Southern California’s beaches bustle with year-round activity—tourists taking selfies, surfers waiting for the perfect wave, seagulls on the prowl for scraps. Beyond the surf, however, sand gives way to mud, and lots of it, on a narrow band of mostly empty continental shelf that stretches some 250 miles along the coast. Scavengers such as crabs and burrowing worms dominate this dull mudscape, which is often obscured by swirling sediment. The culprit behind this wasteland? Cows, says Susan Kidwell, a paleontologist at the University of Chicago who made the surprising connection….
