Gravisauria
Gravisauria is a clade of sauropod dinosaurs that unites the vulcanodontid grade, including Vulcanodon and Tazoudasaurus, with the more derived Eusauropoda. Antetonitrus, Gongxianosaurus and Isanosaurus fall outside it as successively closer relatives (Allain and Aquesbi, 2008). It encompasses essentially the full radiation of the massive, fully graviportal sauropods. Members share dorsal vertebrae that are broader from side to side than front to back and asymmetrical condyles at the lower end of the femur. The clade is thought to have originated in the Early Jurassic, around the Pliensbachian and Toarcian roughly 183 million years ago, as part of a broader faunal turnover that saw the decline of the prosauropods, coelophysoids, and basal thyreophorans.
Diagnosis
- Dorsal neural spines broader transversely than anteroposteriorly
- Asymmetry of the femoral distal condyles, with a transversely broader tibial condyle
- Fully columnar, graviportal forelimbs and hindlimbs
- Four or more sacral vertebrae
Clades within Gravisauria
- Eusauropoda 295 genera
Genera placed directly in Gravisauria
- Rhoetosaurus Callovian–Oxfordian (165.3–154.8 Ma)Australiaunder dispute
- Sanpasaurus Pliensbachian–Toarcian (192.9–174.7 Ma)China
- Tazoudasaurus Pliensbachian–Toarcian (192.9–174.7 Ma)Morocco
- Volkheimeria Toarcian (184.2–174.7 Ma)Argentina
- Vulcanodon Sinemurian–Pliensbachian (199.5–184.2 Ma)Zimbabwe
References
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Allain, R.; Aquesbi, N. (2008). Anatomy and phylogenetic relationships of Tazoudasaurus naimi (Dinosauria, Sauropoda) from the late Early Jurassic of Morocco. Geodiversitas 30(2): 345-424.
Erected Gravisauria and provided the osteological basis for its diagnosis.
allain2008a -
Yates, A. M. (2007). Solving a dinosaurian puzzle: the identity of Aliwalia rex Galton. Historical Biology 19(1): 93-123. doi:10.1080/08912960600866953
Coined Massopoda and argued that Sauropoda, as then defined, had expanded far beyond its traditional content and needed redefinition.
yates2007a