Any vertebrate animal, such as a reptile, bird, or mammal, that possesses an amnion, chorion, and allantois during embryonic development.
Compare: anamniote
Source:
PAC, 2016, 88, 713. 'Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)' on page 720 (https://doi.org/10.1515/pac-2015-1202)