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Evolution of Birds.pptx

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Evolution of Birds.pptx

  1. 1. Advanced Ornithology by Maryam Riasat EVOLUTION OF BIRDS
  2. 2. Evolution of Modern Birds  Birds evolved the definitive features of modern birds and diversified during the cretaceous period  Fossil birds from Spain, China and Patagonia bridge the gap between archaeopteryx and modern birds  Early cretaceous birds Confuciusornis and Jeholornis were intermediate between archaeopteryx and modern birds  Confuciusornis has horny beak like modern birds and Jeholornis has long tail like archaeopteryx
  3. 3. Archaeopteryx
  4. 4. Enantiornithes Cretaceous period Ornithurae Enantiornithes  Dominated the first phase of early avian evolution  Flight capable species  They were as small as sparrows and as large as vultures  Many were arboreal  Laid eggs on the ground  Underwent annual growth cycles recorded as treelike growth rings in cross sections of their limb bones
  5. 5. Sinornis santensis  Sinornis santensis was signature species of this radiation from cretaceous period  Discovered in China 1987  Toothed sparrow-sized bird with many features intermediate between archaeopteryx and modern perching birds
  6. 6. Advancements of Sinornis santensis over archaeopteryx  Strengthening and modifications of hands, forearm and pectoral girdle for flight  Enhance the ability to raise wings high over the body and their folding  A large pygostyle for the support of tail fan
  7. 7.  Perching foot with an opposable rear toe, the hallux  These features suggest that avian flight and perching abilities evolved in small bodied birds that followed Archaeopteryx
  8. 8. All the Enantiornithes disappeared along with dinosaurs in the mass extinction that marked the end of the Mesozoic era The other lineage, the toothed Ornithurae gave rise to modern birds
  9. 9. Ornithurae  Small finch-sized  Arboreal species  Later evolved advanced wing structures and flight abilities and fully developed perching foot  By the late cretaceous, ornithurine birds exhibited a wide range of sizes and life style that mirrored those of modern birds i.e. wading birds, diving birds, perching birds
  10. 10. Most of the ornithurae disappeared along with dinosaurs in the mass extinction that marked the end of the Mesozoic era Among the few survivors, however, were the ancestors of modern birds

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