26 OHIO FOSSILS 



PERMIAN TIME: THE END OF THE SEAS IN OHIO 



The record of Permian time in Ohio is incomplete. Only the lowest Permian series is 

 represented in our state, hence we can only speculate on Permian events after that time. For 

 early Permian time the rocks indicate that conditions in Ohio had not changed greatly since the 

 close of the Pennsylvanian. Coal swamps still existed although their extent and their duration 

 were much reduced. 



During Permian time as a whole, the seas covered only a relatively small portion of North 

 America and interest shifts naturally from marine to non-marine life. This is especially true 

 in Ohio for here, in the Washington formation, are the remains of fresh-water and land animals 

 together with abundant plant remains very similar to those of the Pennsylvanian. Fishes were 

 abundant both in fresh and in brackish water; their remains have been described by Stauffer and 

 Schroyer (1920, pp. 146-147). In the Permian coal swamps amphibians existed but no skeletons 

 or bones have been found in Ohio. The only indication of their presence is indirect: coprolites 

 (fossil droppings) described by Stauffer and Schroyer (1920, p. 147). Sailfin reptiles were 

 scarce in Ohio during the Permian; a single neural (back) spine was found by Stauffer and 

 Schroyer (1920, p. 147). 



Besides the coals, which are poor and mined only locally in small quantities, our Permian 

 rocks yield a few economically important products. Unique among these are the hard sand- 

 stones, five of which have been used in the past for making grindstones. They are also locally 

 used as building stone. The Permian limestones of Ohio have been used for road material and 

 the shales for making brick. 



The remainder of Permian time has been recorded in the rocks of other parts of North 

 America and of the world. The absence of younger Permian rocks in Ohio indicates either 

 that they were not laid down in the state or else that they were laid down and then removed by 

 erosion during the time (more than 200 million years) between the early Permian and the 

 Pleistocene. That tremendous gap in the record of the rocks deserves special treatment. 



THE GREAT GAP IN THE RECORD 



It may well be that late Permian and Mesozoic sediments were deposited in Ohio and it 

 is probable that animals and plants lived in the area. All trace of any such sediments has been 

 destroyed by long erosion. 



It is very likely that dinosaurs lived in Ohio during Mesozoic time but it is almost certain 

 that their remains will never be found here. Like all other animal remains of their time, they 

 would have been swept away by streams. Collectors should be cautious about identifying large 

 bones from Ohio; the chances are practically zero that they will turn out to be dinosaurs. More 

 likely, the large bones belong to the large mammals that lived in the state during the Pleistocene. 

 The dinosaurs became extinct at the end of Mesozoic time. We can be sure of this because the 

 Tertiary period, which followed the Cretaceous, lasted for 60 million years and no Tertiary 

 bed has yielded dinosaur bones. 



Tertiary beds, if they ever existed in Ohio, have not been preserved here. It is only 

 towards the close of Cenozoic time that the record of the rocks is again preserved in Ohio. 



PLEISTOCENE TIME: THE GLACIERS 



About a million years ago, the climate of North America slowly cooled by some 5 or 10 

 degrees. A cooling of that sort at the present time would mean that in the higher parts of 

 Canada some of the snow that falls each winter would remain unmelted during the following 

 summer. As more snow fell during the following winters, it would pile up to enormous thick- 

 nesses and pack down into ice. As the ice got thicker, it would begiD to move outward and we 



