The two appeared at the beginning of the film when Sid the Ground Sloth was shown stepping on their salad and eating an important part of it, the dandelion. This last act angers them to the point of wanting to kill him, but as they were about to, they were stopped by Manfred the Woolly Mammoth, by being hurled through the air.
They held a powerful grudge against Sid for what he had done, and when they next saw him, he was in the same hot mud pool, that they were in and was erroneously referring to them as ladies. Again, Carl and Frank stampeded after the hapless sloth, but were waylaid when they saw that he had already been "killed" by Diego the Saber-Toothed Tiger, which was part of Sid's plan to get them to be fooled into leaving him alone and not trying to kill him off, so they gave up their chase post-haste, defeated. Carl had thick lips and a thick horn, while Frank had more pointed lips and a thinner horn.
- While their species is listed as "Brontotherium," they are more the size of Brontops dispar. It thus cannot be concluded which species they are, short of an amalgamation. Furthermore, brontotheriums were extinct before the Ice Age started.
- Carl and Frank didn't appear in Ice Age: Dawn of the Dinosaurs, but the triceratops in the water looking at the water lilly was a spoof to Carl and Frank's dandelion argument.
- Carl and Frank have not made any further appearances in the film series after the first, although they make an appearance as minor villains in the video game of the third film. In the level "Baby Proofing," while Sid is helping Manny child-proof his playground, Carl and Frank appear towards the end of the level, threatening to destroy the playground. But Sid manages to drive them away when he rides each of them into several large rocks that Manny forgot to remove earlier.