Stockmansella langii
| Stockmansella langii | ||||||||||||
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Stockmansella langii from the layers of the Upper Siegenium from the site of the phosphate elimination plant of the Wahnbach dam. |
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| Temporal occurrence | ||||||||||||
| Early Devonian | ||||||||||||
| 407 to 397 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name of the genus | ||||||||||||
| Stockmansella | ||||||||||||
| Fairon Demaret | ||||||||||||
| Scientific name of the species | ||||||||||||
| Stockmansella langii | ||||||||||||
| ( Stockmans ) Fairon Demaret |
Stockmansella langii is an extinct species of plant. It is known from the Devonian of Belgium and the Rhineland and is one of the basal representatives of vascular plants. It is the only species in the genus Stockmansella .
features
The main axes are bare and branch out forked (dichotomous). A rolled up bud layer (circinate vernation), as it is typical for the leaf formation of ferns , is likely, but not certain.
The spindle-shaped sporangia stand individually at the ends of the axes (terminal) and are more or less sessile. They sit in shallow depressions at the end of the axle, from which they detach. They are not supplied by vascular bundles that end further down the axis. The sporangia were opened through one or perhaps more longitudinal slits.
Little is known about the anatomy. The central vascular bundle is probably cylindrical and consists at least partially of helically thickened cells with S-type cell wall thickenings, as is characteristic of the Rhyniopsida .
The epidermal cells of the axis and the sporangia are elongated, stomata could be identified with reasonable certainty. The spores are around 60 micrometers in diameter and smooth.
The gametophyte is unknown. Stockmansella is discussed as one of the sporophytes to which the gametophyte Sciadophyton could belong.
Systematic position
According to the older system, Stockmansella is part of the Rhyniophyta . Kenrick and Crane placed it in their cladistic analysis in the group of the Rhyniopsida .
Temporal and geographical distribution
The species was first described from the Old Red Sandstone of Belgium, which was dated to the Lower Devonian , late Pragian to late Emsian , which corresponds to an age between 407 and 397 million years. Similar fossils have been described from the same series from Germany.
Botanical history
The fossils now known as Stockmansella langii were first described as Taeniocrada langii . Due to strong morphological differences to the type species of the genus Taeniocrada , it was initially placed in its own genus Stockmansia , but since this name was already assigned to a paleozoic fern, it was finally renamed Stockmansella .
supporting documents
- Paul Kenrick, Peter R. Crane: The Origin and Early Diversification of Land Plants. A Cladistic Study . Smithsonian Institution Press, Washington DC 1997, p. 323. ISBN 1-56098-729-4
Individual evidence
- ↑ Taylor and Taylor, 1993, p. 231.