page_title: Zhuchengtitan
section_title: Description
hierarchical_section_title: Zhuchengtitan / Description
caption_attribution_description: English: Opisthocoelicaudia skarzynskii. Based on skeletal restoration in G. S. Paul 2010, posture based on Schwarz et al. 2007. Head based on Nemegtosaurus.
context_page_description: Zhuchengtitan is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous of Shandong, China. It contains a single species, Z. zangjiazhuangensis, named by Mo Jinyou and colleagues in 2017 from a single humerus. Zhuchengtitan can be identified by the extreme width of the top end of its humerus, as well as the expansion of the deltopectoral crest on its humerus; both of these characteristics indicate that it was likely closely related to Opisthocoelicaudia. However, it differs from the latter by the flatter bottom articulating surface of its humerus. Zhuchengtitan lived in a floodplain environment alongside Shantungosaurus, Zhuchengtyrannus, and Sinoceratops.
context_section_description: The humerus ZJZ-57 (when viewed from the front) measures 108 centimetres (43 in) long, 59.3 centimetres (23.3 in) wide at the top, 23.1 centimetres (9.1 in) wide at midshaft, and 37.5 centimetres (14.8 in) wide at the bottom. It can be identified by the extreme width of its top end compared to other titanosaurs, which is 0.55 times its whole length. This figure is closest to the 0.49 of Saltasaurus and the 0.56 of Opisthocoelicaudia. Consequently, the robustness index (RI) (the ratio between the average of the three width measurements and the length) is also quite high, at 0.39; Saltasaurus has an RI of 0.35, while Opisthocoelicaudia has an RI of 0.38. The width arises from the inner edge of the bone, which is angled more sharply inwards at the top end of the bone than the bottom end.
  Further below, the shaft of the bone is cylindrical in cross-section, with the long axis oriented sideways. The deltopectoral crest, which is located on the front surface near the top end of the bone, is very prominent, and bears a hook-like process about  of the way down its length. It extends downwards to the midshaft of the bone, and sideways so that it occupies the outer  of the bone's width. In Opisthocoelicaudia, the crest is wider, occupying  of the bone's width. The humerus forms a wide depression on the portion of the shaft further inward than the crest.
  Near the top end on the back of the bone, there are two depressions bordering a central ridge, which extends upwards to support the rounded humeral head. On the bottom of the bone, the two condyles that articulate respectively with the radius and ulna are separated by a broad but shallow intercondylar groove, and there is a low but robust ridge on either side of the groove. These structures are more prominent in Saltasaurus and Opisthocoelicaudia. The condyles are expanded towards the front of the bone; viewed from the bottom, the surface of the condyles is very roughened.
caption: Reconstruction of the closely related Opisthocoelicaudia
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