Brachiopods are fascinating but poorly understood bivalved marine animals. They look similar to clams, at least externally, but are only distantly related in a genealogical sense. Even though brachiopods are not commonly found along seashores today, except in parts of New Zealand and Australia, they were common and diverse over 250 million years ago in the Paleozoic Era and were important elements of the Paleozoic marine biota. For this reason, paleontologists are interested in learning about aspects of their ecology, morphology, growth and behavior, and their temporal and geographic distribution, in part to understand their decline and near extinction. Dr. Sandra Carlson of the University of California at Davis is studying the spire-bearing articulate brachiopods, those bearing distinctive structures inside their valves that look much like two cone-shaped springs and that are involved in obtaining food and oxygen and in reproductive behaviors. The current classification of these organisms suggests that these structures have evolved only once, but preliminary work by Dr. Carlson indicates that is not likely the case. If spire- bearing brachiopods have evolved several times, then placing them together in a single taxonomic group confuses their evolutionary history and constrains work on ecological factors responsible for spire evolution. Study of other morphological features of the fossil and extant organisms will help improve the classification and phylogeny of brachiopods, and help in understanding their geological rise and fall in the Paleozoic.
