Puertasaurus is a genus of titanosaurian sauropod dinosaur discovered in Patagonia. It is considered to have been one of the largest dinosaurs known, possibly rivaling its relative Argentinosaurus in size. It lived during the Late Cretaceous period.
The holotype specimen was discovered in January 2001 by Pablo Puerta and Santiago Reuil. It consists of a partial spinal column, a neck vertebra, a dorsal vertebra and two tail vertebrae. The genus was officially named in 2005, the full name of the species, Puertasaurus reuili, is a homage to the original discoverers of the dinosaur.
Of all the fossils, the largest is the back vertebra, measuring 1.06 metres (3 ft 6 in) tall and 1.68 metres (5 ft 6 in) wide. This is the broadest sauropod vertebra known.
Fernando Novas, one of the paleontologists who first described Puertasaurus reuili, estimated its size as being approximately 35 to 40 metres (115 to 131 ft) long and weighed between 80 and 100 metric tons. Scott Hartman made a skeletal reconstruction suggesting a slightly shorter lenght of 27 metres (89 feet) and a total weight of 60–70 metric tons.
Puertasaurus reuili lived during the Late Cretaceous of South America in what is now Patagonia. Like other members of its kind, it was a quadrupedal herbivore with a long neck and a tail. Like other titanosaurs, it may have possessed osteoderms on its back that acted as armor. Puertasaurus is closely related to Mendozasaurus and Futalognkosaurus.