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Walk The New Papers



A couple of good 'uns:



Carpenter, K., and Wilson, Y. 2008. A new species of Camptosaurus
(Ornithopoda: Dinosauria) from the Morrison Formation (Upper Jurassic) of
Dinosaur National Monument, Utah, and a biomechanical analysis of its
forelimb. Annals of the Carnegie Museum 76(4):227-263.

ABSTRACT: A new species, Camptosaurus aphanoecetes, is named for a partial
skeleton of ornithopod dinosaur from the Morrison Formation (Upper Jurassic)
of Dinosaur National Monument, Utah. The specimen was originally described
as Camptosaurus medius Marsh, 1894, and later referred to Camptosaurus
dispar (Marsh, 1879). Comparison of the specimen with a large sample of C.
dispar from Quarry 13 shows differences in the proportions and shape of
various axial and appendicular elements. Based on the dorsoventrally
depressed form of the ilium, Camptosaurus depressus Gilmore, 1909 (Lower
Cretaceous of South Dakota) is assigned to the Barremian genus Planicoxa
DiCroce and Carpenter, 2001, as Planicoxa depressa, new combination. The
well-preserved, undistorted forelimb material of C. aphanoecetes allows for
a biomechanical analysis. The range of motion is rather limited throughout
the forelimb. The analysis supports the quadrupedal locomotion previously
hypothesized for Camptosaurus Marsh, 1885, from limb ratios, fusion of the
wrist, and presence of short digits.



Zhou, Z., Clarke, J., and Zhang, F. 2008. Insight into diversity, body size
and morphological evolution from the largest Early Cretaceous
enantiornithine bird. Journal of Anatomy. doi:
10.1111/j.1469-7580.2008.00880.x.

ABSTRACT: Most of Mesozoic bird diversity comprises species that are part of
one of two major lineages, namely Ornithurae, including living birds, and
Enantiornithes, a major radiation traditionally referred to as 'opposite
birds'. Here we report the largest Early Cretaceous enantiornithine bird
from north-east China, which provides evidence that basal members of
Enantiornithes share more morphologies with ornithurine birds than
previously recognized. Morphological evolution in these two groups has been
thought to be largely parallel, with derived members of Enantiornithes
convergent on the 'advanced' flight capabilities of ornithurine birds. The
presence of an array of morphologies previously thought to be derived within
ornithurine and enantiornithine birds in a basal enantiornithine species
provides evidence of the complex character evolution in these two major
lineages. The cranial morphology of the new specimen is among the best
preserved for Mesozoic avians. The new species extends the size range known
for Early Cretaceous Enantiornithes significantly and provides evidence of
forelimb to hind limb proportions distinct from all other known members of
the clade. As such, it sheds new light on avian body size evolution and
diversity, and allows a re-evaluation of a previously proposed hypothesis of
competitive exclusion among Early Cretaceous avian clades.

(names _Pengornis houi_ and mentions that _Aberratiodontus wui_ isn't an
enantiornithean and may be synonymous with _Yanornis_)



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jerry D. Harris
Director of Paleontology
Dixie State College
Science Building
225 South 700 East
St. George, UT  84770   USA
Phone: (435) 652-7758
Fax: (435) 656-4022
E-mail: jharris@dixie.edu
 and     dinogami@gmail.com
http://cactus.dixie.edu/jharris/

"There's a saying that goes 'people who live in glass houses shouldn't throw
stones'... OK. How about...NOBODY should throw stones. That's crappy
behavior! My policy is 'no stone-throwing regardless of housing situation.'
There's an exception, though. If you're TRAPPED in a glass house...and you
have a stone, then throw it! What are you, an idiot? It's really 'ONLY
people in glass houses should throw stones'... provided they're trapped, in
a house... with a stone. It's a little longer, but you know..."
                                 --- Demetri Martin