250 - 65 Mya
||Nystedt B et al., The Norway spruce genome sequence and conifer genome evolution. Nature. 2013 May 30 497(7451):579-84. doi: 10.1038/nature12211 p.579 left column top paragraphPubMed ID23698360
|| Leslie, A. B. et al. Hemisphere-scale differences in conifer evolutionary dynamics. Proc. Natl Acad. Sci. USA 109, 16217–16221 (2012) doi: 10.1073/pnas.1213621109PubMed ID22988083
||P.579 left column top paragraph: "Gymnosperms are a group of land plants comprising the extant taxa, cycads, Ginkgo, gnetophytes and conifers. Gymnosperms first appeared more than 300 million years ago (Myr ago)(ref 1 and see BNID 105197), well before the angiosperm lineage separated from the stem group of extant gymnosperms (ref 2). The major radiation of conifer families occurred 250–65 Myr ago (primary source), and during their evolution the morphology of conifers has changed relatively little."