200 



THE COAL MEASURES AMPHIBIA OF NORTH AMERICA. 



was published in the Transactions of the Kansas Academy of Science and later copied 

 in the American Journal of Science. Professor Marsh's description (406) of the 

 remains is as follows: 



" The impressions are well preserved in a calcareous shale, which separates readily 

 into thin slabs, each representing a surface of the beach at the time the footprints were 

 made upon it. A few shells in the shale are sufficient to prove that the formation is marine 

 (no shells are evident in the slab at the Museum of the University of Kansas, but the slab 

 is quite arenaceous). Trails of annelids, or perhaps of other invertebrates, are seen on 

 some of the surfaces. The footprints of vertebrate animals, however, are of paramount 

 importance, and the large number and variety of these here recorded on a single surface, 

 if they could be rightly interpreted, would form an interesting chapter of land vertebrate 

 life in the Carboniferous, about which so little is at present known." 



Professor Marsh's description of Dromopus agilis is as follows: 



" The third series of footprints is of special interest, and indicates an animal very 

 distinct from the two already 

 described. The diagram rep- 

 resents the impression of the 

 phalanges sufficiently in de- 

 tail to indicate (406) their 

 number and general form. A 

 striking feature in the fore 

 and hind feet of this animal 

 was the long, slender digits 

 terminated by sharp claws. 

 Another point of interest, as 

 recorded in the footprints, is 

 that the animal in walking 

 swung the hind feet outward, 

 and so near the ground that 

 the ends of the longer toes 

 sometimes made trails in 

 the mud, marking accurately FlG 43 ._ Footprints of Dromopus agUis Marsh> from the Coal Measures of 



the Sweep Of the foot. This Osage County, Kansas. Original slab in University of Kansas Museum. 



would seem to indicate a Greatly reduced. 



comparatively short hind leg, rather than the long, slender one which the footprints 

 themselves naturally suggest. 



' The animal which made these interesting footprints was probably a Lacertilian 

 rather than an Amphibian, but there is also a possibility that it was a primitive Dinosaur." 



Further on Professor Marsh remarks (p. 84) : 



" So far as at present known, land vertebrate life began in the Carboniferous age, 

 no footprints of other remains of this kind having been detected below the Subcarbo- 

 niferous. That such remains will eventually be found in the Devonian, there can be no 

 reasonable doubt, and perhaps even in the Silurian, if the land surfaces then existing 

 can be explored." 



This last statement of Marsh's was, of course, partly demonstrated by the dis- 

 covery of footprints in the Devonian rocks of Pennsylvania, which he described in 

 1896 as Thinopus antiquus. The footprints of Dromopus agilis Marsh which are 



