[1] : The Collaborative International Dictionary of English v.0.48

mammal \mam"mal\, n.; pl. mammals. l. mammalis belonging to
   the breast, fr. mamma the breast or pap: cf. f. mammal.
   zool.
   one of the mammalia.
   1913 webster

   age of mammals. see under age, n., 8.
      1913 webster
see also:
mammals age of mammals age 

[2] : WordNet (r) 2.0

age of mammals
     n : approximately the last 63 million years syn: cenozoic, cenozoic
         era
see also:
cenozoic cenozoic era 

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