Chengia laxispicata gen. et sp nov., a new ephedroid plant from the Early Cretaceous Yixian Formation of western Liaoning, Northeast China: evolutionary, taxonomic, and biogeographic implications

doi:10.1186/1471-2148-13-72

	Chengia laxispicata gen. et sp nov., a new ephedroid plant from the Early Cretaceous Yixian Formation of western Liaoning, Northeast China: evolutionary, taxonomic, and biogeographic implications
	Yang, Yong ; Lin, Longbiao 1; Wang, Qi
	2013
发表期刊	BMC EVOLUTIONARY BIOLOGY
ISSN	1471-2148
卷号	13
摘要	Background: The extant Gnetales include three monotypic families, namely, Ephedraceae (Ephedra), Gnetaceae (Gnetum), and Welwitschiaceae (Welwitschia), all of which possess compound female cones that comprise a main axis and 1 to multiple pairs/whorls of bracts subtending a female reproductive unit or having lower pairs/whorls of bracts sterile. However, the evolutionary origin of such a reproductive architecture in Gnetales is controversial in the light of the competing anthophyte versus gnetifer hypotheses of seed plant relationships. Hence, macrofossils demonstrating the structure of compound female cones of the Gnetales should be important to decipher the early evolution of the order. Results: A new ephedroid plant Chengia laxispicata gen. et sp. nov. is described from the Early Cretaceous Yixian Formation of western Liaoning, Northeast China. The fossil represents a part of a leafy shooting system with reproductive organs attached. The main shoot bears internodes and swollen nodes, from which lateral branches arise oppositely. Reproductive organs consist of female spikes terminal to twigs or axillary to linear leaves. Spikes are loosely arranged, having prominent nodes and internodes. Bracts of the spikes are decussately opposite and comprise 4-8 pairs of bracts. Each bract subtends an ellipsoid seed. Seeds are sessile, with a thin outer envelope and a distal micropylar tube. Conclusions: Chengia laxispicata gen. et sp. nov. provides a missing link between archetypal fertile organs in the crown lineage of the Gnetales and compound female cones of the extant Ephedraceae. Combined with a wealth of Ephedra and ephedroid macrofossils from the Early Cretaceous, we propose a reduction and sterilization hypothesis that the female cone of the extant Ephedraceae may have stemmed from archetypal fertile organs in the crown lineage of the Gnetales. These have undergone sequentially intermediate links similar to female cones of Cretaceous Siphonospermum, Chengia, and Liaoxia by reduction and sterilization of the lower fertile bracts, shortenings of internodes and peduncles as well as loss of reproductive units in all inferior bracts. The basal family Ephedraceae including Ephedra of the extant Gnetales was demonstrated to have considerable diversity by the Early Cretaceous, so an emended familial diagnosis is given here. The Jehol Biota in Northeast China and adjacent areas contains a plethora of well-preserved macrofossils of Ephedra and ephedroids that show different evolutionary stages including primitive and derived characters of Ephedraceae, so Northeast China and adjacent areas may represent either the centre of origination or one of the centres for early diversification of the family.
关键词	Biogeography Chengia Early Cretaceous Ephedraceae Ephedroid Evolution Female cone Gnetales Jehol biota Reduction and sterilization hypothesis Yixian Formation
学科领域	Evolutionary Biology ; Genetics & Heredity
DOI	10.1186/1471-2148-13-72
收录类别	SCI
语种	英语
WOS关键词	SEED PLANT ; REPRODUCTIVE STRUCTURES ; WELWITSCHIA-MIRABILIS ; DOUBLE FERTILIZATION ; GNETUM-PARVIFOLIUM ; FOSSIL EVIDENCE ; GNETALES ; ORIGIN ; MORPHOLOGY ; FEMALE
WOS研究方向	Science Citation Index Expanded (SCI-EXPANDED)
WOS记录号	WOS:000317672400001
出版者	BMC
文献子类	Article
出版地	LONDON
资助机构	National Natural Science Foundation of China(National Natural Science Foundation of China (NSFC)) ; State Key Laboratory of Systematic and Evolutionary Botany, CAS ; State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, CAS(Chinese Academy of Sciences)
作者邮箱	Yang, Yong/S-1202-2019
作品OA属性	gold, Green Published
引用统计	被引频次：16[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://ir.ibcas.ac.cn/handle/2S10CLM1/27866
专题	系统与进化植物学国家重点实验室
作者单位	1.Chinese Acad Sci, Inst Bot, State Key Lab Systemat & Evolutionary Bot, Beijing 100093, Peoples R China 2.China Railway Grp Ltd, Beijing 100039, Peoples R China
推荐引用方式 GB/T 7714	Yang, Yong,Lin, Longbiao,Wang, Qi. Chengia laxispicata gen. et sp nov., a new ephedroid plant from the Early Cretaceous Yixian Formation of western Liaoning, Northeast China: evolutionary, taxonomic, and biogeographic implications[J]. BMC EVOLUTIONARY BIOLOGY,2013,13.
APA	Yang, Yong,Lin, Longbiao,&Wang, Qi.(2013).Chengia laxispicata gen. et sp nov., a new ephedroid plant from the Early Cretaceous Yixian Formation of western Liaoning, Northeast China: evolutionary, taxonomic, and biogeographic implications.BMC EVOLUTIONARY BIOLOGY,13.
MLA	Yang, Yong,et al."Chengia laxispicata gen. et sp nov., a new ephedroid plant from the Early Cretaceous Yixian Formation of western Liaoning, Northeast China: evolutionary, taxonomic, and biogeographic implications".BMC EVOLUTIONARY BIOLOGY 13(2013).

条目包含的文件
文件名称/大小	文献类型	版本类型	开放类型	使用许可
23530702.pdf（1905KB）	期刊论文	出版稿	开放获取	CC BY-NC-SA	浏览请求全文