A new fossil fern is described from the early Albian age (early Cretaceous) Silty Beds of Bedfordshire, England, and assigned to the extant genus Gleichenia of the Gleicheniaceae. The pinnules and rachis fragments are three-dimensionally preserved as charcoal. The rachis is 2-4 mm in diameter with a C-shaped vascular bundle and appears to grow from a previously arrested bud that is surrounded by fimbriate or lacerate scales. Pinnules are opposite on the rachis, 1-2 mm long, thick, with inrolled margins and an extended basal lobe. Pinnules have a single midvein, 0.03 mm in diameter, and once to twice dichotomizing lateral veins. The guard cells of the stomata are sunken with overarching cuticular protrusions from the subsidiary cells. The sorus is composed of five sporangia with an oblique annulus; spores are unknown. A cladistic phylogenetic analysis yielded a single most parsimonious tree with the fossil resolved as sister to extant Gleichenia glauca. Although the fossils described here are similar to the older Wealden material of Gleichenites nordenskioeldii study of three-dimensionally preserved pinnule and rachis specimens using SEM techniques has revealed additional structural details on which to base a new species. This information also facilitates comparisons with previously known extant and extinct taxa. The new species has morphological characters that may be indicative of an environment with arid conditions and periodic fire.
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Plant Science