While body size and lifespan directly impact an individual's cancer risk within species, we see no such correlation when comparing cancer risk between species - a surprise that is known as Peto's Paradox. While there are many ways that Evolution can resolve this paradox, gene duplication stands out as a particularly parsimonious solution to the problem. Inspired by previous test cases where a tumor suppressor gene duplication was found in a large, long-lived species - such as in elephants - we sought to test whether or not tumor suppressor duplicates are especially enriched among duplicated genes in large *Atlantogenatans*. We find that tumor suppressor duplicates are present in all *Atlantogenatan* genomes, and occured throughout the tree. Tumor suppressor duplicates in Elephants show functional transcription, suggesting that these duplicates have preserved a functional role, and may have permitted the sudden increases in body size we observe throughout *Atlantogenata*.