Marsh (1878a) named his new genus from vertebrae (YPM 1874) found by Samuel Wendell Williston at Como Bluff, Wyoming, from rocks of the Morrison Formation.

The type material includes nine partial and two complete tail vertebral centra, which he concluded came from a "fox-sized" animal.

[3] A review by Peter Galton in 1983 found the type of L. gracilis to consist of thirteen back and eight tail centra, and portions of both hindlimbs.

[9] At the time, though, the discovery locality was thought to be in the Early Cretaceous Blairmore Group, but fieldwork at the L. minimus type locality in the early 1930s showed it to be within the Belly River Group, and Loris Russell published a paper in 1949 recognizing this new geologic information, while finding it generically distinct from Laosaurus proper.

First, L. minimus is seen as a possible second species or specimen of Orodromeus (Sues and Norman, 1990),[verification needed] although the remains are too meager to be certain.