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Burn After New Papers



Some more...


Wilkinson, M.T. 2008. Three-dimensional geometry of a pterosaur wing
skeleton, and its implications for aerial and terrestrial locomotion.
Zoological Journal of the Linnean Society 154(1):27-69. doi:
10.1111/j.1096-3642.2008.00409.x.

ABSTRACT: This study reports on the three-dimensional spatial arrangement
and movements of the skeleton of Anhanguera santanae (Pterodactyloidea:
Ornithocheiridae), determined using exceptionally well-preserved uncrushed
fossil material, and a rigid-body method for analysing the joints of extinct
animals. The geometric results of this analysis suggest that the
ornithocheirids were inherently unstable in pitch and yaw. As a result,
pitch control would probably have been brought about by direct adjustment of
the angle of attack of the wing, by raising or lowering the trailing edge
from the root using the legs if, as is indicated in soft-tissue specimens of
a number of unrelated pterosaur species, the legs were attached to the main
wing membrane, or by using long-axis rotations at the shoulder or wrist to
raise and lower the trailing edge from the wingtip. An analysis of the
three-dimensional morphology of the wrist lends support to the idea that the
pteroid - a long, slender wrist bone unique to pterosaurs that supported a
membranous forewing - was directed forwards in flight, not towards the body.
As a result, the forewing could have fulfilled the function of an air-brake
and high-lift device, and may also have had an important role in pitch, yaw,
and roll control. The joint analysis is consistent with a semi-erect
quadrupedal model of terrestrial locomotion in the ornithocheirids.




Tweet, J.S., Chin, K., Braman, D.R., and Murphy, N.L. 2008. Probable gut
contents within a specimen of Brachylophosaurus canadensis (Dinosauria:
Hadrosauridae) from the Upper Cretaceous Judith River Formation of Montana.
Palaios 23(9):624-635. doi: 10.2110/palo.2007.p07-044r.

ABSTRACT: An exceptionally preserved subadult specimen (JRF 115H) of a
hadrosaurid, Brachylophosaurus canadensis, from the Judith River Formation
near Malta, Montana, contains abundant plant fragments concentrated within
the body cavity. We examined the taphonomy of the carcass and analyzed the
gut-region material to test whether the organic remains represent fossilized
gut contents. The dinosaur was buried in a fluvial channel setting, and the
excellent articulation, integument impressions, and lack of scavenging
indicate rapid burial. The organic material occupies a volume of at least
5750 cm3, and comparable material is not found outside the carcass. The
carcass contents include ~63% clay, ~16% undetermined matrix,~12% organic
matter, and ~9% larger inorganic clasts-mostly 50-100 mm quartz grains. Most
of the organics appear to be mm-scale leaf fragments. The most parsimonious
explanation for the presence and composition of the gut-region material is
that much of the plant fossils represent reworked brachylophosaur ingesta
influenced by flowing water that entered through openings in the carcass and
introduced clay. The evidence strongly suggests that the hadrosaurid ate
significant quantities of leaves and processed them into small pieces. This
study provides baseline information for analyzing other cases of putative
gut contents in herbivorous dinosaurs.




Jin, F., Zhang, F., Li, Z., Zhang, J., Li, C., and Zhou, Z. 2008. On the
horizon of Protopteryx and the early vertebrate fossil assemblages of the
Jehol Biota. Chinese Science Bulletin.

ABSTRACT: Protopteryx, a monotypic fossil bird discovered from the Sichakou
basin in Fengning, Hebei, is the most primitive enantiornithine currently
known. The bird-bearing strata do not contain the index fossils of the
Yixian Formation in western Liaoning; the fish and bird fossils have more
primitive features than the related forms found in the Yixian Formation, and
the conchostracans are those usually distributed in the Dabeigou and
Dadianzi formations in northern Hebei. Besides, the Protopteryx-bearing
strata underlie the deposits bearing the index fossils of the Yixian
Formation in the neighboring basin. Thus, it could be confirmed that the
horizon of Protopteryx should be lower than the Yixian Formation, and is
approximately equivalent to the Dadianzi Formation in northern Hebei. This
is the lowest horizon of the known fossil birds in China and Mesozoic
enantiornithine birds in the world. Accompanying Protopteryx, there are
other birds, acipenseriform fishes, salamanders, and mammals, which compose
the Peipiaosteus fengningensis-Protopteryx fengningensis assemblage. This
new assemblage traces the vertebrate evolution history of the Jehol Biota
back to 130.7 Ma before. It is suggested that the demarcation of the Jehol
Biota should be based on the large-scale tectonic-sedimentary cycles, and
Peipiaosteus, instead of Lycoptera, could be taken as the vertebrate
representative of the Jehol Biota.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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/

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