A new gnetalean macrofossil from the Lower Cretaceous of the Laiyang Basin, eastern China  

作　　者：Peihong Jin Mingzhen Zhang Baoxia Du Jing Zhang Bainian Sun 

机构地区：[1]Key Laboratory of Petroleum Resources,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Gansu Province,Lanzhou 730000,China [2]Key Laboratory Western China's Mineral Resources of Gansu Province,Lanzhou University,Lanzhou 730000,China

出　　处：《Plant Diversity》2024年第5期678-682,共5页植物多样性（英文版）

基　　金：supported by the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant No.2019QZKK0704);the National Natural Science Foundation of China(Grant No.42272029).

摘　　要：Gnetophytes are a key group of plant for understanding seed plant phylogeny,partly because of their unique and elusive morphology,such as xylem with vessels,phloem with chaperones,reticular veins,and double fertilization(Endress,1996).In particular,the ovule bears a membranous integument,the upper part of which extends beyond the seed envelope to form a micropylar tube.Therefore,gnetophytes occupy a unique evolutionary position in the phylogeny of seed plants and apparently represent a transition between angiosperms and other gymnosperms(Ran et al.,2018).Modern gnetophytes consist of only three families:Ephedraceae,Gnetaceae,and Welwitschiaceae,and each family contains only one genus.Ephedraceae(Ephedra L.)are the earliest diverging group of Gnetales,with a total of 70 extant species,and usually occur in cold and arid places in Asia,Europe,northern Africa,western North America and South America(Price,1996;Yang et al.,2017b).

关 键 词：PHYLOGENY OCCUPY CRETACEOUS 

分 类 号：Q914[天文地球—古生物学与地层学]