Tabulate Corals, Branching Shapes Tabulate corals are colonial corals. Although colonies, are often thought of as large mound-like groups, colonies also can form delicate branching skeletons. The entire branching coral is called the corallum, while the individual tubular chambers within the corallum are called corallites. Branching coral fossils are generally small, and are covered by very small holes (calices) in which the actual coral animals (polyps) lived. Branching tabulate coral fossils have been found in Silurian and Devonian strata in Kentucky.

Cladopora acupicta Davis
Cladopora acupicta Davis

Cladopora is a type of branching coral found in Devonian limestones at the Falls of the Ohio. This specimen is about 12 cm long. If you look at the fossil in detail you can see the many tiny pores or holes (called corallites) where the coral animals (polyps) lived when the coral was alive. Specimen donated to the Kentucky Geological Survey collection by R. Todd Hendricks and featured in Greb and others, 1993, Fig. 22a. Identification by Alan Goldstein. The genus occurs commonly as both branching and mound-shaped colonies.

 

Emmonsia
Emmonsia

Emmonsia branches are among the most common coral fragments exposed in the upper layers of limestone at the Falls of the Ohio. Most are 2 to 5 cm in diameter. Emmonsia branches are very thin and look like fine, hair-like lines in this section through an Emmonsia branch.

Thamnopora
Thamnopora

Thamnopora is a type of tabulate branching coral. The corallites (holes) in Thamnopora are larger than in Alveolites. The walls around each corallite (hole) are very thin, so that these corals often look sponge like. This specimen on the left is surrounded by a stromatoporoid, which presumably grew around the branching coral during life or shortly after the corals demise. Both specimens are from the Jeffersonville Limestone and were donated to the Kentucky Geological Survey by R. Todd Hendricks. The sample on the right was featured in Greb and others, 1993, p. 20, Fig. 22-b.

Striatopora
Striatopora

Striatopora is a type of branching tabulate coral. Individual calices are generally only a few mm across, but have well-developed walls, so that they stick out slightly from the corullum (the rest of the coral skeleton) somewhat like holes on a flute. This specimen is 5 cm long, and was collected by R. Todd Hendricks and donated to the Kentucky Geological Survey.

branching shape corals were relatively fragile when they were alive, their fossils often occur as broken fragments in limestone matrix.

Because, branching shape corals were relatively fragile when they were alive, their fossils often occur as broken fragments in limestone matrix. At the Falls of the Ohio, many of the fossil corals appear like light gray to white "fingers" in a darker gray rock. If you polish a slab of the same limestone, as in the second photograph, the fossils usually are white in color, and the rock holding the fossils (called matrix) is dark brown to black. In polished sections, the details of the individual corals can be seen. In these examples, and in other Devonian limestone layers where corals are abundant, branching and rugose corals were sometimes broken or dislodged and scattered across the sea floor. When they were buried they became fossilized and appear like little fingers in the rock. Polished specimen donated by R. Todd Hendricks.

 

 

Last Modified on 2021-12-21
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