Soft tissue almost never survives fossilization, but that wasn’t the only surprise. Based on 3-D images from the scans, the 650-pound plant-eater’s heart may have more in common with yours than with a crocodile’s. Modern reptiles are sluggish; their three-chambered hearts let blood flow back to the body before picking up energy-giving oxygen from the lungs. Birds and mammals–and, it seems, Thescelosaurus –have a more efficient four-chamber design, which delivers oxygen-rich blood to the muscles and provides the energy to make us warm-blooded so we don’t have to bask in the sun to get moving in the morning. The new find may be the best evidence yet that dinosaurs had more energy and endurance than once thought. It might also persuade scientists to take another look at the rocks they’ve been throwing away.
