LUPIA, RICHARD*, PATRICK S. HERENDEEN, SUSANA MAGALLON-PUEBLA, PETER R. CRANE, AND JOLANTA KOBYLINSKA. Department of Geology, The Field Museum, Roosevelt Road at Lake Shore Drive, Chicago, IL 60605; Department of Biological Sciences, The George Washington University, 2023 G Street Northwest, Washington, DC; Department of Geophysical Sciences, The University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637. - The Allon flora (Late Cretaceous, Georgia): diversity, abundance, and evolutionary implications.
The Allon locality (late Santonian, Cretaceous) of Crawford County,
Georgia has yielded a diverse flora of angiosperms,
"gymnosperms" and "pteridophytes". Macrofossils,
mesofossils and microfossils record the vegetation that lived around a
floodplain pond. Currently 12 morphotypes of leaves and approximately
50 morphotypes each of mesofossils and palynomorphs are recognized.
"Pteridophytes" are rare in both the macroflora and
mesoflora, but are considerably more diverse and abundant in the
microflora. "Gymnosperms" are represented by several types
of conifers in the mesofloras and microfloras, but only by
taxodiaceous/cupressaceous forms in the macroflora. Angiosperms
dominate all fossil assemblages both in terms of diversity and
abundance. The preserved angiosperm flowers are primarily small and
several are trimerous and epigynous, although other forms are common.
Many flowers have structures resembling nectaries suggesting close
association with insects. Insect interactions with flowers are also
suggested by the presence of coprolites containing a single species of
pollen. The mesoflora at Allon has yielded the earliest members of
the Fagaceae sensu lato, the first flowers from North American with
Normapolles pollen in situ, as well as Actinidiaceae, Hamamelidaceae,
Lauraceae and other families. The preservation of both mesofossils
and microfossils also has permitted the investigation of the
concordance in the composition of these assemblages and reveals that
there are many taxa that are not represented in the dispersed
palynoflora.
Key words: angiosperms, Cretaceous, Georgia, paleobotany, paleoecology, Santonian