An animal whose embryo develops in an amnion and chorion and has an allantois; a mammal, bird, or reptile.‘Vertebral counts in modern amniotes, amphibians, and fish, can vary due to environment or change with growth.’
- ‘The sequence from the early amniotes to the early mammals is the most fully documented of the major transitions in vertebrate evolution.’
- ‘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).’
- ‘The oldest known amniotes - close to the ancestry of all reptiles, birds, and mammals - appeared in the early Pennsylvanian, about 310 million years ago.’
Late 19th century from modern Latin Amniota, back-formation from amniotic.
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