title: Anatomically preserved Cycadeoidea (Cycadeoidaceae), with a reevaluation of systematic characters for the seed cones of Bennettitales.
abstract: Four anatomically preserved ovulate cycadeoid cones have been recovered from three localities in Upper Cretaceous (Turonian/Coniacian-Late Campanian) sediments of Vancouver and Hornby Islands, British Columbia, Canada. All of the specimens are preserved by calcareous cellular permineralization and are quite similar to seed cones described as several species of Cycadeoidea and Bennettites. These cones, described as Cycadeoidea maccafferyi sp. nov., consist of tightly packed interseminal scales and ovulate sporophylls with terminal ovules. Two specimens also preserve remains of a small receptacle. Interseminal scales and ovulate sporophylls are oriented parallel to one another. Ovules are distinctly stellate at the base of the micropylar tube, and the sarcotesta consists of both longitudinally oriented tubular cells and large radially elongated cells attached to the sclerotesta. The vascular strand below each ovule is highly contorted in a pattern that is characteristic of contractile tissue in the roots of living plants. These specimens are the most recent anatomically preserved cycadeoid cones yet discovered, revealing details of the reproductive biology shortly before extinction of the clade. Superb preservation of the British Columbia cones confirms that Bennettitales lack a cupule, have radial seeds, and have a vascularized nucellus (but no integumentary tracheids), and that no pollen chamber is produced. Together with a new species of Williamsonia preserved at one of the same localities, these specimens reveal a clear set of contrasting systematic characters for differentiating between isolated seed cones of Williamsoniaceae and Cycadeoidaceae.
authors.affiliation: Department of Environmental and Plant Biology, Ohio University, Athens, Ohio 45701 USA;
authors.forename: Gar W
authors.initials: GW
authors.lastname: Rothwell
authors.forename: Ruth A
authors.initials: RA
authors.lastname: Stockey