Early holocene vertebrate paleontology

Abstract

The richest concentration of vertebrate fossils and cultural remains in the Page-Ladson site was scattered on the upper surface of stratigraphic Unit 5. This bone layer was encountered most clearly in Test C and was worked, as the site was extended, during seven different field seasons. The two most intensive seasons were June and October, 1995. During that year the Aucilla River Prehistory Project (ARPP) made its primary goal to intensively map and collect on the surface of Unit 5, also known as "the Bolen surface". This extended Test C northward along the west bank of the Aucilla River. After removing the surface leaves and upper few meters of sediment with a 6-in. dredge, an area of 6 m was carefully mapped and excavated. A second goal of the 1995 season was more carefully to distinguish the fine stratigraphic levels above and below the rich "Bolen surface". For that purpose four distinct levels each 10 cm deep were individually removed over the 6 m area. It became evident that a distinct unconformity separated the "Bolen surface" from the overlying sediments. These were assigned to tratigraphic Unit 6. The lowermost 10 cm consisted of nearly white shelly siliceous silts. The excavation teams very carefully "peeled" the shelly silt from the underlying compact dark gray clay of Unit 5 using dental picks and trowel tips. In this chapter, we describe the resulting collections of fossil vertebrates from the upper surface of Unit 5 and the lowermost 10 cm of Unit 6. In a bulk faunal study we list all identifiable vertebrates from all the field seasons that recovered material from that level. In some cases this may include material from the lower 10 cm of Unit 6 as well, since that distinction was not well understood in the first two seasons. We do not include equivalent aged material from Test B as that material came from a distinctly deeper water deposit from the opposite side of the Page-Ladson site. Further more detailed analyses in this chapter are based on the 1995 material. There we clearly distinguished the two levels and, as noted above, we also mapped and point-plotted most vertebrate specimens. We first present the basic list of taxa from each unit, and then we develop further taphonomic analyses to shed light on the mode of deposition of these two strata and their vertebrate contents. We expected to see a heavy impact of human food procurement processes. As the following analyses will show, however, the vast majority of material must be considered naturally accumulated for lack of contrary evidence. The age of the "Bolen surface" has been well determined by a set of four closely corroborative carbon dates with a pooled average of 9959 14C BP. Careful chemical studies (Chapter 15 by Scudder) show that it did not form a soil. There is nevertheless clear evidence from the development of hearths and charred wood that the surface was exposed subaerially for a time, perhaps as much as a century. Stratigraphic Unit 6 was initiated by a rising water table and a return of fully aquatic deposition over and above the "Bolen surface". In this chapter, we present vertebrate faunal and taphonomic evidence about the earlier and the later depositional phases.