Tetraxylopteris
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Tetraxylopteris Temporal range: Middle Devonian to Upper Devonian |
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| Scientific classification | |
| Kingdom: | Plantae |
| Order: | Aneurophytales |
| Genus: |
† Tetraxylopteris C.B.Beck (1957) |
| Species | |
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T. schmidtii C.B.Beck (1957) |
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T. schmidtii C.B.Beck (1957)
T. reposana Hammond & Berry (2005)
Tetraxylopteris is a genus of extinct vascular plants of the Middle to Upper Devonian (around 390 to 360 million years ago). Fossils were first found in New York State, USA. A second species was later found in Venezuela.
Fossils of Tetraxylopteris have so far been discovered in two locations. T. schmidtii was named from the Catskill Clastic Wedge, New York State, United States of America, in rocks of Middle to Upper Devonian age (around 390 to 360 million years ago).T. reposana was found in the Campo Chico Formation, north-west Venezuela, in beds believed to be of Frasnian age (383 to 372 million years ago).
The overall shape of Tetraxylopteris consisted of a complex system of branches. The main stem was 'pseudomonopodial', i.e. it divided dichotomously to produce side stems while the main stem maintained its identity. The main and side stems then bore three orders of branches (i.e. the first branches from the stems divided twice more). (There were possibly four orders in T. reposana.) The branches were arranged in opposite pairs with successive pairs at right angles (decussate). In T. schmidtii, the final order of branches bore appendages arranged oppositely and decussately; in T. reposana, the appendages were opposite and decussate on the penultimate order of branches and spirally or helically arranged on the final order. The appendages branched dichotomously up to three times and were three-dimensional, although some appear flattened in the fossilized specimens. They have been called "non-laminate proto-leaves" by Beerling and Fleming, reflecting the belief that such structures were precursors to true leaves, which evolved by first 'planation' – flattening to produce a two-dimensional branched structure – and then 'webbing' – tissue growing out between the flattened branches.
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