Figure 2.

(a) Mean length of the seed (black bars) and its subtending cone scale (white bars) in conifer species during different time intervals. The number of species per interval is (from left to right) 14, 14, 19, 22 and 94. 95% confidence intervals around the mean were calculated from 10 000 resampled means. (b) Percentage of taxa in each time interval with seed cones composed of compact, tightly interlocking scales. These cones have scales for which the mature shape is determined by the growth of adjacent scales (such as in extant Metasequoia glyptostroboides; see inset photo). Pal, Palaeozoic; Tri, Triassic; Jur, Jurassic; Cret, Cretaceous; Rec, Recent.