Kollikodon ritchiei is a australosphenidan species, often classified as a monotreme but more recently recovered as an outgroup. It is known only from an opalised dentary fragment, with one premolar and two molars in situ. The fossil was found at Lightning Ridge, New South Wales, Australia, as was Steropodon. Kollikodon lived in the lower Cretaceous period, during the middle Albian age (113-101 million years ago). Aside from its size, it is difficult to say what Kollikodon looked like. It is certain that its teeth were specialised to crush food, being perhaps a shellfish-eater or herbivore.