List of Casts, Models, and PJwtographs. 



49 



Giant Reptiles, were the chief inhabitants of the lowlands and 

 marshes. Preeminent in size among these were the Sauropoda 

 or Amphibious Dinosaurs, a herbivorous group, mostly of 

 gigantic size, from forty to seventy-five feet in length,— the 

 greatest of land animals living or extinct, and exceeded in 

 size only by the modern Whales. 



The long neck and small head enabled them to he con- 

 cealed in marshy bayous and lagoons, the body generally im- 

 mersed, the head foraging for food without easily attracting 

 the attention of the great carnivorous reptiles which lived at 

 this time. The long and massive tail was useful both as a 

 support and a propeller. 



Brontosaurus was among the largest of the Sauropoda, 

 seventy feet in length and about eighteen feet in height to the 

 arch of the back. The thigh-bone is six feet long, and weighs 

 in its petrified condition 500 to 600 pounds. 



Marsh, Dinosaurs of North America, Sixteenth Ann. Rep. U. S. Geol. 



Surv., 1896, pp. 166-175, pi. xHi (Brontosaurus excelsus). 

 OsBORN, Bull. Am. Mus. Nat. Hist., X, 1S98, p. 219. 



25. Great Marine Lizard or Mosasaur Tylosaurus. 



Upper Cretaceous Period. 



This restoration is made from the complete skeleton, thirty 

 feet long, in the American Museum. 



The Mosasaurs were carnivorous Sea-Reptiles abundant in 

 the warm, shallow seas of the Upper Cretaceous Period, but not 

 yet found earlier or later. Large fiat head, short neck, four 

 paddle-limbs like the flippers of whales, vertically flattened, 

 swimming tail. Length of different species, from twelve to 

 forty feet. Their nearest living ally is the Monitor Lizard 

 iVaranus) of the Nile Valley. 



OsBORN, A Complete Mosasaur Skeleton, Osseous and Cartilajjinous, 

 Memoirs Am. Mus. Nat. Hist., I, Pt. IV, Oct., 1899, pll. xxi-xxiii 

 and text illustrations. 



WiLLiSTON, Kansas Univ. Quar., VIII, iSoo, pp. 30-41; Univ. Geol. 

 Surv. Kansas, IV, Pt. V, pp. S3-221, pll. x-Lxxii. 



