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Bennettitales

Bennettitales (the '''cycadeoids''') is an extinct order (biology)|order of spermatophyte|seed plants that first appeared in the Triassic period and became extinct toward the end of the Cretaceous.Speer, Brian R., 2000. ''Introduction to the Bennettitales'' http://www.ucmp.berkeley.edu/seedplants/bennettitales.html (''accessed 13 Oct 2005''). Some were characterized by thick trunks and pinnately compound leaves that bore a superficial resemblance to those of cycads, differing primarily in stomatal arrangement.Pigg, Kathleen. 2005 ''The Cycads, Cycadeoids (Bennettitales) and Ginkgophytes'' http://lsweb.la.asu.edu/kpigg/CYCAD.html (''accessed 21 Sept 2007''). It comprises two groups, the Cycadeoidaceae, represented by ''Cycadeoidea'', ''Cycadella'', and ''Monanthesia'' which had stout trunks and bisporangiate Conifer cone|strobili (cones serving as their sexual reproduction|reproductive structures), and the Williamsoniaeae including ''Williamsonia'', ''Williamsoniella'', ''Wielandella'' and ''Ischnophyton'' which had slender, branching trunks and either bisporangiate or monosporangiate strobili. Bennettitales have been placed among the anthophytes, which for some time were considered to be close relatives of the flowering plants on account of their flower-like structures. However, more detailed morphological studies have shown the "anthophytes" to be polyphyletic, with the bennetitales more closely related to the cycads, ginkgo and conifers than to the angiosperms.

Gallery

Image:Bennettitales_stump_top.JPG|A fossilised Bennettitales, squashed by later compression. Image:Bennettitales_stump_side.JPG|Side view. Note embedded "flowers". Image:Bennettitales_flower.JPG|A flower-like structure. Image:Zamites_mariposana.jpg|Fossil leaf of ''Zamites mariposana'' from the Jurassic.

References

External links

- Gymnosperms
- Lecture Notes on Mesozoic Mesophytic Communities Category:Prehistoric plants Category:Mesozoic life

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