Hadrosaurs

Some hadrosaurs had long cranial tubes/crests for unproven purpose. Theories include visual recognition between species, between males & females, acoustic resonance, and thermoregulation. These functions are not mutually exclusive and the crests could have done two to all of them at once. They were quadrupeds that could also move bipedally. Hadrosaurs have the distinction of being dinosaurs who's mummified fossil remains have been found. Natural mummification of a non-intelligent creature that was sealed away from oxygen and corrosive water immediately on death before being preyed upon or scavenged are extremely rare. The resulting mummy is still venerable to deterioration but some remain safe from water and oxygen and remained preserved. 2 nearly complete hardosaurs, with fossilized skin, organs, muscles, tendons, blood, etc. have been found. Scientists don't just have the shape of these body parts (as with a few other dinosaurs), they have the skin itself (though fossilized). Many surprised were reviled. Such has large gaps between the vertibre that were still attached to the skin. This suggests large flexible disks between them that were not cartilage (cartilage would be expected to be preserved as the skin is not near as resilient cartilage) This could mean that the hadrosaur was as flexible as a cat. It could also mean they didn't run very fast (flexible spines generally make for slower animals, though their are exceptions such as the cheetah). Certainly they were even longer that previously thought. Also a surprise, hadrosaurs were heavily muscled. This might indicate that were faster runners that previously thought.