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Re: Alioramus (Theropoda) osteology in new AMNH Bulletin

This is absolutely sensational in its comprehensiveness, and shows the
beautiful material off to great advantage.  Even for those (like me)
who don't care too much for theropods, I highly recommends downloading
this and taking a look.  Papers such as this are really raising the
bar for what constitutes a proper description.

(Only one question -- why are all the specimen photos in monochrome?  See
which coincidentally came out only a couple of days ago.)

-- Mike.

On 2 March 2012 23:24, Ben Creisler <bcreisler@gmail.com> wrote:
> From: Ben Creisler
> bcreisler@gmail.com
> The monograph has now been posted for free download:
> http://digitallibrary.amnh.org/dspace/handle/2246/6162
> =======
> Stephen L. Brusatte, Thomas D. Carr, and Mark A. Norell (2012)
> The Osteology of Alioramus, A Gracile and Long-Snouted Tyrannosaurid
> (Dinosauria: Theropoda) from the Late Cretaceous of Mongolia.
> Bulletin of the American Museum of Natural History:1-197. 2012
> doi: 10.1206/770.1
> http://www.bioone.org/doi/abs/10.1206/770.1
> The Late Cretaceous tyrannosaurid theropod Alioramus has long been one
> of the most puzzling large carnivorous dinosaur taxa, largely because
> for several decades it has been represented only by a single,
> fragmentary specimen that seems to represent a long-snouted and
> gracile individual but is difficult to interpret. The discovery of a
> substantially complete skeleton of Alioramus at the Tsaagan Khuushu
> locality in the Maastrichtian Nemegt Formation of Mongolia, recovered
> during the 2001 American Museum–Mongolian Academy of Sciences
> expedition and described as a new species (Alioramus altai) in 2009,
> definitively shows that this mysterious taxon is a distinct form of
> longirostrine tyrannosaurid that lived alongside the larger and more
> robust Tarbosaurus. Here we describe and figure this remarkably
> preserved skeleton in detail. We provide exhaustive descriptions and
> photographs of individual bones, and make extensive comparisons with
> other tyrannosauroids. This monographic description provides further
> evidence that Alioramus is an unusual long-snouted, gracile, and
> slender-limbed taxon with an unpredecented degree of cranial
> ornamentation among tyrannosaurids and an extremely pneumatized
> skeleton.
> Anatomical comparisons indicate that the long skull of Alioramus is an
> autapomorphic feature that is proportionally longer (relative to femur
> length) than in any other known tyrannosaurid specimen, including
> juveniles, and that Alioramus is morphologically distinctive relative
> to similarly sized individuals of the contemporary and sympatric
> Tarbosaurus. The holotype specimen of A. altai belongs to a young
> individual, and many differences between it and the other known
> specimen of Alioramus (the holotype of A. remotus) may represent
> ontogenetic variation. The unusual longirostrine skull of Alioramus
> was largely produced by lengthening of the snout bones (maxilla,
> nasal, dentary, lacrimal, jugal), rather than the orbiotemporal bones
> (frontal, postorbital, squamosal, quadratojugal). The long snout,
> gracile skull bones, comparatively small attachment sites for jaw
> muscles, and lack of interlocking sutures and a robust orbital brow
> would have precluded the holotype individual from employing the
> characteristic “puncture-pull” feeding style of large-bodied adult
> tyrannosaurids, in which the muscular jaws, thick teeth, and
> interlocking sutures enabled individuals to bite with enough force to
> fracture bone. Whether adult Alioramus could utilize “puncture-pull”
> feeding awaits discovery of mature individuals of the genus. The
> coexistence of the long-snouted Alioramus and robust and deep-snouted
> Tarbosaurus, which are found together at the Tsaagan Khuushu locality,
> demonstrate that multiple large tyrannosaurids were able to live in
> sympatry, likely because of niche partitioning due to differences in
> craniofacial morphology and functional behavior.