order viii DINOSAURIA 223 



found a few detached crocodilian vertebrae of the proeoelous 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 are 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, and to have been inferior to them in number in the New. 

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

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

 prised the most gigantic members of the order {Rhamphosuchus). 



Order 8. DINOSAURIA. Owen. 1 



(Pachypodes, Owen ; Omithoscelida, Huxley.) 



Long-necked and long-tailed reptiles, usual/// of considerable and sometimes of 

 gigantic size, with limbs adapted for habitual support of the bod//. Investing bones 

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

 arcade, and the targe quadrate firmly fixed. No pineal foramen. Teeth thecodont, 

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

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

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

 clavicles and precoracoid absent. Scapula very targe, somt times coossified with the 

 perforate and anteriorly rounded coracoid. All three pelvic elements entering the aceta- 

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

 frequently united in a median symphysis. Pubis directed downwards and forwards, 

 sometimes developing a postpubic process extending backwards parallel with tin ischium. 

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



The order Dinosauria comprises Mesozoic reptiles which are extremely 

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

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

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



1 Literature : 



Baur, G., Der Tarsus der Vogel und Dinosaurier (Morph. Jahrb. vol. VIII. p. 417 . l> s :;. 

 Bemerkuugeu iiber das Becker der Vogel mid Dinosaurier {ibid. vol. X. p. 613 . 1885. Remarks on 

 the Reptiles generally called Dinosauria (Anier. Nat. vol. XXV. p. 434 . L891. Cope, E. />.. 

 Palaeontological Bulletins Nos. 22-28, in Proc. Amer. Phil. Soc. l s 7o'-77.— hollo, L.. Notes sur les 

 Dinosauriens de Bernissart (Bull. Mus. d'Hist. Nat. Belg. vols. I. -1 1 1. . 1»l'-M.- II, dice, J. II'.. 

 Presidential Addresses (Quar. Jouvn. Geol. Soc. vols. XXXIX., XL. . 1883-84.— Huxley, T. II 

 the Animals which are most nearly intermediate between birds and Dinosaurs (Proc. Roy. .^oe. 

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

 affinity between the Dinosaurian Reptiles and Birds (Quar. Journ. Geol. Soc. vol. XXVII. p. 12 , 

 1870. — On the classification of the Dinosauria (ibid. p. 'VI). Marsh, U. C, Numerous contributions 

 in Amer. Journ. Sci. [3], vols. XVI.-L. 1878-96.— The Dinosaurs of North America (16th Ann. Rep. 

 U.S. Geol. Surv.), 1896. — Mehnert, A'., Untersuchungen iiber die Entwickelung des os pubis der 

 Vogel (Morph. Jahrb. vol. XIII. p. 239)j 1888. — Osborn, II. F., Dinosaur Contributions Nos. 1-3 in 

 Bull. Amer. Mus. Nat. Hist. vols. X.-XIL, and Memoirs, vol. I. pt. 5, 1898-99. — Reconsideration of 

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

 1900. — Owen, R., A history of British fossil Reptiles [Reprint from the publications of the 

 Palaeontographical and other Societies], London. 1849-84. — Seeley, II. '•'.. < >u the classification of 

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



