oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Pneumothorax as a predatory goal for the sabertooth cat (Smilodon fatalis)  [PDF]
Ted Wilson, Dirk E. Wilson, Jill M. Zimanske
Open Journal of Animal Sciences (OJAS) , 2013, DOI: 10.4236/ojas.2013.31006
Abstract:

Smilodon fatalis was a large extinct felid distinguished by their two impressive maxillary canines and surprisingly low canine fracture rates. Previous theories regarding their attack strategy have suggested delivering damage by a bite with their maxillary canines. It has also been previously suggested that the canines could have been used to deliver a non-biting stab with an open jaw. It has been generally hypothesized that the attack was delivered to the neck of their large herbivore prey. Smilodon fatalis could have used their canines in a non-biting stab delivered with a closed jaw for the sole purpose of creating a pneumothorax. Creation of a pneumothorax would maximize immediate attack lethality, and minimize exposure of its canines to fracture.

Radiographs Reveal Exceptional Forelimb Strength in the Sabertooth Cat, Smilodon fatalis  [PDF]
Julie A. Meachen-Samuels,Blaire Van Valkenburgh
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0011412
Abstract: The sabertooth cat, Smilodon fatalis, was an enigmatic predator without a true living analog. Their elongate canine teeth were more vulnerable to fracture than those of modern felids, making it imperative for them to immobilize prey with their forelimbs when making a kill. As a result, their need for heavily muscled forelimbs likely exceeded that of modern felids and thus should be reflected in their skeletons. Previous studies on forelimb bones of S. fatalis found them to be relatively robust but did not quantify their ability to withstand loading.
Variation in Craniomandibular Morphology and Sexual Dimorphism in Pantherines and the Sabercat Smilodon fatalis  [PDF]
Per Christiansen, John M. Harris
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0048352
Abstract: Sexual dimorphism is widespread among carnivorans, and has been an important evolutionary factor in social ecology. However, its presence in sabertoothed felids remains contentious. Here we present a comprehensive analysis of extant Panthera and the sabertoothed felid Smilodon fatalis. S. fatalis has been reported to show little or no sexual dimorphism but to have been intraspecifically variable in skull morphology. We found that large and small specimens of S. fatalis could be assigned to male and female sexes with similar degrees of confidence as Panthera based on craniomandibular shape. P. uncia is much less craniomandibularly variable and has low levels of sexual size-dimorphism. Shape variation in S. fatalis probably reflects sexual differences. Craniomandibular size-dimorphism is lower in S. fatalis than in Panthera except P. uncia. Sexual dimorphism in felids is related to more than overall size, and S. fatalis and the four large Panthera species show marked and similar craniomandibular and dental morphometric sexual dimorphism, whereas morphometric dimorphism in P. uncia is less. Many morphometric-sexually dimorphic characters in Panthera and Smilodon are related to bite strength and presumably to killing ecology. This suggests that morphometric sexual dimorphism is an evolutionary adaptation to intraspecific resource partitioning, since large males with thicker upper canines and stronger bite forces would be able to hunt larger prey than females, which is corroborated by feeding ecology in P. leo. Sexual dimorphism indicates that S. fatalis could have been social, but it is unlikely that it lived in fusion-fission units dominated by one or a few males, as in sub-Saharan populations of P. leo. Instead, S. fatalis could have been solitary and polygynous, as most extant felids, or it may have lived in unisexual groups, as is common in P. leo persica.
New evidence of the sabertooth cat Smilodon (Carnivora: Machairodontinae) in the late Pleistocene of southern Chilean Patagonia
PRIETO,ALFREDO; LABARCA,RAFAEL; SIERPE,VíCTOR;
Revista chilena de historia natural , 2010, DOI: 10.4067/S0716-078X2010000200010
Abstract: southern patagonia is rich in late pleistocene mammals, especially herbivores such as camelids, equids and xenarthrans. carnivores, on the other hand, are not commonly found in the paleontological record. one genus, smilodon, is of particular interest because its presence in the region has not been demonstrated. in this paper, we present new fossil dental evidence that supports the presence of smilodon populator (lund) in the region. this evidence corresponds to the most southern record of the genus in the world, and the final step in the colonization of south america after the great american biotic interchange. an ams radiocarbon date on teeth indicates that the remains from southern chilean patagonia are the most recent record for the genus in south america.
New evidence of the sabertooth cat Smilodon (Carnivora: Machairodontinae) in the late Pleistocene of southern Chilean Patagonia Nueva evidencia del gato dientes de sable Smilodon (Carnivora: Machairodontinae) en el Pleistoceno tardío de Patagonia meridional chilena  [cached]
ALFREDO PRIETO,RAFAEL LABARCA,VíCTOR SIERPE
Revista chilena de historia natural , 2010,
Abstract: Southern Patagonia is rich in late Pleistocene mammals, especially herbivores such as Camelids, Equids and Xenarthrans. Carnivores, on the other hand, are not commonly found in the paleontological record. One genus, Smilodon, is of particular interest because its presence in the region has not been demonstrated. In this paper, we present new fossil dental evidence that supports the presence of Smilodon populator (Lund) in the region. This evidence corresponds to the most southern record of the genus in the world, and the final step in the colonization of South America after the Great American Biotic Interchange. An AMS radiocarbon date on teeth indicates that the remains from Southern Chilean Patagonia are the most recent record for the genus in South America. Surpatagonia es particularmente rica en mamíferos finiplesitocenos, particularmente camélidos, équidos y xenartros. Los carnívoros, por su parte, se encuentran representados en menor número en el registro paleontológico. Dentro de estos, el género Smilodon, es de particular interés debido a que su presencia en la región no ha sido convincentemente demostrada. En este trabajo presentamos evidencia dental que permite confirmar la presencia de Smilodon populator (Lund) en la región. Esta evidencia corresponde al registro más sure o de este taxón y al paso final en la colonización de América del Sur después del Gran Intercambio Biótico Americano. Un fechado radiocarbónico directo AMS indica que los restos de Patagonia del Sur corresponden a los registros más tardíos para este género en el subcontinente.
The Making of a Monster: Postnatal Ontogenetic Changes in Craniomandibular Shape in the Great Sabercat Smilodon  [PDF]
Per Christiansen
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0029699
Abstract: Derived sabercats had craniomandibular morphologies that in many respects were highly different from those of extant felids, and this has often been interpreted functionally as adaptations for predation at extreme gape angles with hypertrophied upper canines. It is unknown how much of this was a result of intraspecific postnatal ontogeny, since juveniles of sabercats are rare and no quantitative study has been made of craniomandibular ontogeny. Postnatal ontogenetic craniomandibular shape changes in two morphologically derived sabercats, Smilodon fatalis and S. populator, were analysed using geometric morphometrics and compared to three species of extant pantherines, the jaguar, tiger, and Sunda clouded leopard. Ontogenetic shape changes in Smilodon usually involved the same areas of the cranium and mandible as in extant pantherines, and large-scale modularization was similar, suggesting that such may have been the case for all felids, since it followed the same trends previously observed in other mammals. However, in other respects Smilodon differed from extant pantherines. Their crania underwent much greater and more localised ontogenetic shape changes than did the mandibles, whereas crania and mandibles of extant pantherines underwent smaller, fewer and less localised shape changes. Ontogenetic shape changes in the two species of Smilodon are largely similar, but differences are also present, notably those which may be tied to the presence of larger upper canines in S. populator. Several of the specialized cranial characters differentiating adult Smilodon from extant felids in a functional context, which are usually regarded as evolutionary adaptations for achieving high gape angles, are ontogenetic, and in several instances ontogeny appears to recapitulate phylogeny to some extent. No such ontogenetic evolutionary adaptive changes were found in the extant pantherines. Evolution in morphologically derived sabercats involved greater cranial ontogenetic changes than among extant felids, resulting in greatly modified adult craniomandibular morphologies.
On the predatory habits of Lions and Hyaenas  [cached]
F. C. Eloff
Koedoe : African Protected Area Conservation and Science , 1964, DOI: 10.4102/koedoe.v7i1.805
Abstract: On the predatory habits of Lions and Hyaenas
Spontaneous pneumothorax
Davari R,Rahim MB
Tehran University Medical Journal , 1996,
Abstract: A case with bilateral spontaneous pneumothorax was presented. Etiology, mechanism, and treatment were discussed on the review of literature. Spontaneous Pneumothorax is a clinical entity resulting from a sudden non traumatic rupture of the lung. Biach reported in 1880 that 78% of 916 patients with spontaneous pneumothorax had tuberculosis. Kjergaard emphasized 1932 the primary importance of subpleural bleb disease. Currently the clinical spectrum of spontaneous pneumothorax seems to have entered a third era with the recognition of the interstitial lung disease and AIDS as a significant etiology. Standard treatment is including: observation, thoracocentesis, tube thoracostomy. Chemical pleurodesis, bullectomy or wedge resection of lung with pleural abrasion and occasionally pleurectomy. Little information has been reported regarding the efficacy of such treatment in spontaneous pneumothorax secondary to non bleb disease
Spontaneous pneumothorax
Heinrich Matthys
Multidisciplinary Respiratory Medicine , 2011, DOI: 10.1186/2049-6958-6-1-6
Abstract: From the clinical and etiological standpoint the pneumothorax is classified as: primary spontaneous pneumothorax if occurring without obvious reason or apparent lung disease, secondary spontaneous pneumothorax if due to a well known underlying lung or systemic disease, or as traumatic pneumothorax if it is the result of iatrogenic or non-iatrogenic blunt and/or penetrating chest interventions and injuries.Primary spontaneous pneumothorax (PSP) is therefore defined as the presence of air in the pleural space without apparent underlying lung disease or trauma. The pathogenesis of PSP is not the same for all events. Most authors believe that the communication of air between the alveolar spaces and the pleura is due to a rupture of subpleural blebs or bullae [1].Although most children [2] and adults [3] present blebs or bullae, it is unclear how often this pathology is responsible for the leakage of air from the alveolar into the pleural space [4].During thoracoscopy or surgery often there are other lesions present, such as inflammatory elastofibrotic layers with increased porosity and areas of disrupted mesothelial cells at the visceral pleura, allowing air leakage into the pleural space [5,6].Bullectomy has a recurrence rate of up to 20% without pleurodesis, which may be explained by factors like peripheral airway inflammation due to noxious agents, e.g. tobacco smoke [7], or exposure to high levels of ozone as discussed by Abul et al. in this issue of Multidisciplinary Respiratory Medicine (pp. 16-19). Hereditary factors [8], anatomical abnormalities of the bronchial tree, ischemia at the apices of the lungs [9], low body mass index due to anorexia and other causes of food restriction [10], Marfan syndrome [11] as well as increased aluminium plasma concentrations [12] may also lead to abnormal connective tissue formations (fibrillopathies) predisposing for the occurrence of PSP [13].Secondary spontaneous pneumothorax (SSP) is defined as the presence of air in the ple
Silicosis with bilateral spontaneous pneumothorax  [cached]
Fotedar Sanjay,Chaudhary Dhruva,Singhla Vikas,Narang Rajat
Lung India , 2010,
Abstract: Presentation with simultaneous bilateral pneumothorax is uncommon and usually in the context of secondary spontaneous pneumothorax.The association of pneumothorax and silicosis is infrequent and most cases are unilateral. Bilateral pneumothorax in silicosis is very rare with just a few reports in medical literature.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.