[D] Nanshiungosaurus bohlini
Dong & You, 1997
Cretaceous Early Barremian
Saurischia Theropoda Tetanurae Coelurosauria Therizinosauroidea Nanshiungosauridae
Upper Xinminbao Group, Mazongshan Area, Gansu Province, China
Nanshiungosaurus (Dong, 1979) > Nanshiungosaurus brevispinus (Dong, 1979) > Nanshiungosaurus bohlini (Dong & You, 1997)
Dong & Yu, 1997 placed N.bohlini within order Segnosaurischia Dong, 1992 (a synonym of [Segnosauria]).
Comment by Mickey Mortimer
\\\"Bohlin\\\'s Nanshiung lizard\\\", Dr. Bohlin being a paleontologist who collected dinosaur remains in Gansu Province, and Nanshiung being the area the type species was found in.
(IVPP V 11116) (5.8-7.8 m) atlas, axis (148 mm), third cervical vertebra (146 mm), fourth cervical vertebra (161 mm), fifth cervical vertebra (163 mm), sixth cervical vertebra (164 mm), seventh cervical vertebra (183 mm), eighth cervical vertebra (183 mm), ninth cervical vertebra (184 mm), tenth cervical vertebra (183 mm), eleventh cervical vertebra, cervical ribs, first dorsal vertebra (124 mm), second dorsal vertebra, third dorsal vertebra, fourth dorsal vertebra, fragmentary dorsal ribs
Eleven cervical vertebrae. Also, it is the only segnosaur known with fused cervical ribs and dorsal pleurocoels, which can distinguish it from Alxasaurus and Nanshiungosaurus brevispinus.
The description was originally in English, so it\\\'s much more useful than those in Dong 1973. That said, the photograph quality still leaves much to be desired. This specimen was between 5.8 and 7.8 meters long, comparing the vertebral lengths with Alxasaurus. The upper limit is close to the size of Therizinosaurus, so this is indeed one of the largest segnosaurs, as mentioned by Dong and Yu .
The atlas is represented by an odontoid and the neuropophyses. The odontoid is subcircular and fused to the dorsal half of the axial centrum. The neuropophysis is apparently wing-like in proximal view and has a long sauropod-like posterior process. It is unfortunately not figured.
The axis has relatively long prezygopophyses and well-developed dorsomedially inclined postzygopophyses. The neural arch and spine are long and low.
The postaxial cervical vertebrae have elongate platycoelous centra with pleurocoels. Ventrally, there are two parallel ridges. The neural arches are low, long and massive with long, stout zygopophyses, while the neural spines are also long and low. Three laminae form the diapophyses, which are declined and fused to the cervical ribs. The parapophyses are large rounded cavities on the anterolateral surface.
The internal structure of the cervical vertebrae is cancellous. Dong and Yu find that there are eleven cervical vertebrae, one or two more than other theropods but one less than Dong described for Nanshiungosaurus brevispinus.
The cervical ribs are fused with their respective centra. The dorsal vertebrae have amphiplatyan centra with ventral keels. The keel is poorly developed on the first centrum. Large pleurocoels are present. The zygopophyses are long and stout, while the neural arches and spines are low and narrow. The dorsal ribs are undescribed.
Note: Dong and Yu list different lengths for vertebral centra in the text than they do in the measurement table. In the text, the axis is 152 mm, the seventh and eighth cervicals are 192 mm and the ninth and tenth are 143 mm. They also later state the dorsals are platycoelous, instead of amphiplatyan.
It should be noted that Dong and Yu place segnosaurs in the [Segnosaurischia] and divide them between the Segnosauridae] and the newly formed Nanshiungosauridae, based on whether they are theropod-like or sauropod-like. I prefer a division of segnosaurs into Beipiaosaurus and therizinosauroids , and therizinosauroids into Alxasaurus and therizinosaurids .
Nanshiungosaurus belongs to the oviraptorosaur-segnosaur group (which desperately needs a name!) based on the ventral sulcus on cervical centra delimited by ventrolaterally directed ridges. The cervical vertebrae resemble other segnosaurs in basic morphological features such as the long low centra with long, heavy diapophyses and low neural spines. In addition, oviraptorosaurs lack fused cervical ribs and among theropods, only Nanshiungosaurus brevispinus is known to have more than ten cervical vertebrae.
Comparison to other segnosaurs is difficult due to the fact that only Beipiaosaurus, Alxasaurus, Erlikosaurus, Nanshiungosaurus brevispinus and Segnosaurus are known from presacral vertebrae, and only Alxasaurus is well described. The cervical centra are platycoelous, like Erlikosaurus and Segnosaurus, but unlike the amphiplatyan condition in Alxasaurus or the amphicoelous and opisthocoelous condition in Nanshiungosaurus brevispinus. Which state is derived is difficult to determine, as Caudipteryx has amphicoelous centra, Microvenator has platycoelous centra and the Morrison oviraptorosaur-segnosaur has opisthocoelous centra.
Fused cervical ribs are present, like Erlikosaurus, Nanshiungosaurus brevispinus and Segnosaurus, but unlike Alxasaurus. Nanshiungosaurus bohlini is like Beipiaosaurus and more basal than Alxasaurus and Nanshiungosaurus brevispinus based on the presence of dorsal pleurocoels. The low dorsal neural spines resemble Nanshiungosaurus brevispinus more than Alxasaurus. Nanshiungosaurus bohlini is also supposed to be distinguished from Nanshiungosaurus brevispinus by the narrower dorsal neural spines. It would appear that Alxasaurus also has narrower dorsal neural spines than Nanshiungosaurus brevispinus.
Exactly where Nanshiungosaurus bohlini should be placed within the [Segnosauria] is hard to say. The presence of fused cervical ribs and low dorsal neural spines would suggest placement in the Therizinosauridae, while the presence of dorsal pleurocoels would argue against placement in the Therizinosauroidea . Thus, placement in the Therizinosauridae is slightly better supported. For now, I recommend assigning it to [Segnosauria] incertae sedis.
Should this species be included in the genus Nanshiungosaurus? Several facts argue against such an assignment. First, the presence of dorsal pleurocoels is distinctly more plesiomorphic than Nanshiungosaurus brevispinus, which shares the derived state with Alxasaurus and presumedly other therizinosaurids. Second, the cervical morphology is more similar to Segnosaurus and Erlikosaurus than Nanshiungosaurus brevispinus. Third, no shared derived characters have been found in both species besides more than ten cervical vertebrae and low dorsal neural spines, which are currently unknown in other therizinosaurids. No synapomorphies were suggested by Dong and Yu. Fourth, the temporal distance is rather great. The Xinminbao Group has recently been shown to be Barremian, which is much earlier than the Maastrichtian sediments Nanshiungosaurus brevispinus was found in. I prefer to refer to this species as \\\"Nanshiungosaurus\\\" bohlini.