Paleoecology, brachiopods, Devonian, Lime Creek Formation, Cerro Gordo Member, epibionts, epifauna
Epibionts and borings are common on brachiopods from the Cerro Gordo Member of the Lime Creek Formation (Upper Devonian) at Rockford, Iowa. Occurrences and distributions of epibionts are best explained by attachment and subsequent growth on either living or dead brachiopods. Distribution of Spirorbis, a calcareous worm tube, is best explained by random attachment of worm larvae on living or dead brachiopods. Cornulites, a conical shell of uncertain affinity, commonly occurs with its aperture oriented toward the anterior commissure of brachiopods, suggesting attachment to living shells and subsequent growth in response to the feeding currents of the brachiopod. Some tabulate corals (auloporids) and some bryozoa (Hederella sp.) display growth patterns toward, or parallel to, the plane of commissure of brachiopods. Such patterns are understandable if these colonial epibionts grew on living brachiopods, taking advantage of the brachiopods' feeding currents. Circular borings and dendritic grooves are common on the brachiopod shells and may have caused the death of some brachiopods. Because the Cerro Gordo Member of the Lime Creek Formation was deposited on a muddy seafloor, attachment sites for small suspension feeders were limited. In this environment, brachiopod shells and horn corals provided relatively mud-free sites where epibionts could attach, grow, and survive.
Proceedings of the Iowa Academy of Science
©1982 Iowa Academy of Science, Inc.
Anderson, Wayne I. and Megivern, Kartherine Dimitracopoulos
"Epibionts from the Cerro Gordo Member of the Lime Creek Formation (Upper Devonian), Rockford, Iowa,"
Proceedings of the Iowa Academy of Science, 89(2), 71-80.
Available at: https://scholarworks.uni.edu/pias/vol89/iss2/11