HEPATIC CHARACTERS IN THE EARLIEST LAND PLANTS
HEPATIC CHARACTERS IN THE EARLIEST LAND PLANTS
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DOI：
10.1038/374635a0
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发表时间：
1995-04-13
期刊：
影响因子：
64.8
通讯作者：
RICHARDSON, JB
中科院分区：
文献类型：
--
作者：
EDWARDS, D;DUCKETT, JG;RICHARDSON, JB
在维管植物出现之前的奥陶纪和志留纪时期，陆地植被的证据来自于孢粉形（隐孢子（1）），即非解离的四分体和二分体（2，3）和古孢子（4）。缺乏孢子生产者的巨化石记录通常归因于营养组织的低细胞化潜力，这一点，加上孢子类型（5），有助于假设植物是胚状体/颈卵器，处于brancte水平的组织（3，5，6），并且可能在组织上与现代肝脏最相似（5）。在这里，我们描述了一个来自威尔士边境地区下泥盆统（Lochkovian：micrornatus-newportensis孢子生物带）的微小煤化化石（7），其中含有专性的、平滑涉水的四面体四分体，与奥陶纪首次记录的相似（通过扫描电子显微镜）。据我们所知，这些是关于构成最早胚植物陆地植物群的植物的大体形态和组织的第一批数据（Gray的Eoembryophytic epoch（3）），尽管是从泥盆纪的一个残遗样本中获得的，但当时分散的孢子和巨化石组合的组成表明，（rhyniophytoids）一般开始占主导地位的土地植被（格雷的Eotracheophyta（3））。它的解剖学在胚胎植物中找不到确切的相似之处，但许多个体细胞特征与现存的肝（地钱）相匹配。
EVIDENCE for terrestrial vegetation in Ordovician and Silurian times, before the advent of vascular plants, comes from palynomorphs (cryptospores(1)), that is, non-dissociating tetrads and dyads(2,3) and cuticles(4). The lack of a megafossil record for the spore producers is usually attributed to low fossilization potential of vegetative tissues, and this, plus spore type(5), contributes to the hypothesis that the plants were embryophytes/archegoniates at a bryophyte level of organization(3,5,6) and perhaps most similar in organization to modern hepatics(5). Here we describe a minute coalified fossil from the Lower Devonian (Lochkovian: micrornatus-newportensis Spore Biozone) of the Welsh Borderland(7), which contains obligate, smooth-waded tetrahedral tetrads, similar (by scanning electron microscopy) to those first recorded in the Ordovician. To our knowledge, these are the first data on the gross morphology and tissues of the plants that comprised the earliest embryophyte land flora (Gray's Eoembryophytic epoch(3)), albeit obtained from a relict Devonian example fossilized at a time when the composition of dispersed spore and megafossil assemblages suggests that tracheophytes and tracheophyte-like plants (rhyniophytoids) had generally begun to dominate land vegetation (Gray's Eotracheophyta(3)). Its anatomy in toto finds no exact parallels in embryophytes, but many of the individual cellular features match those in extant hepatics (liverworts).