Another beautiful fossil hard substrate

May 21st, 2010

Megan Innis studying the Ripley Formation rockground near Greenville, Alabama.

GREENVILLE, ALABAMA — I have a soft spot for hard places.  (Always wanted to say that!)  Much of my career has been spent studying marine hard substrates and the communities that have evolved on and in them.  These include rocks, hardgrounds and shells on seafloors which have been encrusted and bored by diverse organisms for hundreds of millions of years.  In all the many marine environments where these substrates occur, we know the organisms faced one common problem: how to occupy and defend space in an essentially two-dimensional world.  This provides a thread to follow through the long evolution of sclerobionts (hard-substrate dwellers, to use one of my favorite words.)

At the top of the Maastrichtian (Upper Cretaceous) Ripley Formation is a rockground which was bored and encrusted on the seafloor in the classic way.  It was ably described in a paper by Jon Bryan, and we were pleased to see that the surface is still exposed and accessible today.  There were some tasty encrusting bryozoans on some of the cobbles here!

Spondylid bivalve encrusting the Ripley Formation rockground.

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