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Yunnanosaurus paper


Zoological Journal of the Linnean Society
Volume 150 Issue 2 Page 319Issue 2 - 341 - June 2007

To cite this article: PAUL M. BARRETT fls, P. UPCHURCH fls, X.-D.
ZHOU, X.-L. WANG (2007)
The skull of Yunnanosaurus huangi Young, 1942 (Dinosauria:
Prosauropoda) from the Lower Lufeng Formation (Lower Jurassic) of
Yunnan, China
Zoological Journal of the Linnean Society 150 (2), 319–341.

The Lower Lufeng Formation (Lower Jurassic: ?Hettangian–?Sinemurian)
of Yunnan Province, China, has yielded an important and diverse fauna
of terrestrial vertebrates that is dominated by early sauropodomorph
dinosaurs (prosauropods and basal sauropods). Nevertheless, few of
these animals have been studied in detail, undermining their potential
significance in understanding sauropodomorph phylogeny, palaeobiology,
and palaeoecology. Here, we present a detailed re-description of the
cranial osteology of Yunnanosaurus huangi Young, 1942 and propose an
emended diagnosis for this taxon on the basis of numerous
autapomorphic characters (including an expanded internarial bar,
unusual midline cranial bosses, and the possession of elongate
maxillary tooth crowns lacking marginal serrations). Incorporation of
these novel anatomical data into existing phylogenetic analyses of
sauropodomorph interrelationships substantially affects the
resolution, length, and topologies of the trees recovered. Although
the phylogenetic position of Yunnanosaurus remains labile, these new
analyses undermine previous suggestions that the former was the sister
taxon of the southern African prosauropod Massospondylus. Several
features of the skull of Yunnanosaurus (small external nares, cranial
bosses, tooth crown morphology, and the lack of maxillary foramina)
indicate that the palaeobiology of Yunnanosaurus may have been rather
different from that of other prosauropods and basal sauropods,
although more detailed functional studies and better material are
needed to confirm this suggestion.  (c) 2007 Natural History Museum,
London. Journal compilation (c) 2007 The Linnean Society of London,
Zoological Journal of the Linnean Society, 2007, 150, 319–341.


Michael D. Barton
    Bozeman, MT
         MSU Bozeman, History-SETS Major

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