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Publication - Mr Evan Saitta

    Structure and Homology of Psittacosaurus Tail Bristles

    Citation

    Mayr, G, Pittman, M, Saitta, E, Kaye, T & Vinther, J, 2016, ‘Structure and Homology of Psittacosaurus Tail Bristles’. Palaeontology, vol 59.

    Abstract

    We examined bristle-like appendages on the tail of the Early Cretaceous basal ceratopsian dinosaur Psittacosaurus
    with laser-stimulated fluorescence imaging. Our study reveals
    previously unknown details of these structures and confirms their
    identification as integumentary appendages. For the first time, we show
    that most bristles appear to be arranged in bundles and that they
    exhibit a pulp that widens towards the bristle base. We consider it
    likely that the psittacosaur bristles are structurally and
    developmentally homologous to similar filamentous appendages of other
    dinosaurs, namely the basal heterodontosaurid Tianyulong and the basal therizinosauroid theropod Beipiaosaurus, and attribute the greater robustness of the bristles of Psittacosaurus
    to a higher degree of cornification and calcification of its integument
    (both skin and bristles). Although the psittacosaur bristles are
    probably homologous with avian feathers in their origin from discrete
    cell populations, it is uncertain whether they developed from a
    follicle, one of the developmental hallmarks of true feathers. In
    particular, we note a striking resemblance between the psittacosaur
    bristles and the cornified spine on the head of the horned screamer, Anhima cornuta, an extant anseriform bird. Similar, albeit thinner keratinous filaments of extant birds are the ‘beard’ of the turkey, Meleagris gallopavo, and the crown of the Congo peafowl, Afropavo congensis.
    All of these structures of extant birds are distinct from true
    feathers, and because at least the turkey beard does not develop from
    follicles, detailed future studies of their development would be
    invaluable towards deepening our understanding of dinosaur filamentous
    integumentary structures.

    Full details in the University publications repository