Graduation Date
Spring 2024
Document Type
Thesis
Program
Master of Science degree with a major in Biology
Committee Chair Name
Dr. Alexandru Mihai Tomescu
Committee Chair Affiliation
HSU Faculty or Staff
Second Committee Member Name
Dr. Terry Henkel
Second Committee Member Affiliation
HSU Faculty or Staff
Third Committee Member Name
Dr. Kelly Matsunaga
Third Committee Member Affiliation
Community Member or Outside Professional
Fourth Committee Member Affiliation
Community Member or Outside Professional
Keywords
Devonian, Wyoming, Beartooth Butte, Cottonwood Canyon, Plant fossil, Compression fossil, Zosterophyll
Subject Categories
Botany
Abstract
The fragmentary state of plant fossils and the modular organization of plants make whole-plant reconstructions of fossil species desirable and feasible. Such reconstructions are key for integrating fossil species in systematic studies. The ca. 410 Ma Beartooth Butte Formation of Wyoming (USA) hosts the only rich Early Devonian plant assemblages in western North America, which fills a major gap in the phytogeography of this interval. I construct a whole-plant concept for a new zosterophyll from the Beartooth Butte Formation based on a detailed morphometric study. More than 600 fragments of the new zosterophyll were observed and 200 of those were measured. Epidermal features were observed in cuticular material recovered on cellulose acetate. Resulting data were used to characterize variability in axis thickness and taper, branching density, and sporangial orientation, based on descriptive statistics, correlations, and principal component analysis. The new zosterophyll, Nowenia wyomingense gen. et sp. nov., consisted of decumbent axes with long internodes that exhibited K-branching and bore more densely branched erect axes, as well as branches with delayed development (dormant lateral meristems and circinate protrusions). Axes had circinate apices and bore isolated bivalvate sporangia in small numbers, primarily on upright portions. Phylogenetic analyses recover Nowenia sister to Forania, from which it differs primarily in the absence of spinescent protrusions. Nowenia is the first zosterophyll for which an empirically-based whole-plant concept, making explicit and extensive use of quantitative data, is available. The approach used to reconstruct the Nowenia plant introduces a method for integrating morphometric data in constructing whole-plant concepts of early tracheophytes with simple body plans. Application of this and similar methods to additional fossil species could produce reconstructions at similar levels of detail and accuracy, crucial for reaching well-supported resolution of early vascular plant relationships.
Citation Style
APA
Recommended Citation
El-Abdallah, Samar R., "Building detailed and accurate whole-plant concepts: A morphometrics-informed reconstruction of a zosterophyll from the lower Devonian of Wyoming" (2024). Cal Poly Humboldt theses and projects. 751.
https://digitalcommons.humboldt.edu/etd/751
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