Fig. 18.17. Reconstruction of 

 Seymouna, a problematic verte- 

 brate from the Permian of Texas. 

 Seymouna had many reptihan 

 characteristics but retained also 

 a number of amphibian features. 

 It is usually assigned to a primi- 

 tive group of reptiles, and in this 

 reconstruction the artist has 

 assumed that it produced typical 

 reptilian eggs, like those known 

 for other early reptiles. (Photo- 

 graph courtesy American Mu- 

 seum of Natural History.) 



Fig. 18.18. Ancient marine reptiles. A, the 

 fossil remains of Ichthyosaurus, showing the 

 remarkable fish-like adaptations to aquatic 

 life. B, reconstruction of a mosasaur, 

 Tylosaurus. {A, photograph courtesy Ameri- 

 can Museum of Natural History; B, redrawn 

 from F. A. Lucas, Animals of the Past, copy- 

 right 1901 by McCIure, Phillips and Co., 

 printed by permission of the American 

 Museum of Natural History.) 



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