Evolution generally follows a path of fish, amphibians, reptiles then mammals. For example, ocean animals came before land animals and tetrapods became amphibians. Animals that moved onto land needed to make some major adaptations to survive. There was a land animal called cothurnocystis that lived before the dinosaurs, was three to eight centimeters long and is thought to be an ancestor of all animals with a backbone. Birds are supposedly descended from dinosaurs, which would explain their scaly legs. Archaeopteryxes are an offshoot from reptiles to birds and were one of the first found “missing links”. The platypus is the earliest known mammal offshoot from reptiles.