Trimerophytophyta
| Trimerophytophyta | ||||||||||||
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Trimerophyton fossil |
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| Temporal occurrence | ||||||||||||
| Lower Devonian to Middle Devonian | ||||||||||||
| 411 to 385 million years | ||||||||||||
| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Trimerophytophyta | ||||||||||||
The Trimerophytophyta are a group of extinct vascular plants , especially from the early Devonian , which are in their characteristics between the Rhyniophyta and the recent ferns and seed plants .
features
The trimerophytes are generally more complex than the Rhyniophyta or the Zosterophyllophyta . The axes branch monopodially or pseudomonopodially. The side branches branch out forked or three-pronged. The name is also derived from the three-pronged branch. The axes are smooth, spotted, or prickly. The xylem strands are clearly defined, the protoxylem is inside (endarch). The tracheids are ladder tracheids or they have court pits.
The sporangia are terminal on the axes, mostly they are concentrated on richly branched side branches. Some species have few sporangia, others have many small ones.
Systematics
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The Trimerophytophyta were established by Harlan P. Banks as one of the three groups in 1968, when he dissolved the diverse and polyphyletic group of psilophytes . The Trimerophytophyta are one of the three basal groups of vascular plants . Banks provided the following genera to the Trimerophytophytina subdivision :
- Trimerophytales
- Trimerophytaceae
- Psilophyton
- Trimerophyton
- Pertica
- Dawsonites
- Hostinella
- Yunia (assignment only as likely)
- Trimerophytaceae
- possibly already higher than trimerophytes:
In 1993 Taylor and Taylor did not include the last three genera in their review of the Trimerophytophyta, which was now classified as a division.
However, cladistic analyzes showed that the trimerophytes sensu Banks or sensu Taylor and Tayler 1993 are not a natural related group. Pertica is quite close to the seed plants, even if many of their characteristics are difficult to interpret; the rest are paraphyletic with respect to the non-moss-like vascular plants.
Kenrick and Crane therefore no longer recognize the trimerophytes as a taxon. The Eophyllophyton bellum , which had not been part of the trimerophytes until then, is close to the other trimerophytes, but they place the previous trimerophyte Yunia dichotoma in the club moss plants .
The trimerophytes are generally considered to be descendants of the Rhyniophyta. You yourself are at the base of the Euphyllophyta , the group to which the ferns and seed plants belong.
Temporal spread
Most of the finds of the trimerophytes come from the early Devonian ( Pragian ). This age began 417 million years ago. Pertica , which actually does not belong to this stage of development, extends into the middle Devonian ( Givetium ), which lasted until 385 million years ago. It is possible that some finds can also be classified in the Lower Carboniferous ( Mississippium ).
supporting documents
- Paul Kenrick, Peter R. Crane: The Origin and Early Diversification of Land Plants. A Cladistic Study . Smithsonian Institution Press, Washington DC 1997, esp.p. 140, 319f. ISBN 1-56098-729-4
- Thomas N. Taylor, Edith L. Taylor: The Biology and Evolution of Fossil Plants . Prentice Hall, Englewood Cliffs 1993, pp. 191-203. ISBN 0-13-651589-4