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Wyświetlanie 1-3 z 3
Tytuł:
A monument of inefficiency: The presumed course of the recurrent laryngeal nerve in sauropod dinosaurs
Autorzy:
Wedel, M.J.
Powiązania:
https://bibliotekanauki.pl/articles/23398.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
laryngeal nerve
sauropod dinosaur
dinosaur
Dinosauria
Sauropoda
larynx
neck
neuron
paleontology
life history
Opis:
The recurrent laryngeal nerve is an often cited example of “unintelligent design” in biology, especially in the giraffe. The nerve appears early in embryonic development, before the pharyngeal and aortic arches are separated by the development of the neck. The recurrent course of the nerve from the brain, around the great vessels, to the larynx, is shared by all extant tetrapods. Therefore we may infer that the recurrent laryngeal nerve was present in extinct tetrapods, had the same developmental origin, and followed the same course. The longest−necked animals of all time were the extinct sauropod dinosaurs, some of which had necks 14 meters long. In these animals, the neurons that comprised the recurrent laryngeal nerve were at least 28 meters long. Still longer neurons may have spanned the distance from the end of the tail to the brainstem, as in all extant vertebrates. In the longest sauropods these neurons may have been 40–50 meters long, probably the longest cells in the history of life.
Źródło:
Acta Palaeontologica Polonica; 2012, 57, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Head and neck posture in sauropod dinosaurs inferred from extant animals
Autorzy:
Taylor, M P
Wedel, M.J.
Naish, D.
Powiązania:
https://bibliotekanauki.pl/articles/22737.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
dinosaur
sauropod dinosaur
extant animal
head posture
neck posture
Dinosauria
Sauropoda
Opis:
The neck posture of sauropod dinosaurs has long been controversial. Recent reconstructions position the cervical vertebrae and skull in an “osteological neutral pose” (ONP), the best fit arrived at by articulating the vertebrae with the zygapophyses in maximum contact. This approach in isolation suggests that most or all sauropods held their necks horizontally. However, a substantial literature on extant amniotes (mammals, turtles, squamates, crocodilians and birds) shows that living animals do not habitually maintain their necks in ONP. Instead, the neck is maximally extended and the head is maximally flexed, so that the mid−cervical region is near vertical. Unless sauropods behaved differently from all extant amniote groups, they must have habitually held their necks extended and their heads flexed. The life orientation of the heads of sauropods has been inferred from the inclination of the semi−circular canals. However, extant animals show wide variation in inclination of the “horizontal” semi−circular canal: the orientation of this structure is not tightly constrained and can give only a general idea of the life posture of extinct animals’ heads.
Źródło:
Acta Palaeontologica Polonica; 2009, 54, 2; 213-220
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The early evolution of postcranial skeletal pneumaticity in sauropodomorph dinosaurs
Autorzy:
Yates, A.M.
Wedel, M.J.
Bonnan, M.F.
Powiązania:
https://bibliotekanauki.pl/articles/21858.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
evolution
postcranial skeletal pneumaticity sauropodomorph dinosaur
dinosaur
Sauropodomorpha
Sauropoda
air sac
Triassic
Jurassic
South Africa
Opis:
Postcranial skeletal pneumaticity (PSP) is present in a range of basal sauropodomorphs spanning the basal sauropodomorph–sauropod transition. We describe the PSP of five taxa, Plateosaurus engelhardti, Eucnemesaurus fortis, Aardonyx celestae, Antetonitrus ingenipes, and an unnamed basal sauropod from Spion Kop, South Africa (hereafter referred to as the Spion Kop sauropod). The PSP of Plateosaurus is apparently sporadic in its occurrence and has only been observed in very few specimens, in which it is of very limited extent, affecting only the posterior cervical vertebrae and possibly the mid dorsals in one specimen. The PSP of Eucnemesaurus, Aardonyx, Antetonitrus, and the Spion Kop sauropod consists of subfossae (fossa−within−fossa structures) that excavate the vertices of the posterior infradiapophyseal fossae of the posterior dorsal vertebrae. These subfossae range from simple shallow depressions (Eucnemesaurus) to deep, steepsided, internally subdivided and asymmetrically developed chambers (Antetonitrus). The middle and anterior dorsal vertebrae of these taxa lack PSP, demonstrating that abdominal air sacs were the source of the invasive diverticula. The presence of pneumatic features within the infradiapophyseal fossae suggest that the homologous fossae of more basal saurischians and dinosauriforms were receptacles that housed pneumatic diverticula. We suggest that it is probable that rigid non−compliant lungs ventilated by compliant posterior air sacs evolved prior to the origination of Dinosauria.
Źródło:
Acta Palaeontologica Polonica; 2012, 57, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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