HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

First published online December 19, 2008; doi:10.3732/ajb.0800202 American Journal of Botany 96: 237-251 (2009) © 2009 Botanical Society of America, Inc.

What's this?

This Article Full Text Full Text (PDF) All Versions of this Article: ajb.0800202v1 96/1/237    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (3) Citing Articles via Google Scholar Google Scholar Articles by Taylor, E. L. Articles by Taylor, T. N. Search for Related Content PubMed Articles by Taylor, E. L. Articles by Taylor, T. N. Agricola Articles by Taylor, E. L. Articles by Taylor, T. N. Social Bookmarking                            What's this?

Seed ferns from the late Paleozoic and Mesozoic: Any angiosperm ancestors lurking there?¹

Department of Ecology and Evolutionary Biology, and Natural History Museum and Biodiversity Research Center, University of Kansas, Lawrence, Kansas 66045-7534 USA

ABSTRACT

Five orders of late Paleozoic–Mesozoic seed ferns have, at one time or another, figured in discussions on the origin of angiosperms, even before the application of phylogenetic systematics. These are the Glossopteridales, Peltaspermales, Corystospermales, Caytoniales, and Petriellales. Although vegetative features have been used to suggest homologies, most discussion has focused on ovulate structures, which are generally interpreted as megasporophylls bearing seeds, with the seeds partially to almost completely enclosed by the megasporophyll (or cupule). Here we discuss current information about the reproductive parts of these plants. Since most specimens are impression-compression remains, homologizing the ovulate organs, deriving angiospermous homologues, and defining synapomorphies remain somewhat speculative. Although new specimens have increased the known diversity in these groups, a reconstruction of an entire plant is available only for the corystosperms, and thus hypotheses about phylogenetic position are of limited value. We conclude that, in the case of these seed plants, phylogenetic analysis techniques have surpassed the hard data needed to formulate meaningful phylogenetic hypotheses. Speculation on angiosperm origins and transitional stages in these fossils provides for interesting discussion, but currently it is still speculation, as the role of these groups in the origin of angiospermy continues to be cloaked in Darwin’s mystery.

Key Words: angiosperm ancestors • caytonialeans • corystosperms • fossil plants • glossopterids • Mesozoic • peltasperms • Permian • seed plant phylogeny

Received for publication 19 June 2008. Accepted for publication 27 October 2008.

FOOTNOTES

¹ The authors thank the following colleagues for kindly supplying figures: J. M. Anderson, C. P. Daghlian, H. Kerp, S. McLoughlin, H. Nishida, P. Ryberg, and M. Zavada, as well as students and postdoctoral scholars in our laboratory who contributed to this work. This research was partially supported by the National Science Foundation (OPP-0229877, ANT-0635477).

² E-mail: etaylor{at}ku.edu; tntaylor{at}ku.edu

CiteULike    Complore    Connotea    Del.icio.us    Digg    Facebook    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				S. Mathews, M. D. Clements, and M. A. Beilstein A duplicate gene rooting of seed plants and the phylogenetic position of flowering plants Phil Trans R Soc B, February 12, 2010; 365(1539): 383 - 395. [Abstract] [Full Text] [PDF]

				J. Wang and H. W. Pfefferkorn Nystroemiaceae, a new family of Permian gymnosperms from China with an unusual combination of features Proc R Soc B, January 22, 2010; 277(1679): 301 - 309. [Abstract] [Full Text] [PDF]

				R. A. Stockey, S. W. Graham, and P. R. Crane Introduction to the Darwin special issue: The abominable mystery1 Am. J. Botany, January 1, 2009; 96(1): 3 - 4. [Full Text] [PDF]

				R. A. Stockey and G. W. Rothwell Distinguishing angiophytes from the earliest angiosperms: A Lower Cretaceous (Valanginian-Hauterivian) fruit-like reproductive structure Am. J. Botany, January 1, 2009; 96(1): 323 - 335. [Abstract] [Full Text] [PDF]