| In some ways, monotremes are very primitive for mammals because, like reptiles and birds, they lay eggs rather than having live birth. |
| The only living monotremes are the platypuses and the echidnas. |
| Molecular evidence now suggests that the marsupials and the monotremes branched off much earlier than the placentals did and that they are therefore the closer relatives. |
| The Australian fossil record of monotremes also includes some quite good Miocene and Pleistocene fossils of giant echidnas. |
| He designed a platypussary, in which one of the monotremes lived for months and was seen by thousands of people. |
| To distinguish them from the marsupials and the placental mammals the monotremes are placed in their own class, the prototheria. |
