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Re: Theropod fauna from Southern Australia



Interestingly, the little theropod _Timimus_ is not only regarded as a
valid genus, but as a possible tyrannosauroid.

Given the chilly climate in southern Australia at the time, I'd bet
this theropod was covered in a down-like plumage.





On Thu, May 17, 2012 at 7:20 AM, Ben Creisler <bcreisler@gmail.com> wrote:
> From: Ben Creisler
> bcreisler@gmail.com
>
> A new paper in PLoS ONE:
>
>
> Benson, R.B.J., Rich, T.H., Vickers-Rich, P. & Hal,l M, (2012)
> Theropod Fauna from Southern Australia Indicates High Polar Diversity
> and Climate-Driven Dinosaur Provinciality.
> PLoS ONE 7(5): e37122.
> doi:10.1371/journal.pone.0037122
> http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0037122
>
>
>
> The Early Cretaceous fauna of Victoria, Australia, provides unique
> data on the composition of high latitude southern hemisphere
> dinosaurs. We describe and review theropod dinosaur postcranial
> remains from the Aptian–Albian Otway and Strzelecki groups, based on
> at least 37 isolated bones, and more than 90 teeth from the Flat Rocks
> locality. Several specimens of medium- and large-bodied individuals
> (estimated up to ~8.5 metres long) represent allosauroids.
> Tyrannosauroids are represented by elements indicating medium body
> sizes (~3 metres long), likely including the holotype femur of Timimus
> hermani, and a single cervical vertebra represents a juvenile
> spinosaurid. Single specimens representing medium- and small-bodied
> theropods may be referrable to Ceratosauria, Ornithomimosauria, a
> basal coelurosaur, and at least three taxa within Maniraptora. Thus,
> nine theropod taxa may have been present. Alternatively, four distinct
> dorsal vertebrae indicate a minimum of four taxa. However, because
> most taxa are known from single bones, it is likely that small-bodied
> theropod diversity remains underestimated. The high abundance of
> allosauroids and basal coelurosaurs (including tyrannosauroids and
> possibly ornithomimosaurs), and the relative rarity of ceratosaurs, is
> strikingly dissimilar to penecontemporaneous dinosaur faunas of Africa
> and South America, which represent an arid, lower-latitude biome.
> Similarities between dinosaur faunas of Victoria and the northern
> continents concern the proportional representatation of higher clades,
> and may result from the prevailing temperate–polar climate of
> Australia, especially at high latitudes in Victoria, which is similar
> to the predominant warm–temperate climate of Laurasia, but distinct
> from the arid climate zone that covered extensive areas of Gondwana.
> Most dinosaur groups probably attained a near-cosmopolitan
> distribution in the Jurassic, prior to fragmentation of the Pangaean
> supercontinent, and some aspects of the hallmark ‘Gondwanan’ fauna of
> South America and Africa may therefore reflect climate-driven
> provinciality, not vicariant evolution driven by continental
> fragmentation. However, vicariance may still be detected at lower
> phylogenetic levels.