[1] It lived in what is now South America, specifically Argentina, during the Upper Cretaceous Period about 95 million years ago.

Martínez, at the Estancia Laguna Palacios of the Goicoechea family in Chubut province, discovered a sauropod skull.

[3] In 2016, the type species Sarmientosaurus musacchioi was named and described by Rubén Darío Francisco Martínez, Matthew Carl Lamanna, Fernando Emilio Novas, Ryan C. Ridgely, Gabriel Andrés Casal, Javier E. Martínez, Javier R. Vita and Lawrence M. Witmer.

The specific name honours the late Eduardo Musacchio, an educator at the Universidad Nacional de la Patagonia San Juan Bosco.

[3] The holotype, MDT-PV 2, was found in the upper Lower Member of the Bajo Barreal Formation, dating from the Cenomanian to Turonian ages.

However, the authors considered an identity as improbable because in their cladistic analysis both genera occupied different positions in the evolutionary tree.

The inner edge of the rear part of the ascending branch of the maxilla touches the rim of the bony nostril with a low but distinct ridge.

The middle neck vertebrae have strut-like, instead of plate-shaped, ridges between the front joint processes and the vertebral centrum.

The build of the teeth is in-between the more spatulate form of basal sauropods and the pencil shape of derived species.

They each have sharply-angled wear facets in a high and a low position which, together with their strange orientation, indicates some special, as yet not fully understood, way of cropping vegetation.

The front joint processes are supported from below by struts with an oval cross-section, apparently formed by a perforation of the normally plate-shaped ridges in this position.

[3] Parallel to the ribs, on the outer side of the neck a cable-shaped structure was discovered with a constant diameter of three millimetres.

Such ossified tendons have never before been found in any fossil dinosaur but some extant bird groups such as the cranes show them, though they are relatively shorter, at most two vertebrae long.