Overosaurus, signifying "Overo lizard" in reference to the Cerro Overo location, is an extinct sauropod dinosaur genus encompassing a sole species, Overosaurus paradasorum. This particular species inhabited the Earth around 86 to 84 million years ago, specifically during the latter part of the Cretaceous Period, in the region that we now know as Patagonia, located in southern Argentina.

In contrast to the larger sauropods found in Patagonia, such as the saltasaurids and other aeolosaurines, Overosaurus paradasorum was relatively small, estimating at around 10 meters (33 feet) in length. It primarily subsisted as a ground-dwelling herbivore. Belonging to the titanosaur group, recognized for massive, long-necked, herbivorous dinosaurs dispersed across various regions during the Mesozoic Era, Overosaurus stood out due to its diminutive size. While titanosaurs were commonly renowned for their colossal dimensions, Overosaurus emerged as a dwarf titan, offering a captivating instance of evolutionary miniaturization.

Similar to its fellow titanosaurs, Overosaurus would have probably been a herbivorous dinosaur, sustaining itself on a diet consisting of plants like ferns, cycads, and conifers.