Archaeoindris fontoynontii was a giant lemur species native to Madagascar. It resembled a sloth with its massive build, measuring up to 1.5 meters and weighing around 200 kg. Adapted to life in trees, it had strong limbs for climbing and a folivorous diet.

Archaeoindris fontoynontii was native to Madagascar, specifically found in the central highlands region. This extinct lemur species was endemic to the island and did not occur naturally elsewhere.

The typical habitat of Archaeoindris fontoynontii included the dry deciduous forests and woodland areas of Madagascar's central highlands. These regions are characterized by a seasonal climate with a distinct wet and dry season, and the vegetation primarily consists of deciduous trees that shed leaves during the dry season.

Archaeoindris fontoynontii occupied a niche similar to that of large herbivores, feeding primarily on leaves and possibly other plant materials available in its forested environment. It was adapted to a terrestrial lifestyle, unlike many other lemur species that are more arboreal.