Page 325 - Introduction to Paleobiology and The Fossil Record

312 INTRODUCTION TO PALEOBIOLOGY AND THE FOSSIL RECORD

Box 12.4 Brachiopod predation

Brachiopods were eaten by gastropods, arthropods and other predators, and the best evidence is
found in Paleozoic examples, especially in the Devonian. Many predatory gastropods feed by drilling
into the shells of their prey, and two types of drill hole are commonly present in Paleozoic brachio-
pods: small, cylindrical holes made by Oichnus simplex and larger, often beveled holes made by O.
paraboloides; these are, of course, ichnogenera (see p. 525) and not actual brachiopods (Fig. 12.13).
After the Devonian peak in drilling diversity, there was apparently a marked drop in the frequency
of drilled shells, particularly after the Mid Carboniferous. Many Carboniferous and Permian groups
such as the productides have thickened shells with an armor of frills, lamellae and spines, all perhaps
acting as defense against marauders. Maybe the prey had won this early arms race or perhaps the
introduction of mollusks into these communities provided fresh and preferable seafood for the preda-
tors. Nevertheless, if we use the Recent Antarctic benthos as a model for the Paleozoic fauna, there
is a lack of fast-moving durophagous predators (Harper 2006). Some authors have speculated that

the toxins within the flesh of some modern groups, such as the rhynchonellids, may have protected
them from attack.

Figure 12.13 Brachiopod predation: boring of Oichnus paraboloides in the conjoined valves of
Terebratulina from the Pleistocene rocks of Barbados. Scale bar is in millimeters. (Courtesy of
Stephen Donovan.)