Premise of research. Numerous trimerous fossil flowers have been collected from Eocene strata in Wyoming, Utah, and Colorado. While many specimens have been assigned tentatively to Arecaceae, they have not been described formally, and their systematic placement within this large family has not been determined. Methodology. Fossils from the Eocene Bridger, Green River, and Wind River Formations were photographed, described, and measured. Pollen extracted from a stamen was studied by transmitted light, epifluorescence, and scanning electron microscopy. The floral and pollen morphological characters were compared to extant and fossil genera of angiosperms with a focus on Arecaceae. Pivotal results. Both macromorphological and palynological characters agree with assignment of the fossils to the extant genus Phoenix (L.). This is significant because Phoenix is native to Africa and southeast Asia today, but these fossils indicate a much broader distribution in the past. In addition, Phoenix cannot tolerate extensive freezing conditions, indicating a mostly frost-free climate when it was growing in the Rocky Mountain region during the Eocene. Conclusions. These fossil flowers represent a new species, Phoenix windmillis S.E. Allen sp. nov., significant because it is the first confirmation of the genus in the North American fossil record. The absence of pinnate induplicate palm leaves in the Eocene of North America that could be interpreted as Phoenix demonstrates the need to examine dispersed reproductive organs, as well as leaves, in evaluating fossil floras.
All Science Journal Classification (ASJC) codes
- Ecology, Evolution, Behavior and Systematics
- Plant Science