Early On - A Natural History of the New World - page 200

for the New World (chap. 1). Eight were present at the beginning of the Cre-
taceous, although they were unique or distant versions of the current ones,
and seven were present in South America by the end of the early Eocene:
The aquatic (Cretaceous) and the lowland neotropical rain forest (Paleo-
cene) are the oldest, and the latter is the oldest forested community to be
readily recognizable in terms of its modern (angiosperm prominent) coun-
terpart. The rain forest graded into a lower to upper montane broad-leaved
forest in places of moderate altitude and in drier habitats. There were early
versions of freshwater herbaceous bog/marsh/swamp, mangrove (without
Rhizophora ), and probably beach/strand/dune ecosystems; and by the mid-
dle Eocene, elements of a shrubland/chaparral-woodland-savanna (steppe)
were present. Absent were even early versions of desert, tundra, alpine tun-
dra (páramo), coniferous forest (which never developed in South America
in the absence of Abies , Picea , and Pinus ; Podocarpus is typically scattered in
temperate and occasionally more lowland forests), and few or no expanses
of grassland.
At the beginning of the middle Eocene, signifi cant climatic and physio-
graphic changes took place in the New World that ushered in an additional
ecosystem (the coniferous forest in northern North America), continued
the modernization of others already present (mangroves with Rhizophora ,
shrubland/chaparral-woodland-savanna), and witnessed the appearance of
elements and early versions of desert, grassland, tundra, and alpine tundra
(páramo).

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