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Wyszukujesz frazę "Computer tomography" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Fused and vaulted nasals of tyrannosaurid dinosaurs: Implications for cranial strength and feeding mechanics
Autorzy:
Snively, E.
Henderson, D.M.
Phillips, D.S.
Powiązania:
https://bibliotekanauki.pl/articles/21688.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Carnosauria
computer tomography
Theropoda
Tyrannosauridae
biomechanics
computer modelling
dinosaur
feeding mechanism
paleontology
theropod dinosaur
tyrannosaurid dinosaur
cranial strength
Opis:
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.
Źródło:
Acta Palaeontologica Polonica; 2006, 51, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The endocranium of the theropod dinosaur Ceratosaurus studied with computer tomography
Autorzy:
Sanders, R K
Smith, D.K.
Powiązania:
https://bibliotekanauki.pl/articles/22430.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
cranial pneumatic system
Ceratosaurus
virtual rendering
paleoneurology
Theropoda
theropod dinosaur
computer tomography
dinosaur
endocranium
paleontology
Opis:
A well preserved specimen of the theropod Ceratosaurusfrom the Upper Jurassic Morrison Formation of western Colorado was recently described and given the name C. magnicornis. The systematics of the genus is outside the scope of the present study but, as a generally accepted basal tetanuran, the braincase was CT scanned to provide a description of the endocranium, inner ear, pneumatic, and venous sinus systems in a primitive member of this clade. Five major subregions of the theropod endocranium are distinguished for the purpose of simplifying cranial computed tomographic interpretation and to provide a systematic means of comparison to other endocrania. The skull morphology of Ceratosaurus influences the overall braincase morphology and the number and distribution of the major foramina. The low pontine angle and relatively unflexed braincase is considered a more primitive character. The orientation of the horizontal semicircular canal confirms a rather horizontal and unerect posture of the head and neck. As in birds, the narrower skull morphology of Ceratosaurusis associated with fewer cranial nerve foramina. Additionally, the maxillary dominated dentigerous upper jaw of Ceratosaurusis felt to share with the alligator a large rostrally directed maxillary division of the trigeminal nerve and a small ophthalmic branch. The upper bill of birds, being dominated by the premaxillary and lacking teeth, is innervated predominantly by the ophthalmic division of the trigeminal nerve. For this reason, avian−based cranial nerve reconstructions are felt to be inappropriate for basal theropods.Ceratosaurusskull pneumatization and possible evidence of olfactory conchal structures is on the other hand very avian in character. Based on computed tomography, Ceratosaurusis determined to have possessed a typical basal theropod endocranium and bipedal vestibular system similar to Allosaurus.
Źródło:
Acta Palaeontologica Polonica; 2005, 50, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A giant boring in a Silurian stromatoporoid analysed by computer tomography
Autorzy:
Beuck, L
Wisshak, M.
Munnecke, A.
Freiwald, A.
Powiązania:
https://bibliotekanauki.pl/articles/20045.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Upper Visby Formation
computer tomography
Sweden
Densastroma pexisum
paleontology
Gotland Island
Silurian
stromatoporoid
trace fossil
Osprioneides kampto
analysis
Opis:
This study describes the largest known Palaeozoic boring trace, Osprioneides kampto igen. et isp. nov., found within a stromatoporoid Densastroma pexisum from the Upper Visby Formation (lower Wenlock, Silurian) on the island of Gotland, Sweden. Differences between the physical properties of the stromatoporoid and the dense micritic infilling of the borings allowed the application of the CT−scan technology for the 2D and 3D−visualisation of this rare trace. The additional application of a stereoscopic technique on these CT images and movies enhances its value for unravelling spatial orientations. This non−destructive method has a great potential for future macroas well as microboring analyses. The trace maker, most likely a worm, infested the hosting colony post−mortem with up to 120 mm long borings measuring 5–17 mm in diameter. Smaller forms of Trypanites and Palaeosabella within the same stromatoporoid preferentially occur in the outer coenosteum and occasionally in abandoned borings of O. kampto. The stratigraphic position of O. kampto follows the “Great Ordovician Biodiversification Event” in time, and reflects the increase in diversity of boring species. Borings with penetration depths of 120 mm are, however, unique findings for the Palaeozoic and were not exceeded until some 260 million years later (Bajocian, Middle Jurassic) when the “Mesozoic Marine Revolution” led to convergent reinventions as a result of enhanced predation, grazing pressure, and ecospace competition.
Źródło:
Acta Palaeontologica Polonica; 2008, 53, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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