Gosslingia
| Gosslingia | ||||||||||||
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| Temporal occurrence | ||||||||||||
| Lower Devonian | ||||||||||||
| Locations | ||||||||||||
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Wales, Germany, Belgium, USA |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Gosslingia | ||||||||||||
| Heard |
Gosslingia is a genus of extinct plants that are mainly known from the Devonian and belong to the Zosterophyllopsida , relatives of the club moss plants . It is named after the British amateur geologist Frank Newbery Gossling (1888–1946).
features
The best known species is Gosslingia breconensis , which is known from the lower Old Red Sandstone of Wales . A rhizome with rhizoids is assumed to be the basis of the plant , but no organically linked finds with the other parts of the plant have been known. The plant was about 50 centimeters high. The main axis has a diameter of up to four millimeters and is pseudo- monopodial , dichotomous in the distal area. As with Sawdonia, the axles are rolled up like a bishop's staff. The shoots have no leaves, but in some specimens they have protuberances some 100 micrometers long. Directly below the dichotomous branching of the main axis sits on one side a subordinate structure called a tubercle. The xylem is elliptical in cross section in the main axis, the protoxylem (with ring tracheids ) lies on the outside, the xylem ripens from the outside inwards (exarches xylem). The metaxylem consists of ladder and net tracheids. A circular xylem cord supplies the tubercles. The axes have a hypodermic layer of thick-walled cells. Little is known about the cuticle of the shoot axes; the epidermis is likely to consist of elongated cells, papillae and possibly also stomata .
The sporangia are oval to kidney-shaped, open with equally sized valves and stand on short stalks in one or two opposite rows in the distal areas of the shoot. In contrast to most of the other representatives of the Zosterophyllopsida, the sporangia are arranged in the shape of an ear, with the long axis parallel to the stem axis. The spores are triangular, have small spines and cones on the surface and are 36 to 50 micrometers in diameter. Scar structures are not known from the spores.
The gametophyte of Gosslingia breconensis is unknown.
distribution
In addition to the type locality in Wales, the genus is also known from Germany, Belgium and Wyoming . There are poorly documented reports of finds from Volhynia and Podolia and from the area of former Czechoslovakia. The finds come mainly from the early Devonian , the finds from Wales from the Pragian .
Systematics
The genus Gosslingia was placed by Kenrick and Crane after cladistic studies together with Tarella and Oricilla in a separate family Gosslingiaceae, which is characterized by the ear-shaped oriented sporangia.
supporting documents
- Paul Kenrick, Peter R. Crane: The Origin and Early Diversification of Land Plants. A Cladistic Study . Smithsonian Institution Press, Washington DC 1997, v. a. P. 334f. ISBN 1-56098-729-4 .
- Thomas N. Taylor, Edith L. Taylor: The Biology and Evolution of Fossil Plants . Prentice Hall, Englewood Cliffs 1993, pp. 208-211, ISBN 0-13-651589-4 .
further reading
- Dianne Edwards: Further Observations on the Lower Devonian Plant, Gosslingia breconensis Heard . Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, Volume 258, 1970, pp. 225-243 (online at JSTOR)