"The First Primates" "Early Primate Evolution: The First Primates" evolution of apes The first primates lived at least 20 million years ago the original "Early Primate Evolution: The First Primates" Fossils from that time are about the size of squirrels "Early Primate Evolution: The First Primates" "Early Primate Evolution: The First Primates" "Early Primate Evolution: The First Primates" Fossils from that time are about the size of squirrels Primate ancestors prosimian