. The bird; its form and function . FiG. 63—Pelvic arch of a Dinosaur bone extending backward from the thigh-socket, sepa-rated from the ischium(except at the extremeend) by a long open other animals thesebones are as different inshape as can be imagined,but, almost without excep-tion, the position of eachis relatively the same. Theextreme extension, forwardand back, of the iliumabove the back-bone, thusjoining with more vertebrae,is directly connected withtwo-legged erect locomo-tion. A parallel conditionis found in some Dinosaurs—those extinct giant rep-tiles — certain of whichwa

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. The bird; its form and function . FiG. 63—Pelvic arch of a Dinosaur bone extending backward from the thigh-socket, sepa-rated from the ischium(except at the extremeend) by a long open other animals thesebones are as different inshape as can be imagined,but, almost without excep-tion, the position of eachis relatively the same. Theextreme extension, forwardand back, of the iliumabove the back-bone, thusjoining with more vertebrae,is directly connected withtwo-legged erect locomo-tion. A parallel conditionis found in some Dinosaurs—those extinct giant rep-tiles — certain of whichwalked more or less ontheir hind legs. Another fundamentalresemblance is found be-tween the thigh-girdles ofDinosaurs and other rep-tiles and that of a bird inthe egg. As is shown inProf. H. F. Osborn.) ^i^^ 63-65, the pubis slants slightly forward in both reptile and embryo bird; but in. Fig. 64.—Pelvic arch of an embryo bird,to show similarity of the two ascontrasted with Fig. (5

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Keywords: ., bookcentury1900, bookdecade1900, booksubjectbirds, bookyear1906