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Several New Papers



Yeah, subject lines like that are boring and redundant and repetitive and redundant...

First, the "official" versions of a couple of previously mentioned papers are out:

Ericson, P.G., Anderson, C.L., Britton, T., Elzanowski, A., Johansson, U.S., Källersjö, M., Ohlson, J.I., Parsons, T.J., Zuccon, D., and Mayr, G. 2006. Diversification of Neoaves: integration of molecular sequence data and fossils. Biology Letters 2(4):543-547. doi: 10.1098/rsbl.2006.0523.

ABSTRACT: Patterns of diversification and timing of evolution within Neoaves, which includes almost 95% of all bird species, are virtually unknown. On the other hand, molecular data consistently indicate a Cretaceous origin of many neoavian lineages and the fossil record seems to support an Early Tertiary diversification. Here, we present the first well-resolved molecular phylogeny for Neoaves, together with divergence time estimates calibrated with a large number of stratigraphically and phylogenetically well-documented fossils. Our study defines several well-supported clades within Neoaves. The calibration results suggest that Neoaves, after an initial split from Galloanseres in Mid-Cretaceous, diversified around or soon after the K/T boundary. Our results thus do not contradict palaeontological data and show that there is no solid molecular evidence for an extensive pre-Tertiary radiation of Neoaves.


Nesbitt, S.J., Turner, A.H., Erickson, G.M., and Norell, M.A. 2006. Prey choice and cannibalistic behaviour in the theropod Coelophysis. Biology Letters 2(4):611-614. doi: 10.1098/rsbl.2006.0524.


ABSTRACT: Direct evidence of prey choice in carnivorous dinosaurs is rare in the fossil record. The most celebrated example pertains to purported stomach contents in the carnivorous dinosaur Coelophysis bauri, which besides revealing prey choice, also points to cannibalistic behaviour as being commonplace (Colbert 1989, 1995). Here, we test this hypothesis by conducting the first comprehensive anatomical and histological examination of the famed Coelophysis 'cannibals'. The results unequivocally show that the gut contents derive from early crocodylomorphs rather than juveniles of Coelophysis. These findings suggest that this taxon is not cannibalistic and bring into question the commonality of this behaviour among non-avian dinosaurs.


Also new:

Schweitzer, M.H., Wittmeyer, J.L., and Horner, J.R. 2006. Soft tissue and cellular preservation in vertebrate skeletal elements from the Cretaceous to the present. Proceedings of the Royal Society of London B. doi: 10.1098/rspb.2006.3705.

ABSTRACT: Soft tissues and cell-like microstructures derived from skeletal elements of a well-preserved Tyrannosaurus rex (MOR 1125) were represented by four components in fragments of demineralized cortical and/or medullary bone: flexible and fibrous bone matrix; transparent, hollow and pliable blood vessels; intravascular material, including in some cases, structures morphologically reminiscent of vertebrate red blood cells; and osteocytes with intracellular contents and flexible filipodia. The present study attempts to trace the occurrence of these four components in bone from specimens spanning multiple geological time periods and varied depositional environments. At least three of the four components persist in some skeletal elements of specimens dating to the Campanian. Fibrous bone matrix is more altered over time in morphology and less likely to persist than vessels and/or osteocytes. Vessels vary greatly in preservation, even within the same specimen, with some regions retaining pliability and other regions almost crystalline. Osteocytes also vary, with some retaining long filipodia and transparency, while others present with short and stubby filipodia and deeply pigmented nuclei, or are pigmented throughout with no nucleus visible. Alternative hypotheses are considered to explain the origin/source of observed materials. Finally, a two-part mechanism, involving first cross-linking of molecular components and subsequent mineralization, is proposed to explain the surprising presence of still-soft elements in fossil bone. These results suggest that present models of fossilization processes may be incomplete and that soft tissue elements may be more commonly preserved, even in older specimens, than previously thought. Additionally, in many cases, osteocytes with defined nuclei are preserved, and may represent an important source for informative molecular data.


Three from _Cretaceous Research_:

Candeiro, C.R.A., Martinelli, A.G., Avilla, L.S., and Rich, T.H. 2006. Tetrapods from the Upper Cretaceous (Turonian-Maastrichtian) Bauru Group of Brazil: a reappraisal. Cretaceous Research 27(6):923-946. doi: 10.1016/j.cretres.2006.05.002.

ABSTRACT: An updated, annotated list of all tetrapods from the Adamantina, Uberaba and Marília formations (Bauru Group), which constitute some of the best studied Upper Cretaceous units in Brazil, is presented. Tetrapod diversity in the Bauru Group is remarkable, including an admixture of typically austral Gondwanan taxa (e.g., abelisaurids, notosuchians) and boreal Gondwanan forms (e.g., carcharodontosaurids). Of note is the absence of Laurasian taxa in the upper portion of the Bauru Group. With the exception of some turtles, an anuran, mesoeucrocodylians and one titanosaur, most taxa from the Bauru Group are based on fragmentary and isolated bones, and as such many specimens can be identified only to a higher taxonomic level. Fishes, turtles, anurans, mesoeucrocodylians, dinosaurs, birds and mammals from the Adamantina and Marília formations resemble the latest Late Cretaceous vertebrate faunas from southern South America, except for the absence of ornithischian dinosaurs.


Mezga, A., Meyer, C.A., Tesovic, B.C., and Gusic, I. 2006. The first record of dinosaurs in the Dalmatian part (Croatia) of the Adriatic-Dinaric carbonate platform (ADCP). Cretaceous Research 27(6):735-742. doi: 10.1016/j.cretres.2006.01.001.


ABSTRACT: The first discovery of dinosaur footprints on the Dalmatian part of the Adriatic-Dinaric carbonate platform (ADCP) is reported. They constitute the geologically youngest record of footprints on the ADCP. The trackbearing layer was formed in the intertidal environment and represents the final stage of a shallowing-upward cycle. Just below it, a heavy dinoturbated limestone layer can be observed. Microfacies analysis, incorporating evidence from benthic foraminifera and algae, indicates a Late Turonian-Early Coniacian age. The overall morphology and size of the footprints points to sauropod dinosaurs; they represent the largest forms recorded so far on the ADCP. This hints at a prolonged sauropod presence on the platform and to its Late Cretaceous connection to the continent rather than isolation.


Dyke, G.J., Malakhov, D.V., and Chiappe, L.M. 2006. A re-analysis of the marine bird Asiahesperornis from northern Kazakhstan. Cretaceous Research 27(6):947-953. doi: 10.1016/j.cretres.2006.05.001.


ABSTRACT: Fossil bird material is exceptionally rare in the Mesozoic of western Asia. With the notable exception of the Upper Cretaceous foot-propelled diving bird Asiahesperornis bazhanovi from northern Kazakhstan, the only bird fossils described from this region have been bone fragments from the Upper Cretaceous of Uzbekistan. In this paper, all material referred to date to the hesperornithiform Asiahesperornis is reviewed and re-described. New postcranial elements of this taxon from the holotype Kushmurun locality (Maastrichtian Zhuravlovskaya Svita) are presented, and the taxonomic history and likely affinities of this ocean-going bird are discussed.


Lastly:

Kong, H., Chen, C.-R., Dang, Y.-M., Yang, J.-G., Huang, Q.-H., and Zhao, C.-B. 2006. On three Cretaceous biotas of Songliao Basin. Acta Palaeontologica Sinica 45(3):416-424.

ABSTRACT: The Cretaceous biotas divided in ascending order into the Jehol Biota in the faulted period, the Songhuajiang Biota in the depressed period and the Mingshui Biota in the atrophied period, are well developed and widely distributed. This paper summarizes systematically the main characters of each biota and reveals the general biota features, the general characters vertically and the significance on the research of biostratigraphy, ecological environment and paleoclimate.


Therrien, F. 2006. Depositional environments and fluvial system changes in the dinosaur-bearing Sânpetru Formation (Late Cretaceous, Romania): post-orogenic sedimentation in an active extensional basin. Sedimentary Geology 192(3-4):183-205. doi: 10.1016/j.sedgeo.2006.04.002.


ABSTRACT: The Sânpetru Formation (Hateg Basin, Romania) was deposited in an active extensional basin in response to the post-orogenic collapse of the Southern Carpathians. Despite being one of the best exposed latest Cretaceous continental successions of Eastern Europe and having great potential to improve knowledge about the Mesozoic evolution of the Carpathian orogen and the latest Cretaceous terrestrial paleoenvironments of Europe, this formation has been the subject of limited sedimentologic research. Fourteen stratigraphic sections were measured in the Sânpetru Formation throughout an 860-m-thick interval exposed along the Sibisel Valley in order to conduct the most detailed stratigraphic and sedimentologic study of this formation to date.
The Sânpetru Formation is a repetitive succession of fining-upward units composed of stratified and structureless sandstones, conglomerates, and mudstones. Facies analysis reveals that the Sânpetru Formation was deposited by braided streams that flowed through a symmetrical, extensional basin. The low variability of paleocurrent direction, the sheet-like architecture of the deposits, and the paucity of channel-shaped scours indicate poorly channelized flow across a shallow, broad braidplain.
Small-scale fluctuations in sandstone/mudstone ratio and maximum grain size of channel deposits in the lower Sânpetru Formation reflect autocyclic shifts in paleochannel position. In the upper Sânpetru Formation, sandstone/mudstone ratios and maximum grain size of channel deposits increase, paleocurrent direction changes significantly, and hydromorphic paleosols become the sole type of paleosols present. These changes reflect an episode of rapid uplift of the source area and the basinward creation of accommodation space below the local water table, which resulted in the creation of extensive wetlands. The wetlands of the upper Sânpetru Formation were not an environment favorable for the formation of dinosaur bonebeds, which are found in the lower part of the formation. The apparent absence of fossils in the upper part of the formation led previous researchers to incorrectly interpret the Cretaceous-Tertiary boundary at the transition between the lower and upper Sânpetru Formation.


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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)