Birds and Mammals from the Pleistocene of Williston, Florida

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A Pleistocene vertebrate locality at Williston, Levy County, Florida, contained the remains of 6 species of birds and 20 of mammals. The bones were in Arredondo clay, of Illinoian age, in a solution pipe in the Eocene Ocala limestone. Two birds are extinct, a large quail (Colinus suilium), and a large jay (Henocitta brodkorbi) which is described as new. Six mammals are extinct: a mustelid of uncertain identity, a pine vole (Pitymys hibbardi) which is described as new, an armadillo (Dasypus bellus), a tapir (Tapirus veroensis), a peccary (Mylohyus sp.), and a horse (Equus sp.). Rabbits of the genus Sylvilagus are represented by 561 fossil elements; in many cases the two species, S. palustris and S. floridanus, can be distinguished on cranial and post-cranial bones. The Pleistocene habitat of the Williston area was probably marshy pineland grading into well drained pineland with open sinks, surrounded by mesophytic vegetation. Six species, 23 percent of the fossil fauna, are larger than their Recent Florida representatives. Five of these six species have larger modern forms to the north. Applying Bergmann's rule, this supports the thesis that Florida had a somewhat cooler climate in the Illinoian glacial stage. The Williston fauna differs from other Pleistocene localities in Florida in its low percentage of extinct mammals. This is because a large number of the Williston mammals are small. If the percentage of extinction is calculated separately for large and small size classes, the Williston fauna resembles that of other Florida Pleistocene localities more closely.