FOSSIL PLANTS/Gymnosperms 443 Sporocarp A closed body or conceptacle containing one or more masses of spores or sporangia Symbiosis A form of interaction where one organism lives in an intimate association with another Thallus The vegetative body of a plant or lichen that is not differentiated into organs such as leaves and stems See Also Biosediments and Biofilms Carbon Cycle Fossil Plants: Calcareous Algae Palaeozoic: Devonian Precambrian: Vendian and Ediacaran Sedimentary Rocks: Chert Tectonics: Hydrothermal Activity Tertiary To Present: Eocene Further Reading Hallbauer DK and van Warmelo KT (1974) Fossilized plants in thucholite from Precambrian rocks of Witwatersrand, South Africa Precambrian Research 1: 199 212 Hass H, Taylor TN, and Remy W (1994) Fungi from the Lower Devonian Rhynie Chert: mycoparasitism American Journal of Botany 81: 29 37 Heckman DS, Geiser DM, Eidell BR, et al (2001) Molecu lar evidence for the early colonization of land by fungi and plants Science 293: 1129 1133 Hueber FM (2001) Rotted wood alga fungus: the his tory and life of Prototaxites Dawson 1859 Review of Palaeobotany and Palynology 116: 123 158 Poinar GO (1992) Life in Amber Stanford, CA: Stanford University Press Purvis W (2000) Lichens Washington, DC and London: Smithsonian Institution Press and The Natural History Museum Stubblefield S and Taylor TN (1986) Wood decay in silici fied gymnosperms from Antarctica Botanical Gazette 147: 116 125 Stubblefield S and Taylor TN (1988) Recent advances in palaeomycology New Phytologist 108: 25 Taylor TN (1993) Fungi In: Benton MJ (ed.) The Fossil Record, vol 2, pp 13 London: Chapman & Hall Taylor TN and Taylor EL (1993) The Biology and Evolution of Fossil Plants Englewood Cliffs, NJ: Prentice Hall Taylor TN and Taylor EL (2000) The Rhynie Chert ecosystem: a model for understanding fungal inter actions In: Bacon CW and White JF (eds.) Micro bial Endophytes, pp 31 47 New York: Marcel Dekker, Inc Taylor TN, Remy W, and Hass H (1992) Fungi from the Lower Devonian Rhynie Chert: Chytridiomycetes American Journal of Botany 79: 1233 1241 Taylor TN, Hass H, and Kerp H (1997) A cyanolichen from the Lower Devonian Rhynie Chert American Journal of Botany 84: 992 1004 Tiffney BH and Barghoorn ES (1974) The fossil record of the fungi Occasional Papers of the Farlow Herbarium of Cryptogamic Botany 7: 42 Waggoner BM (1995) Ediacaran lichens: a critique Paleobiology 21: 393 397 Gymnosperms P Kenrick, The Natural History Museum, London, UK Copyright 2005, Natural History Museum All Rights Reserved Introduction Gymnosperms are an ancient group of plants that include some familiar living forms such as conifers, cycads, and ginkgos as well as a great variety of far less well-known and long-extinct kinds The modest number of living species (approx 750) belies the geological importance of the group Gymnosperms dominated the Mesozoic era It was during this time that many of the major subgroups originated, diversified, and finally succumbed to their ultimate fate, extinction The evolution of gymnosperms and in particular their relationships with the angiosperms (flowering plants) is also the subject of much debate Phylogenetic studies clearly show that these two groups are close relatives, but the exact nature of their kinship is still unclear Knowing how these two groups are related is essential to developing a family tree of gymnosperms and to understanding the origin of the flowering plants Because much of the diversity of gymnosperms is extinct, the fossil record continues to play a crucial role in elucidating evolutionary patterns Recently, molecular systematics has introduced an enormous amount of new comparative data This has brought unprecedented precision in our ability to reconstruct family trees, shedding new light on the evolution of gymnosperms and their lengthy and chequered fossil history