Recent Synchronous Radiation of a Living Fossil
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...
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Veröffentlicht in: | Science (American Association for the Advancement of Science) 2011-11, Vol.334 (6057), p.796-799 |
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Sprache: | eng |
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Zusammenfassung: | 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 phytogenies, 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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ISSN: | 0036-8075 1095-9203 |
DOI: | 10.1126/science.1209926 |