Cretaceous         
adjective  geology specialized uk/krəˈteɪ.ʃəs/ us/krəˈteɪ.ʃəs/
 白垩纪的;来自白垩的(白垩纪为距今约1.44亿年至0.65亿年前的地质时期,有花植物首次出现)
from or referring to the period of time between around 144 and 65 million years ago, in which plants with flowers first appeared
  the Cretaceous period 白垩纪 
 Cretaceous rocks 白垩纪时期的岩石 
 the Cretaceous
noun [ S ] ukus
 白垩纪
the Cretaceous period