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Uruguay sauropod material and other new papers

From: Ben Creisler

A few new papers:

Matías Soto, Daniel Perea, and Andrea Cambiaso (2011) 
First sauropod (Dinosauria: Saurischia) remains from the 
Guichón Formation, Late Cretaceous of Uruguay.
Journal of South American Earth Sciences (advance online 

We report the first sauropod remains recorded in the 
Guichón Formation, western Uruguay. The materials belong 
to a middle-sized sauropod represented by more than one 
individual, and among other remains include more than 
fifty caudal centra. Close to the bones, several eggshell 
fragments resembling Sphaerovum erbeni Mones, 1980 were 
found. We discuss the biostratigraphic implications of 
these findings, which for the first time allow us to 
confidently refer the Guichón Formation to the Late 
Cretaceous. The combination of several synapomorphies 
such as a biconvex first caudal centrum, strongly 
procoelous middle and distal caudal centra, and a 
pyramidal astragalus suggests that the sauropod remains 
belong to a derived lithostrotian, probably related to 
Pellegrinisaurus powelli, Baurutitan britoi and 
Alamosaurus sanjuanensis. A few isolated teeth (now lost) 
referred by Frederich von Huene in 1934 to ornithomimid 
theropods and ornithischians are herein reinterpreted as 
belonging to indeterminate theropods and basal 

Jung-Kyun Kim, Min Huh, Seon-Gyu Lee and Youn-Joong Kim 
Preliminary study on dinosaur rib microstructure by 
applying correlative microscopy techniques.
Geosciences Journal 15(3): 225-235
DOI: 10.1007/s12303-001-0026-1 

A dorsal rib portion from the post-cranial skeleton of a 
small ornithischian dinosaur discovered from the 
fossiliferous locality in Boseong was analyzed through 
Optical Microscopy (OM), Scanning Electron Microscopy 
(SEM), Electron Probe Microanalyser (EPMA), X-ray 
Diffraction (XRD), and Transmission Electron Microscopy 
(TEM) to determine the detailed microstructure and 
components of the fossilized dinosaur bone. The rib bone 
portion was specifically chosen as an initial research 
sample to establish efficient experimental methodology in 
order to apply to future dinosaur osteohistological 
study. Since the fossilized bone was highly compressed by 
the surrounding matrix, distinct features of bone tissues 
were not clearly visible in OM cross sections. Instead, 
we observed two other features: (1) numerous patches of 
calcite crystals in various orientations filling the void 
region; (2) apatite crystals of 10∼200 nm size 
constituting the bone matrix region, which is revealed by 
XRD, EPMA, SEM, and TEM. The data we have obtained so far 
is preliminary to directly elucidate the specific 
microstructural properties of fossilized bone such as 
bone formation and growth patterns, but we have provided 
possibility of revealing the characteristic features of 
dinosaur bone microstructure in nano-scale and 
established efficient specimen preparation methods for 
correlative Optical Microscopy (OM)-Electron Microscopy 
(EM) study. 

M. S. Barash (2011)
Factors responsible for catastrophic extinction of marine 
organisms at the Mesozoic-Cenozoic boundary. 
Oceanology 51(4): 640-651 
DOI: 10.1134/S0001437011040047 

The mass death of organisms at the Cretaceous-Tertiary 
boundary (KT boundary) resulted in the extinction of 
approximately half of marine genera. Some taxa had 
degraded by the end of the Cretaceous to become 
eventually extinct either before or precisely at the KT 
boundary. Most of them became extinct immediately at this 
boundary. The terminal Cretaceous was marked by changes 
in many environmental processes, which influenced the 
biota. These included tectonic events, powerful basalt 
eruptions, falls of large asteroids (impact events), 
anoxia, transgressions and regressions, cooling and 
warming episodes, and the chemistry of the atmosphere and 
seawater. All these factors, except for impact events, 
could stimulate degradation of some groups of organisms, 
not their extinction. The Cretaceous-Tertiary boundary 
was marked by major impact events, which are reflected in 
the occurrence of the Chicxulub, Shiva, Boltysh, 
Silverpit, and, probably some other impact craters. Some 
known craters were left by asteroids at that time or 
slightly earlier. At least as many asteroids undoubtedly 
fell into the ocean. The combination of many factors in 
the terminal Cretaceous harmful for organisms and 
seemingly unrelated to each other may be likely explained 
only by a single supreme cause beyond the Solar System.