Early On - A Natural History of the New World - page 181

the later developing deciduous forest ecosystem, and through the evolution
and immigration of ecologically and taxonomically new lineages and com-
munities. It would be replaced by warm-temperate to subtropical vegeta-
tion in the early Eocene, a more modern deciduous forest in the late Eocene
through the early Miocene, then a boreal forest, and fi nally by tundra at the
extreme high northern latitudes.
To the south, between paleolatitudes 60°N and 50°N, the MAT was
13°C-20°C, and the Late Cretaceous to Paleocene vegetation is called a no-
tophyllous broad-leaved evergreen forest. Note the key difference here is
“evergreen” rather than “deciduous.” Notophyll is a size class of leaves in a
classifi cation frequently used in ecology and for vegetation mapping. Small
leaves (i.e., microphyll and smaller) are commonly associated with cold,
open habitats, and dry climates, and large leaves (notophyll and larger)
with warmer, closed (darker) habitats, and moister climates:

Leptophyll maximum size 0.25 cm 2

Nanophyll 2.25 cm 2

Microphyll 20.25 cm 2

Notophyll 45 cm 2

Mesophyll 182.25 cm 2

Macrophyll 1640.2 cm 2

Megaphyll no maximum size

The notophyllous broad-leaved evergreen forest can be characterized as
follows:

An ecotonal (transitional) vegetation between a temperate fl ora to the north
and a subtropical fl ora to the south; mean of the coldest month about 1°C,
MAT about 13°C; a few broad-leaved deciduous trees present; gymnosperms
not common; buttressing rare, drip tips absent, mesophyll to notophyll size
class; entire-margined leaves 40-60 percent.

Compared to the polar broad-leaved deciduous forest, environmental
conditions in the notophyllous broad-leaved evergreen forest were warmer,
moister, less seasonal, with more light, and much of the vegetation was ev-
ergreen throughout the year, except in unpredictable habitats like stream-
sides and along the margins of shallow lakes. Gymnosperms included the
evergreen Cunninghamia currently of southeastern Asia (Brink et al. 2009),
and members of the Taxodium - Metasequoia - Sequoia - Sequoiadendron (bald
cypress-dawn redwood-coast redwood-big tree) complex—all deciduous