GEL 107 (11)

GEL 107 (11) - 1 GEL107 PALEOBIOLOGY Lecture 12 Evolution...

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Unformatted text preview: 1 GEL107: PALEOBIOLOGY Lecture 12: Evolution Ⅱ What is evolutionary radiation? What is key evolutionary innovation? How do we measure the rates of evolution? What is Evo-Devo? How has diversity changed over geologic time? Evo-Devo What is it? The study of development to elucidate evolution Example of feather evolution Feathers as a significant evolutionary novelty or key evolutionary innovation A A B A B C D A B C D E A B C A B C D E Sometimes: Ontogeny recapitulates phylogeny (The Biogenetic Law: Ernst Haeckel, 1899) But not always! March 2003: Scientific American Feather evolution 2 Two structural classes of feathers in living birds: • plumulaceous • pennaceous Five stages in feather development Stage 1: unbranched hollow cylinder Stage 2: plumulaceous (downy) tuft of barbs Stage 3: formation of rachis; open pennaceous feather Stage 4: barbules formed; closed pennaceous feather Stage 5: asymmetrical vane of flight feather Sinosauropteryx delicate hair-like “feathers” Stage 1: unbranched hollow cylinder 3 Therizinosaurs Stage 2: plumulaceous (downy) tuft of barbs Tyrannosaurids Stage 3: formation of rachis; open pennaceous feather Microraptor Stage 4: barbules formed; closed pennaceous feather Caudipteryx Archaeopteryx Stage 5: asymmetrical vane of “flight” feather 4...
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GEL 107 (11) - 1 GEL107 PALEOBIOLOGY Lecture 12 Evolution...

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