Opisthocoelicaudiinae
Opisthocoelicaudiinae is a subfamily of titanosaurian sauropod dinosaurs from the Late Cretaceous, with fossils known from Mongolia, Argentina, and the United States. Studies have grouped genera such as Alamosaurus and Opisthocoelicaudia within it, and its members are large, robustly built sauropods. They are distinguished above all by opisthocoelous front tail vertebrae — ball-and-socket joints that face the opposite way to the socket-and-ball (procoelous) arrangement seen in most other advanced titanosaurs — along with stout, columnar limbs. Their hands were highly reduced, lacking wrist bones and finger phalanges. The group's relationships remain debated: some analyses place it as a close relative of the saltasaurines, while others have instead linked Opisthocoelicaudia to other Asian sauropods such as Nemegtosaurus and Quaesitosaurus.
Diagnosis
- Opisthocoelous anterior caudal vertebrae
- Robust, columnar limb bones
- Strongly developed neural-spine bifurcation reduced or absent
- Posteriorly positioned, dorsally directed neural spines on anterior caudals
Genera placed directly in Opisthocoelicaudiinae
- Opisthocoelicaudia Maastrichtian (72.2–66.0 Ma)Mongolia
- Qunkasaura Campanian–Maastrichtian (83.6–66.0 Ma)Spain
- Zhuchengtitan Campanian (83.6–72.2 Ma)China
References
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McIntosh, J. S. (1990). Sauropoda. The Dinosauria (Weishampel, D. B.; Dodson, P.; Osmólska, H., eds.) 345-401. University of California Press, Berkeley.
Named the subfamily Opisthocoelicaudiinae, placing it tentatively in Camarasauridae.
mcintosh1990a -
Wilson, J. A.; Upchurch, P. (2003). A revision of Titanosaurus Lydekker (Dinosauria - Sauropoda), the first dinosaur genus with a 'Gondwanan' distribution. Journal of Systematic Palaeontology 1(3): 125-160. Informa UK Limited. doi:10.1017/S1477201903001044
Defined Opisthocoelicaudiinae as all saltasaurids closer to Opisthocoelicaudia skarzynskii than to Saltasaurus loricatus.
wilson2003b