BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 34, pp. 463-468 SEPTEMBER 30. 1923 



PROCEEDINGS OF THE PALEONTOLOGICAL SOCIETY 



LINES OF PHYLETIC AND BIOLOGICAL DEVELOPMENT 

 OF THE ICHTHYOPTERYGIA ^ 



BY F. VOX HUEXE 



{Presented before flie PaUontological Society Decemher SO, 1922) 



CONTENTS 



Page 



Introduction 46?» 



Mesosauria 463 



Omphalosaurus 464 



Latipinnatidae and Longipinnatidae 465 



Introduction 



The great order of the Ichthyopterygia, known from Permian to L^'pper 

 Cretaceous times, is formed by the Ichthyosanria, Omphalosauria, and 

 Mesosauria. 



A special study of all Liassic Ichthyosauria from the English and 

 German Lias led me to a synoptic classification, which has also extended 

 over all Jurassic and Cretaceous forms. Those of the Triassic are al- 

 ready well known from the classic memoirs of Merriam. Through recent 

 additional observations of the extensive Mesosaurus material at Tiibingen 

 (from Brazil) this group may be reinterpreted and reviewed. Therefore 

 it is possible for the first time to form an idea of this highly diversified 

 and long-lived order of the Ichthyopterygia.^ 



Mesosauria 



I need not repeat the reasons why the Mesosauria can not possibly be 

 the forerunners of the Ichthyosauria,^ but many features in the skull and 

 skeleton demonstrate convincingly their common origin. The Mesosauria 



^ Manuscript received by tlie Secretary of the Society March 15, 1923. 

 2 F. von Huene : "Die Ichthyosaurier des Lias und ihre Zusammenhiinge." Ed. by 

 Gebriider Borntraegei-, Berlin, November, 1922, vii, 114 p.. 22 pis. Quarto. 

 3N. Jarhb. f. Min.. etc.. 1910. ii, pp. 29-69. 



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