A preliminary conspectus of the allon flora from the late cretaceous (Late Santonian) of central Georgia, U.S.A.

A preliminary conspectus of the fossil flora from the Allon locality, in Crawford County central Georgia, documents the presence of at least 63 distinct plant organs, based on macrofossils and mesofossils, but excluding dispersed pollen and spores. The fossils are preserved in a clay lens within the Buffalo Creek Member of the Gaillard Formation, and are of late Santonian (Late Cretaceous) age. In general, macrofossils are sparse at this site, but abundant mesofossils have been isolated from bulk samples by sieving. The flora includes sporophytes and gametophytes of fossil mosses (e.g., Eopolytrichum antiquum, Campylopodium allonense), ferns (e.g., cf. Boodlepteris), and conifers, but is dominated by the diverse and abundant remains of angiosperms. Angiosperms in the flora include cf. Detrusandra (Magnoliales), Mauldinia sp. (Lauraceae), Allonia decandra (Hamamelidaceae), and Parasaurauia allonensis (Actinidiaceae). Especially abundant are flowers and cupules of two species of Fagaceae sensu lato (Protofagacea allonensis, Antiquacupula sulcata). The flora also includes fossil flowers of Caryanthus sp. (Juglandales/Myricales) and Bedellia pusilla (cf. Betulaceae), which comprise the first record of Normapolles-producing flowers from North America. The structural and systematic diversity of angiosperms in the Allon flora is comparable to that at other Turonian-Campanian sites in eastern North America and Europe. Together, these fossil floras indicate that angiosperms, and especially eudicots, were already diverse at this relatively early stage in angiosperm evolution. The source vegetation represented by the Allon fossil assemblage was dominated by angiosperms, probably with taxodiaceous conifers also common. Preservation of most of the mesofossils as charcoal indicates that fire may have been an important factor contributing to frequent disturbance of the source plant community.