Abstract: Taxonomic and morphological diversities of fossil groups are two fundamental aspects in studying macroevolution of life,but previous studies have paid little attention to the latter. Late Paleozoic sphenophytes are easily to be recognized and have a rich fossil record,but their diversity pattern remains little known. Based on a compilation of the genera and species record of the Late Devonian-Early Triassic sphenophytes from South China and North China blocks,and a compilation of leaf morphological characters of some selected leafy species,the macroevolution pattern of early sphenophytes is studied with respect to their taxonomic and morphological diversity. The genus/species richness of the sphenophytes from China shows continuous but uneven increase during the Late Paleozoic,including the initial diversification during the Late Devonian,a slow rise from Visean to Sakmarian,and a rapid rise from Sakmarian to Wuchiapingian;and then,the richness sharply declines at the end of the Permian. The diversity per million years also shows significant decease at the Permian-Triassic transition. Sphenophytes from South China are less diverse at both the generic and specific levels than those from North China,and their diversity reaches the peak during the Capitanian-Wuchiapingian;genus diversity of sphenophytes from North China reaches the peak during the Kungurian-Roadian. Leaf morphological diversity of sphenophytes from China,decoupled from the taxonomic richness,is smaller in the Famennian and early Carboniferous,reaches the peak in the Pennsylvanian,and then slightly declines and remains stable in the Permian. Leaf morphologies of the Late Paleozoic sphenophytes show evolution in the following aspects: increase of leaf area;leaf lamina varying from divided to undivided;leaf tip varying from split to round or obtuse round;same-sized leaves to different-sized leaves in the same leaf whorl,and showing leaf mosaic. These changes might be related to variations of light intensity at the understory levels of the Paleozoic plant communities.

Key words: sphenophytes, Late Paleozoic, taxonomic diversity, morphological diversity, macroevolution

摘要： 化石类群的分类单元多样性和形态多样性变化是生物宏演化的2个基本方面,而以往的研究对于后者的关注较少。晚古生代的楔叶类植物易于识别,化石记录丰富,但针对这一类群多样性演化的研究还较为缺乏。基于华北板块、华南板块晚泥盆世至早三叠世楔叶类植物属、种以及叶片形态编码数据库,对楔叶类植物宏演化历程进行详细研究。中国(华北板块和华南板块)楔叶类植物的属、种丰富度在晚古生代呈现出不稳定的持续增长,表现为晚泥盆世的初始兴盛、早石炭世杜内期至早二叠世萨克马尔期的缓慢上升、早二叠世萨克马尔期至晚二叠世吴家坪期的快速上升;晚二叠世长兴期,总体的属种多样性骤减;每百万年属种多样性在二叠纪—三叠纪之交亦有明显降低。华南板块楔叶类植物的属种多样性总体上小于华北板块,达到峰值的时间为卡匹敦期—吴家坪期,而华北楔叶类植物的属级多样性在空谷期—沃德期达到峰值。中国楔叶类植物叶片的形态多样性的剧烈变化与属种丰富度并不同步,表现为法门期至韦宪期较小,在宾夕法尼亚亚纪达到峰值,随后稍微下降并在二叠纪的大部分时段保持平稳。在晚古生代的叶片形态演化过程中,楔叶类植物的叶面积由小变大、叶片由深裂至不裂、叶尖形状由分裂变为圆形或钝圆、叶轮中的叶从大小相等到大小不等并出现叶镶嵌,这可能与当时植物群落中林下层光照强度的变化有关。

关键词: 楔叶类植物, 晚古生代, 分类单元多样性, 形态多样性, 宏演化

CLC Number: 

• Q914.7