1. A member of the subclass Prototheria, the most primitive living mammals that lay eggs, including monotremes such as the platypus and echidna.
Usage: zoology; technical

1. Of, relating to, or characteristic of the Prototheria or egg-laying mammals.
Usage: zoology; technical

Examples

• The platypus is a prototherian mammal native to Australia.
• Prototherians are distinguished from other mammals by their ability to lay eggs.
• Scientists study prototherian fossils to understand early mammalian evolution.
• The echidna is another well-known prototherian species.
• Prototherian reproduction differs fundamentally from that of marsupials and placental mammals.
• Modern prototherians are found primarily in Australia and nearby regions.