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RE: Slum-dog New Papers



Angela C. Milner & S.A. Walsh, 2009. Avian brain evolution: new data from 
Palaeogene birds (Lower Eocene) from England. Zoological Journal [London] 
155(1):198-219. 
ABSTRACT. Investigation of how the avian brain evolved to its present state is 
informative for studies of the theropod-bird transition, and as a parallel to 
mammalian brain evolution. Neurological anatomy in fossil bird species can be 
inferred from endocranial casts, but such endocasts are rare. Here, we use 
computed tomographic analysis to determine the state of brain anatomy in two 
marine birds from the Lower Eocene London Clay Formation of England. The brains 
of Odontopteryx (Odontopterygiformes) and Prophaethon (Pelecaniformes) are 
remarkably similar to those of extant seabirds, and probably possessed similar 
somatosensory and motor capabilities. Each virtual endocast exhibits a degree 
of telencephalic expansion comparable to living avian species. However, the 
eminentia sagittalis (wulst), a feature characteristic of all living birds, is 
poorly developed. Our findings support the conclusion that much of the 
telencephalic expansion of modern birds was complete by the end of the
 Mesozoic, but that overall telencephalic volume has increased throughout the 
Cenozoic through dorsal expansion of the eminentia sagittalis. We suggest that 
improvements in cognition relating to telencephalic expansion may have provided 
neornithine avian clades with an advantage over archaic lineages at the 
Cretaceous-Tertiary boundary, explaining their survival and rapid 
diversification in the Cenozoic. 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
"Dr. Grant, my dear Dr. Sattler....... Welcome to Jurassic Park!"
John Hammond in JP1
______________________________________________ 
Ing. Yasmani Ceballos Izquierdo    <yceballos@uci.cu <mailto:yceballos@uci.cu> 
> 


________________________________

From: owner-DINOSAUR@usc.edu on behalf of Jerry D. Harris
Sent: Mon 26.01.2009 17:09
To: DINOSAUR Mailing List
Subject: Slum-dog New Papers



Allain, R., and Läng, E. 2009. Origine et évolution des saurischiens.
Comptes Rendus Palevol. doi: 10.1016/j.crpv.2008.09.013.

ABSTRACT: We propose here a short synthesis of the saurischian evolutionary
history. Our knowledge of the diversity and evolution of the saurischian
non-avian dinosaurs has increased during the past decade. The generalized
use of cladistics has led to various phylogenetic hypotheses, some of them
in agreement on the evolution of saurischians, even if some controversy
remains. The saurischian evolution is closely linked to two of the five
great mass extinctions, which punctuated life history, but probably also to
a third, less important, extinction event at the end of the Early Jurassic.



Padian, K., and de Ricqles, A. 2009. L'origine et l'évolution des oiseaux :
35 années de progrès. Comptes Rendus Palevol. doi:
10.1016/j.crpv.2008.11.007.

ABSTRACT: Birds are dinosaurs - specifically, small feathered and flighted
theropod dinosaurs that probably originated in Laurasia during the Late
Jurassic over 140 million years ago. They are most closely related to other
small theropods such as dromaeosaurs and troodontids, terrestrial predators
that were fleet-footed hunters. The origin of birds is a classic example of
two kinds of macroevolution: the phylogenetic origin of the group, and the
sequential assembly of adaptations such as flight that are indelibly
associated with birds. These adaptations were not assembled all at once.
Rather, a great many characteristics associated with birds and flight first
appeared in non-avian dinosaurs, where they were used for many purposes
other than flight. These included insulation, brooding, and probably display
and species recognition. Birds diversified steadily but gradually after
their origin, which is identified with the origin of flight (Archaeopteryx);
forelimb and other flight-associated features evolved more rapidly than
features associated with the posterior skeleton. The first birds grew more
slowly than extant birds do, and more like other small Mesozoic dinosaurs;
like them, they probably matured sexually well before they completed their
active skeletal growth. The origin of flight is not a problem of "trees
down" or "ground up," but rather an examination of the order in which
diagnostic flight characters evolved, and what each stage can reveal about
the functions and habits of bird outgroups at those evolutionary junctures.



Pradhan, G.R., and Van Schaik, C.P. 2009. Why do females find ornaments
attractive? The coercion-avoidance hypothesis. Biological Journal of the
Linnean Society 96(2):372-382. doi: 10.1111/j.1095-8312.2008.01131.x.

ABSTRACT: Vertebrates show two major classes of sexually dimorphic traits:
weaponry and ornaments. However, Darwin could not explain why their
expression varies so much across lineages. We argue that coercion-avoidance
can explain both the existence and taxonomic distribution of ornaments.
Females maximize their fitness when they can freely choose their mates, but
males are expected to use sexually dimorphic weaponry not only to displace
other males, but also to overcome female preferences and thus acquire
matings by force whenever they can. Females should therefore avoid coercive
males and avoid using weaponry as a criterion for male quality wherever
possible, and rely on male viability indicators that cannot be used to
coerce females (i.e. ornaments). Ornaments predominate in birds and weaponry
in mammals because female choice is less costly in birds, due to higher
intrinsic female behavioural freedom and lower male monopolization
potential. We also predict that specialized coercive organs occur where
females have low behavioural freedom but males benefit little from weaponry
in male-male contests. A review of the empirical evidence supports the basic
predictions of this coercion-avoidance hypothesis. We also present a simple
mathematical model that confirms the logic of this hypothesis.




Cheng, Y.-N., Ji, Q., Wu, X.-C., and Shan, H.-Y. 2008. Oviraptorosaurian
eggs (Dinosauria) with embryonic skeletons discovered for the first time in
China. Acta Geologica Sinica (English Edition) 82(6):1089-1094.

ABSTRACT: Two elongatoolithid dinosaur eggs from the Upper Cretaceous of
Ganzhou, Jiangxi Province and the embryonic skeletons they bear are
described. They represent the first Oviraptorosaurian eggs with embryonic
skeletons in China and provide the first example that an oospecies can be
correlated to certain dinosaur taxon/taxa. The two eggs are the same as the
pair of the eggs inside a female Oviraptorosaurian pelvis from the same
horizon of the same area in both macro- and micro-structures of the egg
shells, and can be referred to the oospecies, Macroolithus yaotunensis Zhao,
1975. The morphology of the preserved part of the embryonic skeletons
indicates that they may have been laid by an oviraptorid, Heyuannia huangi
from Guangdong Province or a closely related Oviraptorosaurian, which may
have been lived in the Ganzhou area too in the Late Cretaceous. The
embryonic skeletons of the two eggs are not in the same developing stage. In
one of the eggs, the postzygapophysis of the preserved vertebrae are well
ossified, indicating that it was just hatched.



Báez, A.M., Moura, G.J.B., and Gómez, R.O. 2009. Anurans from the Lower
Cretaceous Crato Formation of northeastern Brazil: implications for the
early divergence of neobatrachians. Cretaceous Research. doi:
10.1016/j.cretres.2009.01.002.

ABSTRACT: The upper Aptian-lower Albian lacustrine limestones of the Crato
Formation of northeastern Brazil have yielded one of Gondwana's most
important Cretaceous fossil assemblages. This assemblage includes a few
articulated anuran remains that have been previously referred to a single
neobatrachian taxon, Arariphrynus placidoi Leal and Brito, 2006. Herein we
redescribe these specimens, which document two additional genera and
species, Eurycephalella alcinae and Cratia gracilis, as well as a possible
pipoid. Although the monophyly of neobatrachians can be considered a
well-corroborated hypothesis, neobatrachian interrelationships are still far
from being satisfactorily resolved. In order to address the high-level
relationships of the taxa to which these specimens belong, we conducted a
phylogenetic analysis of a matrix of 42 taxa, including extant
representatives of most of the higher groups of neobatrachians as well as
non-neobatrachians, and 75 mostly osteological characters in TNT 1.1 under
implied weights with different values of the concavity constant (k). As in
other analyses based on morphological data, within Neobatrachia we recovered
a monophyletic Ranoides but hyloid taxa appear as stem-ranoids. Our analysis
consistently place A. placidoi and E. alcinae in nested positions among
hyloid taxa, although the topology of the tree varies slightly, whereas C.
gracilis appears to be a stem neobatrachian or have a basal position within
crown Neobatrachia. Recent studies based on molecular data have estimated
divergence times for several anuran clades and proposed the main radiation
of hyloid neobatrachians, excluding the australobatrachians, as a Late
Cretaceous-Paleogene event. The taxonomically diverse anurans from the Crato
Formation show that some hyloid lineages might have diverged already by the
mid Cretaceous and that the early history of neobatrachians is as yet not
documented in the fossil record.


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

"Life is the art of drawing
sufficient conclusions from
insufficient premises."
               -- Samuel Butler