Diplodocoidea is one of the most iconic clades of the giant sauropod dinosaurs, known for their elongated necks and tails, and distinctive skull morphology. This group, existing from the Middle Jurassic to the early Late Cretaceous, encompasses three main families: Rebbachisauridae, Dicraeosauridae, and Diplodocidae. These sauropods were globally distributed, demonstrating significant diversity in body plans, feeding strategies, and ecological niches. Diplodocoid paleontology has been marked by extensive studies focusing on skeletal morphology, biomechanics, histology, and evolutionary relationships. Significant research has also explored their ontogeny and niche partitioning, suggesting that diplodocoids had specialized adaptations for low- to mid-level browsing. This contribution is the introduction to a special volume that aims to synthesize current research on Diplodocoidea, offering insights into their evolutionary success, with subsequent contributions addressing their phylogenetic relationships, ontogeny, and morphological variation.
