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Wyszukujesz frazę "Psittacosaurus" wg kryterium: Temat


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Tytuł:
Femoral histology and growth patterns of the ceratopsian dinosaur Psittacosaurus sibiricus from the Early Cretaceous of Western Siberia
Autorzy:
Skutschas, P.P.
Morozov, S.S.
Averianov, A.O.
Leshchinskiy, S.V.
Ivantsov, S.V.
Fayngerts, A.V.
Feofanova, O.A.
Vladimirova, O.N.
Slobodin, D.A.
Tematy:
Dinosauria
Ceratopsia
Psittacosaurus
bone histology
Cretaceous
Siberia
Russia
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Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/2082328.pdf  Link otwiera się w nowym oknie
Opis:
The early ceratopsian dinosaur Psittacosaurus sibiricus from the Early Cretaceous of Western Siberia, Russia, is one of the most advanced and largest (up to 2.5 m) members of the genus. Here we present a description of ontogenetic changes in the long-bone histology of this species. Analysis of a growth series of femora demonstrates significant histological maturation during ontogeny, expressed by the progressive appearance of signs of bone remodeling (erosion bays, secondary bone formation), decreasing of vascularity, changing of the orientation of vascular canals from reticular to longitudinal, and appearance of parallel-fibred bone in the outer part cortex. These ontogenetic changes in the longbone histology of P. sibiricus are generally similar to those of another relatively advanced species, P. lujiatunensis from China. The basal P. mongoliensis from Mongolia shows less mature long-bone histology during late ontogeny (e.g., the late appearance of signs of remodeling and the predominance of reticular vascularization at later stages). We suggest that the earlier achievement of histological maturity is an evolutionary trend of the genus Psittacosaurus.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New psittacosaurid highlights skull enlargement in horned dinosaurs
Autorzy:
Sereno, P C
Xijin, Z.
Brown, L.
Lin, T.
Tematy:
Psittacosaurus
systematics
Cretaceous
Dinosauria
China
Marginocephalia
dinosaur
skull length
Yixian Formation
paleontology
Ornithischia
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Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/23127.pdf  Link otwiera się w nowym oknie
Opis:
A new psittacosaurid is based on a nearly complete articulated skeleton from northeastern China that differs principally in skull size as compared to the most common and widespread species, Psittacosaurus mongoliensis. The skull of Psittacosaurus majorsp. nov., is 25% larger despite very similar postcranial skeletal dimensions. Such selective skull enlargement is very unusual. Skull size in ceratopsians, in general, scales with positive allometry relative to body mass: species of greater mass have proportionately larger skulls. This pattern stands in marked contrast to that for other vertebrate herbivores, in which larger−bodied species either have proportionately similar or smaller skulls relative to body mass. Larger−bodied ceratopsians evolved skulls that are 50% or more of trunk length—as measured without their expansive cranial frill. Although contemporaneous duck−billed dinosaurs also exhibit some positive allometry in the skull, skull length remains approximately 35% of trunk length. The evolution of extraordinary absolute and relative skull size among ceratopsians appears to have been driven by sexual selection and involved the tandem evolution of reduced head mobility and an obligate quadrupedal posture.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New data on cranial anatomy of the ceratopsian dinosaur Psittacosaurus major
Autorzy:
You, H -L
Tanoue, K.
Dodson, P.
Tematy:
dinosaur
Yixian Formation
Cretaceous
Dinosauria
paleontology
China
Ceratopsia
Psittacosaurus major
ceratopsian dinosaur
Liaoning
anatomy
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Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/20202.pdf  Link otwiera się w nowym oknie
Opis:
An exceptionally preserved skull and mandible of ceratopsian dinosaur Psittacosaurus major revealed many anatomical details such as the existence of an elliptical median interpremaxillary foramen, a prominent neurovascular canal on the internal wall of the beak, long, slightly divergent basipterygoid processes developed as vertical blades with a deep cleft between them, and horizontally oriented vomer. The new specimen shows two autapomorphies of Psittacosaurus major, the transversely narrow dorsal skull roof and very prominent dentary flanges, confirming the presence of two large−skulled psittacosaur species in the Lujiatun Bed of the Lower Cretaceous Yixian Formation in Beipiao City, western Liaoning Province, China, the longand narrow−skulled P. major, and broad−skulled P. lujiatunensis.
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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