Diego is a Smilodon who was seen in all of the three films.

Smilodon, sometimes called sabre-toothed cat, is an extinct genus of large machairodontine saber-toothed cats that lived between approximately 2.5 million to 10,000 years ago in North and South America. They are called "sabre-toothed" for the extreme length of their maxillary canines. The La Brea tar pits in California trapped hundreds of Smilodon in the tar, possibly as they tried to feed on mammoths already trapped. The Natural History Museum of Los Angeles County has many of their complete skeletons. Despite the colloquial name of "sabre-toothed tiger", Smilodon is not closely related to a tiger, which belongs to another subfamily, the Pantherinae; Smilodon is a member of the extinct subfamily Machairodontinae.

迪亚哥是《冰河世纪》中善战但同样心地善良的剑齿虎，他并不像自己的外表那么吓人，但真实的剑齿虎是这样的么？

剑齿虎一直生活到距今100万年前的更新世。它是大型猫科动物进化中的一个旁支, 生活在距今300 万～1.5 万年前的更新世——全新世时期, 与进化中的人类祖先共同渡过了近300 万年的时间。剑齿虎的体形大约与现代虎差不多，但是它的上犬齿却比起现代虎的犬齿大得多，甚至比野猪雄兽的獠牙还要大，如同两柄倒插的短剑一般。剑齿虎是个孤独的伏击杀手。它是如何利用自己的獠牙捕杀猎物的？人们却对此知之甚少。但根据比较附着在美洲豹头骨上的咬合肌，得知剑齿虎的撕咬能力相当惊人