Evolution of Birds.pptx

Evolution of Birds

1. Advanced Ornithology by Maryam R iasat EVOLUTION OF BIRDS

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. Archaeopteryx

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. 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. 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. 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. 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. 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. w ading birds, diving birds, perching birds

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