ABSTRACT

The diversity of cranial and postcranial elements of dinosaur remains, early mammals and palynomorphs in the Aguja Formation (Campanian) rivals many other Upper Cretaceous localities. Recently, a large, globular reptilian multi-tier coprolite, 5.9 in. (15 cm) in length, 3.5 in. (9 cm) in width, and 4.7 in. (12 cm) in height, of an unknown origin, was collected from the upper shale member of the Aguja Formation in Big Bend National Park, Brewster County, Texas. This rare and unusual find provides for the first evaluation of a large coprolite of this kind from the southwestern United States. The coprolite consists of at least ten individual, somewhat cylindrical or tubular, anisopolar units that curve into half-moon shapes. Organic inclusions include inner and outer bark tissue, conifer wood fragments, amber resin and pollen grains from assorted angiosperms. Inorganic inclusions consist of sand grains, manganese oxide, and secondary infillings of pyrite, fibrous-like chalcedony, iron-stained carbonate and white calcite. The size and structure and contents suggest that this coprolite was deposited by an herbivorous dinosaur.