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terça-feira, 26 de maio de 2015

PALEONTOLOGIA 2015

Nebulasaurus taito • A New Basal Eusauropod from the Middle Jurassic of Yunnan, China, and Faunal Compositions and Transitions of Asian Sauropodomorph Dinosaurs


Nebulasaurus taito
Xing, Miyashita, Currie, You, Zhang & Dong, 2015
Many sauropod ghost lineages cross the Middle Jurassic, indicating a time interval that requires increased sampling. A wide taxonomic spectrum of sauropodomorphs is known from the Middle Jurassic of China, but the braincase of a new sauropod, named here Nebulasaurus taito gen. et sp. nov., is distinct. Nebulasaurus is sister taxon to Spinophorosaurus from the Middle Jurassic of Africa and represents a clade of basal eusauropods previously unknown from Asia. The revised faunal list indicates dramatic transitions in sauropodomorph faunas from the Jurassic to Cretaceous of Asia; these are consistent with geographic isolation of Asia through the Late Jurassic. Non-sauropod sauropodomorphs, non-mamenchisaurid eusauropods (including basal macronarians), and mamenchisaurids successively replaced previous grades through the Jurassic, and titanosauriforms excluded all other sauropod lineages across the Jurassic–Cretaceous boundary.

Key words: Dinosauria, Sauropoda, Eusauropoda, Jurassic, China
Nebulasaurus taito | 太東雲龍
Nebulasaurus is an genus of basal eusauropod dinosaur known from the early Middle Jurassic of Yunnan Province, China. This discovery is significant paleontologically because it represents a clade of basal eusauropods previously unknown from Asia. The only fossil material recovered was a braincase, which was in a good state of preservation.
illustration: Cheung Chung Tat

Fig. 1. Geographical information on the locality of Nebulasaurus.
A. Map of China showing Yunnan Province (shaded black). B. Map of Yunnan Province showing the locality indicated by a silhouette of a sauropod.


Systematic palaeontology
Dinosauria Owen, 1842
Sauropoda Marsh, 1878
Eusauropoda Upchurch, 1995
Genus Nebulasaurus nov.
Type species: Nebulasaurus taito sp. nov.
Included species: Type species only.
Etymology: From Latin nebulae, misty cloud, after the alpine province of Yunnan (= southern cloudy province, Chinese); and from Greek sauros, lizard.
Diagnosis.—As for the type and only species.
Nebulasaurus taito sp. nov.
Etymology: In honor of the Taito Corporation of Japan, which funded the field project in and near the type locality. 
Holotype: LDRC-v.d.1, a braincase (Figs. 2, 3A, B).
Type horizon: Zhanghe Formation, lower Middle Jurassic, Aalenian/Bajocian (Bureau of Geology and Mineral Resources of Yunnan Province 1990).
Type locality: The locality is in Xiabanjing, Jiangyi Rural Area, Yuanmou County of Yunnan Province, China (Fig. 1B). Information regarding precise location of the locality is protected by the local authority and available through LDRC on request.
Xing, L., Miyashita, T., Currie, P.J., You, H., Zhang, J., and Dong, Z. 2015. A New Basal Eusauropod from the Middle Jurassic of Yunnan, China, and Faunal Compositions and Transitions of Asian Sauropodomorph Dinosaurs.
Acta Palaeontologica 
Polonica. 60 (1): 145–154. DOI: 10.4202/app.2012.0151

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