The Archaeopterid Forests of Lower Frasnian (Upper Devonian) Westernmost Laurentia: Biota and Depositional Environment of the Maywood Formation in Northern Wyoming as Reflected by Palynoflora, Macroflora, Fauna, and Sedimentology
The Archaeopterid Forests of Lower Frasnian (Upper Devonian) Westernmost Laurentia: Biota and Depositional Environment of the Maywood Formation in Northern Wyoming as Reflected by Palynoflora, Macroflora, Fauna, and Sedimentology
Premise of research. The flora of the Maywood Formation, one of only three Devonian floras previously recognized in western North America, is known only from a brief report focused on stratigraphy and has never been characterized in more detail. A detailed assessment of this flora and associated animal fossils has implications for the age and depositional environments of the Maywood Formation and for Devonian plant biogeography. Methodology. Fieldwork at the Cottonwood Canyon (Wyoming) exposure of the Maywood Formation produced a measured section characterizing the sedimentology of the unit and samples that we analyzed for palyno-morph, macrofloral, and faunal content using standard methods. Pivotal results. The palynological assemblage is dominated by archaeopterid progymnosperm spores, lacks unequivocally marine components, indicates the low burial depth and temperature (ca. 537C) of the unit, and supports an early Frasnian age. Plant macro-and mesofossils including charcoal, adpressions, sporangia, and spore packages reflect a vegetation with quasi-monodominant archaeopterids but also including (unidentified) plants that produced the seed megaspore Spermasporites (for which the Cottonwood Canyon occurrence represents a geographic range extension). Scales indicate the presence of sarcopterygian and tetrapodomorph fishes. Sedimentary facies, palynofacies, and plant macrofossil taphonomy are consistent with a lagoon or lake margin environment on a carbonate platform disconnected from the open marine realm. Conclusions. The arid carbonate platform of the western margin of early Frasnian Laurentia hosted a fire-prone vegetation cover heavily dominated by archaeopterid progymnosperms. The Maywood Formation preserves fossil assemblages reflecting this vegetation at Cottonwood Canyon (Wyoming), in lagoonal or lacustrine deposits that also host microconchid tube worms and fish. The parent plant of the seed megaspore Spermasporites, present in this vegetation, was widely distributed all across Euramerica.
Devonian, Wyoming, charcoal, fossil, palynology, progymnosperm
465-492
Marshall, John E. A.
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Holterhoff, Peter F.
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El-abdallah, Samar R.
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Matsunaga, Kelly K. S.
03457d30-6639-4e05-8e30-d1538aef13b9
Bronson, Allison W.
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Tomescu, Alexandru M.f.
38498776-f3ee-4704-8a70-fdf966e8994d
1 July 2022
Marshall, John E. A.
cba178e3-91aa-49a2-b2ce-4b8d9d870b06
Holterhoff, Peter F.
fe1f3050-ab96-4f52-bf32-cb1c488172a9
El-abdallah, Samar R.
b1e420ad-2619-4c5b-b90c-f8964ab81bfb
Matsunaga, Kelly K. S.
03457d30-6639-4e05-8e30-d1538aef13b9
Bronson, Allison W.
6a2dd5d7-72ec-4f3a-8c15-c958b1f473aa
Tomescu, Alexandru M.f.
38498776-f3ee-4704-8a70-fdf966e8994d
Marshall, John E. A., Holterhoff, Peter F., El-abdallah, Samar R., Matsunaga, Kelly K. S., Bronson, Allison W. and Tomescu, Alexandru M.f.
(2022)
The Archaeopterid Forests of Lower Frasnian (Upper Devonian) Westernmost Laurentia: Biota and Depositional Environment of the Maywood Formation in Northern Wyoming as Reflected by Palynoflora, Macroflora, Fauna, and Sedimentology.
International Journal of Plant Sciences, 183 (6), .
(doi:10.1086/720736).
Abstract
Premise of research. The flora of the Maywood Formation, one of only three Devonian floras previously recognized in western North America, is known only from a brief report focused on stratigraphy and has never been characterized in more detail. A detailed assessment of this flora and associated animal fossils has implications for the age and depositional environments of the Maywood Formation and for Devonian plant biogeography. Methodology. Fieldwork at the Cottonwood Canyon (Wyoming) exposure of the Maywood Formation produced a measured section characterizing the sedimentology of the unit and samples that we analyzed for palyno-morph, macrofloral, and faunal content using standard methods. Pivotal results. The palynological assemblage is dominated by archaeopterid progymnosperm spores, lacks unequivocally marine components, indicates the low burial depth and temperature (ca. 537C) of the unit, and supports an early Frasnian age. Plant macro-and mesofossils including charcoal, adpressions, sporangia, and spore packages reflect a vegetation with quasi-monodominant archaeopterids but also including (unidentified) plants that produced the seed megaspore Spermasporites (for which the Cottonwood Canyon occurrence represents a geographic range extension). Scales indicate the presence of sarcopterygian and tetrapodomorph fishes. Sedimentary facies, palynofacies, and plant macrofossil taphonomy are consistent with a lagoon or lake margin environment on a carbonate platform disconnected from the open marine realm. Conclusions. The arid carbonate platform of the western margin of early Frasnian Laurentia hosted a fire-prone vegetation cover heavily dominated by archaeopterid progymnosperms. The Maywood Formation preserves fossil assemblages reflecting this vegetation at Cottonwood Canyon (Wyoming), in lagoonal or lacustrine deposits that also host microconchid tube worms and fish. The parent plant of the seed megaspore Spermasporites, present in this vegetation, was widely distributed all across Euramerica.
Text
THE ARCHAEOPTERID FORESTS OF LOWER FRASNIAN
- Accepted Manuscript
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e-pub ahead of print date: 2 June 2022
Published date: 1 July 2022
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Half a century ago, Fran Hueber was collecting Devonian plant fossils high on the walls of Cottonwood Canyon, not in the Maywood Formation but in the older Beartooth Butte Formation. Fran was an intrepid field paleobotanist and a dedicated student of the Devonian vegetation. We dedicate this article to his memory, in recognition of his distinguished career and contributions to Devonian paleobotany. Samples for this study were collected under US Bureau of Land Management (BLM) permit PA10-WY-186 to Alexandru M.F. Tomescu; we thank Brent H. Breithaupt, Delissa L. Minnick, and Gretchen L. Hurley (BLM Wyoming) for assistance. We are indebted to the field crews of two field seasons—Shayda Abidi, Dylan Armitage, Alexander Bippus, Emma Fryer, Rachel Klassen, David Mclean, Ashley Ortiz, Kelly Pfeiler, Glenn Shelton, and Alexa Stefanakis—to Jorge Mondéjar-Fernández for insightful discussions of fish scales, to Rudolph Serbet for facilitating specimen loans from the University of Kansas Biodiversity Institute collections, and to Candela Blanco Moreno for collection management assistance. John E. A. Marshall thanks Shir Akbari for preparing the palynological samples. The manuscript was improved by constructive comments and suggestions from the editor and two anonymous reviewers. This study was funded in part by a US National Science Foundation Graduate Research Fellowship (1546593) to Alexander Bippus and in part by grants to Alexandru M.F. Tomescu from the Humboldt State University Office of Research and Graduate Studies, the Humboldt State University Sponsored Programs Foundation, and the American Philosophical Society. Fieldwork and collection: Peter F. Holterhoff, Kelly K. S. Matsunaga, Alexandru M.F. Tomescu, and Allison W. Bronson. Data collection and analysis: Peter F. Holterhoff, regional geology, stratigraphy, and sedimentology; John E. A. Marshall, palynology; Samar R. El-Abdallah and Alexandru M.F. Tomescu, plant macrofossils; Allison W. Bronson, fauna. Writing: John E. A. Marshall, Peter F. Holterhoff, Alexandru M.F. Tomescu, and Allison W. Bronson. All authors edited the text.
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© 2022 The University of Chicago. All rights reserved.
Keywords:
Devonian, Wyoming, charcoal, fossil, palynology, progymnosperm
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Local EPrints ID: 467951
URI: http://eprints.soton.ac.uk/id/eprint/467951
ISSN: 1058-5893
PURE UUID: eb94fffb-ef42-48ba-b810-d44597d4720b
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Date deposited: 26 Jul 2022 16:51
Last modified: 17 Mar 2024 07:23
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Author:
Peter F. Holterhoff
Author:
Samar R. El-abdallah
Author:
Kelly K. S. Matsunaga
Author:
Allison W. Bronson
Author:
Alexandru M.f. Tomescu
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