Definition of amniote in English:



  • An animal whose embryo develops in an amnion and chorion and has an allantois; a mammal, bird, or reptile.

    • ‘The sequence from the early amniotes to the early mammals is the most fully documented of the major transitions in vertebrate evolution.’
    • ‘The oldest known amniotes - close to the ancestry of all reptiles, birds, and mammals - appeared in the early Pennsylvanian, about 310 million years ago.’
    • ‘Vertebral counts in modern amniotes, amphibians, and fish, can vary due to environment or change with growth.’
    • ‘The ancestral amniotes were small animals, superficially resembling primitive, insectivorous lizards.’
    • ‘Mammals are also amniotes, but they differ from reptiles in the structure of their skulls (especially the regions associated with chewing and hearing).’


Late 19th century: from modern Latin Amniota, back-formation from amniotic (see amnion).