4l6 DINOSAURIA 



CHAP. 



present state of our knowledge — those which have left their 

 three-toed spoors in the Trias of Connecticut^ — were already much 

 specialised hj having attained to an upright bipedal gait, wliile 

 the Sauroijoda, which except for their gigantic size are the most 

 generalised, are of comparatively recent date, none of them being 

 known from strata older than the Upper Jurassic. Twenty years 

 ago, until the discoveries of numerous kinds in the United States, 

 our knowledge of the whole group was very limited. There is a 

 widely spread notion that the birds have sprung from some Dino- 

 saurian stock. Huxley was the first to show clearly that birds 

 were an offshoot of the reptiles, and he said of the Dinosaurs, 

 especially his Ornithoscelida {Iguanodon, Scelidosaurus, Megalo- 

 saurus, Compsognathus, and others), that they " present a large 

 series of modifications intermediate in structure between existing 

 reptiles and Aves." Baur proved to his own satisfaction that we 

 have to look for the ancestors of the Eatitae among the herbi- 

 vorous Dinosaurs, especially the Ornithopoclous forms, whilst the 

 Carinatae are descendants of the Eatitae. However, even he had 

 to give up this absolutely unwarrantable view. 



It is easy to select a considerable number of characters 

 amongst the various Dinosaurs which also occur in birds, and 

 some of these have until a recent date been considered as peculiar 

 to birds. For instance, the double, bifurcated pubic bones of the 

 Orthopoda ; the increased number of vertebrae to which the hori- 

 zontally elongated ilia are attached, especially in the forms with 

 an upright gait, and the bipedal feature itself ; the possession of 

 an ascending process of the astragalus and its fusion witli the 

 tibia in Compsognathns and Cei^atosaurus among the Theropoda, 

 and in Ornithomimus ; the attachment of the distal tarsalia to 

 the metatarsalia, e.g. in Compsognathus, — in fact, the formation 

 of an intertarsal joint, a feature otherwise characteristic of, 

 and peculiar to, l)irds ; the frequent reduction of the fifth 

 metatarsal bone ; tlie backward position of the hallux and the 

 proximal reduction of its metatarsal in Compsognathus ; the 

 elongation and partial fusion of the functional metatarsals in 

 the latter genus and in Ceratosaurus ; the regular increase of the 

 phalangeal numbers of the first four toes from two to five in 

 many of the Ornithopoda ; — in short, the great resemblance 

 between the feet of some of the Dinosaurs and those of the birds. 

 However striking these arguments are, they are instances of con- 



