Biology Reference
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Figure 7.8 Fossil pollen of (a) Oreopanax (Araliaceae) and (b) Prumnopitys (Podocarpus) from
the Mio-Pliocene Pislepampa fl ora, Bolivia. Oreopanax and Prumnopitys growing together
(fi g. 7.9) in the modern cloud forest of Santa Cruz, Bolivia.
speaks clearly of the recent origin of páramo habitats and, thus, of páramo
vegetation. As noted earlier, it is further consistent with taxonomic stud-
ies of modern organisms that indicate páramo species are mostly derived
recently from progenitors growing at lower elevations, rather than from a
long period of in situ evolution at high altitudes.
Other aspects of vegetation history can be inferred from isotopic and
faunal evidence. MacFadden and others (1994) studied the 13 C in tooth
enamel from fossil mammals ranging from 25 million to 7500 years old that
included sites between 3200 and 4000 m elevation in the Bolivian Andes.
The results reveal a change in food resources from shrubs and nongrassy
herbs in the early to middle Miocene, to grassy páramo in the late Miocene
and Pliocene. This is evidence from yet another line of inquiry suggesting
the geologically recent origin of páramo. The consistency of information
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