Since the fossil was found in an ancestral territory of the Native American Crow tribe, the etymology of the generic name is derived from a term in their language, suuwassa, “the first thunder heard in spring”. The root suu, meaning “thunder” and wassa, “ancient”, are a nod to the “thunder lizard” moniker often applied to sauropods. The specific descriptor honours the deceased sponsor of the expeditions that recovered the fossil.
Suuwassea is a basal diplodocoid, estimated to have been 14 to 15 meters long (46 to 49 ft), characterized by skull and axial skeleton features it shares with Diplodocidae and Dicraeosauridae though it is too primitive to pertain to any of the latter clades. The herbivore differs from dicraeosaurids in the unfused state of the frontal, and from diplodocids in the arrangement of bones around the foramen magnum, though it possesses a greater number of similarities with the latter than with clade Dicraeosauridae.
S. emilieae’s find is concurrent with other finds of medium-sized sauropods in Morrison Formation’s northern section contrary to the finds of large animals in the southern reaches. This size difference was possibly due to new environments created as the Middle Jurassic Sundance Sea retreated northward. This sauropod’s phylogenetic analysis puts in doubt a number of autapomorphic characters of both Diplodocidae and Dicraeosauridae, opening the possibility that these are plesiomorphies differentially retained by each family. The presence of dicraeosaurid characters on a Laurasian diplodocoid also raises the question of the origin and distribution of a purported ancestral diplodocoid: Laurasia, Gondwana, or both.