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Re: Amargasaurus braincase and neck posture + Camarasaurus growth + Texas titanosaurs

Sorry to bug the list with a pdf request, but if anybody would be willing to 
send me copies of the papers below, it would be much appreciated.


> From: Ben Creisler <bcreisler@gmail.com>
>To: dinosaur@usc.edu 
>Sent: Tuesday, July 8, 2014 10:39 PM
>Subject: Amargasaurus braincase and neck posture + Camarasaurus growth + Texas 
>Ben Creisler
>Sauropod papers in the new issue of Journal of Vertebrate Paleontology:
>Ariana Paulina Carabajal, José L. Carballido & Philip J. Currie (2014)
>Braincase, neuroanatomy, and neck posture of Amargasaurus cazaui
>(Sauropoda, Dicraeosauridae) and its implications for understanding
>head posture in sauropod.s
>Journal of Vertebrate Paleontology 34(4): 870-882
>The braincase of Amargasaurus cazaui from the Lower Cretaceous of
>Argentina represents the only dicraeosaurid sauropod neurocranial
>material known from South America. It has been computer
>tomographically (CT) scanned and three-dimensional digital
>reconstructions of the endocranium and inner ear have been made. The
>cranial endocast is complete, with a volume of approximately 94–98 ml,
>excluding the dorsal sinuses. The labyrinth of the inner ear is
>dorsoventrally taller than the lagena, which is conical, and
>relatively short. The anterior semicircular canal is longer than the
>posterior and lateral semicircular canals, as in most non-titanosaurid
>sauropods. When the braincase is oriented with the lateral
>semicircular canal positioned horizontally, the occipital condyle is
>oriented posteroventrally, suggesting that the head was held with the
>muzzle pointing downward. The morphology of the atlas and axis,
>together with the reconstruction of the osteological neutral pose of
>the neck, supports this neck and head position, and also indicates the
>presence of the proatlas in this taxon. The evidence presente
kull and neck position of Amargasaurus fits with a midheight
>food-gathering strategy. The presence of titanosauriforms and
>rebbachisaurids, together with Amargasaurus, supports the niche
>partitioning hypothesis for the La Amarga Formation sauropods.
>Katja Waskow & P. Martin Sander (2014)
>Growth record and histological variation in the dorsal ribs of
>Camarasaurus sp. (Sauropoda).
>Journal of Vertebrate Paleontology 34(4): 852-869
>Several histological studies have attempted to derive life history
>parameters of sauropod dinosaurs. However, verification of sexual
>maturity and growth rate has been impeded by strong remodeling in
>sampled sauropod long bones. Here, for the first time, histological
>variation in the rib cage of Camarasaurus sp. is studied based on a
>single, relatively small, mature individual. The focus is on the
>growth history of this individual and its implications for sauropod
>growth, age, and sexual maturity. Different bone tissue types were
>observed in different skeletal elements. The long bones show nearly
>completely remodeled fibrolamellar bone, whereas the ribs show primary
>zonal bone, with fewer secondary osteons. Histology reveals that the
>general direction of growth in the rib shaft was from proximal to
>distal. Therefore, the proximal end of the rib shaft, where growth
>originated, was determined to be the best sampling area in ribs,
>providing an almost complete growth record. This study provides the
>most complete growth record for a sauropod so far, and indicates that
>it took 40 years for Camarasaurus sp. to reach full size and 18–19
>years to become sexually mature. These results show that the growth
>rate and the point of sexual maturity for a small sauropod are
>intermediate between the widely divergent previous estimates. With a
>larger database of rib samples from more individuals of different
>ontogenetic stages, this approach could yield g

>John A. Fronimos & Thomas M. Lehman (2014)
>New specimens of a titanosaur sauropod from the Maastrichtian of Big
>Bend National Park, Texas.
>Journal of Vertebrate Paleontology 34(4): 883-899
>New specimens of a titanosaur sauropod from Maastrichtian strata in
>Big Bend National Park, Texas, include well-preserved dorsal vertebrae
>in association with pelvic elements. Anterior dorsal vertebrae are
>characterized by postspinal and centroprezygapophyseal laminae, with
>spinodiapophyseal laminae convergent on the anterior base of the
>neural spine. Posterior dorsal vertebrae are characterized by
>postzygodiapophyseal laminae and divided spinodiapophyseal laminae,
>with spinoprezygapophyseal laminae contributing to the prespinal
>lamina. The ilium and pubis differ from specimens previously
>collected, indicating a greater morphological disparity among
>titanosaurs in the Maastrichtian of West Texas than previously
>recognized. This disparity may be attributable to intraspecific
>variation or to the presence of multiple taxa. The new material is
>compatible with the only presently known North American titanosaur,
>Alamosaurus sanjuanensis, but is not formally referred due to lack of
>overlap with the hypodigm of that species. Comparison with other
>derived titanosaurs finds the closest affinities to Trigonosaurus
>pricei, Uberabatitan riberoi, and Baurutitan britoi of the Upper
>Cretaceous Brazilian Bauru Group, consistent with a South American
>immigration event at the end of the North American sauropod hiatus.