Cretaceous Ostracoda 

 From Wells in the Southeastern United States 



By 



Frederick M. Swain and Philip M. Brown 



University of Minnesota, Minneapolis, Minnesota 



U. S. Geological Survey, Raleigh, North Carolina 



ABSTRACT 



Two previously undescribed early Cretaceous ostracode faunas, important in the interpretation of 

 Coastal Plain geology, but of different age and geographic distribution, are treated in this paper. A 

 third early Cretaceous collection, previously described, is here re-described because of its stratigraphic 

 importance. 



A marine ostracode fauna of probable Albian age, previously unknown, is described from shallow 

 wells in central and northeastern North Carolina. The assemblage, which includes eleven new species 

 and two new genera, is thought to represent nearshore deposition in a lagoonal environment, charac- 

 terized in part by brackish water. 



Also described is an ostracode fauna from the subsurface Atkinson Formation of southern Ala- 

 bama, northern Florida, and Georgia. The upper member of the Atkinson Formation, that previously 

 has been correlated with the Eagle Ford of Texas, contains four species, one of which is new. The 

 lower member of the Atkinson Formation, that previously has been correlated with the Woodbine of 

 Texas, contains seventeen species, four of which are new. 



Vanderpool's type specimens of Ostracoda from the Lower Cretaceous Trinity Group of north- 

 eastern Texas, southern Arkansas, and northern Louisiana have been examined, described, and re- 

 illustrated. Several taxonomic changes have been made in the Trinity species. 



INTRODUCTION 



Three collections of Cretaceous Ostracoda are 

 described and illustrated in this paper. Although 

 the three collections differ in age and in geograph- 

 ic distribution, they contribute to general knowl- 

 edge of Cretaceous ostracodes of the southeastern 

 United States, and are treated together for this 

 reason. The three collections represent deposits 

 of Trinity age, possible Fredericksburg and 

 Washita age, and Woodbine and Eagle Ford age. 



An assemblage of Ostracoda, collected by 

 Brown from cuttings from water wells in central 

 and northeastern North Carolina, represents an 

 apparent nearshore assemblage of Albian age 

 that does not have a recognizable counterpart 

 among previously described Cretaceous ostracode 

 faunas. In addition, it provides new data concern- 

 ing the areal distribution of marine Cretaceous 

 sediments in the Middle Atlantic States. 



Ostracoda from the Atkinson Formation of 

 southern Alabama, northern Florida, and Georgia 

 were submitted to Swain in 1951 by Paul L. and 



Esther Applin. Scarcity of information on Ostra- 

 coda of this age in the southeastern states, and 

 their relation to the North Carolina material de- 

 scribed in this paper, have led to their inclusion 

 here. 



The Trinity Ostracoda, described by Vanderpool 

 (1928 and 1933) are in need of reconsideration 

 taxonomically, and are, therefore, redescribed and 

 re-illustrated. These ostracodes were first de- 

 scribed by Vanderpool from surface localities in 

 northeastern Texas and southern Arkansas, and 

 recorded from wells in northern Louisiana by 

 Calahan (1939). 



Acknowledgments 



Appreciation is expressed to Paul L. and Esther 

 R. Applin for providing the Atkinson specimens, 

 and to A. R. Loeblich, Jr., for arranging the loan 

 of the Vanderpool collection. 



Type specimens are deposited in the U. S. Na- 

 tional Museum. Museum numbers extend from 

 132376 through 132532. 



