Bryozoans from the Murfreesboro and Pierce Limestones (Early Black Riveran, Middle Ordovician), Stones River Group, of Central Tennessee

The Murfreesboro Limestone and the succeeding Pierce Limestone (Black Riveran, Middle Ordovician) of the Stones River Group, the oldest rocks exposed in central Tennessee, contain a fossil invertebrate fauna including bryozoans. Bryozoans are relatively scarce in the Murfreesboro Limestone but are abundant in the overlying Pierce Limestone. The bryozoan fauna includes the cryptostomes, Escharopora, Graptodictya, Pachydictya, Phylloporina, Stictopora, Stictoporella, Trigonodictya, Ulrichostylus; the trepostomes Amplexopora, Batostoma, Hemiphragma, Nicholsonella, Parvohallopora; and the cystoporates Ceramophylla and Constellaria. These bryozoans are the oldest known in Tennessee and are the only early Black Riveran assemblage in North America described at the species level. Species of Nicholsonella, Pachydictya, and Stictopora in the Murfreesboro and species of Constellaria and Phylloporina? in the Pierce are closely related to those found in rocks of Chazyan age in New York and Vermont. Species of Ceramophylla, Escharopora, and Trigonodictya in the Pierce Limestone of central Tennessee are decidedly similar to species found in Black Riveran strata of New York. The stratigraphic ranges, geographic distribution, and taxonomy of previously described species from Tennessee are updated.