Smilodon is an extinct cat that probably lived in the post flood world.
Recent DNA sequencing data confirm that such distinctions are not fundamental in nature and that all cats share a common genetic ancestry. More recently described hybridizations between great cats and small cats, along with various other studies described in the present article, further support the hypothesis that all cats belong to a single clearly delineated basic type. The Nimravidae (paleosabers), the Machairodontinae (neosabers inclding Smilodon) and the genus Panthera each underwent a prominent radiation during the tertiary period. All three taxa represent cat-like placental carnivores, and they may all have arisen from the same basic type.
http://creation.com/images/pdfs/tj/j25_2/j25_2_118-124.pdf