Hostname: page-component-78c5997874-m6dg7 Total loading time: 0 Render date: 2024-11-08T06:33:49.030Z Has data issue: false hasContentIssue false
  • English
  • Français

Phylogenies and angiosperm diversification

Published online by Cambridge University Press:  08 February 2016

James A. Doyle  and
Michael J. Donoghue
James A. Doyle
Affiliation:
Department of Botany, University of California, Davis, California 95616
Michael J. Donoghue
Affiliation:
Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721
Get access Rights & Permissions [Opens in a new window]

Abstract

Approaches to patterns of diversification based on counting taxa at a given rank can be misleading, even when all taxa are monophyletic. Such “rank-based” approaches are unable to reflect a hierarchy of evolutionary events because taxa of the same rank cannot be nested within one another. Phylogenetic trees specify an order of origination of characters and clades and can therefore be used in some cases to test hypotheses on causal relationships between characters and changes in diversity. “Tree-thinking” also clarifies discussions of the age of groups, by distinguishing between splitting of the stem-lineage from its sister group and splitting of the crown-group into extant clades.

Cladistic evidence that Pentoxylon, Bennettitales, and Gnetales are the sister group of angiosperms implies that the angiosperm line (angiophytes) existed by the Late Triassic. The presence of primitive members of five basic angiosperm clades indicates that the crown-group (angiosperms) had begun to diversify by the mid-Early Cretaceous (Barremian-Aptian), but not necessarily much earlier. The greatest unresolved issue raised by cladistic analyses concerns the fact that the angiosperm tree can be rooted in two almost equally parsimonious positions. Trees rooted near Magnoliales (among “woody magnoliids”) suggest that the angiosperm radiation may have been triggered by the origin of intrinsic traits, e.g., a fast-growing, rhizomatous habit in the paleoherb and eudicot subgroup. However, trees rooted among paleoherbs, which are favored by rRNA data, imply that these traits are basic for angiosperms as a whole. This could mean that the crown-group originated not long before its radiation, or, if it did originate earlier, that its radiation was delayed due to extrinsic factors. Such factors could be a trend from environmental homogeneity and stability in the Jurassic to renewed tectonic activity and disturbance in the Early Cretaceous. Potentially relevant pre-Cretaceous fossils cannot be placed with confidence, but may be located along the stem-lineage (stem angiophytes); their generally paleoherb-like features favor the paleoherb rooting. The history of angiophytes may parallel that of Gnetales: some diversification of the stem-lineage in the Late Triassic, near disappearance in the Jurassic, and vigorous radiation of the crown-group in the Early Cretaceous.

Type
Articles
Information
Paleobiology , Volume 19 , Issue 2 , Spring 1993 , pp. 141 - 167
Copyright
Copyright © The Paleontological Society 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Literature Cited

Ash, S. R. 1972. Late Triassic plants from the Chinle Formation in northeastern Arizona. Palaeontology 15:598–618.Google Scholar
Ax, P. 1985. Stem species and the stem lineage concept. Cladistics 1:279–287.CrossRefGoogle ScholarPubMed
Axelrod, D. I. 1952. A theory of angiosperm evolution. Evolution 6:29–60.CrossRefGoogle Scholar
Axelrod, D. I. 1970. Mesozoic paleogeography and early angiosperm history. Botanical Review 36:277–319.CrossRefGoogle Scholar
Bakker, R. T. 1978. Dinosaur feeding behaviour and the origin of flowering plants. Nature (London) 274:661–663.CrossRefGoogle Scholar
Bond, W. J. 1989. The tortoise and the hare: ecology of angiosperm dominance and gymnosperm persistence. Biological Journal of the Linnean Society 36:227–249.CrossRefGoogle Scholar
Brenner, G. J. 1976. Middle Cretaceous floral provinces and early migrations of angiosperms. Pp. 23–47in Beck, C. B., ed. Origin and early evolution of angiosperms. Columbia University Press, New York.Google Scholar
Brenner, G. J., and Crepet, T. 1986. Paleotropical evolution of angiosperms in the Lower Cretaceous of Northern Gondwana. American Association of Stratigraphic Palynologists 19th Annual Meeting, New York, Abstracts p. 3.Google Scholar
Brown, R. W. 1956. Palm-like plants from the Dolores Formation (Triassic), southwestern Colorado. U. S. Geological Survey Professional Paper 274-H:205–209.Google Scholar
Brooks, D. R., and McLennan, D. A. 1991. Phylogeny, ecology, and behavior. University of Chicago Press, Chicago.Google Scholar
Burger, W. C. 1977. ThePiperales and the monocots. Alternative hypotheses for the origin of monocotyledonous flowers. Botanical Review 43:345–393.Google Scholar
Burger, W. C. 1981a. Heresy revived: the monocot theory of angiosperm origin. Evolutionary Theory 5:189–225.Google Scholar
Burger, W. C. 1981b. Why are there so many kinds of flowering plants? BioScience 31:572, 577–581.CrossRefGoogle Scholar
Carlquist, S. 1975. Ecological strategies of xylem evolution. University of California Press, Berkeley.CrossRefGoogle Scholar
Cornet, B. 1986. The leaf venation and reproductive structures of a Late Triassic angiosperm, Sanmiguelia lewisii. Evolutionary Theory 7:231–309.Google Scholar
Cornet, B. 1989a. Late Triassic angiosperm-like pollen from the Richmond rift basin of Virginia, U.S.A. Palaeontographica Abteilung B 213:37–87.Google Scholar
Cornet, B. 1989b. The reproductive morphology and biology of Sanmiguelia lewisii, and its bearing on angiosperm evolution in the Late Triassic. Evolutionary Trends in Plants 3:25–51.Google Scholar
Cracraft, J. 1981. Pattern and process in paleobiology: the role of cladistic analysis in systematic paleontology. Paleobiology 7:456–468.CrossRefGoogle Scholar
Cracraft, J. 1982. A nonequilibrium theory for the rate-control of speciation and extinction and the origin of macroevolutionary patterns. Systematic Zoology 31:348–365.CrossRefGoogle Scholar
Cracraft, J. 1984. Conceptual and methodological aspects of the study of evolutionary rates. Pp. 95–104in Eldredge, N. and Stanley, S. M., eds. Living fossils. Springer, New York.CrossRefGoogle Scholar
Crane, P. R. 1985. Phylogenetic analysis of seed plants and the origin of angiosperms. Annals of the Missouri Botanical Garden 72:716–793.CrossRefGoogle Scholar
Crane, P. R. 1987a. [Review of] Cornet, B. 1986. The leaf venation and reproductive structures of a Late Triassic angiosperm, Sanmiguelia lewisii. Evolutionary Theory 7:231–309. Taxon 36: 778–779.Google Scholar
Crane, P. R. 1987b. Vegetational consequences of the angiosperm diversification. Pp. 107–144in Friis et al. 1987.Google Scholar
Crane, P. R. 1988. Major clades and relationships in the “higher” gymnosperms. Pp. 218–272in Beck, C. B., ed. Origin and evolution of gymnosperms. Columbia University Press, New York.Google Scholar
Crane, P. R., and Lidgard, S. 1989. Angiosperm diversification and paleolatitudinal gradients in Cretaceous floristic diversity. Science 246:675–678.CrossRefGoogle ScholarPubMed
Crane, P. R. 1990. Angiosperm radiation and patterns of Cretaceous palynological diversity. Pp. 377–407in Taylor, P. D. and Larwood, G. P., eds. Major evolutionary radiations. Clarendon, Oxford.Google Scholar
Crane, P. R., and Upchurch, G. R. Jr. 1987. Drewria potomacensis gen. et sp. nov., an Early Cretaceous member of Gnetales from the Potomac Group of Virginia. American Journal of Botany 74:1722–1736.Google Scholar
Crane, P. R., Donoghue, M. J., Doyle, J. A., and Friis, E. M. 1989. Angiosperm origins. Nature (London) 342:131–132.CrossRefGoogle Scholar
Cronquist, A. 1968. The evolution and classification of flowering plants. Houghton Mifflin, Boston.Google Scholar
Cronquist, A. 1981. An integrated system of classification of flowering plants. Columbia University Press, New York.Google Scholar
Daugherty, L. M. 1934. Schilderia adamanica: a new fossil wood from the petrified forests of Arizona. Botanical Gazette 96:363–366.CrossRefGoogle Scholar
de Queiroz, K., and Gauthier, J. 1990. Phylogeny as a central principle in taxonomy: phylogenetic definitions of taxon names. Systematic Zoology 39:307–322.CrossRefGoogle Scholar
de Queiroz, K. 1992. Phylogenetic taxonomy. Annual Review of Ecology and Systematics 23:449–480.CrossRefGoogle Scholar
Dilcher, D. L. 1989. The occurrence of fruits with affinities to Ceratophyllaceae in Lower and mid-Cretaceous sediments. American Journal of Botany 76 (6, Suppl.):162.Google Scholar
Dilcher, D. L., and Crane, P. R. 1984. Archaeanthus: an early angiosperm from the Cenomanian of the Western Interior of North America. Annals of the Missouri Botanical Garden 71:351–383.CrossRefGoogle Scholar
Donoghue, M. J. 1989. Phylogenies and the analysis of evolutionary sequences, with examples from seed plants. Evolution 43:1137–1156.CrossRefGoogle ScholarPubMed
Donoghue, M. J., and Doyle, J. A. 1989. Phylogenetic analysis of angiosperms and the relationships of Hamamelidae. Pp. 17–45in Crane, P. R. and Blackmore, S., eds. Evolution, systematics, and fossil history of the Hamamelidae, Vol. 1. Clarendon, Oxford.Google Scholar
Donoghue, M. J. 1991. Angiosperm monophyly. Trends in Ecology and Evolution 6:407.CrossRefGoogle ScholarPubMed
Doyle, J. A. 1969. Cretaceous angiosperm pollen of the Atlantic Coastal Plain and its evolutionary significance. Journal of the Arnold Arboretum 50:1–35.CrossRefGoogle Scholar
Doyle, J. A. 1973. Fossil evidence on early evolution of the monocotyledons. Quarterly Review of Biology 48:399–413.CrossRefGoogle Scholar
Doyle, J. A. 1977. Patterns of evolution in early angiosperms. Pp. 501–546in Hallam, A., ed. Patterns of evolution as illustrated by the fossil record. Elsevier, Amsterdam.CrossRefGoogle Scholar
Doyle, J. A. 1978. Origin of angiosperms. Annual Review of Ecology and Systematics 9:365–392.CrossRefGoogle Scholar
Doyle, J. A., and Donoghue, M. J. 1986. Seed plant phylogeny and the origin of angiosperms: an experimental cladistic approach. Botanical Review 52:321–431.CrossRefGoogle Scholar
Doyle, J. A. 1987. The importance of fossils in elucidating seed plantphylogeny and macroevolution. Review of Palaeobotany and Palynology 50:63–95.CrossRefGoogle Scholar
Doyle, J. A. 1992. Fossils and seed plant phylogeny reanalyzed. Brittonia 44:89–106.CrossRefGoogle Scholar
Doyle, J. A., and Hickey, L. J. 1976. Pollen and leaves from the mid-Cretaceous Potomac Group and their bearing on early angiosperm evolution. Pp. 139–206in Beck, C. B., ed. Origin and early evolution of angiosperms. Columbia University Press, New York.Google Scholar
Doyle, J. A., and Hotton, C. L. 1991. Diversification of early angiosperm pollen in a cladistic context. Pp. 169–195in Blackmore, S. and Barnes, S. H., eds. Pollen and spores: patterns of diversification. Clarendon, Oxford.CrossRefGoogle Scholar
Doyle, J. A., Biens, P., Doerenkamp, A., and Jardiné, S. 1977. Angiosperm pollen from the pre-Albian Cretaceous of Equatorial Africa. Bulletin des Centres de Recherches Exploration-Production Elf-Aquitaine 1:451–473.Google Scholar
Doyle, J. A., Jardiné, S., and Doerenkamp, A. 1982. Afropollis, a new genus of early angiosperm pollen, with notes on the Cretaceous palynostratigraphy and paleoenvironments of Northern Gondwana. Bulletin des Centres de Recherches Exploration-Production Elf-Aquitaine 6:39–117.Google Scholar
Doyle, J. A., Hotton, C. L., and Ward, J. V. 1990a. Early Cretaceous tetrads, zonasulculate pollen, and Winteraceae. I. Taxonomy, morphology, and ultrastructure. American Journal of Botany 77:1544–1557.Google Scholar
Doyle, J. A. 1990b. Early Cretaceous tetrads, zonasulculate pollen, and Winteraceae. II. Cladistic analysis and implications. American Journal of Botany 77:1558–1568.Google Scholar
Drinnan, A. N., and Chambers, T. C. 1985. A reassessment of Taeniopteris daintreei from the Victorian Early Cretaceous: a member of the Pentoxylales and a significant Gondwanaland plant. Australian Journal of Botany 33:89–100.CrossRefGoogle Scholar
Drinnan, A. N., Crane, P. R., Friis, E. M., and Pedersen, K. R. 1990. Lauraceous flowers from the Potomac Group (mid-Cretaceous) of eastern North America. Botanical Gazette 151:370–384.CrossRefGoogle Scholar
Eldredge, N., and Cracraft, J. 1980. Phylogenetic patterns and the evolutionary process. Columbia University Press, New York.Google Scholar
Endress, P. K. 1987. The Chloranthaceae: reproductive structures and phylogenetic position. Botanische Jahrbücher für Systematik 109:153–226.Google Scholar
Farrell, B. D., Dussourd, D. E., and Mitter, C. 1991. Escalation of plant defense: do latex and resin canals spur plant diversification? American Naturalist 138:881–900.CrossRefGoogle Scholar
Felsenstein, J. 1985. Phylogenies and the comparative method. American Naturalist 125:1–15.CrossRefGoogle Scholar
Fisher, D. C. 1980. The role of stratigraphic data in phylogenetic inference. Geological Society of America Abstracts with Programs 12:426.Google Scholar
Friis, E. M., and Crane, P. R. 1989. Reproductive structures of Cretaceous Hamamelidae. Pp. 155–174in Crane, P. R. and Blackmore, S., eds. Evolution, systematics, and fossil history of the Hamamelidae, Vol. 1. Clarendon, Oxford.Google Scholar
Friis, E. M., and Crepet, W. L. 1987. Time of appearance of floral features. Pp. 145–179in Friis et al. 1987.Google Scholar
Friis, E. M., Chaloner, W. G., and Crane, P. R., eds. 1987. The origins of angiosperms and their biological consequences. Cambridge University Press, Cambridge.Google Scholar
Gilinsky, N. L. 1991. Cross sections through evolutionary trees: theory and applications. Systematic Zoology 40:19–32.CrossRefGoogle Scholar
Gilinsky, N. L., and Good, I. J. 1991. Probabilities of origination, persistence, and extinction of families of marine invertebrate life. Paleobiology 17:145–166.CrossRefGoogle Scholar
Gould, S. J. 1977. Eternal metaphors of palaeontology. Pp. 1–26in Hallam, A., ed. Patterns of evolution as illustrated by the fossil record. Elsevier, Amsterdam.Google Scholar
Guyer, C., and Slowinski, J. B. 1991. Comparison of observed phylogenetic topologies with null expectations among three monophyletic lineages. Evolution 45:340–350.CrossRefGoogle ScholarPubMed
Hallam, A. 1975. Jurassic environments. Cambridge University Press, Cambridge.Google Scholar
Hamby, R. K., and Zimmer, E. A. 1992. Ribosomal RNA as a phylogenetic tool in plant systematics. Pp. 50–91in Soltis, P. S., Soltis, D. E., and Doyle, J. J., eds. Molecular systematics of plants. Chapman and Hall, New York.CrossRefGoogle Scholar
Harvey, P. H., and Pagel, M. D. 1991. The comparative method in evolutionary biology. Oxford University Press, Oxford.CrossRefGoogle Scholar
Hennig, W. 1965. Phylogenetic systematics. Annual Review of Entomology 10:97–116.CrossRefGoogle Scholar
Hennig, W. 1966. Phylogenetic systematics. University of Illinois Press, Urbana.Google Scholar
Hennig, W. 1969. Die Stammesgeschichte der Insekten. W. Kramer, Frankfort.Google Scholar
Hickey, L. J., and Doyle, J. A. 1977. Early Cretaceous fossil evidence for angiosperm evolution. Botanical Review 43:1–104.CrossRefGoogle Scholar
Hughes, N. F. 1961. Fossil evidence and angiosperm ancestry. Science Progress 49:84–102.Google Scholar
Hughes, N. F. 1976. Paleobiology of angiosperm origins. Cambridge University Press, Cambridge.Google Scholar
Hughes, N. F., and McDougall, A. B. 1987. Records of angiospermid pollen entry into the English Early Cretaceous succession. Review of Palaeobotany and Palynology 50:255–272.CrossRefGoogle Scholar
Janzen, D. H. 1970. Herbivores and the number of tree species in tropical forests. American Naturalist 104:501–528.CrossRefGoogle Scholar
Jefferies, R. P. S. 1979. The origin of chordates—a methodological essay. Pp. 443–477in House, M. R., ed. The origin of major invertebrate groups. Academic Press, London.Google Scholar
Krassilov, V. A. 1977. The origin of angiosperms. Botanical Review 43:143–176.CrossRefGoogle Scholar
Krassilov, V. A. 1986. New floral structure from the Lower Cretaceous of Lake Baikal area. Review of Palaeobotany and Palynology 47:9–16.CrossRefGoogle Scholar
Krassilov, V. A. 1991. The origin of angiosperms: new and old problems. Trends in Ecology and Evolution 6:215–220.CrossRefGoogle ScholarPubMed
Les, D. H., Garvin, D. K., and Wimpee, C. F. 1991. Molecular evolutionary history of ancient aquatic angiosperms. Proceedings of the National Academy of Sciences, USA 88:10119–10123.CrossRefGoogle ScholarPubMed
Lewontin, R. C. 1983. Gene, organism and environment. Pp. 273–285in Bendall, D. S., ed. Evolution from molecules to men. Cambridge University Press, Cambridge.Google Scholar
Loconte, H., and Stevenson, D. W. 1990. Cladistics of the Spermatophyta. Brittonia 42:197–211.CrossRefGoogle Scholar
Loconte, H. 1991. Cladistics of the Magnoliidae. Cladistics 7:267–296.CrossRefGoogle ScholarPubMed
Martin, W., Gierl, A., and Saedler, H. 1989. Molecular evidence for pre-Cretaceous angiosperm origins. Nature (London) 339:46–48.CrossRefGoogle Scholar
Marzluff, J. M., and Dial, K. P. 1991. Life history correlates of taxonomic diversity. Ecology 72:428–439.CrossRefGoogle Scholar
Meyen, S. V. 1988. Origin of the angiosperm gynoecium by gamoheterotopy. Botanical Journal of the Linnean Society 97:171–178.CrossRefGoogle Scholar
Muller, J. 1970. Palynological evidence on early differentiation of angiosperms. Biological Reviews of the Cambridge Philosophical Society 45:417–450.CrossRefGoogle Scholar
Muller, J. 1981. Fossil pollen records of extant angiosperms. Botanical Review 47:1–142.CrossRefGoogle Scholar
Niklas, K. J., Tiffney, B. H., and Knoll, A. H. 1980. Apparent changes in the diversity of fossil plants: a preliminary assessment. Evolutionary Biology 12:1–89.Google Scholar
Novacek, M. J., and Norell, M. A. 1982. Fossils, phylogenies, and taxonomic rates of evolution. Systematic Zoology 31:366–375.CrossRefGoogle Scholar
O'Hara, R. J. 1988. Homage to Clio, or toward an historical philosophy for evolutionary biology. Systematic Zoology 37:142–155.CrossRefGoogle Scholar
Olsen, P. E., Shubin, N. H., and Anders, M. H. 1987. New Early Jurassic tetrapod assemblages constrain Triassic-Jurassic event. Science 237:1025–1029.CrossRefGoogle ScholarPubMed
Osborn, J. M., Taylor, T. N., and Schneider, E. L. 1991. Pollen morphology and ultrastructure of the Cabombaceae: correlations with pollination biology. American Journal of Botany 78:1367–1378.CrossRefGoogle Scholar
Parrish, J. T. 1987. Global palaeogeography and palaeoclimate of the Late Cretaceous and Early Tertiary. Pp. 51–73 in Friis et al. 1987.Google Scholar
Parrish, J. T., Ziegler, A. M., and Scotese, C. R. 1982. Rainfall patterns and the distribution of coals and evaporites in the Mesozoic and Cenozoic. Palaeogeography, Palaeoclimatology, Palaeoecology 40:67–101.CrossRefGoogle Scholar
Patterson, C., and Smith, A. B. 1987. Is the periodicity of extinctions a taxonomic artifact? Nature (London) 330:248–251.CrossRefGoogle Scholar
Pedersen, K. R., Crane, P. R., Drinnan, A. N., and Friis, E. M. 1991. Fruits from the mid-Cretaceous of North America with pollen grains of the Clavatipollenites type. Grana 30:577–590.CrossRefGoogle Scholar
Pons, D., Oliveira-Babinski, M. E., and de Lima, M. 1992. Les Ephédrales de la Formation Santana, Crétacé inférieur du Bassin d'Araripe (Brésil). Organisation Internationale de Paléobotanique, IVème Conférence (Paris), Abstracts 125.Google Scholar
Raikow, R. J. 1988. The analysis of evolutionary success. Systematic Zoology 37:76–79.CrossRefGoogle Scholar
Read, R. W., and Hickey, L. J. 1972. A revised classification of fossil palm and palm-like leaves. Taxon 21:129–137.CrossRefGoogle Scholar
Regal, P. J. 1977. Ecology and evolution of flowering plant dominance. Science 196:622–629.CrossRefGoogle ScholarPubMed
Sanderson, M. J., and Bharathan, G. 1993. Does cladistic information affect inferences about branching rates? Systematic Biology (in press).CrossRefGoogle Scholar
Scott, R. A., Barghoorn, E. S., and Leopold, E. B. 1960. How old are the angiosperms? American Journal of Science 258-A:284–299.Google Scholar
Sepkoski, J. J. Jr. 1978. A kinetic model of Phanerozoic taxonomic diversity I. Analysis of marine orders. Paleobiology 4:223–251.CrossRefGoogle Scholar
Sepkoski, J. J. Jr. 1987. [Reply to Patterson and Smith]. Nature (London) 330:251–252.CrossRefGoogle Scholar
Seward, A. C. 1904. Catalogue of Mesozoic plants in the British Museum. The Jurassic flora, part 1. British Museum (Natural History), London.Google Scholar
Simpson, G. G. 1953. The major features of evolution. Columbia University Press, New York.CrossRefGoogle Scholar
Slowinski, J. B., and Guyer, C. 1989. Testing the stochasticity of patterns of organismal diversity: an improved null model. American Naturalist 134:907–921.CrossRefGoogle Scholar
Smith, A. B., and Patterson, C. 1988. The influence of taxonomic method on the perception of patterns of evolution. Evolutionary Biology 23:127–216.CrossRefGoogle Scholar
Stanley, S. M. 1979. Macroevolution: pattern and process. W. H. Freeman, San Francisco.Google Scholar
Stebbins, G. L. 1974. Flowering plants: evolution above the species level. Harvard University Press, Cambridge, Mass.CrossRefGoogle Scholar
Stebbins, G. L. 1981. Why are there so many species of flowering plants? BioScience 31:573–577.CrossRefGoogle Scholar
Takhtajan, A. L. 1969. Flowering plants: origin and dispersal. Smithsonian Institution, Washington, D.C.Google Scholar
Takhtajan, A. L. 1980. Outline of the classification of flowering plants (Magnoliophyta). Botanical Review 46:225–359.CrossRefGoogle Scholar
Taylor, D. W., and Hickey, L. J. 1990. An Aptian plant with attached leaves and flowers: implications for angiosperm origin. Science 247:702–704.CrossRefGoogle ScholarPubMed
Taylor, D. W. 1992. Phylogenetic evidence for the herbaceous origin of angiosperms. Plant Systematics and Evolution 180:137–156.CrossRefGoogle Scholar
Thorne, R. F. 1976. A phylogenetic classification of the Angiospermae. Evolutionary Biology 9:35–106.Google Scholar
Tiffney, B. H., and Niklas, K. J. 1985. Clonal growth in land plants: a paleobotanical perspective. Pp. 35–66in Jackson, J. B. C., Buss, L. W., and Cook, R. E., eds. Population biology and evolution of clonal organisms. Yale University Press, New Haven.Google Scholar
Trevisan, L. 1980. Ultrastructural notes and considerations on Ephedripites, Eucommiidites and Monosulcites pollen grains from Lower Cretaceous sediments of southern Tuscany (Italy). Pollen et Spores 22:85–132.Google Scholar
Trevisan, L. 1988. Angiospermous pollen (monosulcate-trichotomosulcate phase) from the very early Lower Cretaceous of Southern Tuscany (Italy): some aspects. 7th International Palynological Congress (Brisbane) Abstracts p. 165.Google Scholar
Tucker, M. E., and Benton, M. J. 1982. Triassic environments, climates and reptile evolution. Palaeogeography, Palaeoclimatology, Palaeoecology 40:361–379.CrossRefGoogle Scholar
Upchurch, G. R. Jr. 1984. Cuticle evolution in Early Cretaceous angiosperms from the Potomac Group of Virginia and Maryland. Annals of the Missouri Botanical Garden 71:522–550.CrossRefGoogle Scholar
Upchurch, G. R. Jr. 1989. Terrestrial environmental changes and extinction patterns at the Cretaceous-Tertiary boundary, North America. Pp. 195–216in Donovan, S. K., ed. Mass extinctions: processes and evidence. Columbia University Press, New York.Google Scholar
Upchurch, G. R. Jr., and Dilcher, D. L. 1990. Cenomanian angiosperm leaf megafossils, Dakota Formation, Rose Creek locality, Jefferson County, southeastern Nebraska. U. S. Geological Survey Bulletin 1915:1–55.Google Scholar
Vakhrameev, V. A. 1970. Yurskie i rannemelovye flory. Pp. 213–281in Vakhrameev, V. A., Dobruskina, I. A., Zaklinskaya, Y. D., and Meyen, S. V., eds. Paleozoyskie i mezozoyskie flory Yevrazii i fitogeografiya etogo vremeni. Nauka, Moscow.Google Scholar
Valentine, J. W., ed. 1985. Phanerozoic diversity patterns: profiles in macroevolution. Princeton University Press, Princeton, New Jersey.Google Scholar
Van Konijnenburg-van Cittert, J. H. A. 1992. An enigmatic Liassic microsporophyll, yielding Ephedripites pollen. Review of Paleobotany and Palynology 71:239–254.CrossRefGoogle Scholar
Vrba, E. S. 1980. Evolution, species and fossils: how does life evolve? South African Journal of Science 76:118–126.Google Scholar
Vrba, E. S. 1983. Macroevolutionary trends: new perspectives on the roles of adaptation and incidental effect. Science 221:387–389.CrossRefGoogle ScholarPubMed
Walker, J. W., and Walker, A. G. 1984. Ultrastructure of Lower Cretaceous angiosperm pollen and the origin and early evolution of flowering plants. Annals of the Missouri Botanical Garden 71:464–521.CrossRefGoogle Scholar
Walker, J. W., Brenner, G. J., and Walker, A. G. 1983. Winteraceous pollen in the Lower Cretaceous of Israel: early evidence of a magnolialean angiosperm family. Science 220:1273–1275.CrossRefGoogle ScholarPubMed
Ward, J. V., Doyle, J. A., and Hotton, C. L. 1989. Probable granular magnoliid angiosperm pollen from the Early Cretaceous. Pollen et Spores 33:101–120.Google Scholar
Wing, S. L., and Tiffney, B. H. 1987. Interactions of angiosperms and herbivorous tetrapods through time. Pp. 203–224in Friis et al. 1987.Google Scholar
Wolfe, J. A., and Upchurch, G. R. Jr. 1987. North American nonmarine climates and vegetation during the Late Cretaceous. Palaeogeography, Palaeoclimatology, Palaeoecology 61:33–77.CrossRefGoogle Scholar
Wolfe, J. A., Doyle, J. A., and Page, V. M. 1975. The bases of angiosperm phylogeny: paleobotany. Annals of the Missouri Botanical Garden 62:801–824.CrossRefGoogle Scholar
Wolfe, K. H., Gouy, M., Yang, Y.-W., Sharp, P. M., and Li, W.-H. 1989. Date of the monocot-dicot divergence estimated from chloroplast DNA sequence data. Proceedings of the National Academy of Sciences, USA 86:6201–6205.CrossRefGoogle ScholarPubMed