TAXONOMY AND DISTRIBUTION OF SOLITARY RUGOSE CORALS IN THE SILURIAN ROCKWOOD FORMATION, HAMILTON COUNTY, SOUTHEAST TENNESSEE

A fossiliferous portion of the Silurian Rockwood Formation is exposed in southeastern Tennessee in Tiftonia. The assemblage consists predominantly of brachiopods, corals, bryozoans, blastoid/crinoid columnals, and gastropods. This study examines the population of solitary rugose corals in the Rockwood and identifies and describes the abundance and distribution of the corals within the unit. This research uses a collection of approximately 500 rugose specimens collected from the Tiftonia outcrop over a period of several years. Measurements of the external morphology (calyx diameter and corallum length) and visual comparisons of the internal structure are used to determine taxonomy, and examinations in the field determined how the corals are distributed throughout the 12 meters of exposed Rockwood. The rugose population is dominated by the genus Streptelasma, and an additional genus, Anisophyllum, was identified in the Rockwood during the course of this research. Preliminary results suggest that 85% of the collection is Streptelasma, 3% is Anisophyllum, and the remaining specimens have yet to be identified. Rugose specimens are found almost exclusively in the uppermost layers of the exposure where the lithology contains coarser grains and limestone beds, whereas thick shale intervals characterize lower sections of the Rockwood.