ILLUSTRATION: ELENA LACEY
Wired has an informative article about how to outrun a dinosaur. It goes to the heart of the issue... allometry, which is the study of the relationship of body size to shape, anatomy, physiology and ultimately behavior. And, partial spoiler, we'd probably be safer than you think against the likes of T-rex and similarly sized meat eaters. I'm reminded of the movie "In-Laws" from 1979 with Peter Falk, when he yells "Serpentine, Serpentine!"
IF A MOUSE fell down a 1,000-foot mine shaft, the renowned evolutionary biologist JBS Haldane once proposed, the mouse would rise, shake the dust off itself, and scurry away. Maybe even right back up to do it again.
If a rat fell from the same height, however, it would die.
A human would break, Haldane writes, and a horse would splash.
Haldane does not provide a colorful verb in his 1926 essay On Being the Right Size for what would occur if a 9-ton Tyrannosaurus rex fell into that mine. But the giant predator would scream down the shaft at 172 mph, hit the ground with 120 tons of force and … shatter? Dismember? Detonate? Erupt?
Regardless, the purpose of Haldane’s gruesome thought experiment is to demonstrate the dramatically different relationship large animals have with gravity compared to smaller ones. This relationship, and the differing fates of the mouse and rat, are explained by the "square-cube" law, which is the simple idea that as an object expands, its volume cubes while its surface area merely squares. Because an animal’s surface area provides the brakes when falling, and its mass determines the force of its impact, the falls of various species can be either thrilling, tragic, or messy, depending on seemingly small differences in their size. It may be a simple concept—but because the law involves such rapid growth, it’s exceedingly difficult to intuit its occasionally dramatic effects. That’s particularly true with regards to the largest land animals to have ever walked the earth, and particularly important if you had to outrun them.
