text: hadropithecus hadropithecus is a medium - sized , extinct genus of lemur , or strepsirrhine primate , from madagascar that includes a single species , hadropithecus stenognathus . due to its rarity and lack of sufficient skeletal remains , it is one of the least understood of the extinct lemurs . both it and archaeolemur are collectively known as " monkey lemurs " or " baboon lemurs " due to body plans and dentition that suggest a terrestrial lifestyle and a diet similar to that of modern baboons . hadropithecus had extended molars and a short , powerful jaw , suggesting that it was both a grazer and a seed predator . the monkey lemurs are considered to be most closely related to the living indriids and the recently extinct sloth lemurs , although recent finds had caused some dispute over a possible closer relation to living lemurids . genetic tests , however , have reaffirmed the previously presumed relationship . hadropithecus lived in open habitat in the central plateau , south , and southwest regions of madagascar . it is known only from subfossil or recent remains and is considered to be a modern form of malagasy lemur . it died out around 444 – 772 ce , shortly after the arrival of humans on the island . etymology the common names that hadropithecus shares with archaeolemur , " monkey lemurs " and " baboon lemurs " , come from their dental and locomotor adaptations , which resemble that of modern african baboons . the genus hadropithecus is derived from the greek words , , meaning " stout " or " large " , and , , meaning " ape " . the species name derives from the greek root , , meaning " narrow " , and , , meaning " jaw " or " mouth " . classification and phylogeny hadropithecus stenognathus is classified as the sole member of the genus hadropithecus and belongs to the family archaeolemuridae . this family in turn belongs to the infraorder lemuriformes , which includes all the malagasy lemurs . the species was formally described in 1899 from a mandible ( lower jaw ) found at andrahomana cave in southeastern madagascar by paleontologist ludwig lorenz von , who thought it represented an ape . a year later , lorenz von also described based on photographs of a skull , which upon further review turned out to be a juvenile version of hadropithecus stenognathus . in a publication from 1902 , he declared that stenognathus was not an ape , but a lemur . over 100 years later , the rarity of its skeletal remains has made this species one of the least understood species of subfossil lemur . 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 ) . however , there was some debate over whether the monkey lemurs or the sloth lemurs were more closely related to today 's indriids . the monkey lemurs had skulls that more closely resembled the indriids , but their teeth were very specialized and unlike those of the indriids . the sloth lemurs , on the other hand , had teeth like the indriids , but very specialized skulls . 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 . 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 . however , dna sequencing has reaffirmed the sister group status of the monkey lemurs to indriids and sloth lemurs . anatomy and physiology hadropithecus stenognathus has been estimated to have weighed between 27 and 35 kg ( 60 and 77 lb ) and to have been roughly as large as archaeolemur , although more gracile . newer subfossil finds , however , suggest that hadropithecus may have been more robust , and more like a gorilla than a baboon . it may also have been less agile than old world monkeys . both lemurs were quadrupedal ( walked on four legs ) . there is no evidence of ( adaptations specifically for running ) in either species , and although hadropithecus could have climbed trees , it lacked adaptations for leaping or suspension . 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 , an unusual trait for lemurs . both genera had short limbs and a powerful build . due to its specialized dentition and likely diet , hadropithecus is thought to have been the more terrestrial of the two , since archaeolemur may have sent more time foraging and sleeping in the trees . both genera also have shortened hands and feet , an adaptation for walking on the ground . the face of hadropithecus was shortened and adapted to heavy stress from chewing . the monkey lemurs had highly specialized teeth , but hadropithecus went further by specializing in strong grinding . it had expanded molars that wore down quickly , much like those of ungulates , and its posterior premolars acted like molars to extend the grinding surface . it also had a robust mandible to facilitate crushing hard objects . even the strepsirrhine toothcomb was reduced in this species . its dental formula was 2 . 1 . 3 . 31 . 1 . 3 . 3 × 2 34 the skulls of both hadropithecus and archaeolemur indicate that monkey lemurs had relatively large brains compared to the other subfossil lemurs , with hadropithecus having an estimated endocranial volume of 115 ml . ecology like all other lemurs , hadropithecus was endemic to madagascar . because it died out only recently and is only known from subfossil remains , it is considered to be a modern form of malagasy lemur . it once ranged across the central plateau , south , and southwest regions of madagascar . within its original range , there were few other lemurs to overlap its ecological niche , and it has been shown to be the only subfossil lemur to consume both c3 and c4 ( or cam ) plants , an indication that it lived in more open habitats and had a varied diet . its physiology and dentition suggest that it may have been much like the baboon in locomotion and diet , acting as a manual grazer ( picking grass with the hands ) since its teeth were well - adapted for grinding either grass or seeds . patterns on its teeth , as well as its overly large molars , indicate it processed hard objects like nuts or seeds , making it a seed predator . more recent microwear analysis suggests differences between and hadropithecus , indicating that this extinct lemur may not have been a grazer , but strictly a hard object processor . extinction because of the low number of subfossil finds , hadropithecus is thought to have been rare , and it died out sooner than its sister taxon , archaeolemur . both disappeared shortly after the arrival of humans to the island , but being a large , specialized , terrestrial grazer , hadropithecus would have faced more pressure from domestic livestock , introduced pigs , and spreading human populations than its more generalized cousin . the last known record was radiocarbon dated to around 444 – 772 ce .