. The chordates. Chordata. 806 Comparative Morphology of Chordates. Fig. 608. {Left) Paleolithic drawing of elephant showing heart; from the cavern of Pindal, Asturias, northwestern Spain. {Right) Magdalenian drawings of bison with arrows embedded in the heart; from the cavern of Niaux on the Ariege, southern France. (After Cartailhac and Breuil. Courtesy, Singer: "The Evolution of Anatomy," New York, Alfred A. Knopf, Inc.) definite lines of specialization, each resulting in a type of mammal anatomically and physiologically highly adapted to a particular en- vironment and mode of liv
. The chordates. Chordata. 806 Comparative Morphology of Chordates. Fig. 608. {Left) Paleolithic drawing of elephant showing heart; from the cavern of Pindal, Asturias, northwestern Spain. {Right) Magdalenian drawings of bison with arrows embedded in the heart; from the cavern of Niaux on the Ariege, southern France. (After Cartailhac and Breuil. Courtesy, Singer: "The Evolution of Anatomy," New York, Alfred A. Knopf, Inc.) definite lines of specialization, each resulting in a type of mammal anatomically and physiologically highly adapted to a particular en- vironment and mode of living. The group attains a high degree of success, but within the limitations imposed by its specialization. Such relatively unspecialized animals as the insectivores live where they best can. Their continued survival is due partly to retreat from com- petition and partly to great fecundity. Primates have hit upon an entirely unique line of specialization. Retaining, with only minor modifications, the primitive "generalized" structure of their insectivore ancestors, they act upon their environ- ment in such a way that it not only more readily yields them the primary necessities of living, but so that, in ever increasing degree, they become able to extend their habitats and utilize energies external to their bodies in the performance of a great diversity of activities of a sort never before achieved by any animal. THE PRIMATE LINE OF SPECIALIZATION The primates have reversed the old order of evolution. From the most ancient invertebrates onward, it has always been a tedious process of structural change requiring thousands or millions of years for ani- mals to emerge from aquatic to effective terrestrial living or to acquire capacity for flight. Modification of environment has been limited to. 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
Size: 2047px × 1220px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollect, bookpublisherphiladelphiablakiston
