New Zealand used to have more rare species, but some, mostly birds, were hunted to extinction early in its history. The giant Moa, "Dinornis", is a famous example. The group of birds which the moa belongs to had been in existence since the Cretaceous period. Humans arrived in New Zealand about a thousand years ago, when many moa were living, especially on the South Island. Archaeological sites with evidence of moa hunting are all over New Zealand. The moa became extinct about five hundred years ago. Extinctions closer to today have been caused by habitat change and introduced species like rats, dogs, cats, and possums, which kill the native birds and lizards, or eat their eggs.