[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

New Papers



Hi All -

   Some new goodies (and taxa):

Nobre, P.H., and de Souza Carvalho, I. 2006. Adamantinasuchus navae: a new
Gondwanan Crocodylomorpha (Mesoeucrocodylia) from the Late Cretaceous of
Brazil. Gondwana Research 10(3-4):370-378. doi: 10.1016/j.gr.2006.05.008.

ABSTRACT: A new Late Cretaceous mesoeucrocodylian from the Adamantina
Formation (Bauru Basin), São Paulo State, Brazil is described. The main
features of this new species are the short, high oreinirostral rostrum, the
large laterally positioned orbital notches and external nares in the
anteriormost portion of the rostrum. The mandible is robust and
concave-shaped in relation to the skull. The dentition is highly
specialized, with two prominent incisiform teeth, a hypertrophied
caniniform, and seven molariform teeth. The molariform teeth are ornamented
with denticles in their lingual surface and are smooth on their labial
surface. The molariforms are elliptical in cross-section, presenting the
largest axis in the labial-lingual direction. Such dental characteristics
are unique among the terrestrial crocodylomorphs of the Gondwana.


Salgado, L., de Souza Carvalho, I., and Garrido, A.C. 2006. Zapalasaurus bonapartei, un nuevo dinosaurio saurópodo de La Formación La Amarga (Cretácico Inferior), noroeste de Patagonia, Provincia de Neuquén, Argentina. Geobios 39(5):695-707. doi: 10.1016/j.geobios.2005.06.001.

ABSTRACT: An incomplete skeleton from Puesto Morales (Neuquén Province,
Argentina) is described as a new species of sauropod, Zapalasaurus
bonapartei. The unit that yielded the holotype of this dinosaur is the
Piedra Parada Member of the La Amarga Formation, whose age is regarded as
Barremian-lower Aptian. Several characters are interpreted as autapomorphies
of Zapalasaurus bonapartei: cervical vertebrae with a lamina uniting the
prezygapophysis and the zygapophyseal portion of the postzygodiapophyseal
lamina, cervical vertebrae with the diapophyseal portion of the
postzygodiapophyseal lamina reduced, cervical vertebrae with poorly
developed spinoprezygapophyseal laminae, mid and posterior caudal vertebrae
with anteroposteriorly elongated neural spines, whose anterodorsal corners
are higher than their posterodorsal ones, and caudal centrum length doubles
over first 20 vertebrae. Zapalasaurus bonapartei is considered as the sister
group of the other diplodocoids (excluding Haplocanthosaurus). Diplodocoids
were abundant in the Early Cretaceous, becoming extinct by the early Late
Cretaceous. The record of Zapalasaurus bonapartei shows that, at least in
the Neuquina Basin, basal diplodocoids were more diverse than previously
thought.

    (...yes, I know this was announced already, but this is for those
wedded to page numbers as "official" publication).


Kurochkin, E.N., Saveliev, S.V., Postnov, A.A., Pervushov, E.M., and Popov, E.V. 2006. On the brain of a primitive bird from the Upper Cretaceous of European Russia. Paleontological Journal 40(6):655-667. doi: 10.1134/S0031030106060086.

ABSTRACT: Cerebavis cenomanica gen. et sp. nov. from the Middle Cenomanian
of the Volgograd Region (Russia) is described based on a brain mold. The
brain of Cerebavis is characterized by a mosaic combination of primitive and
advanced features. The brain weight is estimated as approximately 1 g. The
cerebrum is relatively very large, but lacks sulci. The brain mold has long
olfactory lobes with large olfactory bulbs, a well-developed epiphysis, and
a parietal organ. The auditory tubercles on the dorsal surface of the
midbrain are well developed. The optical lobes are located under the
auditory lobes, caudoventral to the cerebral hemispheres. The cerebellum is
not preserved, but its imprints just behind the midbrain suggest that it was
probably relatively small and extended dorsoventrally. The brain of
Cerebavis is similar in some features to that of Archaeopteryx, but is
substantially more advanced and more specialized. Cerebavis is similar to
living ornithurine birds in the large cerebral hemispheres, but differs in
the absence of a well-developed neostriatum, the presence of excessively
developed olfactory lobes, and in the pattern of the midbrain. Thus, senses
of smell, eyesight, and hearing were well developed in Cerebavis. It could
have been equally active in the afternoon and at night. The unique brain
design demonstrated by Cerebavis has not been repeated in subsequent
evolution. It provides evidence for a wide diversity of feathered creatures
in the past. Cerebavis probably belongs to the Enantiornithes.

    Is this a first?  I don't know of any other taxon based on an
endocast...?


Angielczyk, K.D., and Fox, D.L. 2006. Exploring new uses for measures of fit of phylogenetic hypotheses to the fossil record. Paleobiology 32(1):147-165. doi: 10.1666/0094-8373(2006)032[0147:ENUFMO]2.0.CO;2.


ABSTRACT: Intrinsic features of organisms, such as morphology or DNA sequences, and the stratigraphic occurrence of fossils provide distinct evidence of the phylogenetic history of life. Because there is only one true history, we expect the historical signals preserved by these data sets to be similar, and several metrics have been developed to measure the fit of phylogenetic hypotheses to the fossil record. However, a variety of biases affect these metrics, and it is unclear whether they can provide more than an estimate of whether one tree fits the fossil record better than another when used on their own. Here we explore two novel applications of stratigraphic fit metrics when they are used with a combination of phylogeny reconstruction methods that do and do not directly include stratigraphic occurrence data (e.g., cladistics and stratocladistics). In particular, we are interested in whether differences in the stratigraphic fit of cladistic and stratocladistic trees can be used to identify cases in which the stratocladistic results are likely to be more accurate, as well as whether such differences can be used to identify potential problems in the underlying data sets.
Using 550 simulated data sets that were analyzed with cladistics and stratocladistics, we found that the absolute difference in fit to stratigraphy between the results of the two methods was strongly correlated with the probability of character state transition and the accuracy of the stratocladistic results relative to the cladistic results. Completeness of the fossil record and number of taxa included in the analysis were more weakly correlated with stratigraphic fit, and the statistical significance of the differences in fit between the two sets of results did not show a meaningful relationship with improvements in accuracy or potential data problems. These results suggest that measuring the difference in stratigraphic fit between cladistic and stratocladistic trees might be useful for qualitatively estimating whether the addition of stratigraphic data benefited a phylogenetic analysis, and for identifying data sets with high average rates of character state change.



Tumarkin-Deratzian, A.R., Vann, D.R., and Dodson, P. 2006. Bone surface texture as an ontogenetic indicator in long bones of the Canada goose Branta canadensis (Anseriformes: Anatidae). Zoological Journal of the Linnean Society 148(2):133-168. doi: 10.1111/j.1096-3642.2006.00232.x.


ABSTRACT: Growth series of femora, tibiotarsi, and humeri of the Canada goose Branta canadensis were examined to evaluate whether bone surface textures are reliable indicators of relative age and skeletal maturity in this taxon. The relationship between surface texture and skeletal maturity was analysed by comparing element texture types with both size-based and size-independent maturity estimates. A subsample of hindlimb elements was thin sectioned to observe histological structures underlying various surface textures. Three relative age classes of elements are identifiable based on surface texture. Juvenile and subadult bone textures have fibrous and/or porous areas on the bone shaft and are distinguished by the presence (in juveniles) or absence (in subadults) of coarse longitudinal striations in proximal and/or distal regions. Adult bone texture lacks surface porosity. Immature textures are caused by channels in fibrolamellar bone intersecting the bone surface; the presence or absence of striations is determined by channel orientation. Mature textures may be underlain by fibrolamellar bone with little to no surface exposure of channels, or by lamellar bone deposited after rapid growth ceases. The utility of the textural ageing method appears intimately related to the uninterrupted determinate growth regime of Branta. This suggests that bone surface textures may prove useful as skeletal maturity indicators in both modern and fossil taxa with similar growth regimes, but may not necessarily be reliable for taxa with interrupted and/or indeterminate growth.

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

"Trying to estimate the divergence times
of fungal, algal or prokaryotic groups on
the basis of a partial reptilian fossil and
protein sequences from mice and humans
is like trying to decipher Demotic Egyptian with
the help of an odometer and the Oxford
English Dictionary."
-- D. Graur & W. Martin (_Trends
in Genetics_ 20[2], 2004)