New papers in Senckenbergiana Lethaea and more

[bh480@scn.org]

From: Ben Creisler bh480@scn.org

New papers in Senckenbergiana Lethaea and more

I haven't seen these papers yet but the abstracts or 
titles show up in online databases:

Henderson, D.M. & Weishampel, D.B. 2002. Convergent 
evolution of the maxilla-dental-complex among carnivorous 
archosaurs. Senckenbergiana-Lethaea. 82(1): 77-92.
AB: Archosaurs first appeared in the Late Permian, and 
during the subsequent Mesozoic Era they evolved several 
different clades of carnivores, all of which can trace 
their origins back to a primitively carnivorous form. 
Three aspects of the maxillary teeth of carnivorous 
archosaurs were investigated for potential functional 
correspondences with the form of their associated 
maxillary bone: mean and maximal tooth lengths; medio-
lateral and antero-posterior tooth bending strengths; and 
total external surface area of teeth. A fourth 
investigation looked at the depth of the skull relative to 
its length for any potential functional correspondence 
with total tooth area or mean maxillary tooth length. All 
linear and areal dimensions were normalized to correct for 
size-related factors. A good correspondence was found 
between long teeth and teeth with high bending strengths 
and the amount of bone in the ventral region of the 
maxilla; and this condition was observed to have evolved 
independently in rauisuchians, at least three times in 
theropod dinosaurs, and crocodylomorphs. No plausible 
relationship was found between the total surface area of 
the teeth and maxillary form. Working under the assumption 
that larger predators will generally attack and dismember 
larger prey, the observed changes in maxillary form are 
interpreted as a biomechanical response for increasing 
support of the teeth during a phylogenetic increase in 
body size, and the concomitant increase in the size of 
prey. A strong correlation also exists between normalized 
maxillary tooth lengths (mean tooth length divided by 
skull length) and skull aspect ratios (mean skull depth 
divided skull length). It is proposed that increases in 
the length of teeth, and the presumed increase in the 
depth of penetration by the teeth, are associated with an 
increased resistance to sagittal (dorso-ventral) bending 
of the skull for all sizes of carnivorous archosaurs.


Carpenter, K. 2002. Forelimb biomechanics of nonavian 
theropod dinosaurs in predation. Senckenbergiana-Lethaea.  
82(1): 59-76. 
AB: Theoretical models of theropod forelimb biomechanics 
are often tainted with preconceived ideas. Actualistic 
modeling using specimens and casts, coupled with CAT-scans 
and dissections of extant vertebrate forelimbs, 
demonstrates that forelimb motion in theropods is 
considerably less than hypothetical models indicate. The 
forelimbs of Coelophysis, cf. Coelurus. Allosaurus, 
Deinonychus, and Tyrannosaurus were investigated. Motion 
at the shoulder, elbow, wrist, and digits were analyzed 
and compared with those of birds and crocodiles, then 
motion of the entire forelimb was examined. The results 
have considerable implications for forelimb use in 
predation. Three models of predation are recognized: 1) 
long armed grasper-Deinonychus, cf. Coelurus; 2) clutcher -
Tyrannosaurus; 3) combination grasper-clutcher-Allosaurus. 
Analysis of the joints of Deinonychus show that the 
forelimb could not fold avian fashion. The scapula of the 
theropod Unenlagia was oriented incorrectly and differs 
little from the standard theropod scapula.      
                        

Egi, N. & Weishampel, D.B. 2002. Morphometric analyses of 
humeral shapes in Hadrosaurids (Ornithopoda, Dinosauria).  
Senckenbergiana-Lethaea. 82(1): 43-58    
AB: Variation in juvenile and adult humeral morphology 
between the two subfamilies of Hadrosauridae (Ornithopoda, 
Dinosauria) was examined. The sample consisted of five 
hadrosaurine and four lambeosaurine genera and included 
humeri from 28 to 65 centimeters in length. Nineteen 
landmarks associated with articular surfaces and muscle 
attachments were digitized from photographs of humeri in 
posterolateral view, and the data were analyzed using 
three morphometric techniques: Bookstein's coordinates, 
Resistant-Fit Theta-Rho-Analysis, and Euclidean Distance 
Matrix Analysis. Differences in humeral shape were greater 
between adults of the two subfamilies than between the 
juveniles, and the differences between adults and 
juveniles were larger in lambeosaurines than in 
hadrosaurines. Adult lambeosaurines exhibited lateral and 
distal enlargement of the distal part of the deltopectoral 
crest and relative shortening of the shaft distal to the 
deltopectoral crest, resulting in the increased 
performance of the shoulder muscles, particularly Mm. 
pectoralis and deltoides clavicularis. The morphological 
change of the humerus during growth seems to be closely 
associated with the reduction of the humeral length 
relative to antebrachium. The morphological variations in 
hadrosaurid humeri relate to structural adaptations to 
bear increased body size to some extent but also to a 
behavioral specialization among some genera during growth. 
        
Snively, E. &  Russell, A. 2002.T he tyrannosaurid 
metatarsus: Bone strain and inferred ligament function.  
Senckenbergiana-Lethaea. 82(1): 35-42. 
AB: Tyrannosaurid dinosaurs possess a metatarsus with an 
arctometatarsalian proximal constriction of metatarsal 
III, and strongly interlocking proximal articulations. 
Bone and inferred ligament morphologies arc suggestive of 
modes of locomotor energy transmission. CT scanning and 
Finite Element Analysis (FEA) of Gorgosaurus libratus 
metatarsals test two hypotheses of tyrannosaurid 
arctometatarsus function: ligaments mediated transfer of 
energy from the central metatarsal to the outer elements, 
and ligaments arrested anterodorsal rotation of the distal 
portion of the central metatarsal. The results have 
implications for the use of FEA in functional morphology: 
1) strain artifacts are identifiable under low-resolution 
modeling, but higher resolution is better; and 2) bone 
strain aids in testing hypotheses of ligament function. 
Concentrations of bone strain energy under postulated 
loading regimes for Gorgosaurus support the hypothesis of 
axial energy transmission for the tyrannosaurid 
metatarsus, and indirectly support the rotation damping 
hypothesis. Palaeopathology provides a vital complement to 
engineering tests of these hypotheses. 

Stevens, K.A. 2002. DinoMorph: Parametric modeling of 
skeletal structures. Senckenbergiana Lethaea. 82(1): 23-34 
AB: A parametric approach towards modeling is advocated 
for skeletal reconstructions. Three-dimensional digital 
reconstructions are compared with conventional two-
dimensional illustrations, particularly silhouette 
drawings. The advantages of the parametric system provided 
by the DinoMorph<sup>TM</sup> software include: open 
access to all data comprising the model and the rendering 
algorithms for the independent verification of 
reconstructions, tools for parametrically editing and 
manipulating pose, bone, and joint geometry, visualization 
of assemblies in three-dimensions from arbitrary 
perspectives, multiple resolution models of skeletal 
element morphology (from schematic to highly detailed), 
and extensibility to support specific research objectives. 
The system architecture and current capabilities are 
described and illustrated. 
        
Yao, Jinxian, Zhang, Yun  & Tang, Zhilu, 2002. Small 
spheres preserved in a therizinosauroid dinosaur's blood 
vessels from northeast China.  Acta Scientiarum Naturalium 
Universitatis Pekinensis. (2002 Mar 20) 38(2): 221-225.

Caldwell, M.W 2002. From fins to limbs to fins: Limb 
evolution in fossil marine reptiles.
AMERICAN JOURNAL OF MEDICAL GENETICS. (OCT 15 2002) 112 
(3): 236-249
AB: Limb osteology and ontogenetic patterns of limb 
ossification are reviewed for extinct lineages of 
aquatically adapted diapsid reptiles. Phylogenies 
including these fossil taxa show that paddle-like limbs 
were independently derived, and that the varied limb 
morphologies were produced by evolutionary modifications 
to different aspects of the limb skeleton. Ancient marine 
reptiles modify the limb by reducing the relative size of 
the epipodials, modifying the perichondral and periosteal 
surface of elements distal to the propodials, and evolving 
extremes of hyperphalangy and hyperdactyly. Developmental 
genetic models illuminate gene systems that may have 
controlled limb evolution in these animals.