Imperium naturæ C. Linnaeus, 1758 - nature Mundus Plinius - physical world naturalia - natural bodies Regnum Animale C. Linnaeus, 1758 - animal kingdom see Kingdom Animalia Linnaeus, 1758 Class Mammalia Linnaeus, 1758 - mammals Quadrupedia Linnaeus, 1758 see Class Mammalia Linnaeus, 1758 Order Bruta Linnaeus, 1758 Genus Bradypus Linnaeus, 1758 - three-toed tree sloths Bradypus tridactylus Linnaeus, 1758 - pale-throated sloth