Fossil of the month: Quepora
Quepora is a type of tabulate coral, informally called a chain coral. Many people who collect fossils assume that all chain corals are Halysites, which is a common misconception. Halysites is the most frequently pictured genus of a chain coral in fossil identification books. There are, however, many different types of chain corals, including Quepora.
Description.The differences between chain-coral genera are subtle. Many features used to distinguish genera (and especially species) are frequently less than 1 millimeter in width, so require good specimens and a good eye or magnifying glass. Weathering of fossils, dolomitization, and silicification can smooth or obliterate the smaller features, which complicates identification. In Kentucky, chain-coral fossils are commonly silicified or dolomitized, which makes it difficult to see if a specimen has the intervening tubes (called coenenchyme) between major corallites, which are the first-level criteria for determining if a chain coral may be Halysites or Cystihalysites, or is Catenipora or Quepora. In practice, a secondary criteria, the shape of lacunae (the gaps between corallite chains) are sometimes used to determine genera in the field. Specimens with mostly polygonal lacunae and elongated loops (especially contorted loops) are usually identified as Halysites sp. (although they can also be Catenipora). Specimens dominated by mostly circular to elliptical (not contorted) lacunae are probably Quepora. Long chains which don’t often split or rejoin may be Cystihalysites. To learn more about chain corals and criteria for accurately identifying them in Kentucky, see the KGS fossil coral pages.
Species. Two species of Quepora are reported in Kentucky, Q. huronensis and Q. louisvillensis. Quepora huronensis has tiny, oval corallites (<1 mm) arranged in small ranks of 1 to 4 corallites. In contrast, Q. louisvillensis, has larger (>1 mm) and more widely-spaced corallites.
Range and geographic occurrence. Quepora and other chain corals are mostly restricted to the Silurian Period in Kentucky, so are good field indicators of Silurian strata. Quepora has only been reported from the Louisville Limestone in the greater Louisville area. It might possibly be found in other Silurian units in which the similar-appearing Halysites was historically reported, including the Brassfield Dolomite, Crab Orchard Formation, and Bisher Dolomite. Silurian units are exposed at the surface in the Outer Bluegrass Region of the state. Halysites has also been reported in the basal Devonian Jeffersonville Limestone, where they were reworked from erosion of the underlying Silurian Louisville Limestone. Quepora might also occur as eroded fragments in basal Devonian strata in Kentucky. Globally, Quepora has also been found in Upper Ordovician strata (Hill, 1981), but to date, none have been reported from Upper Ordovician strata of Kentucky.
Life and paleoecology. Shallow seas covered Kentucky during much of the Silurian. Chain corals like Quepora formed low-lying “hedge”-shaped corals on the Silurian sea floor. Each tiny corallite tube (hole) in the chain shape was the home of a tiny coral polyp. In life, tiny tentacles would have extended from each polyp for feeding, similar to modern coral polyps.
Learn more about chain and other coral fossils in Kentucky at the KGS coral website.
- Hill, D., 1981, Part F–Coelenterata–Supplement 1-Rugosa and Tabulata, in Teichurt, C., ed., Treatise of Invertebrate Paleontology: Geological Society of America and University of Kansas Press, two volumes, 762 p.
- Stumm, E.C., 1964, Silurian and Devonian corals of the Falls of the Ohio: Geological Society of America Memoirs, v. 93, 184 p.
- Young, G.A. and Noble, J.P.A., 1987, The Llandovery—Wenlock Halysitidae from New Brunswick, Canada: Journal of Paleontology, v. 61, no. 6, p.1125–1147.