sabre-toothed tiger vs tortoise

sabre-toothed tiger

noun
  • Any of numerous species of extinct cat-like mammals, of the Machairodontinae subfamily of the Felidae. 

tortoise

noun
  • Any of various land-dwelling reptiles, of the family Testudinidae (chiefly Canada, US) or the order Testudines (chiefly UK, Australia, New Zealand, Ireland, South Africa, India), whose body is enclosed in a shell (carapace plus plastron). The animal can withdraw its head and four legs partially into the shell, providing some protection from predators. 

  • Synonym of cat (sense 10, a wheeled shelter) 

How often have the words sabre-toothed tiger and tortoise occurred in a corpus of books? (source: Google Ngram Viewer )