A group of mammals that comprises the monotremes and their extinct relatives.Compare with Theria
- ‘They are often placed in a separate subclass from other mammals, Prototheria.’
- ‘As noted, recognition of skull resemblances to monotremes and triconodonts led to later referral to ‘Prototheria,’ within a monophyletic Mammalia.’
- ‘Later cladistic studies, beginning with that of Kemp, called into question the integrity of a broadly conceived ‘Prototheria.’’
- ‘Triconodonta were viewed as broadly ancestral to the extinct Docodonta and to living monotremes, collectively grouped (often with Multituberculata) as Prototheria.’
Modern Latin (plural), from proto- first, original + Greek thēr wild beast.