Upper Cretaceous and Paleocene floras of the Raton Basin, Colorado and New Mexico
— Sidney R. Ash and William D. Tidwell

Fossil plant remains, particularly leaves, occur at many localities in the Upper Cretaceous Trinidad and Vermejo formations and in the Upper Cretaceous and Paleocene Raton Formation in the Raton basin of Colorado and New Mexico. The fossils are especially abundant in the coal-bearing portions of the Vermejo and Raton formations and are of special interest because they can be used to locate the Mesozoic-Cenozoic boundary in the basin. They also enable scientists to visualize the paleoecological conditions in the Raton basin at the time when these formations were being deposited.

The purpose of this paper is to summarize Upper Cretaceous and Paleocene floras in the Raton basin. Although it is based primarily on the monograph published by Knowlton (1917) on the Vermejo and Raton floras, this paper reflects the changes made in the classification and nomenclature of some of these plant fossils since 1917. These changes were proposed by Dorf (1938, 1942), Brown (1962) and Read and Hickey (1972). It is possible that additional changes will be proposed in the future as the Upper Cretaceous and Paleocene floras of the western interior of the United States are currently being restudied by L. J. Hickey of the U.S. National Museum.