Eutherian and Plantigrade

Eutherian noun - Mammals having a placenta; all mammals except monotremes and marsupials.

Plantigrade and eutherian are semantically related. In some cases you can replace term "Plantigrade" with "Eutherian", this nouns are similar.

Plantigrade noun - An animal that walks with the entire sole of the foot touching the ground as e.g. bears and human beings.

Eutherian and plantigrade are semantically related. Sometimes you can use "Eutherian" instead a noun "Plantigrade".