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The New Papers of Despereaux
Canale, J.I., Scanferla, C.A., Agnolin, F.L., and Novas, F.E. 2008. New
carnivorous dinosaur from the Late Cretaceous of NW Patagonia and the evolution
of abelisaurid theropods. Naturwissenschaften. doi: 10.1007/s00114-008-0487-4.
ABSTRACT: A nearly complete skeleton of the new abelisaurid Skorpiovenator
bustingorryi is reported here. The holotype was found in Late
CenomanianâEarly Turonian outcrops of NW Patagonia, Argentina. This new taxon
is deeply nested within a new clade of South American abelisaurids, named
Brachyrostra. Within brachyrostrans, the skull shortening and hyperossification
of the skull roof appear to be correlated with a progressive enclosure of the
orbit, a set of features possibly related to shock-absorbing capabilities.
Moreover, the development of horn-like structures and differential cranial
thickening appear to be convergently acquired within Abelisauridae. Based on
the similarities between Skorpiovenator and carcharodontosaurid tooth
morphology, we suggest that isolated teeth originally referred as
post-Cenomanian Carcharodontosauridae most probably belong to abelisaurids.
Goldberg, E.E., and Igic, B. 2008. On phylogenetic tests of irreversible
evolution. Evolution 62(11):2727-2741. doi: 10.1111/j.1558-5646.2008.00505.x.
ABSTRACT: "Dollo's law" states that, following loss, a complex trait cannot
reevolve in an identical manner. Although the law has previously fallen into
disrepute, it has only recently been challenged with statistical phylogenetic
methods. We employ simulation studies of an irreversible binary character to
show that rejections of Dollo's law based on likelihood-ratio tests of
transition rate constraints or on reconstructions of ancestral states are
frequently incorrect. We identify two major causes of errors: incorrect
assignment of root state frequencies, and neglect of the effect of the
character state on rates of speciation and extinction. Our findings do not
necessarily overturn the conclusions of phylogenetic studies claiming
reversals, but we demonstrate devastating flaws in the methods that are the
foundation of all such studies. Furthermore, we show that false rejections of
Dollo's law can be reduced by the use of appropriate existing models and model
selection procedures.
More powerful tests of irreversibility require data beyond phylogenies and
character states of extant taxa, and we highlight empirical work that
incorporates additional information.
Sukhanov, V.B., Danilov, I.G., and Syromyatnikova, E.V. 2008. The description
and phylogenetic position of a new nanhsiungchelyid turtle from the Late
Cretaceous of Mongolia. Acta Palaeontologica Polonica 53(4):601-614.
ABSTRACT: This paper describes a new nanhsiungchelyid turtle, Kharakhutulia
kalandadzei gen. et sp. nov., based on two partial shells and additional shell
fragments from the lower part of the Bainshire Formation (Upper Cretaceous,
Cenomanianâlower Turonian) of the Khara Khutul locality of Eastern Mongolia.
Our phylogenetic analysis places Kharakhutulia kalandadzei as the most basal
member of the Nanhsiungchelyidae and suggests new relationships within this
group. Previously reported nanhsiungchelyid specimens from the Khara Khutul are
reassigned to Nanhsiungchelyidae indet. and Hanbogdemys sp. indet. Thus the
Khara Khutul includes at least two valid taxa of nanhsiungchelyids. Our
analysis of the nanhsiungchelyid record in Asia shows that other localities
have only a single representative of this clade, making Khara Khutul a unique
site. The basal phylogenetic position of Kharakhutulia kalandadzei emphasizes
the importance of the study of this and other CenomanianâTuronian
localities of Asia to better understand the basal diversification of the
Nanhsiungchelyidae.
Filippi, L.S., and Garrido, A.C. 2008. Pitekunsaurus macayai gen. et sp. nov.,
nuevo titanosaurio (Saurischia, Sauropoda) del CretÃcico Superior de la Cuenca
Nuequina, Argentina. Ameghiniana 45(3):575-590.
ABSTRACT: A new titanosaur is described, Pitekunsaurus macayai gen. et sp.
nov., from mudstone levels asigned to Anacleto Formation (Lower - Middle
Campanian), corresponding to the uppermost beds of the NeuquÃn Group (Upper
Cretaceous of NeuquÃn Basin). The specimen is represented by braincase, left
frontal, one tooth, four cervical vertebrae, three dorsal vertebrae, four
caudal vertebrae, right ulna and scapula, proximal extreme of left femur, rib
fragments and uncertain remains. Pitekunsaurus is characterized by the
following autapomorphies: (1) basipterygoid processes broadly separated and
parallelly projected, (2) anterior cervical vertebrae with small depressions or
longitudinal grooves in the spinal sector of spinopostzygapophyseal lamina, (3)
centropostzygapophyseal lamina forked proximally in anterior dorsal vertebrae,
and (4) posterior centrodiapophyseal lamina with accessory lamina in anterior
dorsal vertebrae. The existence of two types of articulations in the posterior
caudal vertebrae, one amphicoelous and another biconvex, indicates a close
relationship with Rinconsaurus caudamirus Calvo y GonzÃlez Riga, suggesting
that the caudal morphology of titanosaurs is much more complex and more varied
than previously supposed.
Matsumoto, R., Suzuki, S., Tsogtbaatar, K., and Evans, S.E. 2008. New material
of the enigmatic reptile Khurendukhosaurus (Diapsida: Choristodera) from
Mongolia. Naturwissenschaften. doi: 10.1007/s00114-008-0469-6.
ABSTRACT: New material of the enigmatic diapsid Khurendukhosaurus is described
from the Mongolian type locality, Khuren Dukh, providing additional data on the
vertebral column, pelvis, and hind limb. It confirms the choristoderan status
of the genus and permits a more detailed phylogenetic analysis that supports a
relationship between Khurendukhosaurus and the long-necked Asian
Hyphalosauridae. The existence of tall caudal neural spines implies that
Khurendukhosaurus was a deep-tailed swimmer. This and the open sacral
costocentral sutures suggest a primarily aquatic lifestyle.
Rougier, G.W., Chornogubsky, L., Casadio, S., PaÃz Arango, N., and
Giallombardo, A. 2008. Mammals from the Allen Formation, Late Cretaceous,
Argentina. Cretaceous Research 30(1):223-238. doi:
10.1016/j.cretres.2008.07.006.
ABSTRACT: A mammalian fauna from the Late Cretaceous locality of âCerro
Tortuga,â Allen Formation, RÃo Negro Province, Argentina, is described here
based on a sample, represented by 7 isolated teeth which shows similarities
with those reported from the Late Cretaceous Los Alamitos Formation. These two
mammalian faunas largely agree on their overall composition at the
supraspecific level but new species are recognized for some of the specimens
described. Small-sized dryolestoids, mesungulatids and ferugliotheriids are
present in Cerro Tortuga. A new species of Mesungulatum, [Bonaparte, J.F.,
Soria, M.F., 1985. Nota sobre el primer mamÃfero del CretÃcico Argentino,
Campaniano-Maastrichtiano, (Condylarthra). Ameghiniana 21, 177â183] leads to
a reassessment of mesungulatid diversity in the Late Cretaceous South American
mammalian faunas and some provisional considerations on the relative age of the
mammal-bearing units. The South American Late Cretaceous radiation of
dryolestoids has its origins in the early Late Cretaceous, at the latest, and
extends into the Paleocene when their last remnants are obliterated possibly in
relation to the incoming Laurasian tribosphenic mammals. The Late Cretaceous
non-tribosphenic mammals have no clear link with the Jurassic and Early
Cretaceous South American mammals, emphasizing the distinctiveness and episodic
nature of the Mesozoic South American mammalian assemblages. The scant number
of fossils and geochronologically discontinuous record may artificially
accentuate the distinctiveness of the as yet poorly known pre-Late Cretaceous
South American mammals, in particular if an epiric sea separated South Amerca
into northen and southern realms.
Varricchio, D.J., Raven, R.F., Wolbach, W.S., Elsik, W.C., and Witzke, B.J.
2008. Soot and palynologic analysis of Manson impact-related strata (Upper
Cretaceous) of Iowa and South Dakota, USA. Cretaceous Research 30(1):127-134.
doi: 10.1016/j.cretres.2008.06.005.
ABSTRACT: The Campanian Manson impact structure of Iowa represents the
best-preserved, large-diameter complex crater within the continental U.S. To
assess the timing and potential mode of crater infilling and the possible
presence of an impact event horizon, we analyzed samples from both within and
distal to the impact structure for their elemental carbon, soot and
palynomorphs. Within the impact structure, identifiable soot occurred in
fragmented impact breccia and suevite but not in lower impact-melt breccia.
Although most of this soot likely represents reworking of material from older
Cretaceous marine shales, one high soot concentration occurs with melt material
in a Keweenawan ShaleâPhanerozoic clast breccia mix. This represents the
first association of soot and impact-generated materials within an impact
structure and the best sample candidate for Manson impact-generated soot. No
palynomorphs occurred in the impact melt breccia. Overlying suevite (Keweenawan
Shale clast
breccia) of the central peak yielded sparse and thermally altered
palynomorphs, indicating deposition prior to full cooling of the crater debris.
Presence of easily degraded soot also argues for rapid backfilling of the
crater.
Distal samples from South Dakota represent the Sharon Springs and Crow
Creek members of the Pierre Shale 230 km northwest of the Manson impact
structure. Although containing shocked grains, the Crow Creek preserves no
soot. In contrast, the Sharon Springs, generally considered as predating the
Manson impact, has significant soot quantities. Palynomorphs differ markedly
across the unconformity separating the two members with the Crow Creek
containing more terrestrial forms, normapolles, and older reworked
palynomorphs, consistent with a terrestrial impact to the east. Origin of the
Sharon Springs soot remains unclear. Given soot occurrence within four of the
five Cretaceous marine units sampled, the relatively shallow, anoxic bottom
conditions of the Western Interior Cretaceous Seaway may have simply favored
soot preservation. Until a better understanding of the broader occurrence and
preservation of soot is achieved, some soot-impact associations will remain
ambiguous.
Kim, C.-B., Al-Aasm, I.S., Ghazban, F., and Chang, H.-W. 2008. Stable isotopic
composition of dinosaur eggshells and pedogenic carbonates in the Upper
Cretaceous Seonso Formation, South Korea: paleoenvironmental and diagenetic
implications. Cretaceous Research 30(1):93-99. doi:
10.1016/j.cretres.2008.05.003.
ABSTRACT: Stable isotopic compositions of the pedogenic calcites and calcitic
dinosaur eggshells analyzed from the Seonso Formation in southern Korea provide
information on the paleoenvironmental conditions that dominated the region
during the Upper Cretaceous as well as on the nature of the diagenetic fluids.
The Î18O values of the calcites recovered from the paleosols (â15.46 to
â26.22 â VPDB) indicate that they were precipitated and/or altered under a
high temperature regime, whereas the Î13C values (â3.88 to â7.72 â VPDB)
suggest that these carbonates received contributions from hydrothermal fluids
during shallow burial and possibly from C3-type vegetation.
The Î18O and Î13C of partially to well-preserved calcite eggshells are
significantly different from those of the paleosols, indicating a departure
from the earlier environmental conditions. The observed shift in Î18O values
between the dinosaur eggshells (â3.43 to â14.09 â) and pedogenic calcites
indicates different environmental and thermal conditions and suggesting two
possible scenarios; either that the timing of egg laying by the dinosaur and
the soil formation were not synchronous, or that the dinosaur consumed water
from the rivers and evaporated ponds. In contrast, isotopic compositions of
vein calcites cross-cutting paleosols (â19.06 to â21.72 for Î18O, and
â3.78 to â4.79 for Î13C) reflect their precipitation under hydrothermal
conditions.
The narrow range in the Î13C values of the eggshells (â7.04 to â8.69
â) reflect a uniform source for carbon; mostly representing fresh water
charged with CO2 from hydrothermal sources as dissolved carbon.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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 made this letter longer
than usual because I lack the
time to make it shorter."
-- Blaise Pascal