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A sauropod paper and a buttload of ornithopod ones



Christian, A. 2010. Some sauropods raised their necks?evidence for high
browsing in Euhelopus zdanskyi. Biol. Lett. published online before print
June 2, 2010, doi:10.1098/rsbl.2010.0359

Abstract

A very long neck that is apparently suitable for feeding at great heights is
a characteristic feature of most sauropod dinosaurs. Yet, it remains
controversial whether any sauropods actually raised their necks high.
Recently, strong physiological arguments have been put forward against the
idea of high-browsing sauropods, because of the very high blood pressure
that appears to be inevitable when the head is located several metres above
the heart. For the sauropod Euhelopus zdanskyi, however, biomechanical
evidence clearly indicates high browsing. Energy expenditure owing to high
browsing is compared with energy costs for walking a distance. It is
demonstrated for Euhelopus as well as for the much larger Brachiosaurus that
despite an increase in the metabolic rate, high browsing was worthwhile for
a sauropod if resources were far apart.

Open Access: just go to
http://rsbl.royalsocietypublishing.org/content/early/2010/05/29/rsbl.2010.03
59.full

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And a special "all hadrosaurid" issue of the Zoological Journal of the
Linnean Society
(http://www3.interscience.wiley.com/journal/121583668/grouphome/home.html)

Cuthbertson, R.S. & R.B. Holmes. 2010. The first complete description of the
holotype of Brachylophosaurus canadensis Sternberg, 1953 (Dinosauria:
Hadrosauridae) with comments on intraspecific variation. ZJLS 159: 373?397.
DOI: 10.1111/j.1096-3642.2009.00612.x

ABSTRACT

The holotype of Brachylophosaurus canadensis was collected by C.M. Sternberg
in 1936 from the Oldman Formation (Upper Cretaceous) of Alberta, Canada,
with a brief description focusing on the cranium following in 1953. A
re-description of the holotype skeleton confirms its position as a
hadrosaurine dinosaur exhibiting the following unique combination of
characters: paddle-like solid nasal crest; posteriorly elongated prefrontal;
only the anterior tip of the lacrimal contacting maxilla; extremely
elongated anterior maxillary process; and a quadratojugal with a
noncrescentic posterior margin variably forming a paraquadratic foramen with
the quadrate. Comparison of the holotype with other specimens assigned to
the taxon reveals numerous morphological differences. These variable
features include the presence/absence of an accessory premaxillary foramen,
the number of maxillary/dentary vertical tooth rows, the number of
functional teeth per tooth row contributing to the dental occlusal surface,
the bones forming the mandibular glenoid, the presence/absence of a nasal
foramen, nasal crest morphology, the number of cervical vertebrae, and axis
morphology.

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Evans, D.C. 2010. Cranial anatomy and systematics of Hypacrosaurus
altispinus, and a comparative analysis of skull growth in lambeosaurine
hadrosaurids (Dinosauria: Ornithischia). ZJLS 159: 398?434. DOI:
10.1111/j.1096-3642.2009.00611.x

ABSTRACT

The cranial anatomy of the helmet-crested lambeosaurine Hypacrosaurus
altispinus (Ornithischia: Hadrosauridae) is described, with a focus on
ontogenetic and individual variation in phylogenetically significant
characters of the cranial crest, braincase, and facial skeleton. Cranial
material of H. altispinus represents a relatively complete growth series
that includes crestless juveniles of less than half the size of large
individuals with fully developed crests. Cranial ontogeny is compared with
other lambeosaurines using bivariate morphometrics and through qualitative
comparison of a size-standardized cranial growth series. Bivariate analyses
reveal that the relative growth of the skull and cranial crest of H.
altispinus and H. stebingeri are similar, and that Hypacrosaurus more
closely resembles Corythosaurus than Lambeosaurus. Hypacrosaurus altispinus
is systematically revised. The taxon is characterized by five
autapomorphies, most of which are concentrated in the skull, as well as an
enlarged terminal ischial foot. Maximum parsimony and Bayesian likelihood
(Mk+gamma) phylogenetic analyses were conducted to test the monophyly of the
genus. Hypacrosaurus monophyly is corroborated in light of new anatomical
data. Although H. stebingeri and H. altispinus share few derived characters
of the skull, the hypothesis that H. stebingeri is a metaspecies that
represents the ancestor of H. altispinus cannot be rejected.

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Prieto-Márquez, A. 2010. Global phylogeny of hadrosauridae (Dinosauria:
Ornithopoda) using parsimony and Bayesian methods. ZJLS 159: 435?502. DOI:
10.1111/j.1096-3642.2009.00617.x

ABSTRACT

The late Cretaceous hadrosaurids were the most specialized and diverse clade
of ornithopod dinosaurs. Parsimony and Bayesian methods were implemented to
elucidate the phylogenetic relationships of all hadrosaurid species.
Traditional and geometric morphometrics were applied to discover patterns of
variation containing phylogenetic information. In total, 286
phylogenetically informative characters (196 cranial and 90 postcranial)
were defined and documented: the most extensive character data set ever
constructed for hadrosaurid dinosaurs. Of these, 136 characters were used
for the first time in phylogenetic analysis of these ornithopods, and 93
were modified from those of other authors. Parsimony and the Bayesian
analysis (using the Mk model without the gamma parameter) confirmed the
split of hadrosaurids into Saurolophinae and Lambeosaurinae. Saurolophines
included a major clade composed of the Prosaurolophus?Saurolophus and the
Kritosaurus?Gryposaurus?Secernosaurus subclades. Edmontosaurus and
Shantungosaurus were recovered outside the major clade of saurolophines. The
Brachylophosaurus clade was recovered as the most basal clade of
saurolophines in the parsimony analysis, whereas following the Bayesian
analysis it was recovered as the sister clade to the
Kritosaurus?Gryposaurus?Secernosaurus clade. These two analyses resulted in
a Lambeosaurinae composed of a succession of Eurasian sister taxa to two
major clades: the Parasaurolophus clade and the Hypacrosaurs
altispinus?Corythosaurus clade. In contrast, the Bayesian analysis using the
Mk model with the gamma parameter included, resulted in an unbalanced
hadrosauroid tree, with a paraphyletic Saurolophinae, and with the
Prosaurolophus clade, Edmontosaurus, and Shantungosaurus as successively
closer sister taxa to Lambeosaurinae. Based on the strict reduced consensus
tree derived from the parsimony analysis, Hadrosauridae was redefined as the
clade stemming from the most recent common ancestor of Hadrosaurus foulkii
and Parasaurolophus walkeri.

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Prieto-Márquez, A. 2010. Global historical biogeography of hadrosaurid
dinosaurs. ZJLS 159: 503?525. DOI: 10.1111/j.1096-3642.2010.00642.x

ABSTRACT

Hadrosaurids were the most derived ornithopods and amongst the most diverse
herbivore dinosaurs during the Late Cretaceous of Europe, Asia, and the two
Americas. Here, their biogeographical history is reconstructed using
dispersal-vicariance analysis (DIVA). The results showed that Hadrosauridae
originated in North America and soon after dispersed to Asia no later than
the Late Santonian. The most recent common ancestor of Saurolophidae (=
Saurolophinae + Lambeosaurinae) is inferred to have been widespread in North
America and Asia. The split between saurolophines and lambeosaurines
occurred in response to vicariance no later than the Late Santonian: the
former clade originated in North America, whereas the latter did so in Asia.
Saurolophine biogeographical history included a minimum of five dispersal
events followed by vicariance. Four of these dispersals were inferred to
have occurred from North America to Asia during the Campanian and Early
Maastrichtian, whereas a fifth event represented a southward dispersal from
North to South America no later than the Late Campanian. The historical
biogeography of lambeosaurines was characterized by an early evolution in
Asia, with a Campanian dispersal to the European archipelago followed by
vicariance. Reconstruction of the ancestral areas for the deepest nodes
uniting the more derived lambeosaurines clades ('hypacrosaurs',
'corythosaurs', and 'parasaurolophs') is ambiguous. The split between North
American and Asian clades of 'hypacrosaurs' and 'parasaurolophs' occurred in
response to vicariance during the Campanian. The evolutionary history of
North American 'hypacrosaurs' and 'parasaurolophs' was characterized by
duplication events. The latter also characterized the Late Campanian
'corythosaurs', which remained restricted to North America.


Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216                        
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
http://www.geol.umd.edu/~tholtz/
Fax: 301-314-9661               

Faculty Director, Earth, Life & Time Program, College Park Scholars
http://www.geol.umd.edu/~jmerck/eltsite/
Faculty Director, Science & Global Change Program, College Park Scholars
http://www.geol.umd.edu/sgc
Fax: 301-314-9843

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA