demon to find brunch and escape being brunch. But it turns out that feature doesn’t hold for fellow theropods at the other end of the size scale. To be sure, long legs helped T. rex sprint up to maybe 30 mph for 50 to 100 yards—not nearly at the NASCAR speeds suggested in the film, Jurassic Park. But a new study, “The Fast and the Frugal,”1 undercuts the image of T. Rex on a rampage to devour Laura Dern. T. rex evolved long legs to amble through its habitat with a chill gait that conserved its “energy budget”—a giant body requires a massive amount of fuel—and helped the big theropod, “at once efficient and elegant,” rule the land for more than 2 million years. Until an unfortunate asteroid arrived.