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The Lovely New Papers



Zanno, L.E. 2010. Osteology of Falcarius utahensis (Dinosauria: Theropoda):
characterizing the anatomy of basal therizinosaurs. Zoological Journal of
the Linnean Society 158(1):196-230. doi: 10.1111/j.1096-3642.2009.00464.x.

ABSTRACT: Falcarius utahensis, from the lower Yellow Cat Member of the Cedar
Mountain Formation, represents the most complete and morphologically
primitive therizinosaur yet discovered. Since initial publication, only the
braincase, pectoral girdle, and forelimb of this phylogenetically important
taxon have been subject to detailed investigation. This work completes the
description of skeletal material prepared from the Crystal Geyser Quarry
subsequent to the first five years of excavation ?C including elements of
the skull, axial column, pelvis, and hind limb of this phylogenetically
critical theropod ?C and presents an emended and significantly expanded
diagnosis. Results of this study reveal a significant degree of
morphological disparity between Falcarius utahensis and the evidently coeval
primitive therizinosaur Beipiaosaurus inexpectus from the Yixian Formation,
People's Republic of China and help characterize morphological
transformations occurring in the therizinosaur lineage that are of
phylogenetic significance, particularly with regard to the highly derived
presacral axial column. Finally, Falcarius documents that marked heterodonty
?C characterized by elongate, incisiform rostral teeth ?C is present in
basal therizinosaurs and oviraptorosaurs (i.e. Incisivosaurus gauthieri,
Protarchaeopteryx robusta), and either represents a synapomorphy or
symplesiomorphy for these groups or an early phase in the convergent
progression toward rostral endentulism. Nonetheless, heterodonty suggests
that diet was a primary factor in the early evolution of both clades.






Brusatte, S.L., Benson, R.B.J., Currie, P.J., and Zhao, X. 2010. The skull
of Monolophosaurus jiangi (Dinosauria: Theropoda) and its implications for
early theropod phylogeny and evolution. Zoological Journal of the Linnean
Society. doi: 10.1111/j.1096-3642.2009.00563.x.

ABSTRACT: The Middle Jurassic was a critical time in the evolution of
theropod dinosaurs, highlighted by the origination and initial radiation of
the large-bodied and morphologically diverse Tetanurae. Middle Jurassic
tetanurans are rare, but have been described from Europe, South America and
China. In particular, China has yielded a number of potential basal
tetanurans, but these have received little detailed treatment in the
literature. Chief among these is Monolophosaurus jiangi, known from a single
skeleton that includes a nearly complete and well-preserved skull
characterized by a bizarre cranial crest. Here, we redescribe the skull of
Monolophosaurus, which is one of the most complete basal tetanuran skulls
known and the only quality source of cranial data for Middle Jurassic
Chinese theropods. The cranial crest is atomized into a number of
autapomorphic features and several characters confirm the tetanuran
affinities of Monolophosaurus. However, several features suggest a basal
position within Tetanurae, which contrasts with most published cladistic
analyses, which place Monolophosaurus within the more derived Allosauroidea.
Cranial characters previously used to diagnose Allosauroidea are reviewed
and most are found to have a much wider distribution among Theropoda,
eroding an allosauroid position for Monolophosaurus and questioning
allosauroid monophyly. The use of phylogenetic characters relating to
theropod cranial crests is discussed and a protocol for future use is given.
The systematic position of Guanlong wucaii is reviewed, and a basal
tyrannosauroid affinity is upheld contrary to one suggestion of a close
relationship between this taxon and Monolophosaurus.





Mannion, P.D. 2010. A revision of the sauropod dinosaur genus
'Bothriospondylus' with a redescription of the type material fo the Middle
Jurassic form B. madagascariensis. Palaeontology. doi:
10.1111/j.1475-4983.2009.00919.x.

ABSTRACT: The sauropod dinosaur 'Bothriospondylus', originally named on the
basis of Late Jurassic remains from England, is demonstrated to be invalid,
and the characters used to diagnose it are shown to be obsolescent features
which are widespread throughout Sauropoda. Material referred to this genus
spans a temporal range from the Middle Jurassic until the early Late
Cretaceous and has been described from five different countries, across
three continents. These remains represent a wide array of sauropod groups,
comprising non-neosauropod eusauropods, a macronarian, titanosauriforms
(including at least one definite brachiosaurid) and a rebbachisaurid. The
type material of the Middle Jurassic 'B. madagascariensis' represents a
derived non-neosauropod eusauropod and possesses two potential
autapomorphies. However, as a result of the fragmentary nature of the
material and the uncertainty surrounding its association, a new taxon is not
erected. Of the numerous specimens referred to 'Bothriospondylus', however,
several remains are considered diagnostic: Ornithopsis hulkei (Early
Cretaceous, UK), Lapparentosaurus madagascariensis (Middle Jurassic,
Madagascar) and Nopcsaspondylus alarconensis (early Late Cretaceous,
Argentina). At least three types of sauropod were present in the Bathonian
(Middle Jurassic) of north-west Madagascar, with a basal eusauropod
(Archaeodontosaurus), a more derived eusauropod ('B. madagascariensis') and
a titanosauriform (Lapparentosaurus) all approximately contemporaneous.
Palaeocontinental reconstructions suggest that Middle Jurassic Madagascan
sauropods would still have been capable of global biotic interchange, and
this is perhaps reflected in their diverse assemblage. Re-evaluation of
these Malagasy forms has shed new light on this important time period in
sauropod evolution.





Rogers, R.R., and Brady, M.E. 2010. Origins of microfossil bonebeds:
insights from the Upper Cretaceous Judith River Formation of north-central
Montana. Paleobiology 36(1):80-112. doi: 10.1666/0094-8373-36.1.80.

ABSTRACT: Microfossil bonebeds are multi-individual accumulations of
disarticulated and dissociated vertebrate hardparts dominated by elements in
the millimeter to centimeter size range (≥75% of bioclasts ≤5 cm maximum
dimension). Modes of accumulation are often difficult to decipher from
reports in the literature, although predatory (scatological) and
fluvial/hydraulic origins are typically proposed. We studied the
sedimentology and taphonomy of 27 microfossil bonebeds in the Campanian
Judith River Formation of Montana in order to reconstruct formative
histories. Sixteen of the bonebeds examined are hosted by fine-grained
facies that accumulated in low-energy aquatic settings (pond/lake
microfossil bonebeds). Eleven of the bonebeds are embedded in sandstones
that accumulated in ancient fluvial settings (channel-hosted microfossil
bonebeds). In lieu of invoking separate pathways to accumulation based on
facies distinctions, we present a model that links the accumulation of
bioclasts in the two facies. We propose that vertebrate material initially
accumulates to fossiliferous levels in ponds/lakes and is later reworked and
redeposited as channel-hosted assemblages. This interpretation is grounded
in reasonable expectations of lacustrine and fluvial depositional systems
and supported by taphonomic data. Moreover, it is consistent with faunal
data that indicate that channel-hosted assemblages and pond/lake assemblages
are similar with regard to presence/absence and rank-order abundance of
taxa.
     This revised model of bonebed formation has significant implications
for studies of vertebrate paleoecology that hinge on analyses of faunal data
recovered from vertebrate microfossil assemblages. Pond/lake microfossil
bonebeds in the Judith River record are preserved in situ at the scale of
the local paleoenvironment, with no indication of postmortem transport into
or out of the life habitat. Moreover, they are time-averaged samples of
their source communities, which increases the likelihood of capturing both
ecologically abundant species and more rare or transient members of the
paleocommunity. These attributes make pond/lake microfossil bonebeds
excellent targets for paleoecological studies that seek to reconstruct
overall community membership and structure. In contrast, channel-hosted
microfossil bonebeds in the Judith River record are out of place from a
paleoenvironmental perspective because they are reworked from preexisting
pond/lake assemblages and redeposited in younger channel facies. However,
despite a history of exhumation and redeposition, channel-hosted microfossil
bonebeds are preserved in relatively close spatial proximity to original
source beds. This taphonomic reconstruction is counter to the commonly held
view that microfossil bonebeds are biased samples that have experienced
long-distance transport and significant hydrodynamic sorting.






You, H.-L., and Li, D.-Q. 2010. A new basal hadrosauriform dinosaur
(Ornithischia: Iguanodontia) from the Early Cretaceous of northwestern
China. Canadian Journal of Earth Sciences 46(12):949-957. doi:
10.1139/E09-067.

ABSTRACT: A new hadrosauriform dinosaur, Jintasaurus meniscus gen. et sp.
nov., is reported from the Lower Cretaceous Xinminpu Group of the Yujingzi
Basin, Jiuquan area, Gansu Province, northwestern China. It is represented
by an articulated posterior portion of the skull and is unique in having an
extremely long, pendant and crescentic paroccipital process with its ventral
tip projecting far beyond the ventral level of the occipital condyle.
Phylogenetic analysis recovers Jintasaurus as the sister-taxon to
Hadrosauroidea, more derived than other Early Cretaceous hadrosauriforms and
Protohadros from the early Late Cretaceous of North America. This discovery
adds one more close relative to Hadrosauroidea in Asia and supports an Asian
origin for this group.






Sánchez-Villagra, M.R. 2010. Developmental palaeontology in synapsids: the
fossil record of ontogeny in mammals and their closest relatives.
Proceedings of the Royal Society B: Biological Sciences. doi:
10.1098/rspb.2009.2005.

ABSTRACT: The study of fossilized ontogenies in mammals is mostly restricted
to postnatal and late stages of growth, but nevertheless can deliver great
insights into life history and evolutionary mechanisms affecting all aspects
of development. Fossils provide evidence of developmental plasticity
determined by ecological factors, as when allometric relations are modified
in species which invaded a new space with a very different selection regime.
This is the case of dwarfing and gigantism evolution in islands.
Skeletochronological studies are restricted to the examination of growth
marks mostly in the cement and dentine of teeth and can provide absolute age
estimates. These, together with dental replacement data considered in a
phylogenetic context, provide life-history information such as maturation
time and longevity. Palaeohistology and dental replacement data document the
more or less gradual but also convergent evolution of mammalian growth
features during early synapsid evolution. Adult phenotypes of extinct
mammals can inform developmental processes by showing a combination of
features or levels of integration unrecorded in living species. Some adult
features such as vertebral number, easily recorded in fossils, provide
indirect information about somitogenesis and hox-gene expression boundaries.
Developmental palaeontology is relevant for the discourse of ecological
developmental biology, an area of research where features of growth and
variation are fundamental and accessible among fossil mammals.






Jasinoski, S.C., Rayfield, E.J., and Chinsamy, A. 2010. Functional
implications of dicynodont cranial suture morphology. Journal of Morphology.
doi: 10.1002/jmor.10828.

ABSTRACT: Cranial suture morphology of Lystrosaurus and the generalized
dicynodont Oudenodon was investigated to determine the strain environment
during mastication, which in turn may indicate a difference in cranial
function between the two taxa. Finite element (FE) analysis indicated that
less strain accumulated in the cranium of Lystrosaurus during orthal bite
simulations than in Oudenodon. Despite the overall difference in strain
magnitude, moderate to high FE-predicted strain accumulated in similar areas
of the cranium of both taxa. The suture morphology in these cranial regions
of Lystrosaurus and Oudenodon was investigated further by examination of
histological sections and supplemented by observations of serial sections
and computed tomography (CT) scans. The predominant type of strain from
selected blocks of finite elements that contain sutures was determined,
enabling comparison of suture morphology to strain type. Drawing from
strain-suture correlations established in extant taxa, the observed patterns
of sutural morphology for both dicynodonts were used to deduce cranial
function. The moderate to high compressive and tensile strain experienced by
the infraorbital bar, zygomatic arch, and postorbital bar of Oudenodon and
Lystrosaurus may have been decreased by small adjustive movements at the
scarf sutures in those regions. Disparities in cranial suture morphology
between the two taxa may reflect differences in cranial function. For
instance, the tongue and groove morphology of the postorbital-parietal
suture in Oudenodon could have withstood the higher FE-predicted tensile
strain in the posterior skull roof. The scarf premaxilla-nasal suture of
Lystrosaurus provided an additional region of sutural mobility in the
anterior surface of the snout, suggesting that Lystrosaurus may have
employed a different biting regime than Oudenodon. The morphology of several
sutures sampled in this study correlated with the FE-predicted strain,
although other cranial functional hypotheses remain to be tested.



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


"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