Message du 26/11/11 13:24
De : "Rachel Fitzhardinge"
A : pbs@lists.ibiblio.org
Copie à :
Objet : Re: [pbs] Dinosaur-dispersed cycads

Mark,

Apologies, the article in Science was published last month and that's why I don't think that it can be accessed via Science Express any more.

It's in Science vol 334 (6057) 796-799 on 11 Nov. Its title is Recent Synchronous Radiation of a Living Fossil

Abstract: Modern survivors of previously more diverse lineages are regarded as living fossils, particularly when characterized by morphological stasis. Cycads are often cited as a classic example, reaching their greatest diversity during the Jurassic–Cretaceous (199.6 to 65.5 million years ago) then dwindling to their present diversity of ~300 species as flowering plants rose to dominance. Using fossil-calibrated molecular phylogenies, we show that cycads underwent a near synchronous global rediversification beginning in the late Miocene, followed by a slowdown toward the Recent. Although the cycad lineage is ancient, our timetrees indicate that living cycad species are not much older than ~12 million years. These data reject the hypothesized role of dinosaurs in generating extant diversity and the designation of today’s cycad species as living fossils.

Sorry, I can't provide the full article. The abstract doesn't take you any further than what David Ehrlich set out earlier.

Rachel

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