What did Hadropithecus eat, and why should paleoanthropologists care?

Area of Science:

• Paleontology
• Primatology
• Paleoecology

Background:

• The extinct Malagasy lemur Hadropithecus stenognathus exhibits craniodental similarities to basal hominins and geladas.
• Previous studies on Hadropithecus' diet using dental microwear, morphology, and finite element analysis yielded contradictory results.
• The evolutionary reasons for craniodental convergences between Hadropithecus, hominins, and Theropithecus remain unclear.

Purpose of the Study:

• To review existing hypotheses on the diet of Hadropithecus stenognathus.
• To investigate the diet of Hadropithecus using stable carbon and nitrogen isotope data.
• To explain the craniodental convergences observed in Hadropithecus.

Main Methods:

• Review of prior hypotheses concerning Hadropithecus diet.
• Analysis of stable carbon and nitrogen isotope data from Malagasy lemurs, including new data from the central highlands.
• Comparison of isotopic signatures to infer dietary patterns.

Main Results:

• Hadropithecus exhibits a distinct isotopic signature in the central highlands of Madagascar.
• This signature differs significantly from other lemur populations on the island.
• Isotope data suggest Hadropithecus primarily consumed succulent leaves from CAM plants.

Conclusions:

• Hadropithecus stenognathus did not specialize in grasses or hard objects.
• The diet of succulent CAM plant leaves explains the unique isotopic signature and craniodental morphology.
• This dietary specialization offers a resolution to the debated ecological significance of its morphology.