Source : Webster's Revised Unabridged Dictionary (1913)

Amniota \Am`ni*o"ta\, n. pl. [NL. See {Amnion}.] (Zo["o]l.)
   That group of vertebrates which develops in its embryonic
   life the envelope called the amnion. It comprises the
   reptiles, the birds, and the mammals.

Source : WordNet®

Amniota
     n : higher vertebrates (reptiles, birds and mammals) possessing
         an amnion during development