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New Papers of the Damned
Just in time for Halloween (thanks, Mary!):
de Souza Carvalho, I., de Vasconcellos, F.M., and Simionato Tavares, S.A.
2007. Montealtosuchus arrudacamposi, a new peirosaurid crocodile
(Mesoeucrocodylia) from the Late Cretaceous Adamantina Formation of Brazil.
ABSTRACT: We describe a new species of Peirosauridae (Crocodyliformes,
Mesoeucrocodylia), Montealtosuchus arrudacamposi gen. nov. et sp. nov., from
the Late Cretaceous (Turonian-Santonian) strata of the Bauru Basin, Brazil.
Montealtosuchus was found at the outskirts of Monte Alto County in reddish
sandstones of the Adamantina Formation. This specimen is exquisitely
preserved with skull, mandible, postcranial and exoskeletal elements in
articulation that provides critical information of the anatomy of this
group. The occurrence of Peirosauridae in the Adamantina Formation
(Turonian-Santonian) widens the chronostratigraphic range of this
Mesoeucrocodylia taxon in Brazil. Recent analysis suggests that the
Peirosauridae is restricted to the Late Cretaceous deposits of South
Butler, R.J., Upchurch, P., and Norman, D.B. 2007. The phylogeny of the
ornithischian dinosaurs. Journal of Systematic Palaeontology. doi:
ABSTRACT: Ornithischia is a familiar and diverse clade of dinosaurs whose
global phylogeny has remained largely unaltered since early cladistic
analyses in the mid 1980s. Current understanding of ornithischian evolution
is hampered by a paucity of explicitly numerical phylogenetic analyses that
consider the entire clade. As a result, it is difficult to assess the
robustness of current phylogenetic hypotheses for Ornithischia and the
effect that the addition of new taxa or characters is likely to have on the
overall topology of the clade.
The new phylogenetic analysis presented here incorporates a range of new
basal taxa and characters in an attempt to rigorously test global
ornithischian phylogeny. Parsimony analysis is carried out with 46 taxa and
221 characters. Although the strict component consensus tree shows poor
resolution in a number of areas, application of reduced consensus methods
provides a well-resolved picture of ornithischian interrelationships.
Surprisingly, Heterodontosauridae is placed as the most basal group of all
well-known ornithischians, phylogenetically distant from a stem-defined
Ornithopoda, creating a topology that is more congruent with the known
ornithischian stratigraphical record. There is no evidence for a
monophyletic 'Fabrosauridae', and Lesothosaurus (the best-known 'fabrosaur')
occupies an unusual position as the most basal member of Thyreophora. Other
relationships within Thyreophora remain largely stable. The primitive
thyreophoran Scelidosaurus is the sister taxon of Eurypoda (stegosaurs and
ankylosaurs), rather than a basal ankylosaur as implied by some previous
The taxonomic content of Ornithopoda differs significantly from previous
analyses and basal relationships within the clade are weakly supported,
requiring further investigation. 'Hypsilophodontidae' is paraphyletic, with
some taxa (Agilisaurus, Hexinlusaurus, Othnielia) placed outside of
Ornithopoda as non-cerapodans. Ceratopsia and Pachycephalosauria are
monophyletic and are united as Marginocephalia; however, the stability of
these clades is reduced by a number of poorly preserved basal taxa.
This analysis reaffirms much of the currently accepted ornithischian
topology. Nevertheless, instability in the position and content of several
clades (notably Heterodontosauridae and Ornithopoda) indicates that
considerable future work on ornithischian phylogeny is required and causes
problems for several current phylogenetic definitions.
Snively, E., and Russell, A.P. 2007. Craniocervical feeding dynamics of
Tyrannosaurus rex. Paleobiology 33(4):610-638. doi: 10.1666/06059.1.
ABSTRACT: Tyrannosaurus rex and other tyrannosaurid theropods exerted high
bite forces, and large muscle attachments suggest that the tyrannosaurid
neck was a concomitantly powerful component of the feeding apparatus. We
examine accelerative and work-generating capacity (WGC) of neck muscles in
adult Tyrannosaurus rex, using a 3-D vector-based method that incorporates
aspects of muscle force generation, reconstruction of muscle morphology and
moment arms, and rotational inertias of the head and neck. Under
conservative assumptions, radial accelerations of the head by large
superficial muscles (M. transversospinalis capitis, M. complexus, and M.
longissimus capitis superficialis) enabled rapid gaze shifts and imparted
high tangential velocities to food sufficient for inertial feeding. High WGC
by these and deeper muscles under eccentric contraction indicate high
efficacy for tearing flesh, especially with the head and neck in an extended
posture. Sensitivity analyses suggest that assigned density of the
antorbital region has substantial effects on calculated rotational inertia,
and hence on the accuracy of results. However, even with high latitude for
estimation errors, the results indicate that adult T. rex could strike
rapidly at prey and engage in complexly modulated inertial feeding, as seen
in extant archosaurs.
Jerry D. Harris
Director of Paleontology
Dixie State College
225 South 700 East
St. George, UT 84770 USA
Phone: (435) 652-7758
Fax: (435) 656-4022
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"Batman Sues Batsignal: Demands
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