page_title: Fork-marked lemur
section_title: Description
hierarchical_section_title: Fork-marked lemur / Description
caption_attribution_description: English: Masoala fork-marked lemur (Phaner furcifer)
context_page_description: Fork-marked lemurs or fork-crowned lemurs are strepsirrhine primates; the four species comprise the genus Phaner. Like all lemurs, they are native to Madagascar, where they are found only in the west, north, and east sides of the island. They are named for the two black stripes which run up from the eyes, converge on the top of the head, and run down the back as a single black stripe. They were originally placed in the genus Lemur in 1839, later moved between the genera Cheirogaleus and Microcebus, and given their own genus in 1870 by John Edward Gray. Only one species was recognized, until three subspecies described in 1991 were promoted to species status in 2001. New species may yet be identified, particularly in northeast Madagascar.
  Fork-marked lemurs are among the least studied of all lemurs and are some of the largest members of the family Cheirogaleidae, weighing around 350 grams or more. They are the most phylogenetically distinct of the cheirogaleids, and considered a sister group to the rest of the family. Aside from their dorsal forked stripe, they have dark rings around their eyes, and large membranous ears.
context_section_description: Of the mostly small, nocturnal lemurs in family Cheirogaleidae, the genus Phaner contains some of the largest species, along with Cheirogaleus. Their body weight ranges between 350 and 500 g (0.77 and 1.10 lb), and their head-body length averages between 23.7 and 27.2 cm (9.3 and 10.7 in), with a tail length between 31.9 and 40.1 cm (12.6 and 15.8 in).
  Fork-marked lemurs' dorsal (back) fur is either light brown or light grayish-brown, while their ventral (underside) fur can be yellow, cream, white, or pale brown. A black stripe extends from the tail, along the dorsal midline to the head, where it forks at the top of the head in a distinguishing Y-shape leading to the dark rings around both eyes, and sometimes extends down the snout. The dorsal stripe varies in width and darkness. The base of the tail is the same color as the dorsal fur and is usually tipped in black; the tail is bushy. The lemurs' ears are relatively large and membranous. Males have a scent gland on the middle of their throat, which is approximately 20 mm (0.79 in) wide and pink in color. Females have a narrow, bare patch of white skin in the same location, but theirs does not appear to produce secretions.
  These lemurs have relatively long hindlegs. For gripping tree trunks and large branches, they have large hands and feet with extended pads on the digits, as well as claw-like nails. They have a long tongue which assists obtaining the gum and nectar, as well as a long caecum, which helps digest gums. Their procumbent (forward-facing) lemuriform toothcomb (formed by the lower incisors and canines) is long and more compressed, with significantly reduced interdental spaces to minimize the accumulation of gum between the teeth.
  The genus is distinguished from other cheirogaleids by the toothrows on its maxilla (upper jaw), which are parallel and do not converge towards the front of the mouth. The fork-marked lemur dental formula is  × 2 = 36; on each side of the mouth, top and bottom, there are two incisors, one canine, three premolars, and three molars—a total of 36 teeth. Their upper first incisor (I¹) is long and curved towards the middle of the mouth (unique among lemurs), while the second upper incisor (I²) is small with a gap (diastema) between the two. The upper canines are large, with their tips curved. Their upper anterior premolars (P²) are caniniform (canine-shaped) and more pronounced than in any other living lemur. The next upper premolar (P³) is very small, with a single, pointed cusp that contacts the lingual cingulum (a crest or ridge on the tongue side), which circles the base of the tooth. The two cusps on the last upper premolar (P⁴) are a large paracone and a smaller protocone. Like other cheirogaleids, their first lower premolar (P₂) is caniniform and large, while the cingulids (ridges) on the three lower premolars are more developed compared to most other cheirogaleids. The first two upper molars (M1–2) have a developed hypocone, and the buccal cingulum (a crest or ridge on the cheek side) is well developed on all three upper molars. The molars are relatively small compared to other cheirogaleids, with the second upper and lower molars (M² and M₂) having reduced functionality compared to those of mouse lemurs.
  Males have relatively small testes compared to other lemurs, and their canine teeth are the same size as those seen in females. During the dry season, females can weigh more than males. Both patterns of sexual dimorphism are consistent with the theory of sexual selection for monogamous species and female dominance respectively. Females have two pairs of nipples.
caption: P. furcifer, first described in 1839, was illustrated in Brehms Tierleben.
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