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.

迪亞哥是《冰河世紀》中善戰但同樣心地善良的劍齒虎，他并不像自己的外表那么嚇人，但真實的劍齒虎是這樣的么？

劍齒虎一直生活到距今100萬年前的更新世。它是大型貓科動物進化中的一個旁支, 生活在距今300 萬～1.5 萬年前的更新世——全新世時期, 與進化中的人類祖先共同渡過了近300 萬年的時間。劍齒虎的體形大約與現代虎差不多，但是它的上犬齒卻比起現代虎的犬齒大得多，甚至比野豬雄獸的獠牙還要大，如同兩柄倒插的短劍一般。劍齒虎是個孤獨的伏擊殺手。它是如何利用自己的獠牙捕殺獵物的？人們卻對此知之甚少。但根據比較附著在美洲豹頭骨上的咬合肌，得知劍齒虎的撕咬能力相當驚人