Dinosaur-dispersed cycads

lou jost loujost@yahoo.com
Sat, 26 Nov 2011 04:47:45 PST
Thanks Rachel for that article. I think it may have led to some confusion among some readers. The research shows that the individual species that exist today are only a few million years old, but still the group as a whole has changed very little since the time of the dinosaurs. The kinds of changes that define species are relatively minor compared to the characters that define higher taxonomic groups like genera and subtribes. So it is still correct to say that the cycads are living fossils, in the sense that anyone would instantly recognize a 70 Mya cycad as such. It is not correct to say that any given species is a living fossil that has not changed at all in species-level characters since the time of the dinosaurs.

More information about the pbs mailing list