sauropodomoran

Sauropodomorans, or Sauropodomorpha, are a clade of saurischian dinosaurs that includes the early, often smaller and bipedal prosauropods as well as the later gigantic, quadrupedal sauropods. They are characterized by long necks and tails, a large barrel-shaped torso, small heads, and herbivorous dentition. In the early forms the forelimbs and hindlimbs were more similar in length, but sauropods developed columnar, weight-bearing limbs that supported extreme body sizes.

Originating in the Late Triassic, sauropodomorans diversified into several lineages. Prosauropods persisted into the Early Jurassic, while Sauropoda gave rise to various groups including Diplodocoidea and Macronaria, among which titanosaurs became widespread in the Cretaceous. They achieved some of the greatest body sizes of all time.

Anatomically, sauropodomorans show adaptations for high-browsing plant feeding, including reduced skulls and specialized teeth. Their vertebrae and ribs helped support long necks, and many later members developed robust vertebral columns to bear their massive bodies. Respiratory efficiency in many taxa is inferred to have involved air sacs similar to those in modern birds, contributing to respiration and reducing skeletal weight.

Ecologically, they were among the dominant herbivores of many Mesozoic ecosystems, capable of rapid growth and occupying a range of ecological niches. Evidence from trackways and fossils suggests possible social behavior in some groups, though specifics vary by taxon.

Fossils of sauropodomorans are found worldwide, from Triassic to Late Cretaceous formations. Their evolution had a profound impact on herbivore communities and the overall structure of terrestrial vertebrate ecosystems.