[1] In 2014, the type species Leinkupal laticauda was named and described by Pablo Gallina, Sebastián Apesteguía, Alejandro Haluza and Juan Canale.

The generic name combines the Mapudungun lein, "vanishing", and kupal, "family", in reference to Leinkupal being the last, or youngest, known species of the Diplodocidae.

The front tail vertebrae have extremely well-developed transverse processes, as long as the width of the vertebral body, expanded sideways and to below, and possessing robust reinforcing ridges on their top and bottom surfaces.

This formation is composed of red and greenish brown sandstones and conglomerates of fine to coarse grain, in addition to prominent bands of tan siltstones and reddish claystones.

Leinkupal shared its habitat with several theropods including basal tetanurans, possible deinonychosaurians, and possible abelisauroids, in addition to the dicraeosaurid sauropod Bajadasaurus[1][5] and the early titanosaur Ninjatitan.