Revisions to Roland Brown’s North American Paleocene flora

Abstract

The Paleocene megafossil flora of the Rocky Mountains and Great Plains region in the United States of America, including leaves, cones, fruits, and seeds, monographed by Roland W. Brown in 1962, has been reevaluated and updated to include subsequent taxonomic revi- sions. The scope of this investigation included thousands of specimens from more than 450 localities of the Fort Union, Evanston, Ferris, Raton, Bear, Lebo, Melville, Ludlow, Tongue River and Sentinel Butte strata of New Mexico, Colorado, Wyoming, Montana and North and South Dakota. A large number of floristic elements remain uncertain as to their modern familial affinities due to limited diagnostic characters, or insufficient comparative investigations. Nevertheless, many of Brown's determinations have been upheld and several newly recognized genera and families have strong support. The flora includes greater diversity of Platanaceae and Cornales than Brown had recognized. These, together with Fagales (particularly Betulaceae and Juglandaceae), Saxifragales (Trochodendroides, Archeampelos and Nyssidium), are wide- spread and prominent members of the flora. New combinations introduced here include Ensete goldianum (LESQUEREUX) comb. nov., Macgini- tiea nobilis (NEWBERRY) comb. nov., Platanites raynoldsii (NEWBERRY) comb. nov., Trochodendroides genetrix (NEWBERRY) comb nov., Cucurbitaciphyllum lobatum (KNOWLTON) comb. nov., and Mciveraephyllum nebrascense (SCHIMPER) comb. nov. Georeference data are provided for all of the localities cited by Brown.