Simplify the following text for a Grade 5 native English-speaking person.
Original: The Red Kangaroo ( Macropus rufus ) is the largest of all kangaroos , the largest mammal native to Australia , and the largest surviving marsupial .
Simplified: The word macropus means `` big foot '' and rufus means red . It is the largest mammal in Australia , and the largest marsupial in the world .