30 OHIO FOSSILS 



Most of the algae (seaweeds and pond-scums) rot too easily to leave anything more than 

 a shapeless mass of material as fossils; only a few kinds leave recognizable remains that can 

 be referred to the Algae. Among these are the calcareous algae which precipitate calcium car- 

 bonate in a fine film over successive layers of the living algae. The limy films retain the im- 

 print of the algal cells and show some of their characteristics. As much as 25 percent of a 

 coral reef may consist of calcareous algae- Fresh water forms are the "water-biscuits" of 

 certain lakes and the "lake reefs" formed in the same way as marine reefs but by other kinds 

 of algae. Fossil algae have been found sparingly in the rocks of Ohio. 



CLASS FUNGI. The class is best known through the mushrooms and bracket or shelf 

 fungi that grow on trees and rotten logs. Other less familiar forms are numerous and varied 

 in appearance and habits. They include the molds that form on bread, cheese, and other foods 

 and some microscopic forms that live in fresh water and are able to capture and eat protozoans 

 and other microscopic animals. Some molds are parasitic on animals, even man. Penicillin 

 and other antibiotics are produced by fungi. 



The part of the fungus that we usually see is the fruiting body of the plant. The fungi pro- 

 duce enormous quantities of tiny spores (reproductive parts of the fungus) which are borne by 

 the wind. When a spore lands in a favorable environment it produces a network of fine threads 

 (called the mycelium ) which is the feeding system of the fungus. Later the mycelium produces 

 a fruiting body which perpetuates the life cycle of the plant. 



Most of the fungi feed on other plants, either within the dead or living plant or in the 

 ground, where the mycelium reaches out in all directions for decaying plant material. Some 

 fungi attack living or dead animal material; for example, athlete's foot is caused by a fungus. 



Fossil fungi have been recorded in Devonian and younger rocks. Injury caused by fungi 

 has been recognized in fossil wood. There are several records of this sort for Ohio Pennsyl- 

 vanian plants; spores, possibly of fungi, have been recorded in Devonian and younger rocks in 

 Ohio. 



One of the most interesting groups of the algae is that of the Charophytes. They produce 

 small calcareous fruiting bodies that are solid enough to be fossilized. Fossil charophytes 

 are known in Ohio Devonian rocks and they should be found also in younger rocks, including 

 Pleistocene deposits. 



Phylum Bryophyta 



The mosses and liverworts, which make up the phylum Bryophyta, are commonly found 

 in shady, damp places. The most familiar example is the moss that grows on roofs and on 

 rocks. The bryophytes lack vascular tissue, like the thallophytes, and reproduce by means of 

 spores. The spore capsules can be recognized in living mosses; they are borne on stalks that 

 are a little taller than the green moss and both the stalk and the spore -capsules are usually 

 reddish brown. 



/ 

 Phylum Pteridophyta 



The Pteridophyta or ferns have well developed vascular tissue and distinct roots, stems, 

 and leaves. They include small, low plants, such as the familiar ferns found in this country, 

 and the tropical tree ferns which may be as much as 50 feet tall. Ferns reproduce by means 

 of spores borne on the underside of the leaves and on specially modified leaves, a character 

 which distinguishes them from the extinct seed-ferns (see Pteridospermophyta). The leaves, 

 stems, and roots of ferns are well preserved in the rocks, sometimes in great abundance. 

 Fossil ferns are known from the Devonian to the present. 



Beautiful examples of fossil leaves of ancient ferns may be found in the shales above coal 

 beds of Ohio. Collecting is especially good on some mine dumps and on strip-mine spoil banks 



