CHAPTER V. 



THE AMPHIBIA OF THE DEVONIAN AND MISSISSIPPIAN OF NORTH AMERICA. 



Evidences of the earliest land vertebrates are exceedingly scanty in the strata 

 between the close of the Silurian and the opening of the Coal Measures, being repre- 

 sented solely by footprints. In the Devonian our knowledge of the group is con- 

 fined to a single footprint, and in the Mississippian to series of footprints from 

 several localities. These have been described by Lea (371), Rogers (Geology of 

 Pennsylvania, pt. 11, 1856, p. 831), Barrell (21), Dawson (223), and Branson (50). 

 The last-named author has described a new species from the Mississippian of Giles 

 County, Virginia. His description of the footprints, with a photograph of one of 

 the series, are published herewith (plate 18, fig. 3). Branson (50) has given a resume 

 of the knowledge of Mississippian Amphibia in North America. 



Thinopus antiquus Marsh, 1896. 

 Marsh, Am. Jour. Science, ii, p. 374, Nov. 1896, with figure. 



Type: Specimen No. 784, Yale University Museum. 

 Horizon: Near top of Chemung, in the upper Devonian. 



[The] "specimen shows one vertebrate footprint in fair preservation, and with it part 

 of another of the same series. These impressions are of much interest, both on account of 

 their geological age and the size and character of the footprints themselves. The one best 

 preserved [fig. 12] is nearly 4 inches in length, 2.25 inches in width, and was apparently- 

 made by the left hind foot. On the inner side in front 



of the heel, a portion of the margin is split off, and / ' 



this may have contained the imprint of another toe. 

 The other footprint was a short distance in front, but 

 only the posterior portion is now preserved in the 



present specimen. It is probably the imprint of the / I ^-i--—r-~-~^ \ J 



forefoot. "^ ' /^~^nr >• 1 / 



"The specimen [plate 18, fig. 4] . . . was . . . 

 found in the town of Pleasant, one mile south of the 

 Allegheny River, Warren County, Pennsylvania, by 

 Dr. Charles E. Beecher, who presented it to Yale Fig. 12.— Copy of Marsh's drawing of footprint of 



Museum, where it still remains. s^Sf^xIl!"' ^""^ *' Devonian of Penn- 



"The geological horizon is near the top of the 

 Chemung in the upper Devonian. In the same beds are ripple marks, mud cracks, and 

 impressions of rain drops, indicating shallow water and shore deposits. Land plants are 

 found in the same general horizon. Marine molluscs also occur, and one characteristic 

 form {Nuculana) is preserved in the footprint slab" (Marsh). 



This still remains after nearly 20 years the only evidence of air-breathing verte- 

 brates in the Devonian of the world. 



Dromopus aduncus Branson. 

 Br.\nson, Jour. Geo!., xviii, No. 4, pp. 356-358. fig- '. •9io. 



Type and other specimens in Oberlin College Museum. 



Horizon and type locality: Near the bottom of the Hinton formation in Giles 

 County, Virginia. (Plate 18, fig. 3.) 



37 



