Fruitland Formation the Colorado-New Mexico state line, and is one of the most productive areas for coalbed methane in the United States. The Fruitland is underlain by the Pictured Cliffs Sandstone, and overlain by the more recent Kirtland Formation. The sequence of rocks represents the final filling of the Cretaceous seaway. The underlying Pictured Cliffs is a marginal marine sandstone, deposited in an environment similar to offshore barrier islands of the southeast United States. As the seaway retreated, the Pictured Cliffs was covered by the Fruitland Formation, which was deposited in near-shore swampy lowlands. The formation is dated to the late Campanian
Organ Rock Formation seymouriamorph found in the Organ Rock Formation. "Seymouria sanjuanensis" is a unique taxon because of its extensive geographic range. This particular animal was first described by Vaughn (1966) from the Organ Rock Formation. Since this initial find, a number of these individuals have been recovered from localities as distant as Germany. Four early synapsid taxa are present within the Organ Rock Formation. These include Ophiacodon, as well as three sphenacodontids: "Ctenospondylus", "Dimetrodon", and "Sphenacodon ferocior". Most taxa are known from fragmentary material. Early synapsids were dominant members of the terrestrial Permian ecosystem. Some early synapsids adapted an herbivorous diet, however,