Video Assignments. Microraptor PBS The Four-winged Dinosaur Mark Davis SUNY Cortland Library Online

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1 Video Assignments Microraptor PBS The Four-winged Dinosaur Mark Davis SUNY Cortland Library Online Radiolab Apocalyptical Minute 13 through minute 60 Link to this video will be ed but you can search on Youtube for Radiolab Apocalyptical

2 Evolutionary Origin of Birds Outline Why birds are reptiles Archaeopteryx the link to reptiles Birds as dinosaurs What kind of dinosaur Theropods as bird precursors Feathered dinosaurs Molecular evidence

3 Characteristics that Define Birds Feathers Bills Lightweight Bones Furcula Opposable Hallux Efficient Respiratory System External Eggs & Parental Care Finely-tuned Nervous Systems

4 Why Birds are Reptiles Thomas Huxley 19 th Century Naturalist regarded birds as Glorified Reptiles Ancestor of A & B Species A Ancestor of A, B, & C Species B Cladistics classification application that attempts Species C to group organisms based on shared derived traits. (i.e., novel traits that were inherited through a common ancestor)

5 Evolutionary Origins Species A Species B Species C Ancestor of A, B, & C Ancestor of A & B

6 Why Birds are Reptiles Shared Derived Traits Single Occipital Condyle Female Heterogametic Sex Single Middle Ear bone Sclerotic Eye Ring Fused Jaw Bones Nucleated Red Blood Cells Epidermal Scales

7 Archaeopteryx as a Missing Link Archaeopteryx lithographic fossil from lithographic rock quarries in Germany 150 MYA

8 Archaeopteryx as a Missing Link Reptile-like traits Reptilian teeth Long tail Separate pelvic, hand, head, and foot bones Dinosaur-like hip Skull osteology of reptiles Floating gastric ribs

9 Archaeopteryx as a Missing Link Bird-like traits Asymetrical feathers on wings Furcula Reversed hallux (?) What was the life-style of Archaeopteryx? Arboreal or ground-dweller? Volant?

10 More Specimens of Archeopteryx Science 310:1483

11 Who were the direct ancestors to birds? Pterosaurs Pre-dinosaur, pre-crocodilian ancestor (Archosaurs)? Theropod dinosaurs

12 Ornithischians (Stegosaurus, Ankylosaurus, Corythosaurus, Iguanodon) Saurischians Lizard-hipped (Brachiosaurus, T. rex, Velociraptor, Deionychus) DINOSAURS Birds???? Thecodonts--Archosaurs

13 Dinosaur-Bird Connection Ornithischians (Stegosaurus, Ankylosaurus, Corythosaurus, Iguanodon) Saurischians Lizard-hipped (Brachiosaurus, T. rex, Velociraptor, Deionychus) Backward tilted pelvis, Predentary bone, Ossified vertebral tendons Hands rotate around digits III, IV, and V Pelvis tilted forward, No predentary No ossified tendons Digits II, III, and IV DINOSAURS

14 Potential Theropod Precursors Hollow bones Three-toed foot (digit I rotated backwards)

15 Caudipteryx Semilunar carpal Pectoral girdle enlargement Bipedal Reduction in digits and arms Feathers???

16 Elongated feathers worthy of flight Arms and legs of equal length

17 Enlarge pectoral girdle Fusion and reduction of bones Reduction in tail Motor system development Beak development Respiratory efficiency

18 Why Birds are Reptiles Cladistics of Morphology and Molecular Data Shark Amphibians Snakes Lizards Turtles Crocodilians Reptiles Birds Mammals

19 Habits of Archaeopteryx (Feduccia, 1993)

20 Glen & Bennett, 2007.

21 Cuckoos and Road Runners Pigeons

22 The first birds (Mesozoic) were very likely ground foragers and not arboreal foragers.

23 Feathered Dinosaurs Hot bed of dinosaur fossils in Chinese Liaong Province New species of feathered theropod dinosaurs-120 MYA Sinosauropteryx (first Chinese dragon feather) Caudipteryx

24 Caudipteryx zoui Filamentous tail feathers Other specimens that blur the line between dinosaurs and birds include Protoarchaeopteryx, Confuciusornis

25 Birds as Theropods Feathered Theropods Feathers evolved before flight Feathers are no longer a novel feature of birds Share large numbers of advanced traits Evolutionary trends in theropods are consistent with bird evolution

26 The Four-winged Dinosaur Microraptor Significance? What about non-avian dinosaur feet and Chukars?

27 Opposition to Theropod-bird lineage Feduccia--birds share an ancestor with an Archosaur Bird-theropod similarities are due to convergent evolution Bipedalism Flight evolved from the trees down. Deinonychus is 40 MY more recent than Archaeopteryx. Temporal Paradox: you can t be your own grandmother

28 Comparative Embryology Feducia s strongest argument. Top row-alligator Middle row-chicken Bottom row-turtle Assume: Digit IV forms the central axis of modern hands in birds, turtles, and crocodiles Counting backward it appears that birds retain digits II, III, and IV and not digits I, II, and III as in Theropods Photo from Burke and Fedducia, 1997

29 Who cares about finger number? (Pennisi-2005, Science 307:195) Digit I in terrestrial vertebrates has unusual development Digit I depends on the developmental gene Hoxd13 and not Hoxd12 Molecular genetics suggests that Digit I in birds is indeed Digit I

30 Amino Acid Sequence from Bone Collagen of Dinosaurs C, G, I are from Ostrich

31 Amino Acid Sequence of Dinosaur Collagen Birds share a more recent common ancestor with dinosaurs than to early reptiles.

32 Concluding Remarks The origin and evolution of birds is one of the greatest modern day debates in evolutionary biology Birds are reptiles Theropod origin of birds is gaining strength from many biological disciplines Remaining Questions; How did flight arise and & why did feathers evolve?