[ Essays on the Origin of Angiosperms ]
Molecular coevolution of insect and seed plant developmental tool kits, cis-regulatory modules (CRMs), and gene-regulatory networks (GRNs), might explain diversification in Paleozoic seed plant lineages, origin of flowers, and the origin of angiosperms and coevolution with holometabolous insects.
Were insect and shrub coevolutionary compartments of the late Paleozoic hypoxic icehouse and later hot house, venues of the first angiosperms? ... ORIGIN OF ANGIOSPERMS
Pteridosperms might not constitute the "backbone of seed-plant phylogeny." Rather, the "lineage" could suffer spinal bifida ... PALEOBOTANY OF ANGIOSPERM ORIGINS
A growing body of biochemical and morphological evidence suggests that cones and flowers are reproductive short shoots. Fertile spur shoots are demonstrably ancient organs known from Permo-carboniferous seed plant fossils. Further, molecular phylogenetic studies of homeodomain proteins and transcription factors (TFs) posit deep conservation of cone and floral CRMs, GRNs, auxin-based polarity networks, efflux carriers, and PINs.
"Darwin himself referred to the 'early origin and diversification of angiosperms' as 'an abominable mystery,' and the origin of the flower- and therefore flowering plants- is still a question .."
The preceding statement is quoted from Page 86 of Pamela S. Soltis and Douglas E. Soltis (2014), Chapter 4. Flower diversity and angiosperm diversification. Pp. 85-102 In: J. L. Riechmann and F. Wellmer (eds.), Flower Development: Methods and Protocols, Volume 1110. New York: Springer, 475 pp.
Do crown group basal angiosperms and magnoliids represent a loose amalgam of parallel evolutionary lines traceable to Middle Triassic, remarkably divergent, stem group flowering plants? ... EVOLUTION OF MESOZOIC ANGIOSPERMS
[ Topics for Debate and Discussion ]
News commentary includes copyrighted illustrations and links to scientific research articles on the origin of flowering plants, Holometabola, and related subjects ... RESEARCH NEWS
The Charles Darwin Bicentennial Reading List and library book chapter ensemble is intended for students with advanced college level biology training ... KEY TO THE LITERATURE
Student exercises on my web site include a seed plant character homology assessment, a practice data matrix for phylogenetic analysis, and drills in pollen phylogenetics, paleobotany, taphonomy, and theoretical morphospace, and ARC-INFO/GIS, geo-referencing, and paleobiogeography.
Each year I will select a scientific paper, book chapter, or book as being of paramount importance toward finding a solution to the enigmatic origin of angiosperms and certain clades of holometabolous insects ... PUBLICATION OF THE YEAR
[ The Clear Fork Gigantopteroid ]
Misunderstood Late Paleozoic gigantopteroid and taeniopteroid seed plant fossils known only from detached and shed foliar organs might be important in deciphering the ancestry of flowering plants.
The Clear Fork Group of sedimentary rocks were deposited in riverine oxbows along the western coast of pre-Pangaea more than 256 million years ago (MYA) in the Kungurian (Wolfcampian) time interval of the Lower Permian (Cisuralian).
Detached and shed leaves classified as the morphospecies Evolsonia texana and Taeniopteris sp. almost always occur together in similar bedding planes. Do these herbivorized foliar organs belong to short- and long-shoots of a gigantopteroid seed plant, which is neither a cycadophyte or peltasperm?
Vojnovskyales and gigantopteroids are poorly understood Permo-carboniferous gymnosperms with possible evolutionary ties to the flowering plants or Gnetum according to some authors (Chapter 19, T. N. Taylor, E. L. Taylor, and M. Krings, , Paleobotany: The Biology and Evolution of Fossil Plants, Second Edition. Burlington: Elsevier-Academic Press, 1230 pp).
Anatomical studies of permineralized material of Delnortea abbottiae and Evolsonia texana foliar organs and their theoretical morphospace might help decipher the evolutionary relationships of these widespread gymnosperms with sympatric seed plant congeners ... DELNORTEAS AND EVOLSONIAS
Vojnovskyaleans were enigmatic Permo-carboniferous gymnosperms with possible affinities to angiosperms (Valentin A. Krassilov and V. I. Burago, 1981, New interpretation of Gaussia [Vojnovskyales], Review of Paleobotany and Palynology 32: 227-237). The growth habit, bisexual cones, and foliage of Vojnovskyales resembled the Triassic monocot-like plant Sanmiguelia according to others ... VOJNOVSKYALES
[ Statement on Evolution ]
The gigantopteroid web site owner and writer, peer reviewers, and contributors adopt the Botanical Society of America's policy on evolution ... BOTANICAL SOCIETY OF AMERICA
Over millions of years of Paleozoic time as global atmospheric oxygen level fluctuated, certain chewing, crawling, ovipositioning, piercing, siphoning, sponging, stinging and sucking insects probably became obligate residents of host seed plant shrubs and trees.
Air pockets at the base of sheathing leathery leaves and around developing stems and organs, and reproductive modules of monopodial Carboniferous seed plants might have provided phytophagous insects with oxygen gas, food, and shelter from predators, cold, and ultraviolet radiation.
Phytophagous insect associates of developmentally plastic Permian seed plant shrubs survived the end-Permian extinction. Pulsed acidification of substrates, hypoxia, increases in ambient temperature, and "trigger and kill" events adversely affected insects, mycorrhizal fungi, and tetrapods in a hot-house world ... PALEOECOLOGY OF GLOBAL CATASTROPHE
Were Paleozoic changes in atmospheric pO2 the selective force driving the molecular evolution of gas-binding hemocyanin respiratory enzymes and moulting storage proteins of early arthropods? ... INSECT HEXAMERINS
Are the helix-turn-helix (HTH) DNA-binding motifs of seed plant Leafy enzyme and the insect homeodomain protein Engraled, products of molecular coevolution? ... LFY ENZYME STRUCTURE
A key ingredient often left out of the steaming cauldron of past ideas on the origin of flowering plants is the potential modular evolution of a class of mobile chromosome parasites known as transposable elements (TEs) ... LTR RETROTRANSPOSONS
What did external biotic and physical factors have to do with the evo-devo of larval moult cycles and innovative mouthparts of phytophagous insects? ... ORIGIN OF THE HOLOMETABOLA
Consideration of both small gene duplications and whole genome duplications (WGDs) is important in understanding the timing of the origin of angiosperms and radiation of basal flowering plants and eudicots ... GENE DUPLICATIONS
Were secretions of insect eggs, instars, larvae, pupae, and adults, when applied to shoot apical meristems (SAMs) with mechanical force, a source of signals that affected plant growth and development at the genetic level in nuclei of host cells of certain monopodial Permo-Triassic seed plants? ... SIGNALS
When supported by paleobotanical evidence, were reproductive short (spur) shoots of Permo-carboniferous seed plants with spiral phyllotaxis visually discernable to pollinivores, paleodictyopterans, and predatory wasps? ... COEVOLUTION
There is growing consensus among molecular systematists and some paleobotanists on the existence of a 160 million year old ghost lineage beginning with divergence(s) of flowering plants from the most recent common ancestor (MRCA) prior to the end-Permian extinction ... ANGIOSPERM GHOST LINEAGE
Based on biochemical studies of TFs and PINs, some molecular-phylogenetic analyses, and the stratigraphic distribution of Afropollis and other diverse palynomorphs, is the statement [below] on Page 380 of Scott L. Wing and Lisa D. Boucher (1998), Ecological aspects of the Cretaceous flowering plant radiation. Annual Review of Earth and Planetary Sciences 26: 379-421, precise or accurate?
"Despite the singular ecological significance and species diversity of angiosperms, they are not in a genealogical sense one of the major branches of land plants and did not originate with other major land plant clades (e.g. lycopsids, ferns, conifers, cycads, ginkgos) during the middle or late Paleozoic."
The logic of CRMs, GRNs, PINs, and a deeply conserved floral tool kit allows evo-devo models to explain curling, inrolling, and fusion of ovule-bearing Phasmatocycas bridwellii leaves to form carpels, ovaries, and pistils in theoretical morphospace ... HYPOTHETICAL PALEOZOIC PROTOFLOWERS
[ Biostratigraphy of the Permian Standard Section ]
Uplifted and tilted beds in the Del Norte and Glass Mountains of southwestern North America consist of massive Permian marine and transitional, deltaic, sedimentary rock exposures.
Rocks of these mountain ranges yield fossilized coral reefs with brachiopods, conodonts, graptolites, and sponges, and deltaic transitional layers with preserved freshwater snails, walchian conifers, and gigantopteroid seed plants ... ARTICLE
[ Living "Fossil" Magnoliids: Degeneriaceae of Fiji ]
Several island groups of the southern Pacific Ocean possess harmonic faunas and floras reminiscent of larger, continental land masses. Consisting of a single genus and two species Degeneriaceae are endemic to three of the seven "high" islands of the Fiji archipelago.
Degenerias combine several archetypic angiosperm characters including polycotyledony, carpels with evaginating stigmatic secretions "plugs" (hairs are absent), microsporophylls and not stamens, and monosulcate pollen ... NOTES FROM THE FIELD