Jud, Nathan , Wing, Scott .
New fossils and revised ages suggest a geologically brief period for early diversification of angiosperms.
The first unequivocal angiosperm fossils are generally thought to be as old as Valanginian (140-136Ma), while the origin of eudicots (and by implication monocots) is thought to be Aptian (125-113Ma), thus giving 11-27Myr for the initial diversification of flowering plants. Recent improvements in dating of the oldest angiosperm-bearing deposits suggest that the earliest angiosperm pollen and leaf fossils globally are Barremian, with one pollen occurrence possibly late Hauterivian (~130Ma). The oldest angiosperm fossils from North America (Potomac Group of Virginia) were used to document the evolution of angiosperm leaf morphospace during the Aptian-Cenomanian (Hickey and Doyle 1977). New fossils from the lowermost Potomac Group (early-mid Aptian) and from late Aptian-early Albian deposits in the Cloverly Formation (Wyoming) show that leaves characteristic of angiosperm clades such as Nymphaeales, Ranunculales, Proteales, and monocots, occurred earlier in North America than previously recognized, reinforcing the claim that both monocots and eudicots were present by the Early Aptian (125-119Ma). The combination of younger ages for the first angiosperm fossils and older ages for major subclades suggests that the initial angiosperm diversification could have occurred in as little as 5-10 million years.
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1 - University of Maryland, Biological Sciences, Hyattsville, MD, 20742, USA
2 - Smithsonian Institution, Dept. Of Paleobiology NHB 121, PO Box 37012, WASHINGTON, DC, 20013-7012, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Union A/Hyatt
Date: Monday, July 9th, 2012
Time: 9:30 AM