Chitaley, Shyamala .
363 Million Year Old Forest of Ohio, U.S.A.
THREE hundred sixty three million year old late Devonian Forest of Ohio, U.S.A. has been restored from the plant fossils discovered from the Cleveland Shale, the uppermost member of the black shale of Ohio. Normally, the fossils are preserved as compressions, however, in siltstone organic matter is found permineralized with anatomical details preserved. This forest grew on the northeast marshy coast of the shallow Ohioan Sea during the Upper Devonian. It consisted of large trees of Pro-gymnosperms Archeopteris and of Lepidodendron-like lycopsids, the former represented by Callixylon trunks, the latter from the trunks and large fertile cones. From the study of these fossils it has been observed that the forest was dominated by arborescent heterosporous lycopsids, in appearance similar to Carboniferous Lepidodendrons and Sigillarias. There are herbaceous lycopsids with hetersporous cones, ferns, kelp-like Laminaria and Protosalvinia-like fertile thalli growing in this marshy forest. Spores from the lycopod cones differ from cone to cone in size and sculpturing. The cones also differ from each other in size and morphology. Around a dozen different cones and several pieces of different kinds of axes have been discovered, revealing their variety and dominance in the Late Devonian Forest of Ohio so-called Club-moss Forest. This native oldest forest of Ohio is useful in tracing the evolution of the Isoetalean ancestry in Lycopodiales. The presence of vertical habit, unbranched, monopodial stem with short basal appendage, heterosporous cones, presence of Williamsons striations, multiperforate bordered pits, show the origin of the Isoetalean line of the group Lycopdiales. Most interesting is that the Upper Devonian flora found in Cleveland, Ohio, U.S.A., is very similar to that found from the Upper Devonian locality at Kiltorkens Hills of Kilkinney County in southern Ireland, proof that during this period the northern part of America and the southern part of Ireland were connected.
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1 - Cleveland Museum of Natural History, Paleobotany, 1 Wade Oval, University Circle, Cleveland, Ohio, 44106-1767, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Monday, July 31st, 2006
Time: 9:00 AM