areDiplodocoidea

Diplodocoidea is a clade of sauropod dinosaurs within Sauropoda. It includes the two primary families Diplodocidae and Dicraeosauridae, and in some classifications also accommodates Rebbachisauridae as a member of the group. Diplodocoids are known from several continents and are most well documented in the Middle to Late Jurassic, with continued representation in some lineages into the Early Cretaceous in Gondwanan regions, indicating a broad geographic and temporal distribution during the Jurassic and early Cretaceous.

In terms of anatomy, diplodocoids display a range of skull and neck proportions, but many members are characterized by long necks and tails and columnar limbs. Diplodocids, such as Diplodocus and Barosaurus, are among the longest-bodied sauropods, typically possessing slender builds, elongated skulls, and peg-like dentition at the front of the jaws. Dicraeosaurids, including Dicraeosaurus and Amargasaurus, tend to have relatively shorter necks and more robust skulls, with some members showing distinctive spines or ornamentation along the neck.

Notable genera attributed to Diplodocoidea include Diplodocus, Barosaurus, and Apatosaurus from the diplodocid lineage, as well as Dicraeosaurus and Amargasaurus from the dicraeosaurid lineage. The group has played an important role in discussions of sauropod evolution due to its mix of extreme neck elongation in some lineages and more conservative body plans in others, illustrating the diversity of feeding strategies and ecological roles among early giant dinosaurs.