Tracing Vegetation Changes through Carbon Isotopes
Implication for ecosystems and human evolution
•C3 and C4 plants have photosynthetic pathways that fractionate stable carbon isotopes to different degrees •d values between -36.5‰(VPDB) and -22‰ for C3
•d values between -15‰ and -11‰ for C4
•~14‰ enrichment factor in large mammals compared to their diet
[Cerling et al., 1997]
Extant d13C values for herbivore tooth enamel
[Levin et al., 2008]
d13C values in ‰ of tooth enamel for fossil herbivores from:A. As Duma MemberB. Segala Noumou MemberC. Gona Western Margin SouthD. Adu-Asa Formation
Gray bars represent d13C values for averages expected of strict C3 diet from closed-canopy, C3 from forest/bushland, and C4 grassland.
[Levin et al., 2008]
• These fossil herbivore teeth were found in situ with Ardipithecus kadabba and Ardipithecus ramidus.
• Most similar to isotopic values from extant herbivores living in bushland and grassland
What type of environment did early man evolve in?
Ardipithecus ramidus