The men who stare at dinosaurs

[Jocelyn Falconnet <j.falconnet@gmail.com>]

A Jerry Harris' style mail to announce the next release of the following 
papers in Acta Palaeontologica Polonica:

Dermal armor histology of Saltasaurus loricatus, an Upper Cretaceous 
sauropod dinosaur from Northwest Argentina
Ignacio A. Cerda and Jaime E. Powell
Acta Palaeontologica Polonica in press
available online 24 Mar 2010

The first unambiguous evidence of the presence of osteoderms in sauropod 
dinosaurs came from the discovery of Saltasaurus loricatus, a titanosaur 
from the Upper Cretaceous of Argentina. The dermal armor of Saltasaurus 
is composed of bony plates and small dermal ossicles. Here, we analyze 
the bone microstructure of these elements and provide information 
regarding its origin and development. The bony plates are composed 
almost entirely of reconstructed cancellous bone. Remains of primary 
bone consist of coarse bundles of mineralized collagenous fibers towards 
the external surface. Also, woven fibered bone tissue appears in the 
basal and lateral regions. Dermal ossicles lack secondary remodeling, 
and their matrix is formed by three orthogonal systems of collagenous 
fiber bundles. Growth lines are present in both bony plates and 
ossicles. Bone histology reveals that osteoderms mainly originated 
through direct mineralization (metaplasia) of the dermis, although other 
mechanisms are also involved (at least in the origin of dermal plates). 
The common features of development and integumental location of the 
osteoderms of Saltasaurus and other non-related vertebrates (e.g., 
lepidosaurs, crocodylomorphs) are linked to the intrinsic skeletogenic 
properties of the dermis.

http://www.app.pan.pl/article/item/app20091101.html

Evidence for a sauropod-like metacarpal configuration in stegosaurian 
dinosaurs
Phil Senter
Acta Palaeontologica Polonica in press
available online 24 Mar 2010

The stegosaurian forelimb is usually portrayed with the metacarpals 
slanted and distally spread. However, manual manipulation of 
stegosaurian metacarpals reveals that in that configuration they do not 
articulate with each other nor with the rest of the forelimb. Rather, 
they do articulate with each other and with the rest of the forelimb 
when posed vertically and arranged in a compact, semi-tubular 
configuration, as in sauropods. This configuration agrees with data from 
articulated specimens and trackways. As with sauropods, this metacarpal 
configuration makes retention of phalanges awkward for locomotion and 
may be functionally related to the vestigiality of the manual phalanges 
of the outer digits.

http://www.app.pan.pl/article/item/app20091105.html

The digital Plateosaurus II: an assessment of the range of motion of the 
limbs and vertebral column and of previous reconstructions using a 
digital skeletal mount
Heinrich Mallison
Acta Palaeontologica Polonica in press
available online 08 Mar 2010

Scientific literature and museum exhibits are full of explicit and 
implicit claims about the possible postures and motion ranges of 
dinosaurs. For the example of the prosauropod Plateosaurus engelhardti 
Meyer, 1837 I assessed the motion range of limbs and vertebral column in 
a CAD program using a 3D virtual skeletal mount. The range of motion of 
the forelimb is very limited, allowing the grasping of objects placed 
directly ventrally and ventrolaterally of the anterior torso. The manus 
is adapted for grasping. The powerful fore limb can barely reach in 
front of the shoulder, making a quadrupedal walking cycle impractical. 
Only a digitigrade pose of the pes with a steeply held metatarsus is 
feasible, and the morphology of the stylopodium and zeugopodium 
indicates a slightly flexed limb posture. Hind limb protraction and 
retraction are limited by the pelvic architecture. The neck has 
significant mobility both dorsoventrally and laterally, but blocks 
torsion. The dorsal vertebral column is flexible to a degree similar to 
the neck, mainly in the anterior half, but blocks torsion totally in the 
anterior and posterior thirds. The anterior dorsals are similar in shape 
to the posterior cervicals and significantly increase the motion range 
of the neck. The tail is highly flexible due to its large number of 
elements, showing more lateral than dorsoventral mobility. These results 
are compared to reconstruction drawings and museum skeletal mounts, 
highlighting a pattern of errors specific to certain widely used 
reconstruction methods.

http://www.app.pan.pl/article/item/app20090075.html