Nobody knows how they happened to get concentrated there.

Mind, they are bones, not fossils.

This means that the moa has not been extinct very long.

Still, this is the only New Zealand creature which has no mention in that otherwise comprehensive literature, the native legends.

This is a significant detail, and is good circumstantial evidence that the moa has been extinct 500 years, since the Maori has himself--by tradition--been in New Zealand since the end of the fifteenth century.