Many New Papers

["Jerry D. Harris" <jharris@dixie.edu>]

Some still new from '05; others brand-spankin' new!

-------------------

Karl, H.-V., and G. Tichy. 2005. About the first occurrence of pseudosuchian 
body remains (Archosauria: Rauisuchidae) from the Lower to Middle Triassic 
Chirotherian-Sandstone of Thuringia (SE Germany). Studia Geologica 
Salmantiscensia 41:39-43.

ABSTRACT: Moulds of osteoderms from a pseudosuchian reptile are described 
from the Lower to Lower Middle Triassic Thuringian Chirotherian Sandstone of 
Thuringia (SE Germany) and compared with the Anisian reptile _Ticinosuchus_. 
One of the imprints shows clear affinities to this rauisuchid genus.

-------------------

Averianov, A. O., T. Martin, S. E. Evans, and A. A. Bakirov. 2006. First 
Jurassic Choristodera from Asia. Naturwissenschaften 93(1):46-50. doi: 
10.1007/s00114-005-0061-2.

ABSTRACT: Although choristoderes have a good Lower Cretaceous record in 
Asia, they have never previously been recorded from Jurassic deposits. Here 
we describe fragmentary vertebral material referable to Choristodera indet. 
from the Middle Jurassic Balabansai Svita of the Fergana Valley, Kyrgyzstan. 
This provides a significant range extension for the group in Asia and shows 
that choristoderes already had a Pan-Laurasian distribution in the Jurassic.


-------------------

Lü, J., Y. Kobayashi, C. Yuan, S. Ji, and Q. Ji. 2005. SEM observation of 
the wing membrane of _Beipiaopterus chenianus_ (Pterosauria). Acta Geologica 
Sinica (English Edition) 79(6):766-769.

ABSTRACT: The cross-section and surface structures of wing membranes from 
the ctenochasmatid pterosaur _Beipiaopterus chenianus_ were observed through 
a scanning electron microscope (SEM). The results show that the wing 
membrane contains a high density of blood vessels, implying strong 
thermoregulatory function, similar to that of a bat.

-------------------

Schulte, P., R. Speijer, H. Mai, and A. Kontny. 2006. The 
Cretaceous-Paleogene (K-P) boundary at Brazos, Texas: sequence stratigraphy, 
depositional events and the Chicxulub impact. Sedimentary Geology 
184(1-2):77-109. doi: 10.1016/j.sedgeo.2005.09.021.

ABSTRACT: Two cores from Brazos, Texas, spanning the Cretaceous-Paleogene 
(K-P) boundary, are investigated by a multidisciplinary approach aiming at 
unraveling environmental changes and sequence stratigraphic setting. In 
addition, the sedimentology of the K-P event deposit and its correlation 
with the K-P boundary is studied. Foraminifera and nannofossil stratigraphy 
indicates that both cores include a latest Maastrichtian (Zone CF1-CF2) and 
earliest Danian (P0, Pa and P1a) shale sequence with a sandy and Chicxulub 
ejecta-bearing event deposit at the K-P boundary; a hiatus of unknown 
duration may be present by the unconformable base of the event deposit. 
Planktic foraminifera as well as calcareous nannofossil abundance and 
diversity both decline abruptly above the event deposit (K-P mass 
extinction), whereas benthic foraminifera show a pronounced faunal change 
but no mass extinction.
    Mineralogical and geochemical proxies suggest that-except for the 
sandwiched K-P event deposit-no facies change took place across the K-P 
boundary and no evidence for adverse an- or dysoxic sedimentary conditions 
following the Chicxulub impact was observed. Therefore, the interval 
bracketing the K-P event deposit is considered as highstand systems tract. 
Increased coarse detritus input and low planktic/benthic (P/B) foraminifera 
ratios during the earliest Paleocene (P0 and Pa) both suggest an increased 
coastal proximity or relative sea-level lowering, although the K-P mass 
extinction of planktic foraminifera might have influenced the P/B ratios as 
well. Consequently, the sandy shales of the early Paleocene are considered 
as late regressive highstand or as lowstand deposit. During P1a, shales 
assigned as transgressive systems tract overlie a pyrite- and 
glauconite-rich bioturbated transgressive surface or type-2-sequence 
boundary. The smectite-dominated clay assemblage, with minor illite, 
kaolinite and chlorite indicates semiarid-humid climates with no obvious 
shifts across the K-P boundary. The magnetic susceptibility signature during 
the Maastrichtian reveals a subtle cyclic (or rhythmic) pattern, whereas a 
high-amplitude cyclic pattern is present during the early Danian.
    The K-P event deposit shows a succession of high-energetic debris flows 
and turbidites derived from multiple source areas, followed by a period of 
decreasing current energy. Deposition was likely triggered by multiple 
tsunami or tempestites followed by a prolonged period of reworking and 
settling. The Chicxulub ejecta at the base of the K-P event deposit consists 
of Mg-rich smectite-as well as Fe-Mg-rich chlorite-spherules. Their 
mineralogical composition points to target rocks of mafic to intermediate 
composition, presumably situated in the northwestern sector of the Chicxulub 
impact structure. Besides these silicic phases, the most prominent ejecta 
components are limestone clasts, accretionary carbonate clasts, and 
microspar, suggesting that the Texas area received ejecta also from shallow, 
carbonate-rich lithologies at the impact site on the Yucatán carbonate 
platform. The excellent correlation of Chicxulub ejecta at Brazos with 
ejecta found in the K-P boundary layer worldwide - along with the associated 
mass extinction - provides no evidence that Chicxulub predated the K-P 
boundary and allows for unequivocal positioning of the K-P boundary at the 
event deposit.

--------------------------

Ciampaglio, C. N., G. A. Wray, and B. H. Corliss. 2005. A toothy tale of 
evolution: convergence in tooth morphology among marine Mesozoic-Cenozoic 
sharks, reptiles, and mammals. The Sedimentary Record 3(4):4-8.

ABSTRACT: Although mechanisms of niche replacement are discussed thoroughly 
in the evolutionary paleontological literature (i.e., extinctions, 
competition, evolution of new adaptive morphologies), actual studies 
involving quantitative analyses are not common. In this study, morphological 
features of dentition in Late Cretaceous and Cenozoic marine vertebrate 
predators were analyzed.The analysis included species of Late Cretaceous and 
Cenozoic sharks, Late Cretaceous marine reptiles, and Cenozoic marine 
mammals. Dental characters used in the study were both discrete and 
continuous. Species included in the analysis were originally collected from 
Late Cretaceous and Cenozoic rocks from the south-central, southeastern, and 
the mid-Atlantic regions of the United States, as well as Europe and the 
Pacific Rim.
    A morphometric "tooth space" was constructed using the eigenvectors 
generated from Principal Component Analysis of the dental character data.The 
results of the analysis show that Mesozoic marine reptiles occupied a small, 
discrete region of the tooth morphospace, whereas Cretaceous sharks occupied 
a much larger, diffuse region of the morphospace. During the Paleogene a 
profusion of shark tooth morphologies occurred and then expanded into new 
areas of tooth morphospace.Yet, no overlap with the morphospace previously 
occupied by Mesozoic marine reptiles occurred.A large number of novel tooth 
morphologies evolved with the evolution of marine mammals during the 
Cenozoic. Remarkably, many of the tooth forms converged on the Mesozoic 
marine reptile designs, and hence a major overlap of marine mammal tooth 
morphospace with the previously occupied Mesozoic marine reptile morphospace 
occurred.Additionally, the shift from heterodonty (teeth of different types) 
to homodonty (teeth of similar types) occurred in several members of both 
the Mesozoic marine reptiles and the Cenozoic marine mammals.
    Based on dental morphology, this study indicates that following the 
extinction of the Mesozoic marine reptiles during the Late Cretaceous, 
Cenozoic sharks failed to occupy the vacated niches, yet Cenozoic marine 
mammal dentition converged on the previous Mesozoic marine reptile tooth 
designs.Apparently, Cenozoic marine mammals occupied
the vacated Mesozoic marine reptile dietary niches.

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

"Actually, it's a bacteria-run planet, but
mammals are better at public relations."
                                     -- Dave Unwin