Wednesday, 28.06.2017
Jurassic Forum

[ New messages · Members · Forum rules · Search · RSS ]
Page 1 of 11
Jurassic Forum » JURASSIC references & paper reviews » Jurassic around the world » Few articles on possible Jurassic angiosperms (by Chinese paleobotanists)
Few articles on possible Jurassic angiosperms
mhornДата: Sunday, 21.11.2010, 23:11 | Сообщение # 1
Group: Администраторы
Posts: 1060
Reputation: 0
Status: Offline
Wang X. (2010) Schmeissneria: an angiosperm from the Early Jurassic // Journal of Systematics and Evolution. V.48. no.5. P.326–335
The origin of angiosperms has been a focus of intensive research for a long time. The so-called pre-Cretaceous angiosperms, including Schmeissneria, are usually clouded with doubt. To expel the cloud around the enigmatic Schmeissneria, the syntype and new materials of Schmeissneria collected previously in Germany and recently in China are studied. These materials include female inflorescences and infructescences. The latter are old materials but were under-studied previously. Light microscopy and scanning electron microscope observations indicate that the fruits in these infructescences have in situ seeds enclosed, and that the ovaries are closed before pollination. Thus the plants meet two strict criteria for angiosperms: angiospermy plus angio-ovuly. Placing Schmeissneria in angiosperms will extend the record of angiosperms up to the Early Jurassic, more compatible with many molecular dating conclusions on the age of angiosperms, and demanding a reassessment of the current doctrines on the origin of angiosperms. Although the phylogenetic relationship of Schmeissneria to other angiosperms apparently is still an open question, this study adds to research concerning the origin of angiosperms.

Zheng S., Wang X, (2010) An undercover angiosperm from the Jurassic of China // Acta Geologica Sinica. Volume 84, Issue 4. P. 895–902.
Searching for early angiosperms is a riveting activity in botany because it helps to resolve the phylogenetic relationships among seed plants and among angiosperms themselves. One of the challenges for this job is what the target fossils look like. Most possibly early angiosperms may elude our scrutiny with gymnospermous appearances. This possibility becomes a reality in a Jurassic plant, Solaranthus gen. nov, which bears a peltaspermalean appearance and enclosed ovules. According to knowledge available hitherto, the latter feature makes it an angiosperm. However, such a feature is more likely to be eclipsed by its gymnospermous appearance. The early age and unexpected character assemblage of Solaranthus urge for a fresh look on the assumed-simple relationship between angiosperms and gymnosperms. Its resemblance to the order Peltaspermales favors the Mostly Male Theory.

Wang X., Wang S. (2010) Xingxueanthus: an enigmatic Jurassic seed plant and its implications for the origin of angiospermy // Acta Geologica Sinica. Volume 84, Issue 1, P.47–55.
The origin of angiosperms has been tantalizing botanists for centuries. Despite the efforts of palaeobotanists, most of the pre-Cretaceous angiosperms are regarded either non-convincing or misdated. The applications of SEM and LM (light microscope) enable us to recognize a coalified fossil plant, Xingxueanthus sinensis gen. et sp. nov., from the Haifanggou Formation (Middle Jurassic, >160 Ma) in western Liaoning, China. Xingxueanthus is an “inflorescence” with more than 20 female units spirally arranged. Each female unit is situated in the axil of a bract. The female unit is composed of an ovule-container and a style-like projection at the top. There is a vertical column bearing several ovules in the ovule-container. The general morphology and the internal structure of Xingxueanthus distinguish itself from any known fossil and extant gymnosperms, and its structures are more comparable to those of angiosperms. Xingxueanthus, if taken as a gymnosperm, would represent a new class, demonstrate an evolutionarily advanced status of ovule-protection in gymnosperms never seen before, and provide new insights into the origin of angiospermy. Alternatively, if taken as an angiosperm, together with Schmeissneria, it would increase the diversity of Jurassic angiosperms, which has been underestimated for a long time, and suggest a much earlier origin of angiospermy than currently accepted.

Middle Jurassic - Lower Cretaceous ammonites & aptychi
Jurassic Forum » JURASSIC references & paper reviews » Jurassic around the world » Few articles on possible Jurassic angiosperms (by Chinese paleobotanists)
Page 1 of 11
Search: © 2017
Free web hostinguCoz