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Re: Kentrosaurus sexual dimorphism and Tarbosaurus juvenile skull



Yes, it's out, at least as regards being online:
http://www.informaworld.com/smpp/title~db=all~content=g937434119

I have a paper in this issue so radical and wide-ranging in its
implications that it will shake the very foundations of evolutionary
theory.  It's on page 727.  I think we can all agree that this should
have been in Nature or Science.

-- Mike.


On 13 May 2011 22:51, Paul P <turtlecroc@yahoo.com> wrote:
> Is the May JVP out yet? We don't have it online yet so I
> assume it isn't out in hardcopy yet either.
>
>
> --- On Mon, 5/9/11, bh480@scn.org <bh480@scn.org> wrote:
>
>> From: bh480@scn.org <bh480@scn.org>
>> Subject: Kentrosaurus sexual dimorphism and Tarbosaurus juvenile skull
>> To: dinosaur@usc.edu
>> Date: Monday, May 9, 2011, 8:51 PM
>>
>> From: Ben Creisler
>> bh480@scn.org
>>
>>
>> In addition to the new dinosaurs Arcusaurus and Haya, the
>> May JVP has two
>> other dinosaur-related papers:
>>
>> I had an earlier posting on this one based on news stories
>> and press
>> releases:
>>
>> Takanobu Tsuihiji; Mahito Watabe; Khishigjav Tsogtbaatar;
>> Takehisa
>> Tsubamoto; Rinchen Barsbold; Shigeru Suzuki; Andrew H. Lee;
>> Ryan C.
>> Ridgely; Yasuhiro Kawahara; Lawrence M. Witmer
>> (2011)
>> Cranial osteology of a juvenile specimen of Tarbosaurus
>> bataar (Theropoda,
>> Tyrannosauridae) from the Nemegt Formation (Upper
>> Cretaceous) of Bugin
>> Tsav, Mongolia.
>> Journal of Vertebrate Paleontology 31(3): 497 - 517
>> DOI: 10.1080/02724634.2011.557116
>> http://www.informaworld.com/smpp/content~db=all~content=a937433397~frm=absli
>> nk
>>
>> A juvenile skull of the tyrannosaurid Tarbosaurus bataar
>> found in the Bugin
>> Tsav locality in the Mongolian Gobi Desert is described.
>> With a total
>> length of 290 mm, the present specimen represents one of
>> the smallest
>> skulls known for this species. Not surprisingly, it shows
>> various
>> characteristics common to juvenile tyrannosaurids, such as
>> the rostral
>> margin of the maxillary fenestra not reaching that of the
>> external
>> antorbital fenestra and the postorbital lacking the cornual
>> process. The
>> nasal bears a small lacrimal process, which disappears in
>> adults. Lacking
>> some of the morphological characteristics that are adapted
>> for bearing
>> great feeding forces in adult individuals, this juvenile
>> specimen suggests
>> that T. bataar would have changed its dietary niches during
>> ontogeny. The
>> numbers of alveoli in the maxilla (13) and dentary (14 and
>> 15) are the same
>> a
> etically in
>> T. bataar and thus are not consistent with the hypothesis
>> that the numbers
>> of alveoli decreases ontogenetically in tyrannosaurids.
>>
>>
>> Holly E. Barden & Susannah C. R. Maidment (2011)
>> Evidence for sexual dimorphism in the stegosaurian dinosaur
>> Kentrosaurus
>> aethiopicus from the Upper Jurassic of Tanzania.
>> Journal of Vertebrate Paleontology 31(3): 641--651
>> DOI: 10.1080/02724634.2011.557112
>> http://www.informaworld.com/smpp/content~db=all~content=a937432642~frm=title
>> link
>>
>> Sexual dimorphism, the condition whereby males and females
>> differ from one
>> another physically, is one of the most fundamental aspects
>> of the biology
>> of any animal. However, sexually dimorphic characters can
>> be subtle and are
>> mainly related to soft tissue anatomy. They are, therefore,
>> difficult to
>> identify reliably in the fossil record particularly when
>> dealing with small
>> sample sizes and osteology alone. The first geometric
>> morphometric analysis
>> of dimorphism in a thyreophoran (armored) dinosaur shows
>> that the femora of
>> the stegosaurian dinosaur Kentrosaurus aethiopicus (Upper
>> Jurassic,
>> Tanzania) bear a statistically significant shape difference
>> of the proximal
>> end, which is independent of size and is therefore proposed
>> to be a sexual
>> difference. Although the disarticulated nature of the
>> material means that
>> intraspecific variation in other skeletal elements, such as
>> the enigmatic
>> dermal armor, cannot be identified as sexual dimorphism at
>> this time, this
>> study provides a methodology for further work on
>> articulated stegosaurian
>> specimens and has the potential to reveal additional
>> information regarding
>> the palaeobiology and population dynamics of this poorly
>> understood clade.
>>
>>
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>
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