Lots O' New Refs

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

Hi All -

   Everyone's been so good at getting stuff posted here before me, so I 
haven't bothered in a while.  But here's some new stuff...


Kielan-Jaworowska, K., and Hurum, J.H. 2006. Limb posture in early mammals: 
sprawling or parasagittal. Acta Palaeontologica Polonica 51(3):393-406.

ABSTRACT: The limb posture in early mammals is a matter of controversy. 
Kielan-Jaworowska and Gambaryan presented arguments for a sprawling posture 
in multituberculates, based mainly on three characters of the hind limbs 
(deep pelvis, mediolateral diameter of the tibia larger than the 
craniocaudal, and position of MtV, which fits the peroneal groove on the 
calcaneus and is not aligned with the axis of tuber calcanei). Here we 
present two more arguments for sprawling hind limbs in early mammals. One is 
the presence of an os calcaris, supporting the probably venomous spur in 
hind legs of docodontans, multituberculates, eutriconodontans, and 
"symmetrodontans", similar to those of extant monotremes. We argue that 
early mammals (except for boreosphenidans) had sprawling limb posture and 
venomous spur; acquisition of the parasagittal stance was apparently 
characteristic only of boreosphenidans, in which the spur has not been 
found. The second argument is based on taphonomic evidence from lacustrine 
conditions (e.g., Early Cretaceous Jehol Biota), in which the mammalian 
skeletons, except for boreosphenidans (Sinodelphys and Eomaia), have been 
preserved compressed dorso-ventrally, suggesting sprawling stance. In 
similar conditions of the Eocene Messel Biota the skeletons of 
boreosphenidan mammals (except for bats and pangolins) are preserved lying 
on flanks, suggesting parasagittal stance. Sereno argued that forelimbs in 
multituberculates were parasagittal, based on the stated presence of a 
ventrally facing glenoid, a mobile shoulder joint, and an elbow joint with 
enhanced flexion-extension capability. However, these characters are not 
unequivocally indicative of parasagittalism. We demonstrate that the 
structure of the distal end of the multituberculate humerus is condylar, 
with no tendency for developing a trochlea. We reconstruct multituberculates 
and other early mammals with sprawling stance in resting position as 
plantigrade.


Lamanna, M.C., You, H.-L., Harris, J.D., Chiappe, L.M., Ji, S.-A., Lü, 
J.-C., and Ji, Q. 2006. An enantiornithine (Aves: Ornithothoraces) partial 
skeleton from the Early Cretaceous of northwestern China. Acta 
Palaeontologica Polonica 51(3):423-434.

ABSTRACT: Although recent discoveries from Lower Cretaceous sediments in 
northeastern China have greatly improved our understanding of the initial 
stages of avian diversification in eastern Asia, the early evolution of Aves 
elsewhere on the continent remains poorly understood. In 2004, a 
collaborative field effort directed by personnel from the Chinese Academy of 
Geological Sciences and Carnegie Museum of Natural History recovered 
multiple partial to nearly complete avian skeletons from outcrops of the 
Lower Cretaceous Xiagou Formation exposed in the Changma Basin of 
northwestern Gansu Province, China. Here we describe a thrush-sized partial 
skeleton comprised of a fragmentary pelvic girdle and largely complete hind 
limbs. A phylogenetic analysis of 20 avian ingroup taxa and 169 anatomical 
characters places the specimen in Enantiornithes, and within that clade, in 
Euenantiornithes. When coupled with additional recent discoveries from the 
Changma Basin, the new skeleton improves our understanding of early avian 
evolution and diversification in central Asia.


Snively, E., Henderson, D.M., and Phillips, D.S. 2006. Fused and vaulted 
nasals of tyrannosaurid dinosaurs: implications for cranial strength and 
feeding mechanics. Acta Palaeontologica Polonica 51(3):435-454.

ABSTRACT: Tyrannosaurid theropods display several unusual adaptations of the 
skulls and teeth. Their nasals are fused and vaulted, suggesting that these 
elements braced the cranium against high feeding forces. Exceptionally high 
strengths of maxillary teeth in Tyrannosaurus rex indicate that it could 
exert relatively greater feeding forces than other tyrannosaurids. Areas and 
second moments of area of the nasals, calculated from CT cross-sections, 
show higher nasal strengths for large tyrannosaurids than for Allosaurus 
fragilis. Cross-sectional geometry of theropod crania reveals high second 
moments of area in tyrannosaurids, with resulting high strengths in bending 
and torsion, when compared with the crania of similarly sized theropods. In 
tyrannosaurids trends of strength increase are positively allomeric and have 
similar allometric exponents, indicating correlated progression towards 
unusually high strengths of the feeding apparatus. Fused, arched nasals and 
broad crania of tyrannosaurids are consistent with deep bites that impacted 
bone and powerful lateral movements of the head for dismembering prey.


Monsch, K.A. 2006. The PhyloCode, or alternative nomenclature: why it is not 
beneficial to palaeontology, either. Acta Palaeontologica Polonica 
51(3):521-524.


Turner, A.H. 2006. Osteology and phylogeny of a new species of Araripesuchus 
(Crocodyliformes: Mesoeucrocodylia) from the Late Cretaceous of Madagascar. 
Historical Biology 18(3):255-369. doi: 10.1080/08912960500516112.

ABSTRACT: A new species of Araripesuchus present in the Maevarano Formation 
of Madagascar is described. The taxon is known from at least five 
individuals, including a nearly complete animal, three partial skulls and 
associated post-cranial remains, as well as disarticulated post-cranial 
elements. This large sample, coupled with CT-scans, allows a detailed 
description of its morphology. The new form shares a number of derived 
characters with Araripesuchus gomesii and Araripesuchus patagonicus, but is 
distinguished from them by the presence of four autapomorphies. 
Additionally, the new form lacks a number of derived features present in A. 
gomesii and A. patagonicus.
Phylogenetic relationships of Araripesuchus are evaluated using a parsimony 
analysis including 29 mesoeucrocodylian taxa. In all of the most 
parsimonious trees the new taxon is recovered as sister group to A. 
gomesii+A. patagonicus. Araripesuchus is diagnosed by five unambiguous 
synapomorphies and forms a clade with the Malagasy crocodyliform 
Mahajangasuchus insignis and peirosaurids. This group is depicted as more 
closely related to neosuchians than to notosuchians. When Araripesuchus 
wegeneri is included in the analysis, it is recovered as a member of the 
Araripesuchus clade. Although, its position in the clade is unresolved and 
character support is weak, this finding supports A. wegeneri as a valid 
species of Araripesuchus.


O'Connor, P.M. 2006. Postcranial pneumaticity: an evaluation of soft-tissue 
influences on the postcranial skeleton and the reconstruction of pulmonary 
anatomy in archosaurs. Journal of Morphology 267(10):1199-1226. doi: 
10.1002/jmor.10470.

ABSTRACT: Postcranial pneumaticity has been reported in numerous extinct 
sauropsid groups including pterosaurs, birds, saurischian dinosaurs, and, 
most recently, both crurotarsan and basal archosauriform taxa. By comparison 
with extant birds, pneumatic features in fossils have formed the basis for 
anatomical inferences concerning pulmonary structure and function, in 
addition to higher-level inferences related to growth, metabolic rate, and 
thermoregulation. In this study, gross dissection, vascular and pulmonary 
injection, and serial sectioning were employed to assess the manner in which 
different soft tissues impart their signature on the axial skeleton in a 
sample of birds, crocodylians, and lizards. Results from this study indicate 
that only cortical foramina or communicating fossae connected with large 
internal chambers are reliable and consistent indicators of pneumatic 
invasion of bone. As both vasculature and pneumatic diverticula may produce 
foramina of similar sizes and shapes, cortical features alone do not 
necessarily indicate pneumaticity. Noncommunicating (blind) vertebral fossae 
prove least useful, as these structures are associated with many different 
soft-tissue systems. This Pneumaticity Profile (PP) was used to evaluate the 
major clades of extinct archosauriform taxa with purported postcranial 
pneumaticity. Unambiguous indicators of pneumaticity are present only in 
certain ornithodiran archosaurs (e.g., sauropod and theropod dinosaurs, 
pterosaurs). In contrast, the basal archosauriform Erythrosuchus africanus 
and other nonornithodiran archosaurs (e.g., parasuchians) fail to satisfy 
morphological criteria of the PP, namely, that internal cavities are absent 
within bone, even though blind fossae and/or cortical foramina are present 
on vertebral neural arches. An examination of regional pneumaticity in 
extant avians reveals remarkably consistent patterns of diverticular 
invasion of bone, and thus provides increased resolution for inferring 
specific components of the pulmonary air sac system in their nonavian 
theropod ancestors. By comparison with well-preserved exemplars from within 
Neotheropoda (e.g., Abelisauridae, Allosauroidea), the following pattern 
emerges: pneumaticity of cervical vertebrae and ribs suggests pneumatization 
by lateral vertebral diverticula of a cervical air sac system, with sacral 
pneumaticity indicating the presence of caudally expanding air sacs and/or 
diverticula. The identification of postcranial pneumaticity in extinct taxa 
minimally forms the basis for inferring a heterogeneous pulmonary system 
with distinct exchange and nonexchange (i.e., air sacs) regions. Combined 
with inferences supporting a rigid, dorsally fixed lung, osteological 
indicators of cervical and abdominal air sacs highlight the fundamental 
layout of a flow-through pulmonary apparatus in nonavian theropods.


Schwarz, D., and Fritsch, G. 2006. Pneumatic structures in the cervical 
vertebrae of the Late Jurassic Tendaguru sauropods Brachiosaurus brancai and 
Dicraeosaurus. Eclogae Geologicae Helvetiae 99(1):65-78. doi: 
10.1007/s00015-006-1177-x.

ABSTRACT: The presacral vertebrae of sauropod dinosaurs were surrounded and 
invaded by a complex system of pneumatic diverticula, which originated most 
probably from cervical air sacs connected with the respiratory apparatus. 
Cervical vertebrae of Brachiosaurus brancai and Dicraeosaurus sp., two 
sauropods from the Late Jurassic (?Oxfordian-Kimmerigian-Tithonian) eastern 
African locality Tendaguru, were examined with computed tomography to 
visualize internal pneumatic structures. With this method, comparative 
reconstructions of pneumatic diverticula in the neck of these sauropods were 
done that help to understand the biomechanical role of vertebral 
pneumaticity in sauropods. Internal pneumatic structures in Brachiosaurus 
brancai are semicamellate with few large camerae in the vertebral centrum, 
surrounded by pneumatic camellae. Dicraeosaurus exhibits a procamerate 
pneumatization pattern with few deep fossae penetrating to a broad median 
strut in the vertebra, but no internal pneumaticity was found. The 
semicamellate pneumatization pattern of Brachiosaurus brancai corresponds 
with another Late Jurassic Brachiosaurus specimen, whereas in Cretaceous 
brachiosaurid taxa like Sauroposeidon, the complexity of internal 
pneumatization increases to form a fully camellate pneumatization pattern. 
In Dicraeosaurus, internal pneumatization has most likely secondarily been 
reduced.
Brachiosaurus and Dicraeosaurus possess a similar distribution of main 
external pneumatic diverticula, with Brachiosaurus having much more 
subdivided diverticula. Due to the weight reduction achieved by these 
pneumatic diverticula, the neck of Brachiosaurus was up to 25 per cent 
lighter than without pneumatic structures, whereas that of Dicraeosaurus was 
only 6 per cent lighter. Pneumatization of the cervical vertebrae therefore 
can play an important role in lightening some sauropods.


Li, J.-J., Bater, M., Zhang, W.-H., Hu, B.-L., and Gao, L.-H. 2006. A new 
type of dinosaur tracks from Lower Cretaceous Otog Qi, Inner Mongolia. Acta 
Palaeontologica Sinica 45(2):221-234.

ABSTRACT: Thousands of footprints have been documented in 8 localities since 
the first scientific discovery of the dinosaur footprints in the Lower 
Cretaceous of Chabu (Qab) district in Otog Qi , Ordos city, Inner Mongolia 
in 1981 (Gao Shang-yu et al., 1981). The footprints are widely distributed 
on more than 500 square kilometers in Chabu area, including theropod, 
sauropod and bird footprints as well. We did detailed survey on the Chabu 
area in 2002 and 2004 and found many new localities of dinosaur and bird 
fooprints, among which a new type of theropod dinosaur footprints Chapus 
lockleyi ichnogen. et ichnosp. nov has been recognized.


Maidment, S.C.R., and Wei, G. 2006. A review of the Late Jurassic stegosaurs 
(Dinosauria, Stegosauria) from the People's Republic of China. Geological 
Magazine 143(5):621-634. doi: 10.1017/S0016756806002500.

ABSTRACT: Seven genera of stegosaurian dinosaur have been named on the basis 
of material from the Upper Jurassic of China, and this represents a 
diversity of stegosaurs unparalleled around the world at this time. However, 
many of the original specimens used to diagnose and describe these species 
are currently unavailable, and the original descriptions and figures are 
often inadequate. The Chinese stegosaurs have proven 'unstable' in the few 
cladistic analyses of Stegosauria that have been carried out, causing a loss 
of resolution in cladograms. Supplementary data on previously described 
specimens are presented here along with a taxonomic revision. Only 
Tuojiangosaurus multispinus, Chungkingosaurus jiangbeiensis and 
Gigantspinosaurus sichuanensis are considered to be valid taxa, with 
autapomorphies pertaining to features of the ilio-sacral blocks and dermal 
armour in all cases. The holotype specimen of 'Chialingosaurus kuani' is a 
juvenile, bearing no diagnostic characters, and 'Monkonosaurus lawulacus' is 
based on fragmentary and undiagnostic material. 'Changtusaurus' and 
'Yingshanosaurus' have never been described or figured and their whereabouts 
are unknown, so they are regarded as nomina nuda. This taxonomic revision 
significantly reduces known stegosaurian diversity worldwide, and shows that 
the Chinese diversity was similar to that of Europe and North America in the 
Upper Jurassic. Previously, it had been suggested that the diversity of 
Chinese stegosaurs indicated an Asian origin for the clade, a claim that 
cannot now be upheld.


Meekangvan, P., Barhorst, A.A., Burton, T.D., Chatterjee, S., and Schovanec, 
L. 2006. Nonlinear dynamical model and response of avian cranial kinesis. 
Journal of Theoretical Biology 240(1):32-47. doi: 
10.1016/j.jtbi.2005.08.027.

ABSTRACT: All modern birds have kinetic skulls in which the upper bill can 
move relative to the braincase, but the biomechanics and motion dynamics of 
cranial kinesis in birds are poorly understood. In this paper, we model the 
dynamics of avian cranial kinesis, such as prokinesis and proximal 
rhynchokinesis in which the upper jaw pivots around the nasal-frontal (N-F) 
hinge. The purpose of this paper is to present to the biological community 
an approach that demonstrates the application of sophisticated predictive 
mathematical modeling tools to avian kinesis. The generality of the method, 
however, is applicable to the advanced study of the biomechanics of other 
skeletal systems.
The paper begins with a review of the relevant biological literature as well 
as the essential morphology of avian kinesis, especially the mechanical 
coupling of the upper and lower jaw by the postorbital ligament. A planar 
model of the described bird jaw morphology is then developed that maintains 
the closed kinematic topology of the avian jaw mechanism. We then develop 
the full nonlinear equations of motion with the assumption that the M. 
protractor pterygoideus and M. depressor mandibulae act on the quadrate as a 
pure torque, and the nasal frontal hinge is elastic with damping.
The mechanism is shown to be a single degree of freedom device due to the 
holonomic constraints present in the quadrate-jugal bar-upper 
jaw-braincase-quadrate kinematic chain as well as the quadrate-lower 
jaw-postorbital ligament-braincase-quadrate kinematic chain. The full 
equations are verified via simulation and animation using the parameters of 
a Grey Heron (Ardea cinerea). Next we develop a simplified analytical model 
of the equations by power series expansion. We demonstrate that this model 
reproduces the dynamics of the full model to a high degree of fidelity. We 
proceed to use the harmonic balance technique to develop the frequency 
response characteristics of the jaw mechanism. It is shown that this avian 
cranial kinesis model exhibits the characteristics of a hardening Duffing 
oscillator.
Beyond the identification of the characteristics of the underlying dynamics, 
which provides insight into the behavior of the system, the model and 
methodology presented here provides other potential benefits. A framework 
has been developed that could be utilized to study the biomechanics of 
feeding and bite force as well the effects of cranial kinesis on the 
frequency and modulation of bird songs.


Harris, J.D. 2006. The axial skeleton of the dinosaur Suuwassea emilieae 
(Sauropoda: Flagellicaudata) from the Upper Jurassic Morrison Formation of 
Montana, USA. Palaeontology 49(5):1091-1121. doi: 
10.1111/j.1475-4983.2006.00577.x.

ABSTRACT: Vertebrae of Suuwassea demonstrate an interesting combination of 
plesiomorphies and autapomorphies among known members of the 
Flagellicaudata. The cranial cervical vertebrae have proportions close to 
Diplodocus but resemble those of Apatosaurus except by having greatly 
reduced cranial and caudal spinozygapophyseal laminae. As a result, they 
have craniocaudally compressed, caudally positioned spinous processes 
excavated on all sides by fossae. The cranial thoracic vertebrae are again 
similarly proportioned as those of Diplodocus but are morphologically 
similar to those of Apatosaurus. The most distinguishing feature of 
Suuwassea caudal vertebrae are the short, amphiplatyan, distalmost 'whiplash' 
caudal vertebrae. These may be either a retention of or a reversal to the 
plesiomorphic sauropod condition because classic flagellicaudatan, biconvex 
distalmost caudals occur in the Middle Jurassic of England.

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

"Actually, it's a bacteria-run planet, but
mammals are better at public relations."
                                     -- Dave Unwin