Dicraeosaurids are diplodocoid sauropods in the family Dicraeosauridae who are the sister group to Diplodocidae. Dicraesaurids are a part of the Flagellicaudata, along with Diplodocidae. Dicraeosaurids includes genera such as Amargasaurus, Suuwassea, Dicraeosaurus, and Brachytrachelopan. Specimens of this family have been found in North America, Asia, Africa, and South America. Their temporal range is from the Early or Middle Jurassic to the Early Cretaceous. Few dicraeosaurids survived into the Cretaceous, the youngest of which was Amargasaurus.
The group was 1st described by German paleontologist Werner Janensch in 1914 with the discovery of Dicraeosaurus in Tanzania. Dicraeosaurids are distinct from other sauropods because of their relatively short neck size and small body size.
The clade is monophyletic and well-supported phylogenetically with 13 unambiguous synapomorphies uniting it. They diverged from Diplodocidae in the Mid-Jurassic, as evidenced by the diversity of dicraeosaurids in both South America and East Africa when Gondwana was still united by land. However, there is some disagreement among paleontologists on the phylogenetic placement of Suuwassea, the only genus of the Dicraeosauridae to be found in North America. It has been characterized as a basal dicraeosaurid by some and a member of the Diplodocidae by others. The placement of Suuwassea within Dicraeosauridae or Diplodocidae has substantial biogeographic implications for the evolution of Dicraeosauridae.
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