Devonian tropical plant assemblages from Arctic Svalbard

Wyatt, Amy 2025. Devonian tropical plant assemblages from Arctic Svalbard. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

This thesis investigates the evolution, structure and ecology of Devonian plant assemblages from Arctic Svalbard, which during the Devonian lay in equatorial Laurussia. It integrates newly collected and historical material to reconstruct the development of early vascular floras and the rise of tree-dominated vegetation from the Silurian to the Frasnian. Extensive fieldwork and the re-examination of historical collections have provided a basin-wide perspective on the diversity and distribution of early terrestrial plants. Detailed preparation using serial dégagement, camera lucida illustration, photogrammetry and microscopy enabled the documentation of both external and internal structures across a wide range of preservational modes. This approach has allowed the reconstruction of complete plants and the resolution of long-standing taxonomic and anatomical uncertainties. Silurian and Early Devonian assemblages from the Siktefjellet, Red Bay and Wood Bay groups record low-lying vegetation dominated by small axial taxa such as Zosterophyllum fertile and Psilophytites svalbardensis sp. nov. By the Middle–Late Devonian, within the Mimerdalen Subgroup, the flora had diversified into complex forest ecosystems composed of arborescent plants with well-developed trunks, crowns and rooting systems. New analyses of Svalbardia polymorpha and Actinopodium nathorstii demonstrate that they represent different preservational states, clarifying the anatomy and morphology of Archaeopteris in Svalbard. Newly discovered material of Protolepidodendropsis pulchra, including a complete crown and root system, permits the first whole-plant reconstruction and defines its growth architecture and ecological role. Together, these findings reveal that Mid-Late Devonian vegetation of Svalbard formed diverse, mixed forests in which different plants occupied distinct ecological niches across varied substrates. By combining new field evidence with anatomical and morphological data, this study refines the knowledge of equatorial Devonian floras and provides new insight into the emergence and environmental impact of the world’s earliest forest ecosystems.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Schools > Earth and Environmental Sciences
Funders:	NERC GW4+ DTP
Date of First Compliant Deposit:	17 September 2026
Last Modified:	17 Sep 2026 15:50
URI:	https://orca.cardiff.ac.uk/id/eprint/189707

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