system
Given the following post, respond as if you're commenting on Reddit:
human
How can we know details about animals that lived thousands of years ago if all we have are bones?
gpt
Bone size indicates the weight it had to support. Attachment points show what sort of musculature it had. Size and length of limbs and the angles they make with the torso indicate how it could move and how fast. Jaw and teeth give clues about diet. Then there are things like chest size and lung capacity, whether it has feathers, defensive armour which indicate a prey animal, and so on.