Modernizing - A Natural History of the New World - page 249

Figure 7.2 Pollen of Picea (spruce) from the middle Pliocene Paraje Solo Formation near
Coatzacoalcos, Veracruz, Mexico.
surprises. By the Pliocene, the eastern end of the Transvolcanic Belt had
reached moderately high elevations, so there was an altitudinal cline from
mangrove-fringed coastlands with Acrostichum , Hibiscus , Laguncularia , and
Rhizophora (over 96 percent in some samples) upward to montane conifer-
ous forest with Abies , Picea (fi g. 7.2), and probably some high-altitude pines.
In between, the ecosystems included beach/strand/dune with Acacia , Case-
aria , Coccoloba , Terminalia , and Poaceae (grasses); freshwater herbaceous
bog/marsh/swamp with Arecaceae (palms), Cyperaceae (sedges), and Ty-
pha ; aquatic Ceratopteris , Ludwigia , Pachira , Utricularia ; and lower to upper
montane broad-leaved forest; along with a prominent deciduous forest as-
sociation of northern temperate elements like Alnus , Juglans , Liquidambar ,
Populus , Quercus , and Ulmus . As expected at this moist coastal site, there
was no evidence of local desert, shrubland/chaparral-woodland-savanna,
or grassland ecosystems, although they were well-established elsewhere by
this time. Likewise, there was no evidence of páramo, although elements
may have been present at the highest elevations and undistinguishable in
the fossil record from non-páramo taxa or not represented in the lowland
basin of deposition; and there was no tundra, which has never existed in
lowlands of the New World outside the polar regions or along the margins
of glaciers.
One of the unexpected results was the absence of pollen from any of the
nine to eleven genera of trees that now form the dominants of the lowland
neotropical rain forest in Veracruz. In the present arrangement, the rain