What is another word for prototherian?
Pronunciation: [pɹˌə͡ʊtə͡ʊθˈi͡əɹɪən] (IPA) 
Prototherian is a term used to describe the primitive lineage of mammals that includes monotremes. Monotremes are mammals that lay eggs instead of giving live birth, such as platypus or echidnas. There are several synonyms for the word prototherian that can be used interchangeably, such as primitive mammals, egg-laying mammals, platypus-like mammal, and monotremes. These synonyms help to describe the unique characteristics of this lineage of mammals, which have many differences from other mammals. Prototherians are fascinating creatures with a rich evolutionary history that serve as an important example of the diversity of life on Earth.
