MANUMIELLA SEELANDICA AT THE CRETACEOUS/PALEOGENE (K/PG) BOUNDARY IN THE BASS RIVER SECTION, SOUTHERN NEW JERSEY

The dinoflagellate Manumiella seelandica(Lange, 1969)Bujak and Davies 1983 emend. Firth, 1987 ranges from late Maastrichtian to Danian (Paleogene). At the Bass River site in southern New Jersey, it becomes numerically abundant(up to 218 specimens in the total assemblage of 648 specimens, or 33.6%) within the interval just 15cm beneath the K/Pg boundary. Its abundance, and its widespread global distribution, serve as an excellent biostratigraphic marker for dating the boundary. For example,the abundance spike at Bass River is known in many other sections in both Northern and Southern hemispheres, ranging from Antarctica to West Greenland.

M.seelandica ranges within the Navesink highstand sequence tract, a marine regressive unit which extends from late Maastrichtian to Danian. Thus, this species entered the fossil record at Bass River during the period of relative sea level fall and regression. However, its abundance immediately below the K/Pg boundary at Bass River correlates precisely with oxygen isotope evidence there of minor cooling, which suggests that this species became abundant in response to a short episode of cooling during regression.