100 THE AGE OF MAMMALS 



tical in age with the mammals of the celebrated /a «»a of Cernay, which contains the 

 marsupial multitubcrculate, Neoplagiaulax. As tiie coast was rising, this deposit 

 was overlaid by (3) a bed of coarse sands, clays, and lignites, which represents the 

 beginning of the Sparnacian, of a thickness of 17 m.; near this level were found 

 the bones of the giant bird Gastornis, described ])y Lemoine. The coast was still 

 rising, so that superposed (4) is a lagoon or lacustrine formation of marls and lime- 

 stones without fossils. Superposed again are the (5) Sables et argiles lignileuses with 

 a brackish water molluscan fauna of Sparnacian age; in these sands and clay- 

 lignites (21 m. above the Gravier marin de Cernay), have been found limb bones of 

 Coryphodon identical in size with the typical specimen found at Meudon (Marnes 

 de Meudon). 



These records of a sinking and rising Basal Eocene shore line near Rheims 

 are paralleled by the Lower Landenian, a Basal Eocene marine phase of Belgium, 

 probably of the same age as the Cernaysian of Rheims. (1) This marine littoral 

 formation contains no mammals, but a number of very characteristic reptiles, as 

 follows: the large lizard Champsosauriis lemoinei, of the same species as that found 

 near Rheims in the typical Cernaysian, abundantly represented and beautifully 

 preserved; Lxjtoloma, a marine, shore-living turtle with a very powerful mandib- 

 ular symphysis, evidently adapted to crushing the littoral molluscs; the giant 

 bird Gastornis has also been found here. (2) Surely resting on the Lower Landenian 

 is a fluviatile formation attributed to the Upper Landenian stage, and represented 

 at Orsmael and Erquelinnes, localities in Belgium widely separated geographically 

 but containing the same fauna, the genera being provisionally identified as follows: 

 Coryphodon, Phenacodus, Dissaais, Hycjenodidis, Decticadapis, Plesiadapis, also a 

 most important member of the Perissodactyla-Equida?, provisionally identified as 

 Pachynolophus maldani. It appears from this evidence that the Upper Landenian 

 of Orsmael and Erquelinnes, containing Coryphodon and a true perissodactyl, is of 

 more recent age than the Upper Thanetian or Cernaysian, and should be correlated 

 with the lower Sparnacian of France, or the Wasatch of North America. 



Continental transition beds in America. — The gentle transition from 

 the reptilian to the mammalian Age is far more simply shown in the suc- 

 cession of continental depositions in northern Montana. The passage 

 from the Laramie (Hell Creek beds) to the Fort Union, or Lignitic beds, 

 is apparently continuous. The indications are that the late Cretaceous 

 Laramie was a period of open country traversed by sand-bearing rivers. 

 In the succeeding Basal Eocene, or Fort Union, there is evidence that 

 large parts of Montana, Wyoming, Colorado, and the Dakotas were covered 

 with dense coal- or lignite-forming forests. Vast stretches of subtropical 

 and more hardy trees were interspersed with swamps where the vegeta- 

 tion was rank and accumulated rapidly enough to form great beds of 

 lignite. Here were bogs in which bog iron was formed. Amid the glades 

 of these forests there wandered swamp turtles, alligators, and large lizards 

 of the characteristic genus Champsosaurus. Plant remains in the Laramie 

 Hell Creek beds have also been found in the Fort Union at various locali- 

 ties; types common to the Upper Cretaceous and Basal Eocene formations 

 are the fig (Ficus), banana (Musophyllum) , palms similar to the sabal of 



