Fig. 3. Normal and malformed G. cornuta from the lower lake, Rebild Bakker.

(A) Upward increasing percent of malformed and tetrads. (B) Average translucency of G. cornuta showing increased pigmentation as malformations increase. (C) Dispersed phytoclast reflectivity showing a high charcoal content (>2%) through the boundary interval and hence no reduction in ozone from lower atmospheric PO₂. (D and E) Normal specimens of G. cornuta. (F), (H), and (J) show reduced numbers of irregularly distributed spines and increased brown pigmentation. (G) has irregularly developed sinuose processes. (I) has hooked tips. (K) to (M), (P), and (U) have processes that are reduced in number and irregularly fused. (N), (S), and (T) are irregularly distributed, fused in groups, and highly irregular. (O) has irregular sporopollenin masses adhering to inner body. (V) is a tetrad of inner bodies, whereas (Q) is an isolated inner body. (R) and (W) are tetrads, with irregular sculpture, with (W) being pigmented to a dark brown color. Sample and slide numbers plus England Finder coordinates are in table S4. Translucency data are in table S3, and phytoclast reflectivity data are in table S5.