THE DAWN OF QUADRUPEDS 559 



and relationships of animals farther and farther back into geological 

 time. There was a time, not many decades ago, when people knew 

 nothing of the animals of the ancient days. During the life of Cuvier 

 the knowledge of extinct animals had not progressed much farther hack 

 into geological time than the Cretaceous or Jurassic. It was just four 

 years before his death that Jaeger made his important contribution to 

 the Triassic fauna of Europe by the description of the remains of 

 Mastodonsaurus, which he had in 1824 described as Ichthyosauri Sub- 

 sequent researches by a host of observers have carried our knowledge of 

 animals into an antiquity which had not been expected. 



The animals which it is our purpose to treat here are the ancestors 

 of the modern Amphibia. There are few groups of vertebrates whose 

 phylogeny is more obscure than that of our common toads, frogs and 

 salamanders. It is the popular idea that these animals are unknown 

 back in geological time, but that they are of a rather recent origin. As 

 a matter of fact the present-day amphibians are the descendants of the 

 oldest group of vertebrated animals with the exception of the fishes. 

 Our knoAvledge of the fishes begins near the dawn of animal life on 

 earth, and their remains are preserved in the rocks of the Ordovician 

 age, just west of Canon City, Colorado, and in the Big Horn Moun- 

 tains, Wyoming. Our knowledge of the amphibians begins just two 

 ages later, and in the Devonian rocks of Pennsylvania are found the 

 earliest traces of quadrupeds on earth. These evidences consist in foot- 

 prints found by Isaac Lea in 1849 and the announcement of his dis- 

 covery was given to the British Association for the Advancement of 

 Science by Buckland in that year. These footprints represent a rather 

 large animal which may have attained a length of several feet. The 

 footprints were found impressed in the " Old Red Sandstone " of Penn- 

 sylvania which forms a part of the Catskill formation of that state. 

 Marsh, forty-seven years later, announced the discovery of similar 

 footprints from the same horizon and near the same locality but does 

 not mention the discoveries of Lea. From these tracks in the Devonian 

 to the deposits in the Allegheny series of the Pennsylvanian our knowl- 

 edge of the Amphibia is a blank. There is not a trace recorded of any 

 amphibians in the rocks of the Mississippian or in the Pottsville of the 

 Pennsylvanian. 



In the Allegheny series, there are several deposits in the United 

 States, and probably one in Canada, which have produced remains of 

 the early quadrupeds. The principal localities are in Illinois, Pennsyl- 

 vania and Ohio. From the last named state great numbers of these 

 paleontological treasures have been recovered and are preserved in the 

 museums of the east. The most interesting place which has kept for 

 us a record of the amphibian life of this far-off time is a deposit of coal 

 in the eastern part of Ohio in the northern part of Jefferson county. 



