OSTEOLOGY OF CARNIVOROUS DINOSAURS. 



41 



The neural arches are attached to the centra by low, stout pedicles, having ex- 

 panded ends, more especially the posterior. Long, broad diapophyses are given off 

 well up on the arch. On the sixth dorsal they extend backward and upward at an 

 angle of 30° above the horizontal, but passing posteriorly in the series they gradually 

 assume a more and more horizontal position. In the posterior members they also 

 extend outward at right angles instead of backward as in the mid-dorsal region. 

 These processes gradually lengthen from the front to the back, reaching their max- 

 imum length on the ninth and tenth dorsals, posterior of which they decrease 

 slightly in length and also in other proportions. Where they attach, these proc- 

 esses are broad, narrowing slightly outward. Vertically both front and back they 



A b 



Fig. 25.— Ninth dorsal vertebra of Antrodemtjs valens Leidy. No. 8367, TJ.S.N.M. \ nat. size. A, Side view. B 

 Front view, d, diapophysis; p, parapophysis; z, anterior zygapophysis; z', posterior zygapophysis. 



are thin, but supported and strengthened from beneath at mid-breadth by a 

 single vertical lamina that extends outward nearly to the distal end. Proximally 

 it ends below in the posterior lateral pedicle of the arch. 



The par apophyses in all the vertebrae posterior to the sixth occupy approx- 

 imately the same position on the median side of the anterior pedicle, extended 

 outwardly but little, though in Ceratosaurus they stand out prominently. This 

 facet is cupped and subcircular in outline (fig. 24) . 



The large anterior zygapophyses look upward and very little inward, their 

 articular faces being nearly horizontal. All overhang the anterior face of the 

 centra. The posterior zygapopbyses are separated at the center by a thin vertical 

 plate that widens distally, forming a zygosphene articulation as in the Sauropodous 

 dinosauria. 



