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PALAEOBOTANICAL RESEARCH   GROUP   UNIVERSITY  MÜNSTER

The earliest vascular land plants appeared about 425 million years ago in the late Early  Silurian.  This form, Cooksonia, consisted of small naked, dichotomously bifurcting axes bearing terminal sporangia. These plants were only a few centimeters high.  Baragwanathia is a much more robust plant consisting of up to 30 cm long axes with spirally arranged leaves and it has been described from the Upper Silurian of Australia; unfortunately, the quality of the compressions is rather poor and no organic material is preserved.

The Early Devonian is characterized by a very strong radiation of land plants.  Four  major groups can be distinguished: the Rhyniophytes, the Zosterophyllophytes, the Lycopods and the Trimerophytes.  The Rhyniophytes are definitely among the best known land plants.  These ca. 15-20 cm high plants consist of naked, dichotomously branching axes terminally bearing fusiform sporangia.  Rhyniophytes lacked true roots but had single-celled rhizoids for taking up water and nutrients.  The silicified material from the Rhynie chert shows many anatomical details.  The equally sized Zosterophyllophytes are characterized by having dichotomously branching axes bearing laterally inserted sporangia; sporangia may be standing in strobili. Some Zosterophylls had small spine-like enations.  The Trimerophytes have a more complex vascular system and terminally positioned sporangia standing in dense clusters.  Some trimerophytes had monopodial main axes; however, lateral axes still had dichotomous branching.  Some Trimerophytes could reach a considerable height; Pertica from the late Early Devionan may already have attained a height of ca. 3 metres.  The Zosterophyllophytes are considered to be the ancestral group that gave rise to the Lycopods, whereas all other groups of land plants are regarded to have been evolved from the Trimerophytes.  The exquisit preservation of the Rhynie chert material enabled the recognition of the gametophyte stages of some of the earliest land plants.  Gametophytes have also been recognized in compression preservation.

Taxon / Subject	Web Source	Comments	Pics	Info
The oldest land plants 1	Hans Steur's Paleobotany Pages
The oldest land plants 2	Hans Steur's Paleobotany Pages
Pre-Devonian vascular land plants: Baragwanathia and Cooksonia
Baragwanathia is a putatitive early lcopod from the Silurian of southern Australia. The age of these fossils was long controversial, but now it is agreed that they are Silurian.
Baragwanathia	R.A. Spicer, The Open University, Milton Keynes
Baragwanathia	Kathleen Pigg's "Plant Fossils and Evolution"
Baragwanathia	Virtual Paleobotany Laboratory
Cooksonia
Cooksonia hemisphaerica	Virtual Paleobotany Laboratory
Cooksonia	Virtual Paleobotany Laboratory
Cooksonia pertonii	Hans Steur's Paleobotany Pages
Cooksonia pertonii	Hans Steur's Paleobotany Pages
One of the most famous Early Devonian land plant localities is Rhynie in Aberdeenshire, Scotland. The Rhynie Chert is one of the most important fossil plant occurrences because it represents the oldest and most completely preserved terrestrial ecosystem. The Rhynie Chert has been radiometrically dated at 396 Ma (Pragian). Plants remains show excellent cellular preservation. Three groups of plants are represented: the Rhyniophytes, the Zosterphyllophytes and a lycopod. Although plants are preserved in great detail natural affinities of the taxa are not always clear.
Rhynie Chert	Paläobotanik Münster		have a look!
Rhynie Chert	Rhynie Chert Reserach Group, Aberdeen	The site of our friends in Aberdeen
Rhynie Chert	Virtual Paleobotany Laboratory
The Rhyniophytes are a group of early land plants originally described from the Rhynie Chert.  They have naked, dichotomously branching axes with terminally positioned sporangia.  The systematic position of Aglaophyton, Horneophyton and Nothia is not clear, because of differences in the vascular system respectively sporangium morphology; the latter form also shows resemblances with Zosterophyllophytes.  Some authors classify these taxa in separate groups.  Several forms have been interpreted as compression counterparts of the Rhyniophytes; however, this needs further clearification.
Rhynia gwynne-vaughanii
Landscape at Rhynie, Rhynia	R.A. Spicer, The Open University, Milton Keynes
Rhynia gwynne-vaughanii	Hans Steur's Paleobotany Pages
Rhynia gwynne-vaughanii	Hans Steur's Paleobotany Pages	Reconstruction and overview
Rhynia gwynne-vaughanii	Hans Steur's Paleobotany Pages	Cross sections
Rhynia gwynne-vaughanii	Hans Steur's Paleobotany Pages	Epidermis and stoma
Rhynia gwynne-vaughanii	Hans Steur's Paleobotany Pages	Hemispherical projection on axis
Rhynia gwynne-vaughanii	Hans Steur's Paleobotany Pages	Decaying axes
Rhynia gwynne-vaughanii	Paläobotanik Münster		have a look!
Aglaophyton major
Aglaophyton major	Paläobotanik Münster	germinating spore and young  gametophyte	have a look !
Aglaophyton major	Virtual Paleobotany Laboratory
Aglaophyton major	Hans Steur's Paleobotany Pages	Reconstruction and overviews
Aglaophyton major	Paläobotanik Münster		have a look!
Aglaophyton major	Paläobotanik Münster	Stoma	have a look!
Rhynie Chert	Kathleen Pigg's "Plant Fossils and Evolution"
Horneophyton lignieri
Horneophyton lignieri	Virtual Paleobotany Laboratory	Sporangia
Horneophyton lignieri	Hans Steur's Paleobotany Pages	Overview, conducting strand with spores
Horneophyton lignieri	Hans Steur's Paleobotany Pages	Rhizomes with rhizoids
Horneophyton lignieri	Hans Steur's Paleobotany Pages	Sporangium
Horneophyton lignieri	Hans Steur's Paleobotany Pages	Spores
Nothia
Nothia aphylla	Hans Steur's Paleobotany Pages	Reconstruction and overview
The Zosterophyllophytes are a group of Early to Middle Devonian plants with mostly dicotomously branching axes and laterally inserted, usually more or less kidney-shaped sporangia.  Several Zosterphylls have naked axes, others have small spine-like enations.  Very typical are H-shaped branching patterns and coiled axis apices.  Most forms are known as compressions, however also anatomically preserved material is known.
Zosterophylls	Univ. California Museum of Paleontology, Berkeley
Crenaticaulis
Crenaticaulis	Virtual Paleobotany Laboratory
Sawdonia
Sawdonia acanthotheca	Virtual Paleobotany Laboratory
Sawdonia ornata	R.A. Spicer, The Open University, Milton Keynes
Sawdonia	Kathleen Pigg's "Plant Fossils and Evolution"
Serrulacaulis
Serrulacaulis furcatus	Virtual Paleobotany Laboratory
Rebuchia
Rebuchia ovata	Smithsonian, Washington DC
Zosterophyllum
Zosterophyllum divaricatum	Virtual Paleobotany Laboratory
Zosterophyllum rhenanum	Institut für Spezielle Botanik, Jena	Alternation of generations
The Trimerophytes are a group Early and Middle Devonian plants with either dichotomously branching axes, or with a monopodial main axes.  The Trimerophytes were certainly the most robust plants occurring during the Early Devonian.
Trimerophytes	Univ. California Museum of Paleontology, Berkeley
Psilophyton
Psilophyton crenulatum	R.A. Spicer, The Open University, Milton Keynes	Fertile axes
Psilophyton crenulatum	Kathleen Pigg's "Plant Fossils and Evolution"
Psilophyton dawsonii	Kathleen Pigg's "Plant Fossils and Evolution".	Anatomically preserved axis
Psilophyton dapsile	Kathleen Pigg's "Plant Fossils and Evolution"
Psilophyton ornata	Virtual Paleobotany Laboratory
Psilophyton	Univ. California Museum of Paleontology, Berkeley
Pertica
Pertica quadrifaria	Maine Department of Conservation	State fossil of Maine
Pertica	Virtual Paleobotany Laboratory
Early Lycopodiophytes
Asteroxylon
Asteroxylon	Virtual Paleobotany Laboratory
Asteroxylon mackiei	Hans Steur's Paleobotany Pages	Reconstruction and overview
Asteroxylon mackiei	Hans Steur's Paleobotany Pages	Star-shaped xylem
Asteroxylon mackiei	Hans Steur's Paleobotany Pages	Tracheids
Asteroxylon mackiei	Hans Steur's Paleobotany Pages	Leaves

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