Abstract
Premise of research. Despite being an iconic and recognizable zosterophyll from the Early Devonian, sporangia of Sawdonia ornata are not known in any detail from the type locality, being represented by a drawing and a few illustrations from other localities. This has hampered recognition and/or comparison of other zosterophylls or newly discovered plants to that taxon. A detailed study of sporangia obtained from axes of S. ornata from the type locality was conducted to investigate sporangial morphology and range of vegetative features.Methodology. Fertile specimens were prepared by degagement and maceration to expose both vegetative and reproductive features more fully than previously. Maceration produced axes and sporangia that were examined by LM and SEM.Pivotal results. Sporangia of S. ornata from the type locality consist of unequal valves: a larger and more rounded outer/abaxial valve—in which the stalk merges imperceptibly with the back of the valve and both are covered with spines—and a smaller, th...
Highlights
Sawdonia ornata Hueber (1971) is one of the most iconic and recognizable early land plant taxa that holds an important place in both plant systematics (Banks 1968, 1975; Kenrick and Crane 1997) and early land plant ecology (Hotton et al 2001)
Similar axes are geographically and stratigraphically widespread, and the concept of the species has subsequently evolved on the basis of limited evidence from the type locality (Edwards 1924; Lang 1931: cuticle) but mainly from other Early Devonian (Emsian) localities in Canada (Hueber 1992: Abitibi River, sporangia), Scotland (Rayner 1983: anatomy, cuticle, fertile region) and Siberia (Ananiev and Stepanov 1968: sporangia, overall reconstruction)
This is supported by the specimen figured in figure 2, where visible sporangia occur only on one side of the axis but there are stubs indicative of a structure departing alternately to the other side
Summary
Sawdonia ornata Hueber (1971) is one of the most iconic and recognizable early land plant taxa that holds an important place in both plant systematics (Banks 1968, 1975; Kenrick and Crane 1997) and early land plant ecology (Hotton et al 2001) It has been studied since Dawson’s recognition of the existence of Psilophyton princeps var. Sporangia and habit of S. ornata from the type locality have never been described and illustrated This has hampered both recognition/ confirmation of the genus and species in other localities, taxonomic assignment of new fossils that share many of the simple characters regarded as typical of Sawdonia, and paleophytogeographical analysis.
Sign-in/Register to view highlights & summary 
Accepted Version (
Free)
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call