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The Art of the New Papers

Chure, D., Britt, B.B., Whitlock, J.A., and Wilson, J.A. 2010. First
complete sauropod dinosaur skull from the Cretaceous of the Americas and the
evolution of sauropod dentition. Naturwissenschaften. doi:

ABSTRACT: Sauropod dinosaur bones are common in Mesozoic terrestrial
sediments, but sauropod skulls are exceedingly rare?cranial materials are
known for less than one third of sauropod genera and even fewer are known
from complete skulls. Here we describe the first complete sauropod skull
from the Cretaceous of the Americas, Abydosaurus mcintoshi, n. gen., n. sp.,
known from 104.46±0.95 Ma (megannum) sediments from Dinosaur National
Monument, USA. Abydosaurus shares close ancestry with Brachiosaurus, which
appeared in the fossil record ca. 45 million years earlier and had
substantially broader teeth. A survey of tooth shape in sauropodomorphs
demonstrates that sauropods evolved broad crowns during the Early Jurassic
but did not evolve narrow crowns until the Late Jurassic, when they occupied
their greatest range of crown breadths. During the Cretaceous,
brachiosaurids and other lineages independently underwent a marked
diminution in tooth breadth, and before the latest Cretaceous broad-crowned
sauropods were extinct on all continental landmasses. Differential survival
and diversification of narrow-crowned sauropods in the Late Cretaceous
appears to be a directed trend that was not correlated with changes in plant
diversity or abundance, but may signal a shift towards elevated tooth
replacement rates and highwear dentition. Sauropods lacked many of the
complex herbivorous adaptations present within contemporaneous ornithischian
herbivores, such as beaks, cheeks, kinesis, and heterodonty. The spartan
design of sauropod skulls may be related to their remarkably small
size?sauropod skulls account for only 1/200th of total body volume compared
to 1/30th body volume in ornithopod dinosaurs.

Garcia R.A., and Cerda, I.A. 2010. Dentition and histology in titanosaurian
dinosaur embryos from Upper Cretaceous of Patagonia, Argentina.
Palaeontology. doi: 10.1111/j.1475-4983.2010.00937.x.

ABSTRACT: Exceptionally preserved sauropod embryos from the Late Cretaceous
Anacleto Formation in Auca Mahuevo (Neuquén Province, Argentina) have
provided fundamental information on titanosaurian ontogeny. This paper
describes the dental composition, disposition and microstructure of the
specimens. Embryonic teeth show size disparity, with lengths that vary from
1 to 3 mm and diameters ranging from 0.15 to 0.26 mm, with the most frequent
length values between 2.5 and 3 mm. Apparently, a typical 'pencil-like'
tooth morphology and a dental formula of Pm 4, M 7?8/D10? remained constant
during titanosaurian ontogeny, whereas the arrangement of teeth in the skull
shows notable ontogenetic changes. Absence of wear facets on teeth suggests
a lack of prenatal chewing movements. The enamel proportion is significantly
higher in embryos than in mature titanosaurs, which suggests that this
relationship varies during ontogeny. Embryonic bony tissue is composed of
highly vascularized, cellular woven bone. The absence of osteonal tissue,
the high degree of vascularization, the presence of numerous osteocytes and
poor development of periosteal bone reveals that the Auca Mahuevo
titanosaurs would have had a high early growth rate and that they were
buried at a relatively advanced embryonic stage.

Hayashi, S., Carpenter, K., Scheyer, T.M., Watabe, M., and Suzuki, D. 2010.
Function and evolution of ankylosaur dermal armor. Acta Palaeontologica

ABSTRACT: Ankylosaurs have spike-, plate-, and club-shaped osteoderms
probably used as defensive and/or offensive weapons. Previous studies have
proposed the evolution and function of small ankylosaur osteoderms, but
histological variations in their defensive weapons are little known. Here,
we provide comparisons of the internal structures in defensive weapons of
ankylosaurs, which shed light on understanding their evolutionary history
and function. Histological features of spikes, plates, and clubs are similar
to those of small osteoderms in having thin compact bone, thick cancellous
bone with large vascular canals, and abundant collagen fibers. A previous
study demonstrated that each of the three groups of ankylosaurs (the
Polacanthidae, Nodosauridae, and Ankylosauridae) have distinct arrangements
of collagen fibers in small osteoderms. This study shows that spikes and
clubs of ankylosaurs maintain the same characteristic features for each
group despite the differences in shapes and sizes. These histological
similarities suggest that various types of osteoderms in ankylosaurs
retained the thin compact bone and abundant fiber structures of the small
osteoderms during their evolution. Polacanthid spikes show thin compact
bone, with less collagen fibers than in spikes of nodosaurids and spikes and
clubs of ankylosaurids. Also, ankylosaurid plates with hollow bases are very
thin in morphology and show thin compact bone. These results imply that the
bone strengths of polacanthid spikes and ankylosaurid plates are lower than
spikes and clubs of other ankylosaurs, indicating that they may be used more
probably as display and/or thermoregulation rather than as weapons. It is
thus probable that ankylosaur armor in general played more than just a
defensive role.

Otero, R.A., Soto-Acuña, S., and Rubilar-Rogers, D. 2010. Presence of
Mauisaurus Hector (Plesiosauroidea, Elasmosauridae) in the Late Cretaceous
(Maastrichtian) of central Chile. Acta Palaeontologica Polonica.

ABSTRACT: The revision by Hiller et al. (2005) of the species Mauisaurus
haasti Hector (Plesiosauroidea, Elasmosauridae) from the Late Cretaceous of
New Zealand, has provided reliable postcranial characters that permit
recognition of this taxon as distinct among Late Cretaceous elasmosaurid
plesiosaurs from both the Northern and Southern hemispheres. Particularly,
in adult specimens, the femur displays a large, hemispherical capitulum that
seems to be autapomorphic. This unique morphology is present in at least two
specimens recovered from Late Cretaceous (Maastrichtian) beds in central
Chile, which these fossils may be referred to the same taxon with
confidence. The Chilean fossils are considerably larger than those from New
Zealand, suggesting either difference in ontogenetic age or interspecific
variation. The studied material constitutes the second accurate generic
identification of elasmosaurid plesiosaurs from the eastern margin of the
Pacific Ocean, thus complementing the known south-gondwanic
paleodistribution of Mauisaurus during the Late Cretaceous.

Fechner, R. 2009. Morphofunctional Evolution of the Pelvic Girdle and
Hindlimb of Dinosauromorpha on the Lineage to Sauropoda. Fakultät für
Geowissenschaften, Ludwigs Maximilians Universität, Munich, 197 pp.

(available at http://edoc.ub.uni-muenchen.de/10954/1/Fechner_Regina.pdf)

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

"I have noticed even people who
claim everything is predestined, and
that we can do nothing to change it,
look before they cross the road."

                   -- Stephen Hawking

"Prediction is very difficult,
especially of the future."

                   -- Niels Bohr