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Abstract Detail



Macroevolution

HERENDEEN, PATRICK S [1], Friis, Else Marie [2], Pedersen, Kaj Raunsgaard [3], Crane, Peter [4].

Palaeobotanical Redux: Revisiting the age of the Angiosperms.

Angiosperms are the most diverse of all major lineages of land plants and they dominate almost all modern terrestrial ecosystems. As a consequence, their evolutionary and ecological history are of considerable interest, and knowledge of their fossil history is essential for understanding patterns of diversification in other lineages, including insects and other animals. Ever since Darwin noted the apparent sudden appearance of angiosperms in the mid-Cretaceous, the search for flowering plants that predate the Early Cretaceous has been intensive. Two influential reviews published in the 1960s concluded that there were no reliable records of flowering plants from pre-Cretaceous rocks. Over the past several decades extensive new data from macrofossils, mesofossils, and microfossils have corroborated this conclusion. Furthermore, the fossil record shows a more or less synchronous diversification of fossil pollen, reproductive structures, and leaf compression fossils through the Early Cretaceous, in patterns that are consistent with our understanding of angiosperm phylogeny. This pattern is difficult to explain if angiosperms had diversified cryptically for a significant period of time in environments unsuitable for fossil preservation, and only later entered the fossil record. Nevertheless, some recent molecular dating analyses have raised the possibility that angiosperms may have originated and diversified much earlier. Furthermore, several recent reports of putative angiosperms from Triassic and Jurassic rocks have contributed to the renewal of interest in this question. These developments, combined with the substantial increase in quantity and quality of paleobotanical data that have accumulated since the 1960s, have caused us to revisit this question and determine the extent to which the situation has changed. Critical assessment of the reports of pre-Cretaceous angiosperms shows that none provides unequivocal evidence of flowering plants. We note that crown group or stem group angiosperms may ultimately be recognized from Jurassic or earlier rocks, but unambiguous documentation of the diagnostic structural features that separate angiosperms from other groups of extant and extinct seed plants is required for such a report to be viewed as credible. Unsubstantiated assertions of angiosperm affinity for pre-Cretaceous fossils undermine more rigorous paleobotanical research and potentially create confusion, especially in the context of molecular dating analyses that infer pre-Cretaceous ages for angiosperms and certain angiosperm subgroups.


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1 - Chicago Botanic Garden, Senior Scientist, 1000 Lake Cook Road, Glencoe, IL, 60022, USA
2 - Swedish Museum of Natural History, Department of Palaeobiology, Stockholm, SE-104 05, Sweden
3 - University of Aarhus, Department of Earth Science, Aarhus, DK-8000, Denmark
4 - Oak Spring Garden Foundation, 1776 Loughborough Lane, Upperville, VA, 20184, USA

Keywords:
Angiosperm
Paleobotany
Mesozoic.

Presentation Type: Oral Paper
Session: 2, Macroevolution
Location: Fort Worth Ballroom 5/Omni Hotel
Date: Monday, June 26th, 2017
Time: 8:45 AM
Number: 2004
Abstract ID:55
Candidate for Awards:None


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