A New Gnetophyte from the Late Carnian (Late Triassic) of Texas and its Bearing on the Origin of the Angiosperm Carpel and Stamen

Abstract

Over the last 100 years, theories on the origin of the angiosperms have shifted like the ebb and flow of the tide. But even the most recent ideas expressed at the AIBS symposium in Iowa (Angiosperm Origin, Early Evolution and Phylogeny) are not entirely new. The monocot, Amentiferae, gnetalean, and bennettitalean theories of angiosperm origin (Eames, 1961; Arber and Parkin, 1907, Arber and Parkin, 1908) were proposed long before Burger 1977; Burger 1981, Crane (1985), and Doyle and Donoghue (1986b) resurrected the anthophyte, monocot, and paleoherb theories in modified form (see also Tucker and Douglas, Chapter 7). Even concepts about the time of angiosperm origin have been cyclical, ranging from Permo-Triassic (Axelrod, 1952, Axelrod, 1961) to Early Cretaceous (Wolfe et al., 1975; Hughes, 1976; Hickey and Doyle, 1977) and back to Permo-Triassic (Cornet, 1986, Cornet, 1989b; Cornet and Habib, 1992; Doyle and Donoghue, 1986a; Martin et al., 1989; Martin et al., 1993).