Tiny Chinese fossil is earliest primate

"From this almost complete skeleton, we can conclude that our ancestors were a kind of very small animal. It was very active and agile; and it lived in the trees and fed on insects," he told BBC News.

(and)

Many people may be taken aback by the animal's small size - a body just 71mm in length and an estimated weight of about 20-30g. But Archicebus gives us a good idea of what the very first primates on Earth would have looked like. 

Go read the whole thing over at BBC News.