 Mesopropithecus was named in 1905 by Herbert F. Standing using four skulls found at Ampasambazimba . He noted that the animal had characteristics of both Palaeopropithecus and the living sifakas ( Propithecus ) . In 1936 , Charles Lamberton defined Neopropithecus globiceps ( based on one skull from Tsirave ) and N. platyfrons ( based on two skulls from Anavoha ) . He thought that Neopropithecus was a separate , intermediate genus between Mesopropithecus and Propithecus . In 1971 , paleoanthropologist Ian Tattersall merged N. platyfrons into N. globiceps and Neopropithecus into Mesopropithecus . 
