2026/06/01 by Ellen Gieser, Michael P. Donovan, Camila Pizano +1
Agricultural and Biological Sciences · #Plant Diversity and Evolution #Plant and Biological Electrophysiology Studies #Fern and Epiphyte Biology
paper · doi:10.1016/j.revpalbo.2026.105639
Araceae leaves have been known for decades from the Lagerstätte of Fossil Lake (early Eocene) in Wyoming, North America, yet their taxonomic identity and paleoecological significance have not been previously evaluated. We examined a large collection of historical and newly collected fossil leaves housed at the Field Museum and Fossil Butte National Monument using light and fluorescence microscopy, and conducted detailed morphological comparisons with extant and fossil Araceae. We describe two new genera and species, Anomacolocasioides demkovichorum gen. et sp. nov. and Gigantosagittata graingeriana gen. et sp. nov. Anomacolocasioides exhibits a unique combination of venation and laminar characters not observed in any known fossil or extant clade of Araceae. Gigantosagittata represents some of the largest aroid leaves documented in the fossil record and displays venation patterns comparable to large-leaved extant Araceae taxa. These fossils expand the diversity of Araceae during Early Eocene Climatic Optimum (EECO) and provide new evidence for the marginal vegetation of the Fossil Lake system. Although their precise phylogenetic placement remains uncertain in the absence of reproductive structures, future discoveries of associated flowers or fruits will be critical for clarifying their evolutionary relationships within Araceae.