A single flower, detached anthers with in situ pollen grains, and isolated seeds from Campanian strata (Upper Cretaceous) of Georgia, southeastern USA, document the presence of plants assignable to Hamamelidaceae in the Upper Cretaceous. The fossil flower is actinomorphic, pentacyclic and pentamerous. Irregular sepals are preserved as lobes of the floral cup, and petals are narrow, with parallel margins. The androecium has two whorls of functional stamens. Anthers are tetrasporangiate, dehisce through two valves, and have strongly elongate connective protrusions which converge over the center of the flower. The organizational and architectural features of the fossil document its affinity within subtribe Loropetalinae (Hamamelideae. Hamamelideae). Cladistic phylogenetic analyses using parsimony were conducted to explore the relationships between the fossil flower and extant genera of the tribe Hamamelideae. The strict consensus of the four most parsimonious trees shows Hamamelideae and Loropetalinae as well- supported monophyletic taxa. The fossil flower is clearly included within the Loropetalinae, and is placed as sister taxon to the southeastern Asian genus Maingaya. The occurrence of fossils assignable to Loropetalinae during the Campanian documents the existence of Hamamelidaceae with a level of floral organization and character evolution equivalent to that of extant genera, early in the evolutionary history of the family.
- Allonia decandra. - Fossil flower
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Plant Science