St. Marks River Fauna 51 



Megalonyx, Lutra, Mephitis, Urocyon, Ursus, Tapirus, Platygonus, 

 Odocoileus, and Mammut. However, grassland species are well represented 

 also: Glossotherium, Mephitis, Geomys, Equus, Hemiauchenia, 

 Paleolama, Bison, and Mammuthus. From a simple listing it might 

 appear that grassland species are about as common as woodland 

 species. However, when compared by the number of identified 

 specimens per taxon, woodland species are more prevalent. Despite 

 criticism, this method is reliable for a comparison of relative abun- 

 dances of species (Grayson 1984). In addition, a number of species 

 indicate proximity of water: Didelphis, Lutra, Procyon, Ursus, Castor, 

 Neofiber, Ondatra, Synaptomys, and Tapirus are all typically 

 associated with moist, riparian, or standing water habitats. 



Birds — Storrs Olson's collection from the St. Marks River have 

 never been published. He was kind enough to provide a list of the 

 birds identified and has permitted us to include it in the present 

 discussion. Olson (personal communication) felt that "there was very 

 little of interest among the birds" mainly because the list of avian 

 species recovered from the St. Marks River is essentially similar to 

 the modern fauna (Means 1976). As a whole, birds are uninstructive 

 concerning the dating of the St. Marks River fauna. They do, however, 

 provide considerable information relating to the environment of 

 deposition. 



The St. Marks River avian fauna is clearly biased toward large 

 species with predominantly salt and freshwater marshland habitat 

 preferences: Podiceps, Podilymbus, Phalacrocorax, Ardea, Butorides, 

 Egretta, Eudocimbus, Aix, Anas, Aythya, Branta, Bucephala, 

 Lophodytes, Padion, Fulica, Gallinula, and Aramus. In addition, a 

 number of the species are typically associated with woodlands or 

 woodland riparian habitats: Aix, Mergus, Buteo, and Strix. 

 Conspicuously absent are the passeriforms. This probably represents 

 the taphonomic bias referred to above. While a significant number 

 of the birds are often present in saltwater marsh habitats, there are 

 no shorebird (charadriform) species present. 



Reptiles and Amphibians — Many turtles, but few other reptiles, 

 are reported from the St. Marks River. Emydid turtles, in particular, 

 are well represented and make up approximately 90% of the recovered 

 reptilian material. In fact, in numbers alone they make up well over 

 one third the individual elements in the fauna. The emydid turtle 

 species identified from the 1987 collection were Pseudemys concinna, 

 P. floridanus, P. nelsoni, Trachemys scripta, and Terrapene Carolina, 

 all of which are found in the area today. Pseudemys and Trachemys 

 are indicative of a freshwater environment, while Terrapene is 

 terrestrial. An extinct, large, late Pleistocene subspecies of Terrapene 



