EARTH 7 Lecture Notes - Lecture 15: Jacques Gauthier, Avialae, Archaeopteryx
Document Summary
*material from lecture 14 maniraptors and the evolution of birds* Birds: defined by flapping wings (powered flight) and a perching foot. Thomas huxley (1868) suggests that archaeopteryx connects birds and dinosaurs. John ostrom: detailed studies in the 1970s that documented the similarities between archaeopteryx and coelurosaurian theropods. Jacques gauthier: seminal cladistics analysis on bird origins (1986, found over 100 characters that identify archaeopteryx as a coelurosaurian dinosaur, established the term (cid:862)maniraptora(cid:863) Confuciusornis: early cretaceous, liaoning, early avialaean (bird) with pygostyle, pygostyle = short, fused tail vertebrae that support tail feathers and muscles. Ichthyornis: late cretaceous, n. america, avialaean (bird) with a carpometacarpus. Fusion of wrist and finger bones that form the tip of the wings. Strength for flight: ontogeny recapitulating phylogeny. Hoatzin embryo has 3 fingers with claws, similar to archaeopteryx/deinonychus. In adults, the bones of the hand fuse (carpometacarpus) including the semilunate carpal to the metacarpals.
