Dai kyôryû jidai

It is the story of three kids from Japan who, one fateful night, are summoned by an unknown alien intelligence who tells them that mankind is losing its empathy, and, to teach them a lesson about life, death, and the fall of species, said alien intelligence transports the kids to Earth's past and leaves them right in the Mesozoic era, the time when dinosaurs were the supreme rulers of the Earth. (tvtropes.org)