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Re: Neovenator (was Re: Allosauria redefined)



At 03:34 PM 2/4/98 PST, you wrote:
>I've just recently had the chance to take a good look at the 
>*Neovenator* from Surrey, England, and there seems to be a real 
>interesting allocation of this theropod to the African 
>carcharodontosaurids. Perusing the skeleton, and matching it with 
>similar skeletons, I've found that the closest match was with 
>*Afrovenator*. There a list of synapomorphies, which include:
>
>*  broad scapula with shortend rectangular coracoid (Afro's is flanged 
>   at the end, while Neo's is not)

(Trying for his best Obi Wan) "Learn about character polarity, Jaemi..."

>*  ischium is long a slender with small obturator process, and has a\
>   distal boot (this feature is also shared with *Eustreptospondylus*
>   from earlier beds (Oxford Clay) on the mainland)
>*  the tibia has a very large cnemial process (another feature shared
>   by a derived theropod, *Acrocanthosaurus*, to a greater degree and
>   morphological similarity to that dinosaur)
>*  the neural spines of the posterior caudals are hypershortened at
>   the half point in the tail

Again, check polarities.

>*  the maxilla is elongate

Damn, someone should really try clarifying exactly what is meant by this... :-]

>*  the naris is expanded posteroanteriorly

A character common to many non-sinraptorid carnosaurs.

>These synapomorphies

Similarity does not equal synapomorphy.  Two forms may be more similar to
each other than to a third if the first two show the primitive state, and
the third the derived.  That does not suggest a closer phylogenetic
relationship between the two primitive forms.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661