 Until 1986 , Mesopropithecus was only known from cranial ( skull ) remains from central and southern Madagascar , and because these are similar to teeth and skulls of living indriids , particularly those of Verreaux 's sifaka ( Propithecus verreauxi ) , Mesopropithecus was often assigned to the family Indriidae . For example , in 1974 , Tattersall and Schwartz labeled Mesopropithecus as a sister group to sifakas . With the discovery of an associated skeleton of M. dolichobrachion near Ankarana in 1986 , it became clear that Mesopropithecus shared distinct traits with sloth lemurs . Unlike the indriids , but like the sloth lemurs , they had elongated forelimbs and other adaptations for arboreal suspension ( hanging in trees ) , linking them most closely to family <unk> . A comparison of these morphological traits between the sloth lemurs and indriids suggest that Mesopropithecus was the first genus to diverge within the sloth lemur family . 
