Wyniki wyszukiwania

1

Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik

Carved teeth and strange jaws: how glyptodonts masticated

100%

Farina R. A., Vizcaino S. F.

Acta Palaeontologica Polonica

|

2001

|

tom 46

|

nr 2

In this paper, the highly peculiar masticatory apparatus of glyptodonts is studied. The general morphology of the skull is analysed using a morphometric procedure, the Resistant Fit Theta Rho Analysis, which allows comparison among different biological forms. Here, a large terminal form, the late Pleistocene genus Glyptodon, is compared with the smaller primitive Miocene genus Propalaehoplophorus, and with the generalised Recent armadillo Chaetophractus. The masticatory musculature of glyptodonts is reconstructed. Their tooth form and wear facets, as well as their mandibular symphysis and jaw joint, are analysed. A model of jaw movement is constructed based on these analyses. It is demonstrated that the masticatory apparatus of glyptodonts had undergone a telescoping process, which was already underway in the most ancient forms whose skull is known. This process created problems in regard to the way stresses produced by mastication were absorbed by the mandible, and therefore it might be regarded as non-adaptive. Some functional explanatory hypotheses are discussed, such as a requirement of keeping the moment of the weight of the cranium small enough to be counterbalanced by the neck muscles, or fitting the head into the armour.

2

Morphology and development of depressive nerve (nervus depressor) of pig at prenatal stage

84%

Pospieszny N., Kleckowska J., Janeczek M.

Electronic Journal of Polish Agricultural Universities. Series Veterinary Medicine

|

2003

|

tom 06

|

nr 2

3

Axial rotation in the lumbar spine following axial force wrench

84%

Wachowski M. M., Hubert J., Hawellek T., Mansour M., Dorner J., Kubein-Meesenburg D., Fanghanel J., Raab B. W., Dumont B. C., Nagerl H.

Journal of Physiology and Pharmacology. Supplement

|

2009

|

tom 60

|

nr 8

61-64

4

Load transfer by fine threading the implant neck - a FEM study

84%

Rahimi A., Bourauel C., Jager A., Gedrange T., Heinemann F.

Journal of Physiology and Pharmacology. Supplement

|

2009

|

tom 60

|

nr 8

107-112

5

Macroevolutionary and morphofunctional patterns in theropod skulls: A morphometric approach

84%

Foth C., Rauhut O. W. M.

Acta Palaeontologica Polonica

|

2013

|

tom 58

|

nr 1

Theropod dinosaurs are one of the most remarkable lineages of terrestrial vertebrates in the Mesozoic, showing high taxo− nomic and ecological diversity. We investigate the cranial diversity of non−avian theropods and some basal birds, using geometric morphometrics to obtain insights into the evolutionary modifications of the skull. Theropod skulls mostly vary in the shape of the snout and length of the postorbital region (principal component [PC] 1), with further variation in orbit shape, depth of the postorbital region, and position of the jaw joint (PC 2 and PC 3). These results indicate that the cranial shape of theropods is closely correlated with phylogeny and dietary preference. Skull shapes of non−carnivorous taxa dif− fer significantly from carnivorous taxa, suggesting that dietary preference affects skull shape. Furthermore, we found a significant correlation between the first three PC axes and functional proxies (average maximum stress and an indicator of skull strength). Interestingly, basal birds occupy a large area within the morphospace, indicating a high cranial, and thus also ecological, diversity. However, we could include only a small number of basal avialan species, because their skulls are fragile and there are few good skull reconstructions. Taking the known diversity of basal birds from the Jehol biota into account, the present result might even underestimate the morphological diversity of basal avialans.

6

A novel post-and-core restoration system - results of three years of clinical application of the 'Wuerzburg Post'

84%

Rottner K., Boldt J., Proff P., Spassov A., Gredes T., Mack F., Richter E.

Journal of Physiology and Pharmacology. Supplement

|

2008

|

tom 59

|

nr 5

105-115

7

Reconstructed masticatory biomechanics of Peligrotherium tropicalis, a non-therian mammal from the Paleocene of Argentina

84%

Harper T., Adkins C. F., Rougier G. W.

Acta Palaeontologica Polonica

|

2022

|

tom 67

|

nr 1

8

Validity of an inertial measurement unit system to assess lower-limb kinematics during a maximal linear deceleration

84%

Jordan A. R., Carson H. J., Wilkie B., Harper D. J.

Central European Journal of Sport Sciences and Medicine

|

2021

|

tom 33

|

nr 01

9

Hip biomechanics in orthopaedic clinical practice

84%

Antolic V., Kralj-Iglic V., Iglic A., Pompe B.

Cellular and Molecular Biology Letters

|

2002

|

tom 07

|

nr 2

Radiographic and clinical studies, coupled with biomechanical assessment of the hip, are important tools for predicting the development of osteoarthitis of the hip. In order to better understand the treatment of hip dysplasia, it is necessary to determine the contact stress in the hip joint. In this study, a three-dimensional mathematical model was used to determine hip joint contact stress. Because of the discrepancy in the results of analyses of different radiographic indicators of hip dysplasia, the calculation of hip joint contact stress is proposed for a more accurate assessment of the severity of hip dysplasia.

10

Fused and vaulted nasals of tyrannosaurid dinosaurs: Implications for cranial strength and feeding mechanics

67%

Snively E., Henderson D. M., Phillips D. S.

Acta Palaeontologica Polonica

|

2006

|

tom 51

|

nr 3

Tyrannosaurid theropods display several unusual adaptations of the skulls and teeth. Their nasals are fused and vaulted, suggesting that these elements braced the cranium against high feeding forces. Exceptionally high strengths of maxillary teeth in Tyrannosaurus rex indicate that it could exert relatively greater feeding forces than other tyrannosaurids. Areas and second moments of area of the nasals, calculated from CT cross−sections, show higher nasal strengths for large tyrannosaurids than for Allosaurus fragilis. Cross−sectional geometry of theropod crania reveals high second moments of area in tyrannosaurids, with resulting high strengths in bending and torsion, when compared with the crania of similarly sized theropods. In tyrannosaurids trends of strength increase are positively allomeric and have similar allometric exponents, indicating correlated progression towards unusually high strengths of the feeding apparatus. Fused, arched nasals and broad crania of tyrannosaurids are consistent with deep bites that impacted bone and powerful lateral movements of the head for dismembering prey.

11

Functional morphology and biomechanics of the cynodont Trucidocynodon riograndensis from the Triassic of Southern Brazil: Pectoral girdle and forelimb

67%

de Oliveira T. V., Schultz C. L.

Acta Palaeontologica Polonica

|

2016

|

tom 61

|

nr 2

Non-mammalian cynodonts provide insights on several points about mammalian evolution, such as the postural change and locomotory advances within the group. Unfortunately, complete skeletons of Triassic cynodonts are rather uncommon and where more complete specimens are found they can offer a global vision on some traits not available from partial specimens. This is the case of the cynodont Trucidocynodon riograndensis, from the Triassic of Brazil, that has preserved its forelimbs providing some insights into locomotory properties. The movements between interclavicle and clavicle must have been limited, as such as those occurring between the latter and the scapulocoracoid although the long acromion process of this should have permitted a greater degree of freedom. Some of the more significant movements were those on the shoulder joint, in which the maximum adduction should have been ca. 35º relative to the parasagittal plane and the greater abduction ca. 55º. The maximum adduction occurred when the humerus was in the more retracted position during stride and the variation in the adduction/abduction should have been significant to the limb posture during its recovery stroke. The long olecranon and the distal overlapping between radius and ulna suggest the predominance of simple flexion/extension on the forearm without significant pronation/supination. The poorly preserved hand suggests that Trucidocynodon could have evolved a slight semidigitigrad condition in its forelimbs. All these features give to this cynodont an important role in the evolution of the mammalian locomotory properties indicating that some features, such as the possibility of greater humeral adduction, evolved early in cynodont lineage.

12

Reconstructing insect flight performance from fossil evidence

67%

Wootton R. J.

Acta Zoologica Cracoviensia

|

2003

|

tom 46

|

nr Suppl.

Some structural characters and morphometric variables – size, body shape and proportions, wing shape and structure – that appear in insects to be linked with flight performance, are discussed and evaluated, and methods are described for deriving these from fossil material. Some wing design categories associated with particular flight techniques and capabilities are identified. Their use in reconstructing the flight performance of extinct insects is illustrated with reference to Carboniferous palaeodictyopteroids and Mesozoic palaeontinoid Hemiptera.

13

The first dsungaripterid pterosaur from the Kimmeridgian of Germany and the biomechanics of pterosaur long bones

67%

Fastnacht M.

Acta Palaeontologica Polonica

|

2005

|

tom 50

|

nr 2

A partial vertebral column, pelvis and femora of a newly discovered pterosaur are described. The remains from the Upper Jurassic (Kimmeridgian) of Oker (northern Germany) can be identified as belonging to the Dsungaripteridae because the cross−sections of the bones have relatively thick walls. The close resemblance in morphology to the Lower Cretaceous Dsungaripterus allows identification of the specimen as the first and oldest record of dsungaripterids in Central Europe. Furthermore, it is the oldest certain record of a dsungaripterid pterosaur world wide. The biomechanical characteristics of the dsungaripterid long bone construction shows that it has less resistance against bending and torsion than in non−dsungaripteroid pterosaurs, but has greater strength against compression and local buckling. This supports former suggestions that dsungaripterids inhabited continental areas that required an active way of life including frequent take−off and landing phases. The reconstruction of the lever arms of the pelvic musculature and the mobility of the femur indicates a quadrupedal terrestrial locomotion.

14

Biomechanics of Scots pine (Pinus sylvestris L.) coming from mature stands

59%

Jelonek T., Jakubowski M., Remlein A.

Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology

|

2012

|

tom 78

15

The ground sloth Megatherium americanum: skull shape, bite forces, and diet

59%

Bargo M. S.

Acta Palaeontologica Polonica

|

2001

|

tom 46

|

nr 2

Megatherium americanum (late Pleistocene of South America) has traditionally been regarded a herbivore, but its dietary habits have not been considered in terms of a morphofunctional analysis. This study describes and analyses the morphology of the masticatory apparatus in order to interpret the jaw mechanics of M. americanum, and thus to infer its diet and behaviour. The results are compared with those for the mylodontid Glossotherium robustum and the extant sloth Bradypus variegatus. The areas of origin and insertion of the masticatory musculature were reconstructed, and the moment arms generated by this musculature were estimated so that the mechanics of the feeding apparatus might be described. These analyses indicate that M. americanum was well adapted for strong and mainly vertical biting. The teeth are extremely hypsodont and bilophodont, and the sagittal section of each loph is triangular with a sharp edge. This suggests that the teeth were used mainly for cutting, rather than grinding, and that hard and fibrous food was not the main dietary component. The diet of M. americanum merits more rigorous analysis, but the evidence provided here indicates that it probably had a browsing diet in open habitats, but also could have fed on moderate to soft tough food.

Ograniczanie wyników

Carved teeth and strange jaws: how glyptodonts masticated

Morphology and development of depressive nerve (nervus depressor) of pig at prenatal stage

Axial rotation in the lumbar spine following axial force wrench

Load transfer by fine threading the implant neck - a FEM study

Macroevolutionary and morphofunctional patterns in theropod skulls: A morphometric approach

A novel post-and-core restoration system - results of three years of clinical application of the 'Wuerzburg Post'

Reconstructed masticatory biomechanics of Peligrotherium tropicalis, a non-therian mammal from the Paleocene of Argentina

Validity of an inertial measurement unit system to assess lower-limb kinematics during a maximal linear deceleration

Hip biomechanics in orthopaedic clinical practice

Fused and vaulted nasals of tyrannosaurid dinosaurs: Implications for cranial strength and feeding mechanics

Functional morphology and biomechanics of the cynodont Trucidocynodon riograndensis from the Triassic of Southern Brazil: Pectoral girdle and forelimb

Reconstructing insect flight performance from fossil evidence

The first dsungaripterid pterosaur from the Kimmeridgian of Germany and the biomechanics of pterosaur long bones

Biomechanics of Scots pine (Pinus sylvestris L.) coming from mature stands

The ground sloth Megatherium americanum: skull shape, bite forces, and diet