Bennettitales
| Bennettitales Fossil range: Triassic to Cretaceous | ||||||||
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 A Cycadeoid, showing an "inflorescence" in the top-right | ||||||||
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Bennettitales (the cycadeoids) is an extinct order of seed plants that first appeared in the Triassic period and became extinct toward the end of the Cretaceous.[1] Some were characterized by thick trunks and pinnately compound leaves that bore a superficial resemblance to those of cycads, differing primarily in stomatal arrangement.[2]
It comprises two groups, the Cycadeoidaceae, represented by Cycadeoidea, Cycadella, and Monanthesia which had stout trunks and bisporangiate strobili (cones serving as their 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.[1] 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.[3]
Gallery
 A fossilised Bennettitales, squashed by later compression. |
 Side view. Note embedded "flowers". |
 A flower-like structure. |
 Fossil leaf of Zamites mariposana from the Jurassic. |
References
- a b Speer, Brian R., 2000. Introduction to the Bennettitales http://www.ucmp.berkeley.edu/seedplants/bennettitales.html (accessed 13 Oct 2005).
- Pigg, Kathleen. 2005 The Cycads, Cycadeoids (Bennettitales) and Ginkgophytes http://lsweb.la.asu.edu/kpigg/CYCAD.html (accessed 21 Sept 2007).
- Crepet, W. L. (2000). "Progress in understanding angiosperm history, success, and relationships: Darwin's abominably "perplexing phenomenon"". Proceedings of the National Academy of Sciences 97: 12939. doi:.
External links
Source: adapted by the editor from Wikipedia, the free encyclopedia; from the article "Bennettitales". Image Credit.
