BIONOMIC CHARACTERS OF REPTILIA 1037 



and Pseudosuchia) are all found in terrestrial — partly fluviatile and 

 partly eolian — deposits, such as the Newark beds of eastern North 

 America, the Stuben Sandstein of Germany, the Elgin sandstone 

 of Scotland, and the Gondwana beds of India. They appear to have 

 been land and river form?. The Mesosuchia in Jurassic and Co- 

 manchic time had taken to a marine life, but in the Cretacic and 

 later periods, the crocodiles were chiefly fluviatile or terrestrial. 

 In the Pliocenic alligators and crocodiles became extinct in Eu- 

 rope, but in America they continued in the tropical and sub-tropical 

 districts. The crocodiles inhabit, further, nearly all the larger 

 streams and many lakes of Africa, India, and the north coast of 

 Australia (Heilprin). The Dinosaurs are wholly confined to the 

 Mesozoic, where they were represented by a wealth of types. They 

 comprise three groups: ist, carnivorous land forms (Theropoda), 

 varying in size from that of a cat (Conipsognathus) to that of an 

 elephant {Megalosauriis, Trias to Cretacic), and mostly very gro- 

 tesque in appearance. They walked upon their hind limbs, the 

 shorter fore limbs being lifted from the ground and the body being 

 further balanced and supported by a huge tail. Some leaping or 

 kangaroo-like forms likewise occurred (Trias to Cretacic). 2d. 

 Massive herbivorous quadrupedal forms without dermal armor 

 {Saiiropoda, Middle and Upper Jurassic and Lower and Upper 

 Cretacic), and comprising some of the most prodigious land animals 

 known; Brontosaurus having a length upward of 18 meters, and 

 Diplodocus upward of 20 meters. 3d. {Prcdentaki). Large herbiv- 

 orous unarmored bipedal ( Iguanodonts), and armored quadru- 

 pedal forms with small skulls (Stegosauyidrc), or with large horned 

 skulls (Ceratopsidcr). The carnivorous dinosaurs were frequenters 

 of the estuaries and deltas of rivers, and roamed about the low, 

 flat, and muddy flood plains of rivers, as shown by the countless 

 footprints preserved in the rocks of the Newark system, the Bunter 

 Sandstein, and other non-marine dejjosits of early Mesozoic age. 

 The Pterosauria or Ornithosaurs (Jurassic and Cretacic) were a 

 remarkable group of bird-like lizards, with hollow bones and fore 

 limbs adapted for flight, after the manner of bats ; some forms be- 

 ing strong and others weak flyers. 



AvES. Birds are essentially aerial nekton. A number of living 

 and extinct forms {Dromccognathcc, with the Struthiones, the New 

 Zealand Apteryx and the South American Tinamous), are either 

 nearly wingless or have wholly or to a considerable extent lost 

 the power of flight, even though possessing small wings. To com- 

 pensate for this loss the legs are generally powerfully developed, 

 especially in the Struthious birds (ostriches, rheas, cassowaries. 



