Teleostean otoliths reveal diverse Plio-Pleistocene fish assemblages in coastal Georgia (Glynn County)

Abstract

Extensive bulk sampling at seven Plio-Pleistocene sites spanning approximately 4.5 Ma to 120,000 years ago in age near Brunswick, Glynn County, Georgia, produced 1,803 teleostean otoliths. The otolith assemblage was relatively diverse with 50 taxa (representing 18 families) of Plio-Pleistocene teleosts. The otoliths represented mainly shallow-marine fishes, which were all extant except for four species. The assemblage was dominated by 16 sciaenid taxa that represented 65.8% of the total number of otoliths. The Plio-Pleistocene otoliths indicated fishes that are almost identical to the marine fishes from present-day coastal Georgia. The teleostean otoliths are considered especially important for several reasons. This study represents the first description of fish otoliths from the Plio-Pleistocene of coastal Georgia and describes the bony fishes present from approximately 4.5 Ma (Raysor Marl equivalent) to 120,000 years ago (late Pleistocene). This time interval includes the late Neogene climatic changes as well as the glacial-interglacial climatic cycles in North America. Also, the preservation of aragonitic otoliths is rare in coastal Georgia given the very high water table and the intense and rapid weathering. Furthermore, there is a paucity of Plio-Pleistocene fossils, especially bony fishes, in coastal Georgia related to various geological constraints such as highly erosive transgressive sequences. The Plio-Pleistocene otolith assemblage from coastal Georgia contains 13 families representing 28 taxa not recognized by skeletal fossils in Georgia. Although the Ariidae and Sciaenidae were previously recognized based on skeletal fossil material in Georgia, there are 14 newly reported taxa based on otoliths in these families (1 and 13 respectively) including Protosciaena kirbyorum n. sp., the first fossil species of this genus in the U.S. Otolith data also verified fishes previously indicated by skeletal remains and provided greater specificity in several cases.