Lemuroid

Lemurs ( ) (from Latin ''lemures'' – ghosts or spirits) are wet-nosed primates of the superfamily Lemuroidea (), divided into 8 families and consisting of 15 genera and around 100 existing species. They are endemic to the island of Madagascar. Most existing lemurs are small, have a pointed snout, large eyes, and a long tail. They chiefly live in trees and are active at night.

Lemurs share resemblance with other primates, but evolved independently from monkeys and apes. Due to Madagascar's highly seasonal climate, lemur evolution has produced a level of species diversity rivaling that of any other primate group. Until shortly after humans arrived on the island around 2,000 years ago, there were lemurs as large as a male gorilla. Most species have been discovered or promoted to full species status since the 1990s; however, lemur taxonomic classification is controversial and depends on which species concept is used.

Lemurs range in weight from the mouse lemur to the indri. Lemurs share many common basal primate traits, such as divergent digits on their hands and feet, and nails instead of claws (in most species). However, their brain-to-body size ratio is smaller than that of anthropoid primates. As with all strepsirrhine primates, they have a "wet nose" ( rhinarium). Lemurs are generally the most social of the strepsirrhine primates, and communicate more with scents and vocalizations than with visual signals. Lemurs have a relatively low basal metabolic rate, and as a result may exhibit dormancy such as hibernation or torpor. They also have seasonal breeding and female social dominance. Most eat a wide variety of fruits and leaves, while some are specialists. Two species of lemurs may coexist in the same forest due to different diets.

Lemur research during the 18th and 19th centuries focused on taxonomy and specimen collection. Modern studies of lemur ecology and behavior did not begin in earnest until the 1950s and 1960s. Initially hindered by political issues on Madagascar during the mid-1970s, field studies resumed in the 1980s. Lemurs are important for research because their mix of ancestral characteristics and traits shared with anthropoid primates can yield insights on primate and human evolution. Many lemur species remain endangered due to habitat loss and hunting. Many lemur species have already gone extinct in the last 2000 years due to human activity, and are collectively referred to as the "subfossil lemurs". These are typically larger than extant lemurs, with the largest, ''Archaeoindris'', being the size of a gorilla. Although local traditions, such as fady, generally help protect lemurs and their forests, illegal logging, economic privation and political instability conspire to thwart conservation efforts. Because of these threats and their declining numbers, the International Union for Conservation of Nature (IUCN) considers lemurs to be the world's most endangered mammals, noting that up to 90% of all lemur species confront the threat of extinction in the wild within the next 20 to 25 years. As an iconic flagship species that exemplifies the biodiverse fauna of Madagascar, however, lemurs have facilitated the emergence of eco-tourism in Madagascar in World Heritage Sites, such as the Rainforests of the Atsinanana in eastern Madagascar. In addition, conservation organizations, such as the Lemur Conservation Foundation and the Duke Lemur Center, increasingly seek to implement community-based approaches, such as encouraging local communities to adopt sustainable agriculture and afforestation initiatives, to expand employment opportunities for ecological programs, preserve lemur habitats as well as promote public awareness and appreciation for lemurs.

Etymology

The name lemur is derived from the Latin '' lemures'', which refers to specters or ghosts that were exorcised during the Lemuria festival of ancient Rome.

Carl Linnaeus, the founder of modern binomial nomenclature, gave lemurs their name as early as 1758, when he used it in the 10th edition of ''Systema Naturae''. He included three species under the genus ''Lemur'': ''Lemur tardigradus'' (the red slender loris, now known as ''Loris tardigradus''), ''Lemur catta'' (the ring-tailed lemur), and ''Lemur volans'' (the Philippine colugo, now known as ''Cynocephalus volans'').

Although the term "lemur" was first intended for slender lorises, it was soon limited to the endemic Malagasy primates, which have been known as "lemurs" ever since. According to Linnaeus' own explanation, the name was selected because of the nocturnal activity and slow movements of the slender loris. Being familiar with the works of Virgil and Ovid and seeing an analogy that fit with his naming scheme, Linnaeus adapted the term "lemur" for these nocturnal primates.

It was noted in 2012 that it has been commonly and falsely assumed that Linnaeus was referring to the ghost-like appearance, reflective eyes, and ghostly cries of lemurs. It has also been speculated that Linnaeus may also have known that some Malagasy people have held legends that lemurs are the souls of their ancestors, but this is unlikely given that the name was selected for slender lorises from India.

Evolutionary history

Lemurs are primates belonging to the suborder Strepsirrhini. Like other strepsirrhine primates, such as lorises, pottos, and galagos, they share ancestral (or plesiomorphic) traits with early primates. In this regard, lemurs are popularly confused with ancestral primates; however, lemurs did not give rise to monkeys and apes (simians). Instead, they evolved independently in isolation on Madagascar. All in strepsirrhines including lemurs are traditionally thought to have evolved from early primates known as adapiforms during the Eocene (56 to 34 mya) or Paleocene (66 to 56 mya). Adapiforms, however, lack a specialized arrangement of teeth, known as a toothcomb, which nearly all living strepsirrhines possess. A more recent hypothesis is that lemurs descended from lorisoids (loris-like) primates. This is supported by comparative studies of the cytochrome b gene and the presence of the strepsirrhine toothcomb in both groups. Instead of being the direct ancestors of lemurs, the adapiforms may have given rise to both the lemurs and lorisoids, a split that would be supported by molecular phylogenetic studies. The later split between lemurs and lorises is thought to have occurred approximately 62 to 65 mya according to molecular studies, although other genetic tests and the fossil record in Africa suggest more conservative estimates of 50 to 55 mya for this divergence. However, the oldest lemur fossils on Madagascar are actually subfossil