Graduation Date
Spring 2020
Document Type
Thesis
Program
Master of Science degree with a major in Biology
Committee Chair Name
Dr. Alexandru M.F. Tomescu
Committee Chair Affiliation
HSU Faculty or Staff
Second Committee Member Name
Gar Rothwell
Second Committee Member Affiliation
Community Member or Outside Professional
Third Committee Member Name
Paul Kenrick
Third Committee Member Affiliation
Community Member or Outside Professional
Fourth Committee Member Name
Michael Mesler
Fourth Committee Member Affiliation
HSU Faculty or Staff
Keywords
Euphyllophyte, Anatomy, Secondary growth, Devonian, Fossil, Quebec, Wood
Subject Categories
Botany
Abstract
Secondary growth from a vascular cambium has a deep fossil record among euphyllophytes, with the earliest occurrence dated to 407 Ma. To date, Armoricaphyton and Franhueberia represent the only instances of secondary growth formally documented in the Early Devonian. Secondary growth diversified rapidly and was present in all major euphyllophyte lineages by the Middle Devonian. Here, I describe two new Early Devonian euphyllophytes exhibiting secondary growth, from the Emsian (c. 400-395 Ma) Battery Point Formation (Québec, Canada): Gmujij tetraxylopteroides gen. et sp. nov. and Perplexa praestigians gen et sp. nov. Both these plants possess mesarch actinosteles with Psilophyton-type tracheid thickenings, and each represents a new type of anatomical organization among Early Devonian wood-producing euphyllophytes. These new Early Devonian plants reveal an unexpected level of diversity in the early stages of the first major tracheophyte radiation. Importantly, Gmujij and Perplexa, together with the other Early Devonian euphyllophytes exhibiting secondary growth, reinforce existing hypotheses about the modular regulation of vascular cambial growth and demonstrate that vascular cambial growth is an assemblage of regulatory modules whose deployment followed a mosaic pattern in the evolution of tracheophytes.
Citation Style
Papers in Palaeontology
Recommended Citation
Pfeiler, Kelly C., "Exploring the origins of secondary growth – two Lower Devonian (Emsian) euphyllophytes from Gaspé, Canada, and their implications for the evolution of secondary growth" (2020). Cal Poly Humboldt theses and projects. 400.
https://digitalcommons.humboldt.edu/etd/400
Tracheid measurements for Chapter 1
Pfeiler2020_Chapter2_MetaxylemTracheidMeasurements.csv (2 kB)
Metaxylem tracheid measurements for Chapter 2
Pfeiler2020_Chapter2_SecondaryXylemTracheidMeasurements.csv (4 kB)
Secondary xylem tracheid measurements for Chapter 2
Pfeiler2020_Chapter2_RoundnessCircularity.csv (60 kB)
Metaxylem roundness and circularity measurements for Chapter 2
Pfeiler2020_Chapter2_RoundnessCircularityOutlines.pdf (9834 kB)
Metaxylem roundness and circularity outlines for Chapter 2