The remains of fossils give scientists clues as to what the world may have been like a long tome ago. If fish fossils are found on the side of a mountain, there may have been a lake there. If a skeleton is found, they can decide what creature it was.
The answer is ‘the only truly distinctive primate trait’. Prehensile hands are a distinctive trait of primates an opposable thumb (capable of grasping). The digits have nails instead of claws, and tactile pads enriched with sensory nerve fibers at the ends of digits to feel to manipulate objects.
m - Meter - Length.
s - Second - Time.
A - Ampere - Electric Current.
K - Kelvin - Temperature.
kg - Kilogram - Mass.