Fossil in situ spores and pollen grains: an annotated catalogue

Taphonomy plays diverse roles in paleobiology. These include assessing sample quality relevant to ecologic, biogeographic, and evolutionary questions, diagnosing the roles of various taphonomic agents, processes and circumstances in generating the sedimentary and fossil records, and reconstructing the dynamics of organic recycling over time as a part of Earth history. Major advances over the past 15 years have occurred in understanding (1) the controls on preservation, especially the ecology and biogeochemistry of soft-tissue preservation, and the dominance of bi- ological versus physical agents in the destruction of remains from all major taxonomic groups (plants, invertebrates, vertebrates); (2) scales of spatial and temporal resolution, particularly the relatively minor role of out-of-habitat transport contrasted with the major effects of time-averaging; (3) quantitative compositional fidelity; that is, the degree to which different types of assemblages reflect the species composition and abundance of source faunas and floras; and (4) large-scale var- iations through time in preservational regimes (megabiases), caused by the evolution of new bod- yplans and behavioral capabilities, and by broad-scale changes in climate, tectonics, and geochem- istry of Earth surface systems. Paleobiological questions regarding major trends in biodiversity, major extinctions and recoveries, timing of cladogenesis and rates of evolution, and the role of environmental forcing in evolution all entail issues appropriate for taphonomic analysis, and a wide range of strategies are being developed to minimize the impact of sample incompleteness and bias. These include taphonomically robust metrics of paleontologic patterns, gap analysis, equal- izing samples via rarefaction, inferences about preservation probability, isotaphonomic compari- sons, taphonomic control taxa, and modeling of artificial fossil assemblages based on modern an- alogues. All of this work is yielding a more quantitative assessment of both the positive and neg- ative aspects of paleobiological samples. Comparisons and syntheses of patterns across major groups and over a wider range of temporal and spatial scales present a challenging and exciting agenda for taphonomy in the coming decades.

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Taphonomy and paleobiology

Phylogenetic analysis of seed plants and the origin of angiosperms

We present a numerical cladistic (parsimony) analysis of seed plants plus progymnosperms, using characters from all parts of the plant body, outgroup comparison, and a method of character coding that avoids biases for or against alternative morphological theories. The robustness of the results was tested by construction of alternative trees and analysis of subsets of the data. These experiments show that although some clades are strongly supported, they can often be related to each other in very different but nearly equally parsimonious ways, apparently because of extensive homoplasy. Our results support Rothwell’s idea that coniferopsids are derived fromCallistophyton- like platyspermic seed ferns with saccate pollen, but the hypothesis that they evolved fromArchaeopteris- like progymnosperms and the seed arose twice is nearly as parsimonious. Meyen’s division of seed plants into radiospermic and primarily and secondarily platyspermic lines is highly unparsimonious, but his suggestion that ginkgos are related to peltasperms deserves attention. Angiosperms belong among the platyspermic groups, as the sister group of Bennettitales,Pentoxylon, and Gnetales, and this “anthophyte” clade is best related toCaytonia and glossopterids, although relationships with other combinations of Mesozoic seed fern taxa are nearly as parsimonious. These results imply that the angiosperm carpel can be interpreted as a modified pinnate sporophyll bearing anatropous cupules (=bitegmic ovules), while gnetalian strobili are best interpreted as aggregations of highly reduced bennettitalian flowers, as anticipated by Arber and Parkin and Crane. Our most parsimonious trees imply that the angiosperm line (though not necessarily all its modern features) extended back to the Triassic, but a later derivation of angiosperms from some species ofCaytonia or Bennettitales, which would be nearly as parsimonious, should also be considered. These results raise the possibility that many features considered key adaptations in the origin and rise of angiosperms (insectpollinated flowers, rapid reproduction, drought tolerance) were actually inherited from their gymnospermous precursors. The explosive diversification of angiosperms may instead have been a consequence of carpel closure, resulting in increased speciation rates due to potential for stigmatic isolating mechanisms and/or new means of dispersal. DNA sequencing of extant plants and better information on anatomy, chemistry, sporophyll morphology, and embryology of Bennettitales and Caytoniales and the morphological diversity of Mesozoic anthophytes could provide critical tests of relationships.

Seed plant phylogeny and the origin of angiosperms: An experimental cladistic approach

The late Paleozoic deglaciation is the vegetated Earth9s only recorded icehouse-to-greenhouse transition, yet the climate dynamics remain enigmatic. By using the stable isotopic compositions of soil-formed minerals, fossil-plant matter, and shallow-water brachiopods, we estimated atmospheric partial pressure of carbon dioxide (pCO2) and tropical marine surface temperatures during this climate transition. Comparison to southern Gondwanan glacial records documents covariance between inferred shifts in pCO2, temperature, and ice volume consistent with greenhouse gas forcing of climate. Major restructuring of paleotropical flora in western Euramerica occurred in step with climate and pCO2 shifts, illustrating the biotic impact associated with past CO2-forced turnover to a permanent ice-free world.

/pdf/co2-forced-climate-and-vegetation-instability-during-late-1ewvfujdxb.pdf

CO2-Forced Climate and Vegetation Instability During Late Paleozoic Deglaciation

Early Permian (late Leonardian Series) plant assemblages from King, Knox, and Stonewall Counties of North-Central Texas are dominated by seed plants, some apparently congeneric with taxa heretofore known only from the Late Permian or the Mesozoic. Conifers are the dominant elements, including one or more species of Ullmannia, Pseudovoltzia liebeana, both known from the Late Permian Zechstein flora of Germany and England, Podozamites sp., characteristic of the Mesozoic, and Walchia sp., abundant in Early Permian floras. Locally common are Taeniopteris cf. eckardtii, a Zechstein species, an unidentified plant represented by pinnule-like laminae with fine parallel veins, similar to pinnules of some Mesozoic cycads, and calamite stems. Rarely encountered are leaf fragments of the Paleozoic ginkgophyte Dicranophyllum, flabellate ginkgophyte leaves, leaves with a broad midvein and narrow, fimbriate lamina, and Wattia, typical of the Early Permian. Associated with these foliar remains are ovulate reprod...

An early permian flora with late permian and mesozoic affinities from north-central texas

Upper Paleozoic rocks in the southwestern United States contain several taxa of fossil plants that appear to represent a lineage from the Pennsylvanian pteridosperms. to the modern cycads. The oldest genus, Spermopteris Cridland and Morris, is a megasporophyll that has surficial seeds borne in two rows along the sides of presumably abaxial fac,es of taeniopterid foliage; it was first found in the Virgilian Lawrence Formation of Kansas, and a poorly preserved specimen is now known from the Leonardian Wellington Formation of Oklahoma. The putatively derivative cycadean genera Phasmatocycas Mam:a.y and A rchaeocycas Mamay occur in lower Leonardian rocks of Kansas and Texas. P hasmatocycas (type-species: P. kansana Mamay) is a fertile axis that has two lateral rows of naked ovules. In P. kansana, the ovules are represented by well-preserved double cuticles similar to those of the Jurassic cycad Beania; small resinoid spherules, interpreted as remains of glands, alternate with the ovules. Taeniopterid foliage associated with P. kansana bears abundant spherules identical with those on the fertile axis; on the basis of the spherules and the known seed habit of Taeniopteris, Phasmatocycas is reconstructed as a cycadlike. megasporophyll with an elaminar, fertile base and a t31eniopterid distal lamina. The glands may be primitive nectaries, poss.ibly involved in an early stage in the development of entomophily. Phasmatocycas is regarded as hav.ing been derived from a spermopterid ancestor through reduction of numbers of seeds and loss of the basal foliar lamina. Althoug'h the type specimen of Phasmatocycas is from' the Wellington Formation of Kansas, a poorly preserved specimen is known from the younger Vale Formation of Texas, where it is associated with structures strongly reminiscent of male cycadean cones. Archaeocyca.s Mamay, typified by A. whitei Mamay, is approximately contemporary with Phasmatocycas kansana, occurring at two localities in the Belle Plains Formation of Texas. It resembles Phasmatocycas in having a basal s·eedbearing area and a sterile distal lamina. In Archaeocycas, however, the seeds are attached to the basal lamina, which is inrolled and at least partly encloses. the seed. A rchaeocycas probably represents a form intermediate between Spermopteris and Phasmatocycas. Alternativ·ely, Archaeocycas might be a fertile appendage evolving in the direction of a carpellike organ through proliferation and fusion of the laminar margins; this alternative, however, is not preferred. Associated with the cycadean megasporophylls are a single specimen of Cycadospadix (C. yochelsoni Mamay, n. sp.) and various other plants. C. yochelsoni cannot be determined as cycadalean or bennettitalean, although it is possible that it is either and that the two orders may have been distinct as long ago as the Early Permian. Among other plant associates, only Taeniopteris is common to all the cycad-bearing assemblages; this strengthens the hypothesis that Taeniopteris was the leaf of primitive cycads, as indicated by Spermopteris. Stratigraphic distribution of the plants supports the idea of derivation of the cycads from the Pennsylvanian spermopterids and of a lineage to the modern cycads through the Triassic genera Palaeocycas-Bjuvia and Dioonitocarpidium. Horizontal and vertical distribution of the Paleozoic taxa emphasizet the importance of the lower Leonardian of the southwestern United States as a temporal and geographic locale for rapid and dramatic plant evolution. Modern cycadean leaves are thought to be derived from taeniopterid stock in the Paleozoic and Mesozoic through progressive incision of the laminar margin. In one line of foliar evolution, shallow marginal dentation, in which each tooth receives only one· vein, becomes progressively deeper, resulting in the cycadaceous leaf type in which each leaflet has a :single vein; a parallel .series of known forms involved several veins to a segment and could have produced the zamiaceous leaf type·. The Stangeria leaf type could have arisen from a compound taeniopterid with little modification, whereas marginal incision of a compound taeniopterid might have produced the Bowenia type of leaf. Cumulative evidence indicates that the cycads extend back into the Late Pennsylvanian instead of only the Late. Triassic; thus they rival the conifers as the oldest extant seed plants.

/pdf/paleozoic-origin-of-the-cycads-1iabbjquob.pdf

Paleozoic origin of the cycads

Some American Carboniferous Fern Fructifications

-__---_--__-___--__--_____________________ Introduction _______________________________________ Acknowledgments__ _ _ _____________________________ The antecedent floras._-__------__-_______-____-____ Upper Paleozoic floral zones__. _____________--__--__-Mississippi an floral zones. _-____-___--_--_-_____Zone 1. Zone of Adiantites spp______________ Zone 2. Zone of Triphyllopteris spp__________ Zone 3. Zone of Fryopsis spp. and Sphenopteridium spp..__-___-________-_______---_Pennsylvanian floral zones__._______-__-__-_--__Zone 4. Zone of Neuropteris pocahontas and Mariopteris eremopteroides________________ Zone 5. Zone of Mariopteris pottsvillea and of common occurrence of Aneimites spp_ _______ Zone 6. Zone of Neuropteris tennesseeana and Mariopteris pygmaea, and to some extent of Ovopteris communis, Alloiopteris inaequilateralis, and Alethopteris decurrens___________ Zone 7. Zone of common occurrence of Megalopttris spp_______________________________ Zone 8. Zone of Neuropteris tenuifolia. _______ Zone 9. Zone of Neuropteris rarinervis. _______ Zone 10. Zone of Neuropteris flexuosa and appearance of abundant Pecopteris spp______ rage Page Kl Upper Paleozoic floral zones Continued 1 Pennsylvanian floral zones Continued 2 Zone 11. Zone of Lescuropteris spp___-----__Kll 2 Zone 12. Zone of Danaeites spp______________ 12 4 Zones 11 and 12 (locally combined). Zone of 4 Odontopteris spp. _________________________ 12 4 Permian floral zones___________-__-____-__--_-12 5 Zone 13. Zone of Callipteris spp_____________ 12 Zone 14. Zone of the older Gigantopteris flora in 5 parts of Texas, Oklahoma, and New Mexico, 6 equivalent zone of Glenopteris spp. in Kansas, and equivalent zone of the Supaia flora in 6 New Mexico and Arizona.-----.----------13 The Supaia flora_-__-_----___----------13 7 The Glenopteris flora.__________-_---___14 The Gigantopteris flora_---__--__--_-----14 Zone 15. Zone of the younger Gigantopteris flora 15 Upper Paleozoic floral provinces-.-.-----------------16 7 Mississippian floral provinces-.-----------------16 Pennsylvanian floral provinces-------------------16 7 Permian floral provinces___---_-__-_------------16 9 References----------------------------------------18 9 Glossary of stratigraphic terms, by Grace C. Keroher__. 19 References to glossary.-___________-____-___--_-_ 29 10 Index__._____-_ __ 33

Upper Paleozoic floral zones and floral provinces of the United States, with a glossary of stratigraphic terms

Plant fossils from Lower Permian strata of the southwestern United States have been interpreted as cycadalean megasporophylls. They are evidently descended from spermopterid elements of the Pennsylvanian Taeniopteris complex; thus the known fossil history of the cycads is extended from the Late Triassic into the late Paleozoic. Possible implications of the Permian fossils toward evolution of the angiosperm carpel are considered.

https://science.sciencemag.org/content/sci/164/3877/295.full.pdf

Sergius H. Mamay

Papers

An early permian flora with late permian and mesozoic affinities from north-central texas

Paleozoic origin of the cycads

Some American Carboniferous Fern Fructifications

Upper Paleozoic floral zones and floral provinces of the United States, with a glossary of stratigraphic terms

Cycads: Fossil Evidence of Late Paleozoic Origin