Since direct observation of a fossil animal's behavior isn't possible, paleontologists use comparison and contrast with living animals for guidance. Tracks can sometimes reveal further clues.
Extinct Pleistocene capybara assumed to be gregarious, highly social, like their living relatives.
Similar skull, limbs and skeletal proportions to modern capybara suggest similar non-specialized, but competent, swimming ability.
Many predators - mammals, birds, and reptiles would have fed on capybara.
Herrera & Macdonald (1989, 1993)