Carbon and strontium isotope ratios shed new light on the paleobiology and collapse of Theropithecus, a primate experiment in graminivory

The rise and spread of tropical grasslands was a signal event in the Cenozoic, causing many ungulates to evolve adaptations diet graminoid tissues, or graminivory. In parallel, lineage monkeys (Theropithecus) is distinguished among primates for its large size commitment graminivory, trait expressed by species throughout Plio-Pleistocene fossil record T. gelada, sole surviving today. An open question concerns mechanics how Theropithecus handled tissues. They might have exhibited preference, selecting tissues within given tuft, they practiced indiscriminate bulk-feeding manner similar grazing ungulates. To differentiate between these handling behaviors, we used time- graminivore-calibrated carbon stable isotope values show progressive reliance on high-throughput Variation this behavior explains significant amount variation body mass through time, describe covarying traits, which peaked during Pleistocene, as evolutionary traps. support characterization, report evidence temporal increases strontium variability North African theropiths, result that suggests greater lifetime travel energetic costs response diminishing food resources, probable factor extinction oswaldi, largest monkey ever lived.