File:The origin and evolution of life, on the theory of action, reaction and interaction of energy (1917) (14786048653).jpg

Identifier: originevolutiono00osbo (find matches)
Title: The origin and evolution of life, on the theory of action, reaction and interaction of energy
Year: 1917 (1910s)
Authors: Osborn, Henry Fairfield, 1857-1935
Subjects: Evolution Life -- Origin
Publisher: New York, C. Scribner's Sons
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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d,there occurred among thestruthious birds, such as theostriches, a secondary terres-trial phase in which thepowers of flight were secon-darily lost and rapid cursoriallocomotion on the ground wassecondarily developed. Thisinterpretation of the foot andlimb structure associatedwith the loss of teeth, whichis characteristic of all the higher birds, will explain the closeanalogies which exist between the ostrich-like dinosaur Stru- FiG. 109. Restoration of the AncientJurassic Bird, Archaopteryx. Capable of relatively feeble flight. AfterHeilman. 230 THE ORIGIN AND EVOLUTION OF LIFE thiomimus and the modern cursorial flightless forms of birds,such as the ostriches, rheas, and cassowaries. In the opposite extreme to these purely terrestrial forms,the flying arboreal birds also gave off the water-living birds,one phase in the evolution of which is represented in the loon-like Hesperornis, the companion of the pterosaurs and mosa-saurs in the Upper Cretaceous seas. It was on the jaws of the
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Fig. iio. Reversed Aquatic Evoli;ti(l\ ok Wim, axd Body Form. Wing of a penguin (.4) transformed into a fin externally resembling the fin of a shark (B).Skeleton of Hesperornis (C) in the American Museum of Natural History and restora-tion of Hesperornis (D) by Heilman, both showing the transformation of the flying birdinto a swimming, aquatic type, and its convergent evolution toward the body shape ofthe shark, ichthyosaur, and dolphin (compare Fig. 41). Hesperornis and smaller Ichthyornis that Marsh made his sen-sational announcement of the discovery of birds with teeth,a discovery confirmed by his renewed studies of the classicfossil bird type, the Jurassic Archceopteryx. These divers ofthe Cretaceous seas (Hesperornis) are analogous to the modernloons, and represent one of the many instances in which thetempting food of the aquatic habitat has been sought by ani-mals venturing out from the shore-lines. As in the most highlyspecialized modern swimming birds, the Antarctic penguins,

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