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bébé dino

Nombre de messages : 44
Age : 33
Localisation : 35 (près de Rennes)
Emploi : Etudiant en géosciences
Loisirs : Foot, fouille
Date d'inscription : 30/05/2006

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MessageSujet: News   News EmptyMer 28 Mar - 14:27

Anchisaurus misinterpreted

Fedak, T.J., and Galton, P.M. 2007. New information on the braincase and skull of Anchisaurus polyzelus (Lower Jurassic, Connecticut, USA; Saurischia: Sauropodomorpha): implications for sauropodomorph systematics; pp. 245-260 in Barrett, P.M. and Batten, D.J. (eds.), Evolution and Palaeobiology of Early Sauropodomorph Dinosaurs. Special Papers in Palaeontology 77. Palaeontological Association, London.

ABSTRACT: A skull of Anchisaurus polyzelus (YPM 1883) has been misinterpreted for over 120 years as a result of deformation during preservation and loss of a small piece of the skull block shortly after collection in 1884. The only other skull of this taxon (YPM 209), from a smaller individual, has been largely ignored in previous studies owing to distortion and incomplete preparation. Additional preparation of the latter specimen has exposed several new elements, including the nearly complete parabasisphenoid, a region that is damaged and incomplete in YPM 1883.

Based on this new information, a phylogenetic analysis supports the recent hypothesis that Anchisaurus was a basal sauropod. However, the strength of this hypothesis has been greatly reduced, and is also undermined further by the possibility that the specimens of Anchisaurus are skeletally immature. In general, the skull and braincase of Anchisaurus resembles those of 'prosauropods' more closely than those of derived sauropods.

New material of pterosaur Sinopterus

Lü, J., Liu, J., Wang, X., Gao, C., Meng, Q., and Ji, Q. 2006. New material of pterosaur Sinopterus (Reptilia: Pterosauria) from the Early Cretaceous Jiufotang Formation, western Liaoning, China. Acta Geologica Sinica (English Edition) 80(6):783-789.

ABSTRACT: Based on a new nearly complete postcranial skeleton of an adult specimen of Sinopterus from the Early Cretaceous Jiufotang Formation of western Liaoning, China, the diagnosis of Sinopterus is amended. The revised diagnosis of Sinopterus includes skull relatively elongate with weakly developed cranial crest; ratio of the length of Ph2d4 to that of Ph1d4 is approximately 0.73; ratio of the length of wing metacarpal to that of metatarsal 3 is 4.5; ratio of the length of mt3 to that of tibia is approximately 0.21, and wing phalanges 1 and 2 are straight.

Comparison between the ratios of the limb bones between non-adult and adult individuals of Sinopterus indicates that during the ontogenetic process,some ratios between bones are constant, such as the first wing phalanx to the second wing phalanx, the wing metacarpal to the metatarsal 3, metatarsal 3 to the tibia, but others are not, such as humerus to wing metacarpal and femur to tibia, in which the former grows faster than the latter.

Source: dinodata
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