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Hepatic characters in the earliest land plants

Edwards, Dianne, Duckett, J. G. and Richardson, J. B. 1995. Hepatic characters in the earliest land plants. Nature 374 (6523) , pp. 635-636. 10.1038/374635a0

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EVIDENCE for terrestrial vegetation in Ordovician and Silurian times, before the advent of vascular plants, comes from palyno-morphs (cryptospores1), that is, non-dissociating tetrads and dyads2,3 and cuticles4. The lack of a megafossil record for the spore producers is usually attributed to low fossilization potential of vegetative tissues, and this, plus spore type5, contributes to the hypothesis that the plants were embryophytes/archegoniates at a bryophyte level of organization3,5,6 and perhaps most similar in organization to modern hepatics5. Here we describe a minute coal-ified fossil from the Lower Devonian (Lochkovian: micrornatus-newportensis Spore Biozone) of the Welsh Borderland7, which contains obligate, smooth-walled 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 epoch3), 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 Eotracheophyta3). Its anatomy in toto finds no exact parallels in embryophytes, but many of the individual cellular features match those in extant hepatics (liverworts).

Item Type: Article
Date Type: Publication
Status: Published
Schools: Earth and Ocean Sciences
Subjects: Q Science > QE Geology
Q Science > QK Botany
Publisher: NPG
ISSN: 0028-0836
Last Modified: 04 Jun 2017 02:09

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