The female mammoth wounded by primitive human hunters. Despite this she accepts to befriend modern human Nigel and follows him in the modern-day park.
Another example is the same mammoth being accepted by the African elephants' matriarch after risking to "die for loneliness" due to refusing to eat any food.
That example is even cooler when reading the behind the scenes about it. They made a giant puppet of a mammoth head, then animated it in front of the elephant. They weren't sure how she'd react, but to their surprise the elephant interacted with it and welcomed it as it would for a real elephant.