FOSSIL PLANTS OF JANCOCATA 209 



ation of this conclusion. The question of change in altitude 

 between then and now is more obscure. The Pteris, Phrag- 

 mites, Alnus, Osteomeles and Polylepis all range upward to 

 10,000 feet or more where there is sufficient humidity, and 

 the upper limit of two of these, namely the Osteomeles and 

 the Polylepis is still higher. On the other hand the Callian- 

 dra, Csesalpinia and Melastomites are similar to Amazon 

 basin types, although all three range upward in the wet 

 montana zone that skirts the Eastern Andes and constitutes 

 the Yungas of Bolivia. The Cassia could belong in either of 

 the two foregoing categories. The upper limit of range of 

 all of these forms is not necessarily a measure of the altitude 

 of the fossils, since all of their existing relatives find their 

 optimum conditions considerably below their upper limits. 

 There appears to have been some elevation since this fossil 

 flora was living, but this may be only apparent, and it seems 

 possible that with the Eastern Andes much lower than at pres- 

 ent there would have been sufficient moisture in the plateau 

 region for this flora to have existed without any great change 

 of level. 



The present study shows a close correlation with the pres- 

 ence of large extinct herbivorous mammals in this region and 

 largely confirms the s.urmise of Pompeckj, who, from a 

 study of the mammals inferred the presence of more mois- 

 ture and a more abundant vegetation at the time they flour- 

 ished than at present. He, however, referred to it as a steppe 

 climate. It was still more genial than that term usually con- 

 notes. The Pliocene Altaplanacie may legitimately be pictured 

 as having an abundant rainfall with abundant grasses and 

 trees, and in every way suitable for sustaining the large mam- 

 mals which we know inhabited it. 



