What is Gravisauria?

The most recent common ancestor of Tazoudasaurus and Saltasaurus, and all of its descendants. Gravisauria is a major clade within Sauropoda, named by Allain and Aquesbi in 2008 and formally defined as the most recent common ancestor of Tazoudasaurus and Saltasaurus, and all of its descendants. Despite the name, not all members of Gravisauria — the "Heavy Lizards" — were especially heavy by sauropod standards; some remained only moderately sized, but the name reflects their shift toward a more weight-supporting (graviportal), column-limbed body plan rather than literal mass. Arising in the Early Jurassic, this clade marks the consolidation of the architecture that would underpin later gigantism.

Gravisauria contains two major branches: a basal assemblage of early, robust-limbed sauropods traditionally grouped as Vulcanodontidae, and the expansive radiation of Eusauropoda, which encompasses all "classic" sauropods. As a lineage, Gravisauria moves decisively toward large, quadrupedal herbivores characterized by increasingly columnar limbs, expanded weight-bearing joints, and vertebrae that were beginning to hollow internally — not yet to the extreme seen in later sauropods, but enough to lighten the growing frame. Their forelimbs lengthened relative to earlier sauropodomorphs, and their hands evolved toward the horseshoe-shaped, semi-tubular structure that would become standard for sauropod locomotion.

In evolutionary terms, Gravisauria represents a structural inflection point: the shift from lightly built, occasionally bipedal sauropodomorphs to the fully graviportal, obligate quadrupeds that would dominate Jurassic ecosystems. The earliest representatives enter the fossil record shortly after the first true sauropods, with early sauropod lineages spreading across parts of Gondwana and, soon after, Laurasia. As the eusauropod radiation accelerates, the basal forms diminish, but the clade’s legacy is profound: every major sauropod lineage — Diplodocoidea, Macronaria, Titanosauria — descends from Gravisauria. It is the foundational architecture of the sauropod body plan.

Click here to search Dinochecker for Gravisaurians. Gravisauria is derived from the Latin "gravis" (heavy), and the Greek "sauros" (lizard) and "-ia" (neuter plural).