- A mammal of the group Prototheria, which comprises the monotremes and their extinct relatives.More example sentences
- Extant mammals, including prototherians (egg-laying mammals) and therians (marsupial and placental mammals), probably last shared a common ancestor about 160 million years ago.
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- Relating to or denoting prototherians.More example sentences
- In his classification of prototherian mammals Hopson queried the allocation of Haramiyidae to the Multituberculata.
- They had a common ancestor more recently than either had with the monotremes or, probably, any other prototherian group.
More definitions of prototherianDefinition of prototherian in:
- The US English dictionary