Paleontology of Ogallala Formation, northeastern New Mexico

Abstract

Two outstandingly productive sections in northeastern New Mexico yielded fossil seed floras that confirm the correlation between clay-mineral zonation in the Ogallala Formation and that based on fossil floras. The fossil seed floras place the sections in the Ash Hollow and lower Kimball members. The Kimball Clayton South section is remarkable for the substantial seed flora it contains and is unique for the well-preserved molluscan fauna of 26 taxa, three of which have been described as new. The Seneca Northeast section not only contains a distinctive seed flora but is outstanding for the occurrence of three species of hackberry: Celtis hatcheris Chaney, hitherto known only from Oligocene sediments; C. willistoni (Cockerell) Berry, the common and widespread hackberry in the Ogallala Formation; and C. cf. reticulata Torrey, a species living in the area today. Ecological implications of the Clayton South molluscan fauna indicate no remarkable difference from present climate, except for lesser temperature extremes and rainfall sufficient to maintain natural marshes and/or (possibly ephemeral) ponds.