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Re: Nanotyrannus valid as member of Albertosaurinae, based on dentary groove



Copy-paste problem (blame Windows). Here's the citation with the doi:

Joshua D. Schmerge & Bruce M. Rothschild (2016)
Distribution of the dentary groove of theropod dinosaurs: Implications
for theropod phylogeny and the validity of the genus Nanotyrannus
Bakker et al., 1988.
Cretaceous Research 61: 26-33
doi:10.1016/j.cretres.2015.12.016
http://www.sciencedirect.com/science/article/pii/S0195667115301415

On Thu, Jan 14, 2016 at 12:03 PM, Ben Creisler <bcreisler@gmail.com> wrote:
> Ben Creisler
> bcreisler@gmail.com
>
> A new paper:
>
> Joshua D. Schmerge & Bruce M. Rothschild (2016)
> Distribution of the dentary groove of theropod dinosaurs: Implications
> for theropod phylogeny and the validity of the genus Nanotyrannus
> Bakker et al., 1988.
> Cretaceous Research 61: 26-33
> Joshua D. Schmerge & Bruce M. Rothschild (2016)
> http://www.sciencedirect.com/science/article/pii/S0195667115301415
>
>
>
> This study examines the phylogenetic distribution of a morphologic
> character, described as a groove containing pores, on the lateral
> surface of the dentary bone in theropod dinosaurs. The nature of this
> groove is a feature unique to theropods. Of the 92 theropod taxa
> examined for the presence and absence of this feature, 48 possessed
> and 44 lacked this feature. Distribution of this character was
> compared to published phylogenetic analyses of theropods, in order to
> evaluate the utility of the dentary groove as a diagnostic feature.
> 80% of pre-Tyrannoraptoran theropods possessed the dentary groove,
> with only 6 reversals in basal theropod clades. Theropods with beaks
> or edentulous jaws all lacked a dentary groove. Tyrannosauroidea is
> marked by mosaic distribution of this character. Among
> tyrannosauroids, the dentary groove occurs only in Dryptosaurus and
> the Albertosaurinae (Albertosaurus + Gorgosaurus). Nanotyrannus
> lancensis, sometimes described as representing juvenile Tyrannosaurus
> rex, also possesses this groove, unlike the remainder of the
> Tyrannosaurinae. Nanotyrannus lancensis was included in a phylogenetic
> analysis of Tyrannosauroidea and was recovered within Albertosaurinae.
> We recommend that Nanotyrannus stand as a valid taxon nested within
> the Albertosaurinae, based on the presence of this groove, as well as
> other features of the skull.