While many hatchling turtles are rather small, most species attain lengths in excess of 4 inches once mature. Contrary to the claims of ignorant or unscrupulous dealers who assert that turtles will remain small if kept in tiny enclosures, healthy turtles grow quickly when provided with proper care. Nevertheless, a few turtle species remain relatively small and are pretty easy to accommodate making for great compact turtle companions.
Moose generally give birth between May and June of each year. Their  gestation period is approximately 280 days and it is rare that they  give birth to twins. 1 person found this useful.
For Rhesus monkeys it is 164 days and baboons 187 days. For small animals such as rabbits the period is about 33 days and for mice about 20 days. So it takes a longer time for a big animal such an elephant to grow a baby than for a smaller animal such as a mouse. The baby of the bigger animal is of course bigger but there are the bigger resources of the big animal to promote that growth so it is not obvious that bigger animals would have longer gestation periods.