Araucarioxylon Kraus is a widely known fossil-genus generally applied to woods similar to that of the extant Araucariaceae. However, since 1905, several researchers have pointed out that this name is an illegitimate junior nomenclatural synonym. At least four generic names are in current use for fossil wood of this type: Agathoxylon Hartig, Araucarioxylon, Dadoxylon Endl. and Dammaroxylon J.Schultze-Motel. This problem of inconsistent nomenclatural application is compounded by the fact that woods of this type represent a wide range of plants including basal pteridosperms, cordaitaleans, glossopterids, primitive conifers, and araucarian conifers, with a fossil record that extends from the Devonian to Holocene. Conservation of Araucarioxylon has been repeatedly suggested but never officially proposed. Since general use is a strong argument for conservation, a poll was conducted amongst fossil wood anatomists in order to canvass current and preferred usage. It was found that the community is divided, with about one-fifth recommending retention of the well-known Araucarioxylon, whereas the majority of others advocated use of the legitimate Agathoxylon. The arguments of the various colleagues who answered the poll are synthesized and discussed. There is clearly little support for conservation of Araucarioxylon. A secondary aspect of the poll tackled the issue as to whether Araucaria-like fossil woods should be either gathered into a unique fossil-genus, or whether two fossil-genera should be recognized, based on the respective presence or absence of axial parenchyma. A majority of colleagues favoured having one fossil-genus only. Agathoxylon can be used legitimately and appears to be the most appropriate name for such woods. However, its original diagnosis must be expanded if those woods lacking axial parenchyma are to be included.
During the late Paleocene to early Eocene, clastic fluvial sediments and coals were deposited in northern high latitudes as part of the Margaret Formation at Stenkul Fiord (Ellesmere Island, Nunavut, Canada). Syn-sedimentary tectonic movements of the Eurekan deformation continuously affected these terrestrial sediments. Different volcanic ash layers occur, and unconformities subdivide the deposits into four sedimentary units. Rare vertebrate fossils indicate an early Eocene (Graybullian) age for the upper part of the Stenkul Fiord outcrop. Here, we present carbon isotope data of bulk coal, related organic-rich mud and siltstones, a plant leaf wax-derived alkane, and additional plant remains. These data provide a complete carbon isotope record of one stratigraphic section with defined unconformity positions and in relation to other Eurekan deformation features. A previously dated ash layer MA-1 provided a U-Pb zircon age of 53.7 Ma and is used as a stratigraphic tie point, together with a discrete negative carbon isotope excursion found above MA-1 in a closely sampled coal seam. The excursion is identified as the likely expression of the I-1 hyperthermal event. Based on our isotope data that reflect the early Eocene dynamics of the carbon cycle, this tie point, and previous paleontological constraints from vertebrate fossils, the locations of the Paleocene-Eocene Thermal Maximum (PETM) and Eocene Thermal Maximum 2 (ETM-2) hyperthermals and their extent along the complete section are herein identified. Within the intervals of the PETM and ETM-2 hyperthermal events, increasing amounts of clastic sediments reached the site toward the respective end of the event. This is interpreted as a response of the fluvial depositional system to an intensified hydrological system during the hyperthermal events. Our study establishes an enhanced stratigraphic framework allowing for the calculation of average sedimentation rates of different intervals and considerations on the completeness of the stratigraphic record. As one of the few high-latitude outcrops of early Eocene terrestrial sediments, the Stenkul Fiord location offers further possibilities to study the effects of extreme warming events in the Paleogene.
Aus dem miozänen Braunkohlentagebau Berzdorf in der Oberlausitz (Sachsen) werden erstmals autochthone Braunkohlenhölzer in großer Anzahl mit über 300 Fossilien beschrieben. Mit den Ergebnissen dieser Untersuchungen wird nachgewiesen, dass das Berzdorfer Braunkohlenmoor eine geringe phytofazielle Amplitude aufwies, sich jedoch unterschiedliche Vegetationsbereiche ausgebildet hatten. Es stellt sich heraus, dass die von der Niederlausitz bekannten Vegetationen auch in stratigraphisch älteren Braunkohlenablagerungen vorkommen. Die xylotomischen Ergebnisse führen zur Deklarierung des Berzdorfer Kohlenkomplexes als Glyptostrobus/Sequoia‐Typus. Eine biostratigraphische Korrelierung dieses isolierten terrestrischen Braunkohlenvorkommens von Berzdorf mit den sequenz‐ und biostratigraphisch gut eingestuften Niederlausitzer Flözen war möglich. Verschiedene, für diese Region neue Holzarten wurden festgestellt: Glyptostroboxylon tenerum, G. rudolphii sp. nova, Taxodioxylon gypsaceum, T. germanicum, T. cryptomerioides, Cupressinoxylon cupressoides, Pinuxylon parryoides. Glyptostroboxy‐lon tenerum wurde anhand des Typusmaterials von KRAUS neu untersucht, emendiert und botanisch zu Cunninghamia gestellt. Glyptstroboxylon rudolphii sp. nova wird aufgestellt für Glyptostrobus‐ähnliche Hölzer. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
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