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Subacute exposure to amygdalin influences compact bone remodeling of rabbits

100%

Kovacova V., Sarocka A., Omelka R., Bauerova M., Grosskopf B., Formicki G., Kolesarova A., Martiniakova M.

Journal of Physiology and Pharmacology

2019

tom 70

nr 4

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Carapace bone histology in the giant pleurodiran turtle Stupendemys geographicus: phylogeny and function

80%

Scheyer T. M., Sanchez-Villagra M. R.

Acta Palaeontologica Polonica

2007

tom 52

nr 1

Stupendemys geographicus (Pleurodira: Pelomedusoides: Podocnemidae) is a giant turtle from the Miocene of Venezuela and Brazil. The bone histology of the carapace of two adult specimens from the Urumaco Formation is described herein, one of which is the largest of this species ever found. In order to determine phylogenetic versus scaling factors influencing bone histology, S. geographicus is compared with related podocnemid Podocnemis erythrocephala, and with fossil and Recent pelomedusoides taxa Bothremys barberi, Taphrosphys sulcatus, “Foxemys cf. F. mechinorum”, and Pelomedusa subrufa. Potential scaling effects on bone histology were further investigated by comparison to the Pleistocene giant tortoise Hesperotestudo (Caudochelys) crassiscutata and the Late Cretaceous marine protostegid turtle Archelon ischyros. A diploe structure of the shell with well developed external and internal cortices framing interior cancellous bone is plesiomorphic for all sampled taxa. Similarly, the occurrence of growth marks in the shell elements is interpreted as plesiomorphic, with the sampled neural elements providing the most extensive record of growth marks. The assignment of S. geographicus to the Podocnemidae was neither strengthened nor refuted by the bone histology. A reduced thickness of the internal cortex of the shell elements constitutes a potential synapomorphy of the Bothremydidae. S. geographicus and H. crassiscutata both express extensive weight−reduction through lightweightconstruction while retaining form stability of the shell. The bone histology of A. ischyros presents features likely related to an open marine lifestyle.

Bone microstructure and growth patterns of early mammals

80%

Chinsamy A., Hurum J. H.

Acta Palaeontologica Polonica

2006

tom 51

nr 2

We present results of the first studies of the bone microstructure of early mammals, based on the Early Jurassic Morganucodon, the Late Cretaceous multituberculates, Kryptobaatar and Nemegtbaatar, and the Late Cretaceous eutherians Zalambdalestes and Barunlestes. Our results show that the two eutherian taxa grew relatively slowly with periodic pauses in growth indicated by the presence of rest lines, while the multituberculates and Morganucodon had a faster rate of bone formation that suggests an overall rapid growth rate that slowed down later in ontogeny. Comparisons of the early mammalian bone microstructure with that of non−mammalian cynodonts, extant monotremes, and placentals are also made, and significant differences in the rate of osteogenesis in the various groups are documented. Our findings suggest differences in the growth rate between the multituberculates and the Mesozoic eutherians, and moreover, both groups appear to have slower growth rates as compared to modern monotremes and placentals. Our results further suggest that the determinate growth strategy typical of extant mammals evolved early in the evolution of the non−mammalian therapsids. We speculate that the sustained, uninterrupted bone formation among the multituberculates may have been an adaptive attribute prior to the K−T event, but that the flexible growth strategy of the early eutherians was more advantageous thereafter.

Ograniczanie wyników

2 Acta Palaeontologica Polonica

1 Journal of Physiology and Pharmacology

1 Bauerova M.

1 Chinsamy A.

1 Formicki G.

1 Grosskopf B.

1 Hurum J. H.

1 Kolesarova A.

1 Kovacova V.

1 Martiniakova M.

1 Omelka R.

1 Sanchez-Villagra M. R.

1 Sarocka A.

1 Scheyer T. M.

1 2019

1 2007

1 2006

Wyniki wyszukiwania

Subacute exposure to amygdalin influences compact bone remodeling of rabbits

Carapace bone histology in the giant pleurodiran turtle Stupendemys geographicus: phylogeny and function

Bone microstructure and growth patterns of early mammals