Planet of the New Papers

["Jerry D. Harris" <jharris@dixie.edu>]

A few more things -- thanks to SP for these!:


Mallison, H. 2007. Virtual Dinosaurs -- Developing Computer Aided Design and
Computer Aided Engineering Modeling Methods for Vertebrate Paleontology.
Ph.D. dissertation, Geowissenschaftliche, Eberhard-Karls-Universität
Tübingen, 102 pp.  (available at
http://tobias-lib.ub.uni-tuebingen.de/volltexte/2007/2868/html/index.html)

ABSTRACT: The use of personal computers offers many benefits to researchers
compared to conventional methods, not the least of them the easy
visualization of three-dimensional (3D) structures. With rapidly increasing
computing power, the last few decades have seen the rise of a large number
of new applications for many purposes, some of which have been successfully
employed for vertebrate paleontology. Here, a description is given on how to
use several commercially available computer aided design (CAD) and
kinetic/dynamic Computer Aided Engineering (CAE) modeling software programs
as tools for paleontological research. The focus rests on the creation and
use of ?virtual? bones, for biomechanical analyses and use in reconstruction
of entire skeletons, the use of these ?virtual? skeletons as tools for the
creation of 3D ?flesh? models, which are helpful in mass estimates, and
finally on multi-body kinetic/dynamic modeling, using these ?flesh? models
to analyze posture and gait of extinct dinosaurs.
     Specifically, the following techniques are described, most of which
have been newly developed or significantly improved:
- Mechanical digitizing of fossil bones using Rhinoceros 3.0® and NURBS
curves
- Mechanical digitizing of fossil bones using Rhinoceros 3.0® and point
clouds
- Mounting ?virtual? skeletons from either mechanically digitized bones or
CT-based data
- Creating 3D ?flesh? models from ?virtual? skeletons
- Creating 3D ?flesh? models from laser scan point cloud data of mounted
skeletons
- Creating 3D ?flesh? models from silhouette drawings of skeletons
- Evaluating the accuracy of 2D and 3D reconstructions using ?virtual?
skeletons
- Modeling posture, motions and locomotion of vertebrates in
MSC.visualNastran 4D®.
     CAD and kinetic/dynamic modeling using 3D CAE (Computer Aided
Engineering) computer software prove to be useful tools for vertebrate
paleontology, the latter being especially useful for biomechanical analysis.
     These techniques were employed to study the prosauropod Plateosaurus
engelhardti MEYER from the Löwenstein formation of South-West Germany. Aside
from providing a new insight on mass estimates, it is shown that:
- Plateosaurus was not capable of pronating its manus sufficiently to use
them in a support role during locomotion, nor can the animal have employed
them in knuckle-walking with medially directed palms
- Plateosaurus was not well-balanced in a quadrupedal stance
- Plateosaurus was thus not capable of quadrupedal locomotion
- in addition, quadrupedal locomotion would be ineffective in Plateosaurus
- Plateosaurus was well-balanced when standing in a bipedal posture with a
sub-horizontal backbone and tail
- Plateosaurus can execute all necessary motions, such as lying down and
getting up from the ground from and into a bipedal stance, and can move the
head to the ground without risking the stability of a bipedal stance.
     A locomotion cycle for Plateosaurus was created in the kinetic/dynamic
CAE software, showing bipedal locomotion to be feasible.
     Furthermore, it becomes apparent that
- there is a large amount of variation in the pes morphology of Plateosaurus
engelhardti, requiring further study. Possibly, two or more species have
been included in the taxon.
- Plateosaurus would likely have produced Otozoum-like tracks when walking
bipedally, and Plateosaurus? manus fits the manus imprints of Otozoum, made
in a rare resting pose. The Otozoum-trackmaker was a biped.
- bipedal Pseudotetrasauropus tracks do not stem from animals with the pes
morphology of the skeleton GPIT 1, but may have been produced by closely
related animals.
     Form these results it can be concluded that Plateosaurus was an
obligate biped, and far closer to the basal mode of locomotion in
sauropodomorphs than previously expected. It can be confidently refuted that
plateosaurid dinosaurs created ichnofossils similar to Tetrasauropus.





Nevitt, G.A. 2008. Sensory ecology on the high seas: the odor world of the
procellariiform seabirds. Journal of Experimental Biology 211(11):1706-1713.
doi: 10.1242/jeb.015412.

ABSTRACT: Procellariiform seabirds wander the world's oceans aided by
olfactory abilities rivaling those of any animal on earth. Over the past 15
years, I have been privileged to study the sensory ecology of
procellariiforms, focusing on how olfaction contributes to behaviors,
ranging from foraging and navigation to individual odor recognition, in a
broader sensory context. We have developed a number of field techniques for
measuring both olfactory- and visually based behaviors in chicks and adults
of various species. Our choice of test odors has been informed by long-term
dietary studies and geochemical data on the production and distribution of
identifiable, scented compounds found in productive waters. This
multidisciplinary approach has shown us that odors provide different
information over the ocean depending on the spatial scale. At large spatial
scales (thousands of square kilometers), an olfactory landscape superimposed
upon the ocean surface reflects oceanographic or bathymetric features where
phytoplankton accumulate and an area-restricted search for prey is likely to
be successful. At small spatial scales (tens to hundreds of square
kilometers), birds use odors and visual cues to pinpoint and capture prey
directly. We have further identified species-specific, sensory-based
foraging strategies, which we have begun to explore in evolutionary and
developmental contexts. With respect to chemical communication among
individuals, we have shown that some species can distinguish familiar
individuals by scent cues alone. We are now set to explore the mechanistic
basis for these discriminatory abilities in the context of kin recognition,
and whether or not the major histocompatibility complex is involved.




Weir, J.T., and Schluter, D. 2008. Calibrating the avian molecular clock.
Molecular Ecology 17(10):2321-2328. doi: 10.1111/j.1365-294X.2008.03742.x.

ABSTRACT: Molecular clocks are widely used to date phylogenetic events, yet
evidence supporting the rate constancy of molecular clocks through time and
across taxonomic lineages is weak. Here, we present 90 candidate avian clock
calibrations obtained from fossils and biogeographical events.
Cross-validation techniques were used to identify and discard 16
inconsistent calibration points. Molecular evolution occurred in an
approximately clock-like manner through time for the remaining 74
calibrations of the mitochondrial gene, cytochrome b. A molecular rate of
approximately 2.1% (± 0.1%, 95% confidence interval) was maintained over a
12-million-year interval and across most of 12 taxonomic orders. Minor but
significant variance in rates occurred across lineages but was not explained
by differences in generation time, body size or latitudinal distribution as
previously suggested.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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