Mammals Whose Gestation Period Lasts Longer Than That of Humans

1. Cow – 284 days
2. Horse – 336 days
3. Sea Lion – 360 days
4. Whale – 360 days
5. Donkey – 374 days
6. Camel - 400 days
7. Giraffe – 425 days
8. Rhino, Gray – 480 days
9. Rhino, Black – 540 days
10. Elephant, Indian – 624 days

Source: http://www.vaughns-1-pagers.com/biology/gestation-periods.htm