Arundel Formation


The Arundel Formation, also known as the Arundel Clay, is a clay-rich sedimentary rock formation, within the Potomac Group, found in Maryland of the United States of America. It is of Aptian age. This rock unit had been economically important as a source of iron ore, but is now more notable for its dinosaur fossils. It consists of clay lenses within depressions in the upper part of the Patuxent Formation that may represent oxbow swamp facies. It is named for Anne Arundel County, Maryland.

Vertebrate paleofauna

Dinosaurs

Dinosaurs present include cf. Acrocanthosaurus, the poorly known theropods "Allosaurus" medius, "Creosaurus" potens, and "Coelurus" gracilis, the ornithomimosaurian "Dryosaurus" grandis, as well as another indeterminate ornithomimosaurian, the sauropod Astrodon, the nodosaurid Priconodon, a possible basal ceratopsian, and potentially the ornithopod Tenontosaurus. Other vertebrates are not as well known from the formation, but include a freshwater shark, a lungfish, at least three genera of turtles, and at least one crocodilian.

Pterosaurs

Unassigned pteradactyloid tracks.

Other fossils

W. B. Clark described lignitized trunks of trees often found in upright positions with their roots still intact.
G. J. Brenner described spores and pollen within the formation.

Footnotes