[D] Probactrosaurus mazongshanensis [Su]
Dong & Azuma, 1996 vide Lü, 1997
Cretaceous Early ?Barremian
Ornithischia Ornithopoda Iguanodontia
Xinminbao Group, Mazongshan Area, Gansu Province, China
Seems to be a rather bulky iguanodontid. Based on the posterior part of a skull and referred postcrania.
Norman, 2002, removed this species from the genus Probactrosaurus because (based on fragmentary remains) the dentary crowns of this species are not very similar to those of Probactosaurus gobiensis, instead they bear a closer resemblance to those of Altirhinus.
Carpenter & Ishida (2010) Early and “Middle” Cretaceous Iguanodonts in Time and Space Journal of Iberian Geology 36 (2) 145-164
“Probactrosaurus” mazongshanensis Lu 1997
Near Gongpoquan, Gansu Province, People’s Republic of China.
Middle Grey Unit of Xinminbao Group
Albian (Tang et al., 2001)
“Probactrosaurus” mazongshanensis is an immature individual as evidenced by the incomplete fusion of the neural arch with the centrum. As noted by Norman (2002), the taxon is distinct from Probactosaurus gobiensis.
We note the following differences: Broad, flat dorsal surface of the parietal in “P.” mazongshanensis (narrow sagittal crest in P. gobiensis); large, well developed occipital condyle on a relatively long neck (less prominent condyle lacking a neck in P. gobiensis); straight nuchal crest (embayed, V-shaped nuchal crest in P. gobiensis); short, wide supratemporal fenestra in “P” mazongshanensis (long and narrow in P. gobienesis); teeth with large marginal crenulations (small, less developed in P. gobiensis); dentary teeth significantly larger than maxillary teeth (nearly same size in P. gobiensis); sacrum rounded ventrally (keeled in P. gobiensis); and scapula expanded distally (nearly parallel-sided in P. gobiensis). Equijubus normani and “Probactrosaurus” mazongshanensis were found in the Middle Grey Unit of the Xinminbao Group in the Gongpoquan Basin. The two taxa, however, may be separated by the dentary teeth being larger than the maxillary teeth in “Probactrosaurus” rather than more equal in size in Equijubus (You et al., 2003a), and by the more extensive and prominent marginal crenulations of the teeth of “Probactrosaurus”.
The teeth of “P.” mazongshanensis most closely resemble those of Altirhinus as noted by Norman (2002), however, the scapula is expanded distally more than in Altirhinus. The holotype specimen represents a second iguanodontid in the Gongpoquan Basin and warrants a new generic name.