Table 6.

Correlations of Cretaceous bird ghost ranges (GDE) with bird-bearing FFCs, read as a strict FFC, representing only those formations with the named bird taxa (from Chiappe & Witmer 2002) and wider FFC figures (from Fountaine et al. 2005), showing rank-order correlations for the raw data and for first differences (FD). Correlations between these measures and TDE and PDE are also given. Data are calculated from Berriasian to Campanian only, to avoid the edge effects of wide variation in number of ghost ranges in the first time bin (Tithonian), and necessary absence of ghost ranges in the last (Maastrichtian)

Spearman's ρP
GDE v. Strict FFC−0.440.180
GDE v. Wider FFC−0.220.518
GDE v. FD strict FFC−0.430.191
GDE v. FD wider FFC−0.170.619
TDE v. Strict FFC0.900.000**
TDE v. Comprehensive FFC0.650.032*
PDE v. Strict FFC0.380.248
PDE v. Comprehensive FFC0.470.147