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Re: Noasaurid claws



It should be pointed out, though, that not all abelisaurids have those
short stubby arms. The Indosuchus material described by Chatterjee and
Rudra (1996) included forelimb elements which were pretty substantial,
described as proportionally similar to allosaurs.

On Fri, Dec 4, 2009 at 9:08 AM, Thomas R. Holtz, Jr. <tholtz@umd.edu> wrote:
> http://www.springerlink.com/content/2t560640g1136511/fulltext.html
>
> Agnolin, F.L. & P. Chiarelli. 2009. The position of the claws in Noasauridae
> (Dinosauria: Abelisauroidea) and its implications for abelisauroid manus
> evolution. Paläontologische Zeitschrift Online First. DOI
> 10.1007/s12542-009-0044-2
>
> Abstract  In this note we reassess the position of putative pedal phalanges
> of some South American noasaurid theropods (Abelisauroidea). Noasaurids were
> considered as to be distinctive abelisauroids with a peculiar “sickle claw”
> on the second toe of the foot, convergently developed with that of
> deinonychosaurians. Among noasaurids, the Argentinean species Noasaurus
> leali (latest Cretaceous) and Ligabueino andesi (Early Cretaceous) are known
> from incomplete specimens, including dissarticulated non-ungueal phalanges,
> and, in N. leali, a claw. A detailed overview of these elements indicates
> that the supposed raptorial claw of the second pedal digit of N. leali
> actually belongs to the first or second finger of the manus, and the
> putative pedal non-ungual phalanges of both genera also pertain to the
> manus. Thus, the new interpretations of noasaurid pedal morphology blur the
> distinctions between Noasauridae and Velocisauridae proposed by previous
> authors. Finally, we suggest, on the basis of phalangeal and metacarpal
> morphology, that abelisaurids probably lost their manual claws by means of
> the loss of function of the HOXA11 and HOXD11 genes. Thus Noasauridae
> differs from Abelisauridae in retaining plesiomorphic long forelimbs with
> well developed claws, as occurs plesiomorphically in most basal theropods
> (e.g., Coelophysis).
>
> Thomas R. Holtz, Jr.
> Email: tholtz@umd.edu   Phone: 301-405-4084
> Office: Centreville 1216
> Senior Lecturer, Vertebrate Paleontology
> Dept. of Geology, University of Maryland
> http://www.geol.umd.edu/~tholtz/
> Fax: 301-314-9661
>
> Faculty Director, Earth, Life & Time Program, College Park Scholars
> http://www.geol.umd.edu/~jmerck/eltsite/
> Faculty Director, Science & Global Change Program, College Park Scholars
> http://www.geol.umd.edu/sgc
> Fax: 301-314-9843
>
> Mailing Address:        Thomas R. Holtz, Jr.
>                        Department of Geology
>                        Building 237, Room 1117
>                        University of Maryland
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>
>