the extinct species. The Central Highlands saw the greatest species loss, but was not the only region or habitat type to witness extinctions. The least-understood region is the eastern rainforests, which have not yielded subfossil lemur remains. Consequently, it is impossible to know what percentage of lemur taxa were recently lost there; studies of Malagasy customs (ethnohistory) along with archaeological evidence suggests the eastern rainforests were more ecologically disturbed in the past than they are today. Hunting and trapping by humans may have severely impacted large lemurs in this region as well. Comparisons of species counts from subfossil deposits and remnant populations in neighboring Special Reserves has further demonstrated decreased diversity in lemur communities and contracted geographic ranges. At Ampasambazimba in central Madagascar, 20 species of subfossil lemur have been found. At nearby Ambohitantely Reserve, only 20% of those species still survive. Only six of 13 species found at Ankilitelo and Ankomaka Caves in the southwest still survive at Beza Mahafaly Reserve. In the extreme north, the caves of Ankarana have yielded 19 species, yet only nine remain in the surrounding forests. In the northwest, 10 or 11 subfossil species have been found at Anjohibe, whereas only six species remain at nearby Ankarafantsika National Park. As with the extinctions that occurred on other land masses during the late Pleistocene and Holocene (known as the Quaternary extinction event), the disappearance of Madagascar's megafauna is tightly linked with the arrival of humans, with nearly all extinctions dating to around the same time of the earliest evidence of human activity on the island or significantly later. The exact date of human arrival is unknown; a radius (arm bone) of a Palaeopropithecus ingens with distinct cut marks from the removal of flesh with sharp objects dates to 2325 ± 43 BP (2366–2315 cal yr BP). Based on this evidence from Taolambiby in the southwest interior, as well as other dates for human-modified dwarf hippo bones and introduced plant pollen from other parts of the island, the arrival of humans is conservatively estimated at 350 BCE. Measurements of stratigraphic charcoal and the appearance of exotic plant pollen dated from Holocene core samples confirm these approximated dates for human arrival in the southwestern corner of the island and further suggest that the central and northern parts of the island did not experience significant human impact until 700 to 1,500 years later. The humid forests of the