 The second species, "M. hakataramea", was discovered in the Kokoamu Greensand of New Zealand.Mammalodon fossils have been found in Australia and New Zealand

"Mammalodon" was, at first, considered to be a member of Archaeoceti, an ancient group of whales, which was evidenced by its apparent ancient features, such as the variety of differently shaped teeth in its jaw (heterodonty) that modern whales lack.