FIGURE 14 in Pteropoda (Mollusca, Gastropoda, Thecosomata) from the Paleocene-Eocene Thermal Maximum (United States Atlantic Coastal Plain)

FIGURE 14. Stratigraphy and lithology for the Bass River core, after Stassen et al., 2015. The number of pteropods recognized (red) is compared to the B/Ca values (purple) in the planktonic foraminiferal genus Acarinina, a surfacewater (mixed layer) dweller (Babila et al., 2016), and with δ13C values of bulk carbonate (orange), indicating the location of the carbon isotope excursion (Stassen et al., 2015). The change in B/Ca is interpreted as reflecting a decline in pH by ~0.3-0.4 pH units (Babila et al., 2016). The irregularity of pteropod distribution is likely because they were transported to these sites, and do not represent an in situ population.