Decombeix, Anne-Laure , McLoughlin, Stephen , Meyer-Berthaud, Brigitte , Galtier, Jean .
A new tree from the Mississippian (early Carboniferous) of Queensland, Australia.
Despite several reports indicating the presence of anatomically preserved gymnosperm trunks in Mississippian localities of eastern Australia, no studies have been conducted on these fossils since the late 1800 – early 1900’s. Silicified woods have recently been collected in middle-Tournaisian to late Visean localities from the Burdekin, Clarke River, Drummond, and Yarrol basins (Queensland). These specimens are preserved in marine or terrestrial volcanigenic sediments. In the Burdekin and Drummond basins, they are associated with arborescent zygopterid ferns. These permineralized fossils complete the record of Mississippian plants from Australia that, up to now, was essentially based on compressions and indicated a dominance of lycophytes as elsewhere in Gondwana. Here we describe a new lignophyte trunk of late Visean age from the Yarrol Basin. The specimen is decorticated and has a maximum diameter of 15 cm. The central part consists of a wide eustele with a parenchymatous pith containing scattered secretory cells. Small primary xylem strands, 300Âµm in maximum diameter, are arranged in a ring separated from the secondary xylem by 2-6 rows of parenchyma cells. A few strands in contact with the wood are significantly larger and represent departing leaf traces. The wood exhibits growth-rings with distinct boundaries. Wood tracheids are 17-75Âµm in transverse section. Their radial walls show araucarian pits with slit-like apertures. Parenchymatous rays are up to 5 cells wide and 60 cells high. The specimen shows a number of similarities with Pitus and Eristophyton from the Mississippian of Western Europe. However preliminary observations suggest differences in leaf trace emission and the possibility of referring the specimen to a new taxon is discussed. This discovery adds credit to recent statements indicating that Mississippian floras from Australia were more diverse than previously thought. This is especially important when trees are involved because of their importance in shaping landscapes.
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1 - Université Montpellier 2, Botanique et Bioinformatique de l'Architecture des Plantes (AMAP), c/o CIRAD, TA-A51/PS2, Bd de la Lironde, Montpellier, F-34398, France
2 - The Swedish Museum of Natural History, Box 50007, Stockholm, 104 05, Sweden
3 - Cnrs, Botanique et Bioinformatique de l'Architecture des Plantes (AMAP), c/o CIRAD, TA-A51/PS2, Bd de la Lironde, Montpellier, F-34398, France
4 - Cnrs, Botanique et Bioinformatique de l'Architecture des Plantes (AMAP), c/o CIRAD, TA-A51/PS2, Bd de la Lironde, Montpellier, F-34398, France
Presentation Type: Poster:Posters for Sections
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM