ape, but retained some monkey-like characteristics of the backbone, pelvis, and forelimbs that suggest it was quadrupedal , rather than a brachiator Lowered sea levels 17 - 16.5 million years ago provided a land bridge between Africa and Eurasia, and some of these early apes used it to enter Eurasia, along with elephants, pigs and antelopes, and rodents. By this stage the apes had developed a thick coating of enamel on their teeth, which enabled them to eat the harder foods (such as nuts and tough-coated seeds) that weren't available to Proconsul . This evolutionary innovation was significant, as within 1.5 million years of apes moving into Eurasia they had diversified into at least eight different forms. By 13 million years ago apes were found throughout Eurasia, including the lineages of Dryopithecus (in Europe) and Sivapithecus (in Asia). Both had very similar anatomy to modern great apes. These two lineages survived the major climate changes that marked the end of the Miocene, while the many other Eurasian ape species became extinct. They survived by moving into Southeast Asia ( Sivapithecus ) and back into Africa ( Dryopithecus ). The living great apes are descended from these two lineages. Phylogenetic analyses indicate that Sivapithecus is the likely ancestor of the orang-utan, while Dryopithecus is probably the forebear of African apes and humans. Evidence from molecular biology strongly suggests that humans and chimpanzees last shared a common ancestor no more than 5-8 million years ago, and in recent years researchers have focused