finds from other subfossil sites, data suggests that it used to range across the northern, northwestern, central, and eastern parts of the island. It is unclear whether these locations were wetter in the past or whether distinct subpopulations or subspecies occupied the drier forests, much like modern diversity of sifakas. In addition to previously having expanded geographic ranges, extant subfossil lemurs exhibited significant variation in size. Researchers have noted that subfossil bones of living species are more robust and generally larger than their present-day counterparts. The relative size of living species may be related to regional ecological factors, such as resource seasonality, a trend that is still observable today, where individuals from the spiny forests are, on average, smaller than individuals from the southwestern succulent woodlands or the dry deciduous forests. Ecology As a group, the lemurs of Madagascar are extremely diverse, having evolved in isolation and radiated over the past 40 to 60 million years to fill many ecological niches normally occupied by other primates. In the recent past, their diversity was significantly greater, with 17 extinct species sharing body proportions and specializations with lorises and various non-primates, such as tree sloths, giant ground sloths, koalas, and striped possums (genus Dactylopsila). The diversity of lemur communities today can be as high as 10 to 12 species per region; communities of 20 or more lemur species existed as recently as 1,000 years ago in areas that now have no lemurs at all. Just like living species, many of the extinct species shared overlapping ranges with closely related species (sympatry) through niche differentiation (resource partitioning). Among all the late Quaternary assemblages of megafauna, only Madagascar was dominated by large primates. Although anatomical evidence suggests that even the large, extinct species were adapted to tree-climbing, some habitats, including gallery forests and the spiny forests of southern Madagascar, in which they occurred would not have allowed them to be strictly arboreal. Even today, most lemur species will visit the ground to cross open areas, suggesting that the extinct species did the same. Monkey lemurs (family Archaeolemuridae), including Archaeolemur majori and Hadropithecus stenognathus, have been reconstructed as being primarily terrestrial. In contrast, the sloth lemurs (family Palaeopropithecidae) were highly arboreal despite the large size of some species. Species of both extinct and living (extant) lemur vary in size based on habitat conditions, despite their differences in niche preference. Within related groups, larger species tend