tracing vegetation changes through carbon isotopes

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