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A fossil seed cone with characters that have been hypothesized as transitional to the origin of crown group gnetophytes has been discovered in Lower Cretaceous deposits on Vancouver Island, British Columbia, Canada. This cone, described as Protoephedrites eamesii gen. et sp. nov., provides the first anatomically preserved fossil evidence for the evolution of gnetophyte cones with seeds. The cone is a compound shoot system consisting of a primary axis with nodes that bear bracts and axillary fertile shoots in an opposite/decussate arrangement. The secondary fertile shoot axis produces one or two pairs of diminutive bracteoles and a pair of erect ovules in an opposite/decussate pattern. In contrast to crown group gnetophytes, bracteoles subtend rather than surround and enclose the ovules. Ovules have a single multiseriate integument that is adnate to the nucellus in the basal region and free distally. The micropylar tube is short with a thick integument, but it displays distinctive cells of the inner integumentary epidermis that are characteristic of gnetophyte seeds. Each seed produces a large pollen chamber with a uniseriate wall. Paired erect ovules conform to the pleisomorphic morphology previously hypothesized for Ephedra seed cones, thus supporting the proposal that ancestral gnetophyte seeds are borne terminally on oppositely arranged sporophylls. The combination of gnetophyte synapomorphies and putative pleisomorphic characters displayed by Protoephedrites broadens the known range of morphologies for the most ancient gnetophytes. Detailed comparisons to several species of Bennettitales confirm that there are fundamental structural differences separating the seeds of Gnetales from those of Bennettitales, support the hypothesis that the outer seed envelope evolved within the gnetophyte clade, and suggest that Bennettitales are not as closely related to Gnetales as hypothesized by some authors. [ABSTRACT FROM AUTHOR]

A cylindrical permineralized conifer seed cone has been identified from the Officer Member of the Trowbridge Formation, near Izee, in east-central Oregon. The cone is preserved in a Middle Jurassic (Callovian) marine calcium carbonate concretion, associated with araucarian seed cones, conifer twigs and wood, cycad seeds, fern rachides, and lycopodialean remains and was prepared by the cellulose acetate peel technique. The specimen is abraded, 2.8 cm long and 1.3 cm wide, and consists of a cone axis with helically arranged bract/scale complexes, with a large ovuliferous scale and a broad, flattened bract. The bract/scale trace arises as a cylindrical unit from the cone axis, in which the bract and scale traces are separated by ground tissue. The traces separate immediately in the cortex to form a crescent-shaped bract trace and a horseshoe-shaped scale trace with associated sclerenchyma bands that form two triangular bundles toward the distal end of the scale. Ovuliferous scale tissue covers one inverted seed per scale, forming a pocket that contains the seed. Seeds are attached at the chalaza to the inside of the pocket. Seed integuments have an outer epidermis of isodiametric cells with dark contents; one or two layers of palisade cells, occasionally appearing in I-beam configuration; and several inner layers of randomly arranged cells. The nucellus is adnate to the integument, to near the apex, where it forms a cellular mound of tissue. Cylindrical cones with helically arranged bract/scale complexes, bract and scale free to the base, one seed per scale enclosed in a pocket, and triangular sclerenchyma bands are characteristic of the genus Vararaucaria, which recently has been placed in the extinct conifer family Cheirolepidiaceae. This third species extends the known range of Pararaucaria from the Southern Hemisphere to the Northern Hemisphere and emphasizes that the association of araucarian and pararaucarian conifers extended over a wide geographic area during the Jurassic. [ABSTRACT FROM AUTHOR]