Agustinia is a genus of sauropod dinosaur from the late Aptian to Albian ages of the Early Cretaceous Period (116 to 100 million years ago) that lived in what is now South America. It was discovered in the Lohan Cura Formation of Neuquen Province, Argentina. It is named for the one who discovered the fossil, Agustin Martinelli. It was originally named Agustia in 1998, however this name was already taken by a beetle, so it was changed to Agustinia. One named species exists, A. ligabuei, which is named in honor of Dr. Giancarlo Ligabue, who provided financial support for the expedition which found the remains.
Like other known sauropods, Agustinia was quadrupedal and herbivorous. Agustinia had unique body armor, unlike other sauropods. It had a series of wide, vertical spikes and plates down the center of the back, much like the unrelated Stegosaurus. Other than armor, very little is known about this dinosaur. The lower leg bone that was recovered was about 3 feet long. Based on this bone size, it is estimated that Agustinia may have been about 50 feet long.
Agustinia had been assigned to its own family, Agustiniidae, but due to its similarities with both diplodocids and titanosaurians, its own family status is not highly accepted. Since both of the groups to which it closely resembles lived in Early Cretaceous Argentina at the same time as Agustinia, and due to lack of definitive remains, Agustinia may belong to one of those two groups.