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Wyszukujesz frazę "Yixian Formation" wg kryterium: Temat


Wyświetlanie 1-4 z 4
Tytuł:
Caudipteryx as a non-avalian theropod rather than a flightless bird
Autorzy:
Dyke, G J
Norell, M.A.
Powiązania:
https://bibliotekanauki.pl/articles/22434.pdf
Data publikacji:
2005
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
bird
Avialae
feather
Cretaceous
Caudipteryx zoui
China
Theropoda
Dinosauria
Yixian Formation
paleontology
Opis:
Caudipteryx zoui is a small enigmatic theropod known from the Early Cretaceous Yixian Formation of the People’s Republic of China. From the time of its initial description, this taxon has stimulated a great deal of ongoing debate regarding the phylogenetic relationship between non−avialan theropods and birds (Avialae) because it preserves structures that have been uncontroversially accepted as feathers (albeit aerodynamically unsuitable for flight). However, it has also been proposed that both the relative proportions of the hind limb bones (when compared with overall leg length), and the position of the center of mass in Caudipteryx are more similar to those seen in extant cusorial birds than they are to other non−avialan theropod dinosaurs. This conclusion has been used to imply that Caudipteryx may not have been correctly interpreted as a feathered non−avialan theropod, but instead that this taxon represents some kind of flightless bird. We review the evidence for this claim at the level of both the included fossil specimen data, and in terms of the validity of the results presented. There is no reason—phylogenetic, morphometric or otherwise—to conclude that Caudipteryx is anything other than a small non−avialan theropod dinosaur.
Źródło:
Acta Palaeontologica Polonica; 2005, 50, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New psittacosaurid highlights skull enlargement in horned dinosaurs
Autorzy:
Sereno, P C
Xijin, Z.
Brown, L.
Lin, T.
Powiązania:
https://bibliotekanauki.pl/articles/23127.pdf
Data publikacji:
2007
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Psittacosaurus
systematics
Cretaceous
Dinosauria
China
Marginocephalia
dinosaur
skull length
Yixian Formation
paleontology
Ornithischia
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.
Źródło:
Acta Palaeontologica Polonica; 2007, 52, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
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.
Powiązania:
https://bibliotekanauki.pl/articles/20202.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
dinosaur
Yixian Formation
Cretaceous
Dinosauria
paleontology
China
Ceratopsia
Psittacosaurus major
ceratopsian dinosaur
Liaoning
anatomy
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.
Źródło:
Acta Palaeontologica Polonica; 2008, 53, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cranial anatomy of the iguanodontoid ornithopod Jinzhousaurus yangi from the Lower Cretaceous Yixian Formation of China
Autorzy:
Barrett, P M
Butler, R.J.
Xiao-Lin, W.
Xing, X.
Powiązania:
https://bibliotekanauki.pl/articles/19937.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Cretaceous
Yixian Formation
Dinosauria
Jinzhousaurus yangi
paleontology
China
cranial anatomy
Ornithopoda
ornithopod
Liaoning Province
iguanodontoid ornithopod
Lower Cretaceous
dinosaur
Iguanodontia
non-avian dinosaur
Opis:
The Yixian Formation (Lower Cretaceous) of Liaoning Province, China, is justifiably famous for its exceptionally preserved fauna, which includes a remarkable diversity of non−avian dinosaurs. Here, we provide the first detailed description of the cranial skeleton of the iguanodontian ornithopod Jinzhousaurus yangi. Many previously unrecorded features have been recognised, permitting a new and more robust diagnosis for this taxon, which is based on a suite of autapomorphic features. Jinzhousaurus and an unnamed sauropod represent the largest, but some of the least abundant, animals in the Jehol Biota, a situation that contrasts with many other Lower Cretaceous faunas in which large dinosaurs are common faunal components. This rarity may be due to either palaeoenvironmental constraints or taphonomic bias, although it is not possible to choose between these alternatives on the basis of current data.
Źródło:
Acta Palaeontologica Polonica; 2009, 54, 1; 35-48
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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