BIRDS WITH TEETH. 



25 



The skull was very Inrgo in jtroportion to tlie rest of the skeleton, the dispropor- 

 tion being well shown in the accompanying cut, Fig. 9. Tlie cranial sutures were 

 nearly obliterated. The quadrate bone, as shown in Fig. 8, has onlv a single facet on 

 its articular head, agreeing in that respect with Jlesperornis and the Strutiiionine 

 birds. The brain was small, and, like that of Jltsperoniis, which it resembles more 

 nearly than that of any other known bird, in its main feattn-es strongly reptilian, as in 

 the elongated form and the prominent optic lobes. The two rami of the lower jaw 

 were entirely separate, 

 having been united in 

 front only by caililage, 

 and the tooth-bearing 

 jiortion is so similar to 

 that of some of the smal- 

 ler Jlosasauroid reptiles that, 

 without other jiortions of the skel- 

 eton, the two could hardly be dis- 

 tinguished. The teeth were im- 

 l)lauted in distinct sockets, thus 

 differing widely from what was 

 the case in llesperorms ; they 

 were all sharp, pointed, and 

 strongly recurved, those of the 

 up])er jaw apparently larger than 

 the lower ones. Whether the an- 

 terior i)ortion of the upper jaw, 

 the preinaxilla, contained teeth is 

 uncertain, but Professor 3Iarsh 

 thinks it ]irol)able that they were 

 absent, as in Hcsperornis. The 

 M-hole surface of the tooth above 

 tlie jaw was covered with smooth 

 enamel. The succession of the 

 teeth took place vertically, as in 

 crocodiles and Dinosaurs, and not 

 laterally, as in Iftsperoniis and 

 the Mosasaurs. The yoimg teeth 

 were much inclined when they 

 first appeared above the jaw, after 

 the old teeth had been expelled. 



The presacral vertebne were more remarkable than those of any other known bird 

 e.xeept Arclueopteryx, for they were not saddle-sliaped, but biconcave as shown in Figs. 

 10, 11, which show clearly the cuji-shaped articulation of the centrum. However, the 

 third vertebra of tiu' neek, but no other, jiresents a modified form (Fig. VI), evi<lently 

 l>roduced by the necessity of providing for an easy vertical motion of the neck at its 

 iirst bend. The tail is remarkable for being of the same type ns is that of all mod- 

 ern birds, namely, com|>aratively short, and the last vertebra; anchylosed into a 

 ]>ygosfyle. 



The fore extremities, including the shoulder girdle, were, so far as known, cssen- 



Fio. 9. — Ifcstoratioii of Irhtlii/omu. 



