ORDER VIII ' DINOSAURIA 223 



found a few detached crocodilian vertebrae of the procoelous type, but it is 

 not until the Upper Cretaceous that typical Eusuchia with extended secondary 

 palate and closed eustachian passages become dominant. The Eusuchia, 

 like their Jurassic forerunners, comprise both long-snouted and broad- 

 snouted genera, but whether the gavials were derived independently from the 

 modern crocodiles and alligators, or all aue traceable to a common Mesosuchian 

 ancestor, is still uncertain. During the Tertiary, alligators and crocodiles 

 prevailed both in Europe and North America, only becoming extinct in Europe 

 during the Pliocene. The alligators, which appear to have surpassed crocodiles 

 in the Old World, und to have been inferior to them in number in the New, 

 are now restricted to the warmer regions of North America. Eemains of both 

 gavials and crocodiles occur in the Tertiary of India, among which are com- 

 prised the most gigaiitic members of the order (Bhamphosuchus). 



Order 8. DINOSAURIA. Owen.i 



(Pacht/podes, Owen ; Ornithoscelida, Huxley.) 



Lomj-necked aud long-tailed reptües, usually of coiisiderable and sometimes of 

 (jlgantic size, with limbs adapted for haUtual snpport of the hody. lavesting bones 

 of the temporal region of the skull contracting into an upper and a lower temporal 

 arcade, and the large quadrate firmly fixed. Ä^o piiteal foramen. Teeth thecodoiif, 

 confined to margin of the jaw-bones. Vertebrae opisthocoelous or amphiplatyan, rarely 

 amphicoelous, sometimes hollow or with deep lateral cavities ; sacrum comprising from 

 two to ten anchylosed vertebrae. Ribs double-headed. Sternum incompletely ossified, 

 clavicles and p^ecoracoid absent. Scapula very large, sometimes cobssified with the 

 'perforate and anteriorly rouncled coracoid. All three pelvic elements erdering the aceta- 

 bulum. Ilium large, antero-posteriorly extended. Ischia usually slender and elongated, 

 frequently united in a median Symphysis. Puhis directed doimwards and forwards, 

 sometimes developing a postpubic prücess extending backwards parallel with the ischium. 

 Fore-limbs shorter than the hinder pair ; progression very commonly bipedal. 



The Order Dinosauria comprises Mesozoic reptiles which are extremely 

 varied in Organisation, and exhibit a number of rhynchocephalian, crocodilian, 

 lacertiliän, and even ornithic characters, the latter due chiefly to homoplastic 

 or parallel development. Among the latter, as first noticed by Gegenbaur, 



^ Literat Lire : 



Baur, G., Der Tarsus der Vögel und Dinosaurier (Morph. Jalirb. vol. VIII. p. 417), 1883. — 

 Bemerkungen über das Becker der Vögel und Dinosaurier {ibid. vol. X. p. 613), 1885. — Reniarks on 

 tlie Reptiles generally called Dinosauria (Anier. Nat. vol. XXV. p. 434), 1891. — C(>/>^, E. D., 

 Palaeontological Bulletins Nos. 22-28, in Pi'oc. Anier. Phil. Soc. 187Ö-77. — J)ollo, L., Notes sur les 

 Diuosauriens de Bernissart (Bull. Mus. d'Hist. Nat. Belg. vols. T.-III.), 1882-84. — //«/Xy, J. H'., 

 Presidential Addresses (Quar. Journ. Geol. Soc. vols. XXXIX., XL.), 1883-84.— //«.(•%, T. //., On 

 the Aninials which are niost nearly intermediate betvveen birds and Diuosaurs (Proc. Koy. Soc. 

 p. 278), 1868. Also Ann. Mag. Nat. Hist. [4], vol. I. (1868), p. 220.— Further evidence on the 

 artiuity between the Dinosaurian Reptiles aud Birds (Quar. Journ. Geol. Soc. vol. XXVII. p. 12), 

 1870. — On the Classification of the Dinosauria {ibid. p. 32). — Marsh, 0. C, Numerous contributions 

 in Anier. Journ. Sei. [3], vols. XVI.-L. 1878-96.— The Diuosaurs of North America (16th Ann. Rep. 

 U.S. Geol. Surv.), 1896. — Mehnert, E., Untersuchungen über die Entwickelung des os pubis der 

 Vögel (Morph. Jahrb. vol. XIII. p. 239), 1888.— (Mor«, //. F., Dinosaur Contributions Nos. 1-3 in 

 Bull. Amer. Mus. Nat. Hist. vols. X.-Xll., aud Memoirs, vol. I. pt. f), 1898-99. — Reconsideratiou of 

 the evidence for a common Dinosaur-avian stem in the Permian (Amer. Nat. vol. XXXIV. p. 777), 

 1900. — Qiveih R-^ A history of British fossil Reptiles [Reprint from the publications of the 

 Palaeontographical and other Societies], London, 1849-84.— »SVf/^//, //. ^'., On the classilication of 

 the Dinosauria (Proc. Roy. Soc. vol. XLIIL), 1887. 



