Animal evolutionary tree by Haeckel, 1874. This evolutionary tree describes the evolution of animals through prehistoric time (timescale down left). It includes groupings such as fish, amphibians, reptiles, birds and mammals. In his studies on evolution, German naturalist Ernst Haeckel (1834-1919) incorrectly gave the impression through trees like this that mammals in general (at top right), and humans in particular, are the most highly evolved organisms. This page is from an 1874 edition of Haekel's work 'Naturliche Schopfungsgeschichte' (The History of Creation), first published in 1868.