Agathoxylon Temporal range: Late Carboniferous-Maastrichtian
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Agathoxylon fossil trunks from the Bumi Hills area of Zimbabwe | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Gymnospermae |
Division: | Pinophyta |
Class: | Pinopsida |
Order: | Pinales |
Genus: | †Agathoxylon Hartig 1848 |
Type species | |
†Agathoxylon cordaianum Hartig 1848
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Species | |
Synonyms | |
Agathoxylon (also known by the synonyms Dadoxylon and Araucarioxylon[3]) is a form genus of fossil wood, including massive tree trunks. Although identified from the late Palaeozoic to the end of the Mesozoic,[4] Agathoxylon is common from the Carboniferous to Triassic.[5] Agathoxylon represents the wood of multiple conifer groups, including both Araucariaceae[6] and Cheirolepidiaceae,[7] with late Paleozoic and Triassic forms possibly representing other conifers or other seed plant groups like "pteridosperms".[8]
Agathoxylon were large trees that bore long strap-like leaves and trunks with small, narrow rays.[5] Often the original cellular structure is preserved as a result of silica in solution in the ground water becoming deposited within the wood cells. This mode of fossilization is termed permineralization.
As a genus, Dadoxylon was poorly defined, and apart from Araucariaceae, has been associated with fossil wood as diverse as Cordaitales,[9] Glossopteridales and Podocarpaceae. Furthermore, it may be the same form genus as Araucarioxylon, hence the usage Dadoxylon (Araucarioxylon).[10] The genus Agathoxylon, classified under the family Araucariaceae,[11] has nomenclatural priority over the genera Araucarioxylon and Dadoxylon.[12][13][8]
Several Dadoxylon species, such as D. brandlingii and D. saxonicum have been identified as Araucarites.[14] D. arberi and D. sp.1 were synonymised with the glossopterid species Australoxylon teixterae and A. natalense, respectively; while D. sp. 2 was transferred to Protophyllocladoxylon.
Agathoxylon is common in many parts of the world, found in sites of both Gondwana and Laurasia and reported from southern Africa,[27][28] Asia,[29] the Middle East,[30] Europe,[14] South America,[31][3] and North America.[5]
In southern Africa, Agathoxylon is widespread in the Karoo Supergroup.[32] In Zimbabwe, it is especially encountered in the Pebbly Arkose Formation,[27] and also reported frequently from the Angwa Sandstone Formation.[33][34]