to inhabit wetter, more productive habitats, while smaller sister taxa are found in drier, less productive habitats. This pattern suggests that populations of both living and extinct lemur species had become geographically isolated by differences in habitat and evolved in isolation due to varying primary production within different ecosystems. Thermoregulation may also have played a role in the evolution of their increased body size. Yet despite this pressure to specialize and differentiate, some of the extinct subfossil lemurs, such as Archaeolemur, may have had island-wide distributions during the Holocene, unlike the living lemurs. If this is the case, it may suggest that some larger lemurs might have been more tolerant to regional differences in ecology than living lemurs. Diet Research on subfossil lemur diets, particularly in southern and southwestern Madagascar, has indicated that ecological communities have been significantly affected by their recent extinction. Many extinct subfossil lemurs were large-bodied leaf-eaters (folivores), seed predators, or both. Today, leaf-eating along with seed predation is only seen in mid-sized lemurs, and is far less common than it was in the past. Strict folivory is also less common, now found primarily in small lemurs. In certain cases, subfossil lemurs, such as the sloth lemurs and koala lemurs, may have used leaves as an important fallback food, whereas other species, such as the monkey lemurs and the giant aye-aye, specialized on structurally defended resources, such as hard seeds and wood-boring insect larvae. Last, Pachylemur was primarily a fruit eater (frugivorous). Subfossil lemur diets have been reconstructed using analytical tools, including techniques to compare tooth anatomy, structure, and wear; biogeochemistry (analysis of isotope levels, like carbon-13); and the dissection of fecal pellets associated with subfossil remains. The diets of most subfossil lemurs, most notably Palaeopropithecus and Megaladapis, consisted primarily of C3 plants, which use a form of photosynthesis that results in higher water loss through transpiration. Other subfossil lemurs, such as Hadropithecus and Mesopropithecus, fed on CAM and C4 plants, which use more water-efficient forms of photosynthesis. Fruit and animal matter was more common in the diets of subfossil lemurs including Pachylemur, Archaeolemur, and the giant aye-aye. In southern and southwestern Madagascar, the subfossil lemurs of the spiny forests generally favored the C3 plants over the more abundant CAM plants, although closely related sympatric species may have fed upon the two types of plants in different ratios, allowing each to divide resources and coexist. Since plants