Wooster’s Fossil of the Week: The tabulate coral Aulopora (Devonian of northwestern Ohio)

January 2nd, 2011

We’re going to start 2011 with a new blog feature: Fossil of the Week! My colleagues, of course, are welcome to also start “Mineral of the Week”, “Structural Geologic Feature of the Week”, or “Climate Event of the Week”.  The more the better to keep our blog active through the winter!


This week’s fossil was collected by Brian Bade of Sullivan, Ohio, and donated to Wooster as part of my hederelloid project.  It is a beautiful specimen of the tabulate coral Aulopora encrusting a brachiopod valve from the Silica Shale (Middle Devonian — about 390 million years old) of northwestern Ohio.  Auloporid corals are characterized by an encrusting habit, a bifurcating growth pattern, and horn-shaped corallites (individual skeletal containers for the polyps).

What is especially nice about this specimen is that we are looking at a well preserved colony origin.  The corallite marked with the yellow “P” is the protocorallite — the first corallite from which all the others are derived.  You can see that two corallites bud out from the protocorallite 180° from each other.  These two corallites in turn each bud two corallites, but at about 160°.  This pattern continues as the colony develops (a process called astogeny).  The angles of budding begin to vary depending on local obstacles; they never again go below 160°.

The polyps inside the corallites are presumed to have been like other colonial coral polyps.  Each would have had tentacles surrounding a central opening, and all were connecting by soft tissue within the skeleton.  They likely fed on zooplankton in the surrounding seawater.  This type of coral went extinct in the Permian, roughly 260 million years ago.

Again, we thank our amateur geologist friends for such useful donations to the research and educational collections in the Geology Department at Wooster.

3 Responses to “Wooster’s Fossil of the Week: The tabulate coral Aulopora (Devonian of northwestern Ohio)”

  1. Stephanie Jarvison 04 Jan 2011 at 1:15 pm

    Sweeeeeeeet!!!! I’m super excited about this new feature :)

  2. [...] This entry is posted, by the way, on the one-year anniversary of Wooster’s Fossil of the Week. It is the 53rd in the series. Here is the very first post, which was on a gorgeous little Devonian auloporid. [...]

  3. [...] This post, by the way, marks the completion of the second year of Wooster’s Fossils of the Week. So far we’ve had 104 posts. Check out our very first edition about a sweet auloporid coral! [...]

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