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

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.

About Mark Wilson

Mark Wilson is a Professor of Geology at The College of Wooster. He specializes in invertebrate paleontology, carbonate sedimentology, and stratigraphy. He also is an expert on pseudoscience, especially creationism.
This entry was posted in Uncategorized and tagged , , , . Bookmark the permalink.

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

  1. Stephanie Jarvis says:

    Sweeeeeeeet!!!! I’m super excited about this new feature 🙂

  2. Pingback: Wooster Geologists » Blog Archive » Wooster’s Fossil of the Week: A Tully Monster! (Late Carboniferous of Illinois)

  3. Pingback: Wooster Geologists » Blog Archive » Wooster’s Pseudofossil of the Week: Manganese dendrites from Germany

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.