TASK DEFINITION: Combine the given two facts to write a concluding fact. Note that there should be some parts of the first and second facts that are not mentioned in this conclusion fact. Your combined fact should be the result of a chain between the two facts. Chains form when two facts connect together to produce a concluding fact. An example of a chain is: "pesticides cause pollution" (fact1) + "pollution can harm animals" (fact2) → "pesticides can harm animals" (conclusion fact). Parts of the concluding fact overlap with the first and the second fact. To construct such a  concluding fact, a useful way is to borrow the subject from one fact and the ending conclusions from another fact.
PROBLEM: Fact 1: Infancy is the period of most rapid growth after birth. 
Fact 2: While a baby is very young, during infancy, co-sleeping is very convenient for feeding schedules.

SOLUTION: Very young babies have the period of most rapid growth after birth.

PROBLEM: Fact 1: being burried under soil and mud changes peat into coal through extreme heat and pressure in a swamp over a long period of time. 
Fact 2: Most coal is fossil peat.

SOLUTION: fossils turn into coal over time.

PROBLEM: Fact 1: Birds have relatively large brains and a high level of intelligence. 
Fact 2: Large brains require large skulls.

SOLUTION:
Birds have relatively large skulls and a high level of intelligence.