Figure 2
From: Seasonal calibration of the end-cretaceous Chicxulub impact event
Bone growth patterns reflected in isotopic and histological data. (A) δ18O data from a sturgeon pectoral fin spike (FAU.DGS.ND.755.57.T) shows a repeated fluctuation between saline (arrows) and freshwater living conditions. The freshwater zones of bone growth correlate with peak times in biological productivity (blue bands in [B]), while the saline zones correlate with lowest productivity that are histologically consistent with winter months13,24,25,26. (B) δ18C values for incremental samples from the same thick section, taken 1 mm adjacent to the samples in (A), showing multi-year fluctuations that inversely relate to the oxygen data. (C) a photomicrograph of the same fin spike, showing fluctuations in annual growth history that correlate with the isotopic data. Red arrows point to annual lines of arrested growth (LAGs) deposited during winter. (D) an idealized schematic of the histological patterns in (C), with subdivisions of growth bands labelled according to their season of growth13,24,25,26.
