A NEW SAUROPOD DINOSAUR FROM THE OJO 

 ALAMO FORMATION OF NEW MEXICO 



By Charles W. Gilmore, 

 associate curator, division of paleontology, united states national museum 



(With Two Plates) 



INTRODUCTION 



In a brief note ^ I have recently announced the discovery by Mr. 

 John B. Reeside, Jr., geologist of the United States Geological Survey, 

 of Sauropodous dinosaur remains in the Upper Cretaceous of New 

 Mexico, and it is now proposed to give a more detailed account of the 

 specimens and of their exact geological occurrence than was possible 

 in the preliminary notice. 



The remains so far recovered consist of a left scapula and a right 

 ischium, both in a good state of preservation. The great importance 

 of these particular bones lies in the fact that the remains of Sauro- 

 podous dinosaurs have not previously been known to occur above the 

 Lower Cretaceous in North America, so that the extension of their 

 geological range into the L^pper Cretaceous is of the greatest paleon- 

 tologic and geologic interest. 



It is particularly fortunate that this discovery should have been 

 made by a trained geologist of Mr. Reeside's attainments, and in a 

 section so well established as to preclude the possibility of question as 

 to their late position in the geological column. 



That these bones pertain to a member of the Sauropoda is indicated 

 by their immense size and also by their close general resemblance to 

 homologous elements of the typical Sauropoda from the Morrison 

 formation. Marked differences in details, however, more especially 

 in the ischium, in conjunction with the very late geological occurrence, 

 makes it necessary to establish a new genus and species for their 

 reception, for which the name Alauwsaurus sanjuancnsis is proposed. 



DESCRIPTION 

 ALAMOSAURUS, new genus 

 The characters of this genus are included in the following descrip- 

 tion of the type species : 



^Science (N. S.), vol. LIV, 1921, p. 274. 



Smithsonian Miscellaneous Collections Vol. 72, No. 14 



