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[dinosaur] Polar dinosaur feather assemblage from Australia




Ben Creisler
bcreisler@gmail.com

A new paper:

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Martin KundrÃt, Thomas H. Rich, Johan Lindgren, Peter SjÃvall, Patricia Vickers-Rich, Luis M.Chiappe & Benjamin P.Kear (2019)
A polar dinosaur feather assemblage from Australia.
Gondwana Research (advance online publication)
doi: https://doi.org/10.1016/j.gr.2019.10.004
https://www.sciencedirect.com/science/article/abs/pii/S1342937X19302850

Highlights

Fossil feathers from the Koonwarra Fossil Bed in southeastern Australia record the first demonstrable dinosaur (including birds) integumentary structures described from the Mesozoic polar regions.
This diverse range of non-avian theropod (paravian) and bird feathers more than doubles the number of Mesozoic fossil feather specimens and morphologies recovered from the Gondwanan landmasses to date.
Possible traces of eumelanosomes imply original dark colouration and patterning. Some of the geologically oldest barbicel-like structures also evince advanced avian-grade flight feather morphologies in the Early Cretaceous.

ABSTRACT

Exceptionally preserved Mesozoic feathered dinosaur fossils (including birds) are famous, but recognized from only very few localities worldwide, and are especially rare in the Southern Hemisphere. Here we report an assemblage of non-avian and avian dinosaur feathers from an Early Cretaceous polar (around 70ÂS) environment in what is now southeastern Australia. The recovered remains incorporate small (10â30 mm long) basal paravian-like tufted body feathers, open-vaned contour feathers, and asymmetrical bird-like wing feathers that possess high-angled barbs with possible remnants of barbicels â amongst the geologically oldest observed to date. Such morphological diversity augments scant skeletal evidence for a range of insulated non-avian theropods and birds inhabiting extreme southern high-latitude settings during the Mesozoic. Although some of these fossil feathers exhibit what may be residual patterning, most are uniformly toned and preserve rod-shaped microbodies, as well as densely-packed microbody imprints on the barbules that are structurally consistent with eumelanosomes. Geochemical analysis detected no identifiable residual biomolecules, which we suspect were lost via hydrolysis and oxidization during diagenesis and weathering. Nevertheless, an originally dark pigmentation can be reasonably inferred from these melanic traces, which like the coloured feathers of modern birds, might have facilitated crypsis, visual communication and/or thermoregulation in a cold polar habitat.