. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. The Skeleton 615. Ilium—'%-r*-:— f The primitive character of the earliest known bird, Archaeopteryx, is clearly shown by its small pelvic girdle bones with distinct sutures between them and by the presence of an unbirdlike pubic symphysis (Fig. 543), as well as by the fact that the ilia connect with only six vertebrae, instead of the larger number char- acteristic of modern birds. The only other bird with a symphysis pubis is the African ostrich, Struthio
. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. The Skeleton 615. Ilium—'%-r*-:— f The primitive character of the earliest known bird, Archaeopteryx, is clearly shown by its small pelvic girdle bones with distinct sutures between them and by the presence of an unbirdlike pubic symphysis (Fig. 543), as well as by the fact that the ilia connect with only six vertebrae, instead of the larger number char- acteristic of modern birds. The only other bird with a symphysis pubis is the African ostrich, Struthio, while an ischiac symphysis occurs only in the South American ostrich, Rhea, in which the symphysis lies dorsal to the digestive tract. In mammals generally the three embryonic bones on either side of the pelvic girdle fuse to- gether to form the single innominate bone (Fig. 544). Where the innominate bones of the two sides meet ventrally, the monotremes, marsupials, many rodents, insectivores, ungulates, and carni- vores have a symphysis ischiaticum, as well as a symphysis pubis, but in pri- mates, while the pubic bones unite in a symphysis, the ischia separate, form- ing two posterior skeletal projections that support the sitting animal. It would Pubis—pX , „. W %,: Ischium -?5^ Fig. 542. Left-side view of the pelvic girdle of an em- bryo bird showing the nat- ural position of the pubis before its backward migra- tion. (After Mehnert.) Ilium Sacrum. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Walter, Herbert Eugene, b. 1867; Sayles, Leonard Perkins, 1902-. New York : Macmillan Co.
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Keywords: ., bookcentury1900, booksubjectanatomycomparative, booksubjectverte
