She's often said how delighted she'd have been if one of these creatures had been a total klutz, tripped over its own feet, fallen flat in the volcanic ash, stood up, brushed itself off, and left a soft tissue impression for us to find. And that's one reason Mann likes teeth. More of our early ancestors' teeth have survived than anything else of theirs. Teeth are also informative in ways that bones can't be. The shell of enamel covering the crown of a tooth is the hardest part of an animal and one of the few substances that preserves a record of its owner's development.
Bone is a dynamic material.
It's constantly being remodeled. It's always being changed. But enamel is formed by cells that secrete an organic matrix around which a mineral crystal is deposited. Once the enamel is formed, it never changes. So enamel preserves a record of the animal's growth and development, its youth, and any metabolic disturbances it experienced.