01750nas a2200205   4500008004100000245005300041210005300094260001000147300001600157490000700173520121900180653001701399653001101416653000801427653001101435653001201446653001701458100002401475856004501499       2001                        eng d00aGlobal biodiversity and the ancient carbon cycle0 aGlobal biodiversity and the ancient carbon cycle  cApril  a4305–43100 v983 a10.1073/pnas.071047798 Paleontological data for the diversity of marine animals and land plants are shown to correlate significantly with a concurrent measure of stable carbon isotope fractionation for approximately the last 400 million years. The correlations can be deduced from the assumption that increasing plant diversity led to increasing chemical weathering of rocks and therefore an increasing flux of carbon from the atmosphere to rocks, and nutrients from the continents to the oceans. The CO concentration dependence of photosynthetic carbon isotope fractionation then indicates that the diversification of land plants led to decreasing CO levels, while the diversification of marine animals derived from increasing nutrient availability. Under the explicit assumption that global biodiversity grows with global biomass, the conservation of carbon shows that the long-term fluctuations of CO levels were dominated by complementary changes in the biological and fluid reservoirs of carbon, while the much larger geological reservoir remained relatively constant in size. As a consequence, the paleontological record of biodiversity provides an indirect estimate of the fluctuations of ancient CO levels.10abiodiversity10acarbon10aco210acycles10ahistory10apaleontology1 aRothman, Daniel, H.  uhttp://dx.doi.org/10.1073/pnas.071047798