摘要
记述甘肃酒泉盆地早白垩世地层中发现的两种掌鳞杉科植物化石Pseudofrenelopsis dalatzensis(ChowetTsao,1977)Cao ex Zhou和P.gansuensissp.nov.。其中,归入P.dalatzensis的标本无论是小枝形态还是表皮构造都与产于吉林延吉盆地大砬子组的模式标本一致。定为新种的标本小枝较粗,可能只有一枚叶;节间角质层厚25—30μm,表面没有乳突和表皮毛,气孔器和表皮细胞均规则成行排列;气孔器圆形或椭圆形,较大,整体下陷。副卫细胞通常5—7个,少数可达8—9个。保卫细胞仅部分保存。已发现的Pseudofrenelopsis均分布于北半球,时代限于早白垩世,且多为早白垩世晚期,其中P.dalatzensis在模式标本产地与丰富的被子植物共生,应为早白垩世Aptian到Albian期。该种在酒泉盆地中沟组的出现说明该组的时代最高可到Aptian或Albian期。已有资料还表明,Pseudofrenelopsis主要生活于有季节变化、盐度较高或较干旱的环境中,这与酒泉盆地早白垩世沉积物和其他门类的化石所指示的环境特征相符合。
Two species of cheirolepidiaceous conifers are described based on the materials collected from the Lower Cretaceous Xiagou and Zhonggou formations of Jiuquan Basin, Gansu, northwestern China for the first time. Numerous specimens assigned to Pseudofrenelopsis dalatzensis （Chow et Tsao, 1977） Cao ex Zhou are morphologically identical with the holotype from Jilin, Northeast China. P. gansuensis sp. nov. is characterized by wide shoots, thick internode cuticles （25-30 μm） having a smooth outer surface, nearly isodiametrical epidermal cells arranged in rows, well-defined stomatal files, large and sunken stomata with 6-7 subsidiary cells. The geographical and stratigraphical distributions and the ecological characters of Pseudofrenelopsis are summarized. The present finds also provide new evidence for the Early Cretaceous age of the fossil-bearing strata. Sedimentological and cuticle analyses indicate that these conifers were xeromorphic plants adapted to halophytic habitats.
出处
《古生物学报》
CAS
CSCD
北大核心
2005年第4期505-516,共12页
Acta Palaeontologica Sinica
基金
国家自然科学基金项目(No.49872008)
国家科技部973项目(2006CB701400)资助课题。
