Produced by the Population Genetics and Evolution class, Furman University

The Silurian: Corals
Fossils of tabulate and rugose corals are common in Silurian deposits in Pennsylvania and Kansas. The coral polyps shared numerous morphological traits, such as hard outer skeletons and tentacles for feeding (Kansas Geological Survey 2010). They were both capable of sexual and asexual reproduction (Kazlev 2003). The tabulate corals (order Tabulata) formed colonies consisting of many hexagonal cells called corallites, which were encased in calcium carbonate skeletons variously described as having moundlike, sheetlike, chainlike, or branching shapes (Kansas Geological Survey 2010). Their name comes from their horizontal internal partitions within the cells, known as tabulae (Waggoner and Collins 1994). Some tabulate coral colonies aggregated together to form large reefs; the first extensive coral reefs in earth history (Waggoner and Collins 1994). The rugose corals (order Rugosa) were named for their wrinkled appearance; the Latin word for wrinkled is “rugulose” (Kansas Geological Survey 2010). They consisted of both solitary and colonial forms, with each type having its own distinctive morphology. Solitary rugose corals, which were more common than colonial forms, were typically horn-shaped, had a diameter up to 14 centimeters, and a maximum height of nearly one meter (Kazlev 2003). Colonies of rugose corals grew up to 4 meters in diameter, and rarely formed reefs. Both the tabulate and the rugose corals died out in the late Permian at thePermo-Triassic extinction (Kazlev 2003).

Page by Bob Mazgaj
Pennsylvania rugose corals from the species Caninia torquia. Photo credit: Kansas Geological Survey

Kansas Geological Survey. 2010. Fossil corals. Accessed 17 Feb. 2010.

Kazlev MA. 2003. Rugosa. Horn Corals. www.palaeos.com. Accessed 17 Feb. 2010.

Waggoner BM, Collins A. 1994. Introduction to the Tabulata. University of California Museum of Paleontology. Accessed 17 Feb. 2010.