anterior lower premolar (P2). Also more aligned with dwarf lemurs, the first two upper molars (M1–2) have a more anterior hypocone that sits opposite the metacone, compared to the mouse lemurs' more posterior hypocone, which is presumably a symplesiomorphic (ancestral) trait. Also on M1 and M2, the cingulum (a crest or ridge on the tongue side) comprises two small cuspules. In all other dental characteristics, giant mouse lemurs are noticeably similar to both dwarf and mouse lemurs. Giant mouse lemurs have two pairs of mammae, one on the chest (pectoral) and one on the abdomen (abdominal). Their fur is typically grayish-brown on the dorsal (back) side and more gray in color on the ventral (front) side. The tail is typically black-tipped. The new population found by WWF in 2010 has an overall lighter color, along with reddish or rusty patches near the hands and feet on the dorsal side of the arms and legs. This population also has a red tail, which darkens at the end. Vibrissae are found above the eyes (superciliary), above the mouth (buccal), under the lower jaw (genal), near the top of the jaw (interramal), and on the wrist (carpal). Like mouse lemurs, the ears are large and membranous. Ear size is one differentiating factor between the northern giant mouse lemur and Coquerel's giant mouse lemur, with the former having shorter, rounded ears, while the latter has relatively large ears. The northern giant mouse lemur is generally larger and also has a shorter tail and shorter canine teeth. This species also has the largest testicles relative to body size of any living primate, with an average volume of , corresponding to 5.5% of its body weight. If human males had comparably sized testes, they would weigh and be the size of a grapefruit. Distribution and habitat Coquerel's giant mouse lemur has a spotty distribution across western Madagascar's dry deciduous forests due to the forest fragmentation throughout the region. The dry forests in this lowland region vary in elevation from sea level to . The range of this species is divided into northern and southern subpopulations, which are separated by several hundred kilometers. Both historical and current populations between these ranges are uncertain. The southern region is bound by the Onilahy River in the south and the Tsiribihina River in the north, while the northern population is found in the northwestern corner of the island at Tsingy