Tortilicaulis
| Tortilicaulis Temporal range:
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Scientific classification 
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| Kingdom: | Plantae |
| Clade: | Streptophyta |
| Clade: | Embryophytes |
| Clade: | Polysporangiophytes |
| Class: | †Horneophytopsida (?) |
| Genus: | †Tortilicaulis D.Edwards (1979)[1] |
| Type species | |
| Tortilicaulis transwalliensis D.Edwards (1979)
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| Species | |
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Tortilicaulis is a
Whilst it is generally accepted that Tortilicaulis was moss-like, it has not yet been recovered in a sufficiently good state of preservation to allow the detailed study necessary to firmly assign it to a taxonomic group. Fossils consist of an elongate apical sporangium (spore-forming organ), which may be branched, with spiralled walls attached to an undivided stalk that is also twisted.[3][5] Unusually for plants of its time, spores of Tortilicaulis were covered all over with small granules.[6][7]
The initial suspicions of its describer, Dianne Edwards, were that it was a bryophyte,[1] and comparisons have been made with several groups.[5] A potential association with the moss Takakia is supported by features of the sporangia, such as the elongate shape, unusual twisting, and terminal position of the sporangia.
As the sporangia of Tortilicaulis are branched, cladistic analysis suggests that the genus may instead belong to the Horneophytopsida, a class of the polysporangiophytes, which unlike bryophytes, have branched stems bearing sporangia.[2] Its precise nature and hence classification remains unclear.[8] For the cladogram, see the Horneophytopsida article.
References
- ^ a b Edwards, D. (1979). "A late Silurian flora from the Lower Old Red Sandstone of south-west Dyfed". Palaeontology. 22: 23–52.
- ^ ISBN 1-56098-730-8.
- ^ .
- ]
- ^ ISBN 0-13-651589-4.
- .
- .
- ISBN 978-0-12-373972-8., p. 165