The Neuropteris ovata frond and its cyclopteroids: Micromorphology-spectrochemistry-fractal taxonomy. Propositions for restructuring and taxonomy (Pennsylvanian, Canada)

Abstract

The primary study material consists of the 65-cm frond Neuropteris ovata (Hoffmann) var. simonii, associate petiole with organically attached cyclopteroid leaflets and trunk. Ancillary N. ovata material is used, all from the Asturian-Cantabrian strata of the Sydney Coalfield, Canada. This material is appropriate for the objective of the study to present an ovata-frond Aufbau in terms of micromorphology coupled with chemistry using an holistic sampling design (co-ordinating epidermal microscopy with chemistry per sample location). Chemical analyses were obtained by the reliable FTIR technique (Fourier transform infrared spectroscopy) and interpreted via chemometrics by methods of principal component analysis. Fractal geometry is introduced as a promising taxonomic parameter. The main conclusions include that the N. ovata plant can be characterized by three distinct epidermal structures: (1) rectangular elongate (trunk and petiole), (2) elongate (rachides of three orders), and (3) undulate (pinnule), which to a certain extent agrees with the chemistry of the frond Aufbau. The frond was also complex - architecturally, histologically, physiologically, chemically and autecologically. It was photosynthetic, had secretory organs (implying a characteristic plant aroma), supporting rodlets, divers epicuticular features, and a distinct chemical composition/structure. The frond was likely 4 m long with complex-pinnate cyclopteroid leaflets, fimbriate or entire-margined, below and above the main bifurcation, which begs the question of cyclopteroid definition and function. The overall results will be beneficial to taxonomy/systematics, and guide pteridospermous reconstruction into a new paradigm.