Lemurs are strepsirrhine primates, all species of which are endemic to Madagascar. They include the smallest primate in the world, Madame Berthe's mouse lemur, which weighs , and range up to the size of the indri, which can weigh as much as . However, recently extinct species grew much larger. As of 2010, five families, 15 genera, and 101 species and subspecies of lemur were formally recognized.<ref name="LoM3_pgs101-103List|classified]] eight as Critically Endangered, 18 as Endangered, 15 as Vulnerable, four as Near Threatened, eight as Least Concern and 41 as Data Deficient; seven were yet to be evaluated. From 2000 through 2008, 39 new species were described and nine other taxa resurrected. By 2014, the number of species plus subspecies recognized had increased to 113; of the 105 species then known, the IUCN classified 24 as critically endangered, 49 as endangered, 20 as vulnerable, three as near threatened, three as least concern and four as data deficient; two were yet to be evaluated. The number of lemur species is likely to continue growing in the coming years, as field studies, cytogenetic and molecular genetic research continues. There is not complete agreement over the latest revisions to lemur taxonomy, with some experts preferring an estimated 50 lemur species. The debates are likely to continue, as some scholars label the explosive growth of species numbers as taxonomic inflation. In many cases, classifications will ultimately depend upon which species concept is used. In the case of the lemurs of Madagascar, which have suffered extensively from deforestation and habitat fragmentation, nearly 70% of all species were either endangered or critically endangered as of 2014, most have yet to be extensively studied, and nearly all populations are in decline. For these reasons, taxonomists and conservationists favor splitting them into separate species to develop an effective strategy for the conservation of the full range of lemur diversity. Implicitly, this means that full species status will help grant genetically distinct populations added environmental protection. At least 17 species and eight genera are believed to have become extinct in the 2,000 years since humans first arrived in Madagascar. All known extinct species were large, ranging in weight from . The largest known subfossil lemur was Archaeoindris fontoynonti, a giant sloth lemur, which weighed more than a modern female gorilla. The extinction of the largest lemurs is often attributed to predation by humans and possibly habitat destruction. Since all extinct