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Wyszukujesz frazę "bone histology" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Diversity of tissues in acanthodians with Nostolepis-type histological structure
Autorzy:
Valiukevicius, J
Burrow, C.J.
Powiązania:
https://bibliotekanauki.pl/articles/22517.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
histology
acanthodian
dentine
Devonian
Acanthodii
Silurian
bone
Nostolepis
tissue
paleontology
mesodentine
Opis:
Acanthodian scales with Nostolepis−type histological structure are separated into five groups based on the presence/absence and extent of stranggewebe, odontocytic and syncitial mesodentine networks, cellular unipolar mesodentine, bone−like mesodentine and durodentine in scale crowns. Two new families of acanthodians are erected, based primarily on histological structure of scales: the Vesperaliidae (stranggewebe extending throughout the scale crown) and the Acritolepidae (bone−like mesodentine in the scale crown). The latter family includes species erected for articulated fish. The families Tchunacanthidae and Lenacanthidae are united in the single family Tchunacanthidae, characterized by having scale crowns with mesodentine formed mainly by unipolar cells. A sixth group, which we exclude from the Nostolepis−type, has scale crowns composed of dentine without lacunae, plus durodentine, and bases with only rare osteocyte cavities. The new groups promote the revision and reassignment of many “nostolepid” taxa, in particular removing many species from the genus Nostolepis. Four new genera are erected: Pechoralepis (including part of Nostolepis), assigned to Acritolepidae nov.; and three genera assigned to an indeterminate family, which scales are composed of only odontocytic mesodentine without stranggewebe: Nostovicina (including part of Nostolepis), Nobilesquama (including part of Nostolepis), and Peregrinosquama (including part of Watsonacanthus). Histological structures are considered the primary characters of taxonomical value when based on isolated scales. Unfortunately, scale histology is unknown for most articulated acanthodians.
Źródło:
Acta Palaeontologica Polonica; 2005, 50, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Growth and life habits of the Triassic cynodont Trirachodon, inferred from bone histology
Autorzy:
Botha, J
Chinsamy, A.
Powiązania:
https://bibliotekanauki.pl/articles/22174.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
histology
cynodont
Triassic
growth pattern
bone
life style
Trirachodon
growth
life habit
paleontology
Opis:
Growth pattern and lifestyle habits of the Triassic non−mammalian cynodont Trirachodon are deduced from bone histology and cross−sectional geometry. Several skeletal elements of Trirachodon were examined in order to document histological changes during ontogeny, as well as histovariability in the skeleton. The bone histology of all the elements consists of a moderately vascularized, periodically interrupted, fibro−lamellar bone tissue. This suggests that the overall growth of Trirachodon was probably rapid during the favourable season, but decreased or ceased during the unfavourable season. As the environment is thought to have been semi−arid with seasonal rainfall, it is possible that Trirachodon was sensitive to such environmental fluctuations. Some inter−elemental histovariability was noted where the number and prominence of growth rings varied. Limb bone cross−sectional geometry revealed a relatively thick bone wall and supports earlier proposals that Trirachodon was fossorial.
Źródło:
Acta Palaeontologica Polonica; 2004, 49, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Unique bone histology in partial large bone shafts from Upper Triassic of Aust Cliff, England: An early independent experiment in gigantism
Autorzy:
Redelstorff, R.
Sander, P.M.
Galton, P.M.
Powiązania:
https://bibliotekanauki.pl/articles/945884.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
Reptilia
Dinosauria
bone
histology
large bone shaft
primary osteon
secondary osteon
osteon
Upper Triassic
Triassic
Aust Cliff
England
gigantism
Opis:
Two giant partial bone shafts, possible femora, from the Rhaetian Bone Bed (Upper Triassic) of Aust Cliff in SW England continue to conceal their origin. The most striking characteristic of these bones is their size, showing that dinosaur-like gigantism had already evolved by the Late Triassic. Based on their characteristic, columnar shaft morphology, it was previously suggested they came from a prosauropod or stegosaur. The bone histology of both specimens is very similar: the cortex is always rather thin, not exceeding 10 mm, and is of fibrolamellar type with longitudinal primary osteons. The primary osteons show a rather unusual feature, the development of a secondary osteon inside the primary one. The bone surface in both specimens shows open vascular canals, suggesting that the animals were still growing at the time of death, but an external fundamental system (EFS) is visible in the outermost cortex of specimen BRSMG Cb3870. The external cortex shows dense growth marks, but their annual nature is difficult to ascertain. The bones are probably dinosaurian, as indicated by the fibrolamellar bone, and possibly belong to an unknown basal sauropodomorph lineage. Alternatively, some very large pseudosuchians may have evolved fibrolamellar bone independently as an adaptation for reaching giant size.
Źródło:
Acta Palaeontologica Polonica; 2014, 59, 3; 607-615
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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