Yunnanosaurus huangi, YOUNG, 1942

Barrett, Paul M., Upchurch, P., Zhou, X. - D. & Wang, X. - L., 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), pp. 319-341 : 320-321

YUNNANOSAURUS HUANGI YOUNG, 1942

1942 Y. huangi ( Young, 1942: 64, figs 1–17).

1965 L. huenei Young, 1941 ( Rozhdestvensky, 1965: 103) .

1970 Y. huangi ( Steel, 1970: 52) .

1981 Massospondylus huenei, Young, 1941 ( Cooper, 1981: 804) .

1990 Y. huangi ( Galton, 1990: 335) .

2004 Y. huangi ( Galton & Upchurch, 2004: 236) .

Holotype: NGMJ 004546 , an almost complete skeleton consisting of the following: the skull, atlas, and axis; three other cervical vertebrae; nine dorsal vertebrate and dorsal rib fragments; sacrum; eight caudal vertebrae and six haemal arches; left scapula; sternum; right and left humeri; right ulna; partial left manus; right and left ilia, pubes, and ischia; right and left femora, tibiae, fibulae, astragali, and calcanea; and two metatarsals.

Locality and horizon: Huangchiatien village, Lufeng County, Yunnan Province, China. Dark Red Beds of the Lower Lufeng Formation, Lower Jurassic (Sinemurian: Luo & Wu, 1994, 1995).

Emended diagnosis (cranial features only): Small external naris (∼10% of maximum skull length); robust, rostrocaudally expanded nasal process of the premaxilla; presence of a ventral projection from the caudal margin of ascending maxillary process; lack of nutritive foramina on lateral surface of maxilla; shallow, subcircular fossa present on lateral surface of ventral lachrymal process; presence of a midline boss near to the rostral end of the frontals; prominent midline boss present on the parietals; rostrolateral process of the parietal rostrocaudally expanded relative to the width of the caudolateral process; maxillary teeth are mesiodistally narrow and lack denticles.

Comments: Young (1942) designated this specimen with the catalogue number V 20. This number was later changed to NGMJ V 0116 (as indicated on the label within the display case), but the correct accession number is now NGMJ 004546. The postcranial skeleton of Yunnanosaurus will be described elsewhere.

The original diagnosis of Y. huangi incorporated a large number of cranial characteristics ( Young, 1942: 64–65; see also Young, 1951: 56): skull elongate, with width to length ratio of 3.8; skull equivalent in length to four anterior caudal vertebrae; external nostril small; antorbital fenestra large; orbit circular and largest skull opening; supratemporal fenestra ‘beanshaped’ in dorsal view and partly visible in lateral view (i.e. the upper temporal bar is ventrally displaced with respect to the skull roof); lower jaw slender; small external mandibular fenestra; 15 maxillary and 13 dentary teeth; teeth slender, rounded, and pointed; teeth generally lacking denticles. Some of these characters do appear to be unique to Yunnanosaurus and have been modified for inclusion in the emended diagnosis given above (e.g. tooth morphology). However, many of the other features listed do not differ substantially from those seen in other basal sauropodomorphs (e.g. tooth counts, orbit size, and shape, ventral deflection of the upper temporal bar and size of the external mandibular fenestra) and cannot be regarded as diagnostic for Yunnanosaurus (see below for further details).