THE COLLECTION OF FOSSIL VERTEBRATES 31 



Crocodiles in their palmier days were of world-wide distribu- 

 tion and corr.prised marine as well as fresh-water types. Turtles 

 are among the commonest of fossils in the Bad-lands and some 

 of them of very large size. Lizards and snakes, the only common 

 reptiles of modern times, are very rare and fragmentary as 

 fossils, and little is known about them. 



Besides these surviving groups, several extinct groups of rep- 

 tiles are shown on the south side of the hall. The Belodonts, 

 of the dawn of the Reptilian Era, were partly intermediate be- 

 tween Dinosaurs and Crocodiles. The still older Pelycosaurs 

 were remarkable for an enormous rigid bony fin on the back; 

 among the contemporary Theriodonts there existed perhaps the 

 remote ancestors of the Mammals. The Pterodactyls or Fly- 

 ing Reptiles were the most extraordinary of reptiles, tailless, with 

 batlike wings, supported on the enormously lengthened Httle fin- 

 ger, and with a spread in the largest species of twenty feet from 

 tip to tip. The Rhynchocephalians are an interesting group 

 of very primitive reptiles, of which a single species, the Tuatara, 

 still survives in New Zealand. 



Fossil Amphibians. 

 The Age of Reptiles was preceded by an Age of Amphibians, 

 when the dominant animals were aUied to modern Frogs, Toads 

 and Salamanders, but had the skulls covered by a Armored 

 solid bony roof and the bodies by more or less scaly Amphibi- 

 armor. These Armored Amphibians have been called ans tStego- 



, / 111 i\ T 1 cephalia). 



Stegocephaha {ffreyj^, uecpaXi] = deck-head) or Laby- 

 rinthodonts (Xa/Svpivdo?, odov? = labyrinth-tooth, from the com- 

 pHcated fluting or infolding of the enamel on the teeth). Some 

 of them, Hke Eryops, were large animals with heads eighteen 

 inches long and a foot wide ; others resembled colossal tad- 

 poles ; but the majority of them were quite small animals, either 

 proportioned like salamanders or else long and eel-like with 

 minute lim.bs or none at all. 



These fossil Amphibians are the most ancient of fourfooted 

 animals, and are not far removed from the central type from 

 which all the higher vertebrates are believed to be descended. 

 They are exhibited near the middle of the south side of the Hall 

 of Fossil Reptiles. 



