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Inglourious New Papers

Benson, R.B.J., and Barrett, P.M. 2009. Dinosaurs of Dorset: Part I, the
carnivorous dinosaurs (Saurischia, Theropoda). Proceedings of the Dorset
Natural History & Archaeological Society 130:133-147.

ABSTRACT: Theropod dinosaurs in Dorset are found in the Lower Jurassic (Blue
Lias Formation), the Middle Jurassic (Inferior Oolite and Forest Marble
Formations), the Late Jurassic (Kimmeridge Clay and Portland Stone) and the
Lower Cretaceous (Purbeck Limestone Group and ?Wealden Beds?). They include
representatives of several major theropod groups: the megalosaurids
Duriavenator and Magnosaurus, the sinraptorid Metriacanthosaurus, the basal
tyrannosauroid Stokesosaurus and the dromaeosaurid Nuthetes. Theropod
fossils from Dorset have been reported since 1835 and the record from the
county is one of the oldest globally. It continues to yield new data on
dinosaur evolution and biogeography and will contribute to our understanding
and insight of theropod evolution into the foreseeable future.

Pierce, S.E., Angielczyk, K.D., and Rayfield, E.J. 2009. Morphospace
occupation in thalattosuchian crocodylomorphs: skull shape variation,
species delineation and temporal patterns. Palaeontology. doi:

ABSTRACT: Skull shape variation in thalattosuchians is examined using
geometric morphometric techniques in order to delineate species, especially
with respect to the classification of Callovian species, and to explore
patterns of disparity during their evolutionary history. The pattern of
morphological diversity in thalattosuchian skulls was found to be very
similar to modern crocodilians: the main sources of variation are the length
and the width of the snout, but these broad changes are correlated with size
of supratemporal fenestra and frontal bone, length of the nasal bone, size
of the orbit and premaxilla and position of the narial opening. Patterns of
shape variation, in combination with discrete-state morphology and
stratigraphic and geographic range data were used to distinguish nine
species of teleosaurid and 14 species of metriorhynchid, with the four
currently recognized Callovian species being split into eight.
Metriorhynchids were found to be more disparate from the average shape of
morphospace than teleosaurids. However, short-snouted metriorhynchids and
long-snouted teleosaurids showed the greatest amount of disparity with
respect to snout morphotypes, indicating that each group tended to explore
opposite areas of morphospace. Phylogeny was found to have a moderate
influence on the pattern of morphospace occupation in metriorhynchids, but
little effect in teleosaurids suggesting that other factors or constraints
control the pattern of skull shape variation in thalattosuchians. A
comparison of thalattosuchians with dyrosaur/pholidosaurids shows that
thalattosuchians have a unique skull morphology, implying that there are
multiple ways to construct a 'long snout'. Moreover, the skull geometry of
the problematic species Pelagosaurus typus was found to converge on the
teleosaurid area of morphospace. Finally, the temporal distribution of
thalattosuchian species and morphotypes demonstrate a clear and highly
correlated relationship with sea level curves and mass extinction events
through the Jurassic and the Early Cretaceous.

Pierce, S.E., Angielczyk, K.D., and Rayfield, E.J. 2009. Shape and mechanics
in thalattosuchian (Crocodylomorpha) skulls: implications for feeding
behaviour and niche partitioning. Journal of Anatomy. doi:

ABSTRACT: Variation in modern crocodilian and extinct thalattosuchian
crocodylomorph skull morphology is only weakly correlated with phylogeny,
implying that factors other than evolutionary proximity play important roles
in determining crocodile skull shape. To further explore factors potentially
influencing morphological differentiation within the Thalattosuchia, we
examine teleosaurid and metriorhynchid skull shape variation within a
mechanical and dietary context using a combination of finite element
modelling and multivariate statistics. Patterns of stress distribution
through the skull were found to be very similar in teleosaurid and
metriorhynchid species, with stress peaking at the posterior constriction of
the snout and around the enlarged supratemporal fenestrae. However, the
magnitudes of stresses differ, with metriorhynchids having generally
stronger skulls. As with modern crocodilians, a strong linear relationship
between skull length and skull strength exists, with short-snouted
morphotypes experiencing less stress through the skull than long-snouted
morphotypes under equivalent loads. Selection on snout shape related to
dietary preference was found to work in orthogonal directions in the two
families: diet is associated with snout length in teleosaurids and with
snout width in metriorhynchids, suggesting that teleosaurid skulls were
adapted for speed of attack and metriorhynchid skulls for force production.
Evidence also indicates that morphological and functional differentiation of
the skull occurred as a result of dietary preference, allowing closely
related sympatric species to exploit a limited environment. Comparisons of
the mechanical performance of the thalattosuchian skull with extant
crocodilians show that teleosaurids and long-snouted metriorhynchids exhibit
stress magnitudes similar to or greater than those of long-snouted modern
forms, whereas short-snouted metriorhynchids display stress magnitudes
converging on those found in short-snouted modern species. As a result,
teleosaurids and long-snouted metriorhynchids were probably restricted to
lateral attacks of the head and neck, but short-snouted metriorhynchids may
have been able to employ the grasp and shake and/or 'death roll' feeding and
foraging behaviours.

Knoll, F., and Schwarz-Wings, D. 2009. Palaeoneuroanatomy of Brachiosaurus.
Annales de Paléontologie. doi: 10.1016/j.annpal.2009.06.001.

ABSTRACT: An overview of the palaeoneuroanatomy (brain and spinal cord) of
the sauropod dinosaur Brachiosaurus is given. Although having a flexed brain
configuration, Brachiosaurus presents on the whole a rather moderately
derived neuroanatomical pattern. As other sauropods, Brachiosaurus shows an
enlargement of the spinal cord in the sacral area. New Encephalization
Quotients are calculated and found to be about 0.62 or 0.79 (depending on
the body volume taken into consideration) when Hurlburt's formula is used.
This suggests that Brachiosaurus, although it may not have been as a low
encephalized taxon (by reptilian standards) as previously believed, did have
an undersized relative brain volume.

de Valais, S. 2009. Ichnotaxonomic revision of Ameghinichnus, a mammalian
ichnogenus from the Middle Jurassic La Matilde Formation, Santa Cruz
Province, Argentina. Zootaxa 2203:1--21.

ABSTRACT: The ichnological assemblage from the Estancia Laguna Manantiales,
from the Middle Jurassic La Matilde Formation, Santa Cruz province,
Argentina, is exceptional both in diversity and abundance. It is composed of
mammal, dinosaur, invertebrate, and root traces. The most significant and
abundant specimens are those assigned to the ichnogenus Ameghinichnus
Casamiquela, 1961. This ichnogenus is revised and an emendation of its
diagnosis is suggested. The inclusion of all the known specimens to the type
ichnospecies, Ameghinichnus patagonicus Casamiquela, 1961, is challenged and
some specimens are placed in a new ichnospecies, Ameghinichnus
manantialensis isp. nov. Similar tracks from other ichnological localities
worldwide were previously referred to Ameghinichnus, but only
Eopentapodiscus (Ellenberger, 1970), from South Africa is considered as a
junior synonym of Ameghinichnus. The ichnotaxobases used to classify tracks
with mammalian affinities at ichnogeneric and ichnospecific levels are
evaluated and re-assessed ichnotaxonomic criteria are proposed. Different
criteria used to distinguish mammalian imprints from non-mammalian tracks
are commented.

Schoch, R.R., and Witzmann, F. 2009. Osteology and relationships of the
temnospondyl genus Sclerocephalus. Zoological Journal of the Linnean Society
157(1):135-168. doi: 10.1111/j.1096-3642.2009.00535.x.

ABSTRACT: The temnospondyl Sclerocephalus from the Permo-Carboniferous of
Germany is one of the most completely preserved and most abundant Palaeozoic
tetrapods. Here, we review the complete osteology of the genus, based on a
range of fully grown specimens housed in public collections. Among the four
valid species, Sclerocephalus haeuseri and Sclerocephalus nobilis reached an
adult size of well beyond 1 m in length, and had robust postcranial
skeletons. In the skull, the exoccipital and sphenethmoid bones were
ossified, completing the well-known ossification sequence in S. haeuseri.
Large adults had an elongate trunk and a laterally compressed tail, and some
individuals also retained lateral line sulci: features that taken together
suggest an aquatic life. The coracoid, pubis, carpals, tarsals, and the bony
tail are fully ossified in the largest specimens. The genus Sclerocephalus
forms a weakly supported clade nesting firmly at the base of the
Stereospondylomorpha, and the close resemblance between Sclerocephalus,
Onchiodon, and Eryops is found to be partially based on shared derived
states, but is mostly based on symplesiomorphies. Cladistic analysis of 54
characters and 18 taxa finds more support for the Eryopoidea hypothesis
(Eryopidae + Stereospondylomorpha) than for the Euskelia hypothesis
(Eryopidae + Zatracheidae + Dissorophoidea). This indicates that the large
temnospondyls of the Permian and Mesozoic probably formed a natural group,
and that the terrestrial adaptations of Eryops and the dissorophoids
probably evolved by convergence.

Maxwell, E.E., and Larsson, H.C.E. 2009. Comparative ossification sequence
and development of the postcranium of palaeognathous birds (Aves:
Palaeognathae). Zoological Journal of the Linnean Society 157(1):169-196.
doi: 10.1111/j.1096-3642.2009.00533.x.

ABSTRACT: Palaeognaths constitute one of the most basal lineages of extant
birds, and are also one of the most morphologically diverse avian orders.
Their skeletal development is relatively unknown, in spite of their
important phylogenetic position. Here, we compare the development of the
postcranial skeleton in the emu (Dromaius novaehollandiae), ostrich
(Struthio camelus), greater rhea (Rhea americana) and elegant
crested-tinamou (Eudromia elegans), focusing on ossification. All of these
taxa are characterized by element loss in the appendicular skeleton, but
there are several developmental mechanisms through which this loss occurs,
including failure to chondrify, failure to ossify and fusion of cartilages
prior to ossification. Further evidence is presented here to support a
reduction in size of skeletal elements resulting in a delay in the timing of
ossification. This study provides an important first look at the timing and
sequence of postcranial ossification in palaeognathous birds, and discusses
the influence of changes in the pattern of skeletal development on
morphological evolution.

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

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