Geoscience Reference
In-Depth Information
Origins of the Asian-Pacific Rainforest
As noted in the Chapter 2, during the Tertiary Period (55 mya) the tropical rainfor-
est formed an almost continuous belt from Africa, across Europe into Asia and
Southeast Asia, and into the Far East. Although occasionally broken up by narrow
seaways, the regions of Africa and Asia were able to share many taxa. By about 10
mya, climatic cooling and drying separated the two areas and led to the develop-
ment of savannas and deserts, and the connection was lost. During the Pleistocene
Epoch, additional cycles of drying and cooling, which significantly restricted the
tropical rainforests of Africa and the Neotropics, are thought to have had a lesser
effect on the Asian-Pacific rainforest.
More than 40 mya, the island continent of Australia and New Guinea snapped
free of the large landmass that included Antarctica and South America and began
to drift toward the Equator. Cut off from the rest of the world, the super-island
evolved its own distinctive flora and fauna. When the split occurred, the Australian
Figure 3.15 Wallace's Line denotes the end of the Sunda Shelf and separates the West
and East Malesian regions.
(Map by Bernd Kuennecke.)
