Microborings within Late Ordovician shells of the brachiopod Raphinesquina alternata from the Tanner Creek Formation, Richmond Group, of southeastern Indiana, were studied by scanning electron microscopy of their resin casts. The shells have been exposed to microbial boring in quiet and illuminated waters below the wave base and then buried with skeletal fragments of ramose bryozoans, echinoderms, trilobites, and rugose corals.

Four morphotypes of microborings have been characterized on the basis of shape, branching patterns, and diameter size and variation. Statistically evaluated measurements for populations of microborings indicate four ichnotaxa.

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