Hadropithecus lived in open habitat in the Central Plateau, South, and Southwest regions of Madagascar.

[1] The species was formally described in 1899 from a mandible (lower jaw) found at Andrahomana cave in southeastern Madagascar by paleontologist Ludwig Lorenz von Liburnau, who thought it represented an ape.

[7] A year later, Lorenz von Liburnau also described Pithecodon sikorae based on photographs of a skull, which upon further review turned out to be a juvenile version of Hadropithecus stenognathus.

[4] Daubentoniidae †Megaladapidae Lemuridae Cheirogaleidae Lepilemuridae †Archaeolemur majori †Archaeolemur edwardsi †Hadropithecus stenognathus †Palaeopropithecidae Indriidae Based on similarities in their skull and teeth, it was later thought that monkey lemurs (Hadropithecus and Archaeolemur) were a sister group to the living indriids and the recently extinct sloth lemurs (family Palaeopropithecidae).

The matter was settled with the discovery of new skeletons of Babakotia and Mesopropithecus, two genera of sloth lemur, both of which had indriid-like skulls and teeth.

[11] More recently, postcranial remains of Hadropithecus found in the early 2000s prompted the suggestion that the monkey lemurs were more closely related to the lemurids.

[4] Although fewer postcranial remains have been discovered for Hadropithecus than for Archaeolemur, what has been found indicates that both were adapted for a terrestrial or semi-terrestrial lifestyle,[1][5][6][12] an unusual trait for lemurs.

[11] Due to its specialized dentition and likely diet, Hadropithecus is thought to have been the more terrestrial of the two,[12] since Archaeolemur may have sent more time foraging and sleeping in the trees.

[14][15] More recent microwear analysis suggests differences between Gelada Baboons and Hadropithecus, indicating that this extinct lemur may not have been a grazer, but strictly a hard object processor.

[4] Because of the low number of subfossil finds, Hadropithecus is thought to have been rare,[12] and it died out sooner than its sister taxon, Archaeolemur.