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. 2011 Nov 11;334(6057):796-9.
doi: 10.1126/science.1209926. Epub 2011 Oct 20.

Recent synchronous radiation of a living fossil

N S Nagalingum  1 , C R Marshall, T B Quental, H S Rai, D P Little, S Mathews
Affiliations

Recent synchronous radiation of a living fossil

N S Nagalingum et al. Science. .

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.

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