Structurally Preserved Plants from the Pennsylvanian (Monongahela Series) of Southeastern Ohio

Structurally preserved vascular plants have recently been discovered in calcite petrifactions near the town of Shade, Ohio The florule includes representatives of all of the major groups of Carboniferous-age vascular plants, with members of the Calamitales and Marattiales appearing in the highest percentages. The relationships between the Shade coal-ball plants and other coal-ball floras in North America are discussed. Investigations of fossil plants contained within calcite petrifications known as coal balls have greatly increased our knowledge of the anatomy, morphology, ontogeny, and phylogeny of Pennsylvanian-age plants. Coals balls contain some of the best preserved fossil plants available for critical study. There are, for example, reports of well preserved gametophytes (Brack, 1970), apical meristems (Good and Taylor, 1972), and cell organells (Baxter, 1950) in coal-ball plants. Preservation of these plants is often so excellent that microscopic observations of fossil preparations yield almost as much information about plant internal cellular structure as equivalent preparations of living plants. Most research on North American coal-ball floras has been based on material of upper and middle Pennsylvanian strata from the Interior Basin of North America, particularly Indiana, Illinois, Iowa, Kansas, and western Kentucky. Much of this work was reviewed by Andrews (1951). Although many coal ball localities have been described from the Eastern Interior Basin (Frankenberg and Eggert, 1969), only two coal-ball occurrences from the Appalachian Basin are noted in the literature (Schopf, 1961; Cross, 1967). To our knowledge, no coalball occurrence have been reported in the state of Ohio, but recent inquiries have indicated the presence of at least two previously unreported coal-ball localities in the state. This is a report of a Pennsylvanian-age petrifaction flora occurring near the town of Shade, Ohio was recently brought to our attention by the efforts of Dr. Arthur H. Blickle, Ohio University. The coal balls occur in the bank of a Shade River Middle Branch tributary known locally as Fossil Run Creek. The outcrop is located in the N W ^ N E ^ Sec. 21, T 4 N, R 13 W of the Shade, Ohio, quadrangle, 1.0 miles northeast of Shade townsite. Stratigraphically the coal balls occur in a seam equivalent to either the Pittsburgh (No. 8) or Redstone (No. 8A) coals of the Monongahela Series. The stratigraphic section of this area has been measured and is recorded as Section 11536 of the Ohio Division of Geological Survey (Sturgeon, 1958). Although this section indicates that the coal represents a portion of the Pittsburgh Cyclothem, the ubiquitous occurrence of the microspore Endosporites ornatus in the petrifactions suggests to us that the coal balls may represent instead a segment of the slightly younger Redstone Cyclothem (Kosanke, 1943; Clendening, 1965). The coal balls at the Shade locality typically occur as flattened lenticular nodules which in many cases are covered with a hard black slate-like layer of coal. Other nodules, in which the outer coaly layer has been weathered away, appear yellow-buff in coloration. Nodules of a similar size with olive-green coloration also occur at the Shade locality immediately below the coal seam. These iManuscript received September 13, 1973 (73-68). THE OHIO JOURNAL OF SCIENCE 74(5): 287, September, 1974 288 CHARLES W. GOOD AND THOMAS N. TAYLOR Vol. 74 latter nodules, however, lack any recognizable plant fragments. Although the apparent organic content of the coal balls is relatively high, as evidenced by the very dark matrix observed on cut and polished sections, recognizable and easily delimited plant fragments represent a relatively low percentage of the nodule volume. This is in marked contrast to typical Eastern Interior Basin coal balls, in which the plant material is closely crowded together and represents a high percentage of the total volume. Despite the relatively low frequency of structurally preserved plants, the general level of preservation in Shade coal balls is quite exceptional (fig. 2). These petrifactions range in minerologic composition from specimens of almost pure calcite to others in which the pyrite composition is rather high.