The Argentinosaurus Herd were a group of sauropods that appeared in the Primal episode, Plague of Madness. This massive herd of dinosaurs lived peacefully amongst each other and were building nests to lay their eggs. But suddenly, a Parasaurolophus, who is severely ill with a deadly flesh-eating virus, runs around and infects one of the sauropods when it bit its leg. Soon after, the sauropod slowly starts to become infected by the bite mark, and the goes on a violent rampage, decimating the entire herd and smashing the eggs. Spear and Fang later arrived and were horrified at the sight of the carnage until they were then pursued by the infected sauropod.