Table 1 shows the timeline of fossil evidence for several transitional species in the evolutionary history of cetaceans (whales) from terrestrial ancestors.
Table 1
| Species | First appearance (mya) | Last appearance (mya) |
|---|---|---|
| Pakicetus inachus | 52.1 | 47.8 |
| Ambulocetus natans | 48.6 | 42.3 |
| Rodhocetus kasrani | 47.2 | 45.9 |
| Basilosaurus isis | 41.3 | 33.8 |
| Dorudon atrox | 40.4 | 33.8 |
Calculate the number of years Basilosaurus isis is thought to have existed on Earth.
