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Taylor (2009), Xin Wang (2009), Dilcher (2010), Magallón (2010), Stephen A. Stewart and Rothwell (1993) recapitulated the main steps needed to form the conduplicate carpel using glossopterid-, other seed fern-, and early angiosperm fossils as examples. Cambridge: Cambridge University Press, 521 pp., with additional comments distilled from E. Further, White proposed that the glossopterid Megafructi were a second basal group upon which ranalian angiosperms, monocotyledonous flowering plants including Pandanus (Pandanaceae, Pandanales, Arecidae), Williamsonia (a bennettitalean), additional cycads, and certain other angiosperms evolved (M. Principal morphologic innovations in angiosperms and gymnosperms according to Krassilov (1997) are: Paleoherb hypothesis. Burger published a paper in 1981 suggesting that the earliest angiosperms were monocotyledonous plants. Molecular tracers include naturally occurring but fossilized triterpenoids known as oleanone triterpanes (oleananes). These TSBs are a stratigraphically-important but "inconvenient truth," which is often buried or ignored in modern syntheses on the origin and evolution of flowering plants. Flowers and simple cones are reproductive short- (spur-) shoots according to Christianson and Jernstedt (2009). A novel "Mosaic Theory for the Evolution of the Dimorphic Perianth" proposed by Warner et al. Melville develops his earlier ideas on a Gonophyll Theory (1969) in a review published in 1983 that proposes a Permian origin of angiosperms from glossopterids. Rothwell (1993), Paleobotany and the Evolution of Plants (second edition). Mary White (1986) proposes that glossopterid Microfructi were basal to several parallel but sometimes branching and reticulate lines of evolution leading to the Caytoniales, angiosperms, Cycas (Cycadaceae, Cycadales), Podocarpaceae (Podocarpales), Araucariaceae (Araucariales), and certain catkin-bearing angiosperms including the Casuarinaceae. The polyphyletic-polychromic-polytopic hypothesis (Z.-Y. Cyclic angiospermization is reviewed by Krassilov (1997) and Ponomarenko (1998) within the context of a polyphyletic origin of angiosperms. Clifford (1982), The Monocotyledons: A Comparative Study. A discussion of this theory and how it links to the anthophyte hypothesis is presented by T. A few elements of ideas proposed by Cascales-Miñana et al. Armen Takhtajan's often criticized proposal on a "neotenous" origin of flowering plants (1969, 1976, and previous papers) is my starting place. Equally puzzling is that despite intense interest in the origins of seed plants and angiosperms throughout the entire last century, few have looked at the problems from a life cycle evo-devo perspective, with perhaps one exception (Takhtajan 1976), who alluded to neoteny as one of the possible mechanisms contributing to the origin of angiosperms." "Some authors seem curiously determined to prove that pre-Cretaceous fossils are crown-group angiosperms, but for understanding most aspects of the origin of angiosperms [other than their age], close stem relatives would be far more significant ..." (page 318, J. Doyle 2012) Based on four decades of study of the problem by Professor Emeritus J. Doyle, where on the Pangaean continent (and when) do students of angio-ovuly and the origin of flowering plants focus the search for "close stem relatives" of the group? Surprising and often ignored clues shedding light on the shadowy origin of flowering plants originate from oil and gas exploration data and the geochemistry of taxon-specific biomarkers (TSBs) and molecular traces, which are recoverable from mud logs of well boreholes, or from coal balls, compressions, and permineralizations (Moldowan and Jacobson 2002). Mud-loggers are able to ascertain higher plant input into a core segment of a stratigraphic horizon pulled-up from the well-site gas chromatography and mass spectrometry, and microscopic analysis of animal and plant microfossils including pollen and vascular plant fragments in core samples. Rudall (2006), Morphological and molecular phylogenetic context of the angiosperms: contrasting the 'top-down' and 'bottom-up' approaches used to infer the likely characteristics of the first flowers, Journal of Experimental Botany 57(13): 3471-3503. Flowering plants probably did not appear "suddenly," and the concept of a so-called "first flower" including proposals published by Albert et al. The reproductive short- (spur-) shoots of these Permo-carboniferous seed plants were equivalent to theoretical constructs of the protoflower proposed by Leppik (1960, 1968). (1985), Labandeira and Sepkoski (1993), Farrell (1998), Labandeira (1998), Danforth and Ascher (1999), Grimaldi (1999), Wilf et al. 2009, Specht and Bartlett 2009, Licausi 2011, Glover 2014, among others). Evidence of arthropod-plant interactions in the Upper Triassic of the Southwestern United States. All total in this rich flora of some 6,000 species, there are 812 endemic angiosperms and conifers, 12 endemic genera, and one endemic flowering plant family (A. Distant pinnacles and spires are weathered calc-alkaline Miocene andesites known as the Namosi Volcanics (Rodda and Kroenke 1984). (2008), Specht and Bartlett (2009), Dilcher (2010), D. Isoptera (termites) are hemimetabolous insects (Grimaldi and Engel 2005). The insect developmental tool kit is comprised of certain homeotic selector genes (including Hox genes), zygotic (gap- maternal-, and pair-rule-) genes, field-specific selector genes, compartment selector genes, cell-type-specific selector genes, and segment polarity genes; and the TFs they encode (Rosenberg et al. In addition, the insect developmental tool kit is comprised of controlling factors behind the cessation of insect growth including bioactive PTTH, JH, juvenile hormone esterases, and ecdysone steroids (Truman and Riddiford 2002, Nijhout 2003, S. Juvenile hormone biosynthesized in the corpora allata of the insect brain is a sesquiterpenoid epoxide methyl ester (Hartfelder 2000). Key elements of the Drosophila molecular tool kit include: Evolution of the Hox complex. Ice-free terrestrial environments in the Late Silurian were covered in vegetation. Understanding the origin and diversification of holometabolous insects in deep-time.
The three essays on the succeeding web pages are written from this research perspective. Gómez-Zurita and Galián (2005) discuss the utility of molecular phylogenetic characters appearing in the entomological literature in a review paper, which is organized along the lines of Floyd and Bowman (2007) for land plants (see section below). Understanding the land plant developmental tool kit and gene regulation from a deep time research perspective ties-in with models of cone and floral organization, cell geometry and regulation of growth from SAMs, paleobiology of homeodomain TF trafficking, phyllotaxis, leaf development, and morphogenesis of fertile organs. On the other hand, certain hemimetabolous bugs (Hemiptera) possess abdominal stretch receptors that activate secretion of PTTH (Nijhout 2003). 2005, among others) of the Drosophila Hox complex are: Ancestral arthropods possess two additional homeotic selector genes of the Hox cluster that together comprise the HOM-C, ten gene complex (see discussion in Negre et al. These additional genes are: Genomic analyses suggest that derived winged insects lost functional copies of ftz and Hox3 through disintegration of the HOM-C complex (Negre et al. Duplication of the Hox3 gene of ancestral Cyclorrhaphan flies gave rise to two maternal effect genes, bcd and zen (Stauber et al. Based upon this study it is important to include Hox3 as part of the ancestral diverging insect developmental tool kit. Possible candidates for the early divergent insect developmental tool kit might include certain homeotic selector genes of the Hox complex such as homologs and paralogs of abd-A, Abd-B, Hox3, pb, Scr (Rogers et al. 2002) are probably behind many insect body plan novelties seen in the paleontologic record of the past 400 million years of arthropod and crustacean evolution (Pavlopoulos and Akam 2011, Pavlopoulos and Averof 2002). Plant evolution occurs as variation in genetic and epigenetic developmental processes is winnowed by ecology..." The preceding quotation is from page 161 of P. Once JH circulating in the hemolymph is destroyed by juvenile hormone esterases, then PTTH secretion resumes under circadian (22-24 hour) photoperiodic control (Nijhout 2003). The importance of Ubx protein encoded by the Ubx gene in the early divergent insect developmental tool kit cannot be neglected in the present analysis since significant changes in the carboxy-terminal (C-terminal) region (Galant and Carroll 2002) and serine/threonine phosphorylation sites (Ronshaugen et al. Doyle (1978, 1994, 2005, 2006, 2008, 2012), Friis et al. (2008), Berendse and Scheffer (2009), Friedman (2009), Specht and Bartlett (2009), E. A differing proposal by Dahlgren and Clifford (1982) suggests: "The ancestors of the monocotyledons were probably shrublets or subshrubs which by environmental conditions (a pronounced alternation between wet and dry periods) evolved compact underground stems, mainly short or long rhizomes from which herbaceous aerial stems were developed ..." The preceding quotation is from page 344 of R. Class 1c resin constituents associated with Mesozoic angiosperm amber are known from 320 million year old (Paleozoic) amber samples (Bray and K. Almost certainly, accomplished studies of the Amborella trichopoda genome, though useful in disentangling aspects of the evolution of GRNs and horizontal transfer (HT), will not help paleobiologists determine the origin(s) of angiosperms. 2014), and detailed analyses of paleobiological data (Labandeira 2014). If fertile spur shoots are demonstrably ancient organs known from late Paleozoic seed plant fossils then how could the flower possibly originate in the late Mesozoic? "The flower remains ill-defined and its mode (or modes) of origin remain hotly disputed; some definitions and hypotheses of evolutionary relationships preclude a role for the flower in delimiting the angiosperms." The preceding statement is from the abstract on page 3471 of R. Floral morphologies are deeply-conserved in angiosperms according to Melzer et al. According to Stewart and Rothwell (1993) these main steps were: The above bulleted quotes are from pages 461-462 of W. Flowering plants evolved from herbaceous forms possessing ovule and pollen bearing organs that coalesced over time producing modern flowers according to D. Professor Burger proposed six hypothetical trends in the early evolution of angiosperms: The above bulleted quotation is from pages 191-194 of W. Burger (1981), Heresy revived: the monocot theory of angiosperm origin, Evolutionary Theory 5: 189-225. Oleananes, together with ursenes, lupenes, and taraxerenes are important TSBs that belong to a class of Β-amirin triterpenoids (Moldowan and Jacobson 2002). Oleananes occur in fossilized leaf material of certain gigantopterids, bennettitaleans, and flowering plants (Moldowan and Jacobson 2002), but are absent from samples of several other fossil seed plants (D. Problems with Contemporary Data Sets: Controversial assertions abound in the scientific literature of the 20th Century and three categories of credible hypotheses and theories exist (Rothwell et al. None of these ideas when taken as a whole are neither compelling or plausible to many scientists, including the author. Based on a discussion of floral evo-devo by Becker (2016), there are other points of view to be considered. Deciphering evo-devo of short- (spur-) shoots on growing mother plants in hybridizing Permo-carboniferous seed plant populations is probably a central tenet in disentangling at least some aspects of the allopolyploid origin of the flowering plants.