Cycadeoidea

Taxonomy

William Buckland originally gave the name to two species he described, C. megalophylla and C. microphylla, in 1828, seeing characteristics akin to living cycads. Robert Brown and Mr. Loddiges of Loddiges Nursery in Hackney had seen living cycads and urged him to name the fossils after them. The original type specimens of both taxa have not been located, so new type material has been chosen.

Classification of species within the genus is very difficult, as several trunks have been described as species, and a further fourteen species are known from detached leaf remains, but there is no way of telling which leaf remains go with which trunk remains (if any).

Description

Cycadeoidea stems were "short and barrel-shaped," with a "crown of pinnate leaves" atop the stem. The majority of Cycadeoidea species were bisexual. The genus may have undergone self-pollination, although it is also possible that insects were involved in the process. The size and shape of the trunk has been used to distinguish species, however forms intermediate between two species suggest the two might be merely different-sized or aged plants can't be excluded.

Fossil sites and species

The Isle of Portland was the site of the first specimens recovered, described by Buckland as C. megalophylla (the type species) and C. microphylla.

Cycadeoidea gibsoniana is a species collected from Lower Greensand from Luccombe Chine on the Isle of Wight, notable for the remarkable state of preservation of its plant parts. The original specimen has been extensively broken and sliced to examine its anatomy.

Four well preserved cones of a species C. maccafferyi were uncovered in Upper Cretaceous beds on Vancouver and Hornby Island in British Columbia.