AET. 24 NEW REPTILE FROM THE OREGON CRETACEOUS — GILMORE 5 



From a review of all available evidence it is my conclusion that 

 the two vertebrae now before me belong to this free series. The fact 

 of their being coossified does not necessarily argue against this con- 

 clusion, for in living birds aged individuals often show ossification of 

 ligaments as well as the coossification of the spinous, transverse, and 

 zygapophysial processes of the vertebrae, and it does not seem un- 

 reasonable to believe that a somewhat similar condition might take 

 place in the backbone of these extinct flying reptiles. 



When compared with the free vertebrae of Pteranodon the greatest 

 dissimilarity noted is in the more prominent development of the ball 



Fig. 2. — Dorsal vbbtebrab op Pteranodon ( ?) oeegonensis. Type, a, Lateral 

 VIEW from the left side ; &, ventral view ; c, anteeior view ; d,, posterior 

 VIEW. All fiqdebs natural size 



in the Oregon specimen, which gives the centrum a correspondingly 

 increased length. The pedicels of the arches are also relatively wider 

 anteroposteriorly. The transversely oval shape of the cup, the large 

 size of the neural canal, the steep inclination of the zygapophysial 

 facets are all features in close accord with the dorsals of Pteranodon. 



Meastiretnents of cooss-ified vertebrae 



Millimeters 



Greatest length of coossified centra ■*0 



Greatest transverse diameter of anterior centrum 18.5 



Greatest vertical diameter of anterior centrum 15.0 



Greatest vertical diameter of posterior centrum I'l-O 



Width across anterior zygapophyses 18-5 



o 



