Cretaceous forests mapped

[Ben Creisler <bcreisler@gmail.com>]

From: Ben Creisler
bcreisler@gmail.com

An article in Geology that might interest some DML members:

Emiliano Peralta-Medina and Howard J. Falcon-Lang (2012)
Cretaceous forest composition and productivity inferred from a global
fossil wood database.
Geology 40 (3): 219-222
doi: 10.1130/G32733.1
http://geology.gsapubs.org/content/40/3/219.abstract

Abstract

Global patterns of Cretaceous forest composition and productivity are
analyzed using a comprehensive fossil wood database (n = 2238). To
ascertain forest composition, records were classified by botanical
affinity, plotted on georeferenced paleomaps, and analyzed with ArcGIS
tools. Results confirm previous conjecture that araucarioid and
podocarpoid conifers were globally codominant in Early Cretaceous
time, especially in humid tropical and paratropical biomes, but
drastically reduced in numbers and range during the Late Cretaceous.
Cupressoid conifers, which were most common in seasonally dry
mid-latitudes, and pinoid conifers, which were associated with
temperate conditions at higher northern latitudes, also declined at
the same time, though less markedly. Spatial analysis suggests that
the loss of conifer forests (especially araucarioids) was linked to
the rise of co-occurring angiosperms. Our data also show that while
angiosperms explosively diversified in mid-Cretaceous time, they did
not become forest dominants until the latest Cretaceous (25 m.y.
later), by which time the modern relictual pattern of conifer
distribution had been established. To ascertain forest productivity,
mean tree-ring width data were obtained from direct measurements and
literature reviews (n = 284) and plotted by paleolatitude. Comparison
with modern data shows that Cretaceous forest productivity was
significantly elevated (×2) in mid- and high paleolatitudes, implying
a poleward displacement of the temperate zone by >15°. Our data
provide quantitative verification of Cretaceous climate-vegetation
models and improve the understanding of the long-term effects of
future global warming.

For a news story:
http://planetearth.nerc.ac.uk/news/story.aspx?id=1170