a. The Southern Cross was important to the aboriginal people, who believed the pattern of the stars was of a wedge-tailed eagle.
The sentence above doesn't contain a run-on or isn't a run-on sentence.
A run-on is a phrase,
statement or sentence of two or more independent clauses –clauses are
independent phrases which has an subject and predicate and, can stand by its
own self- that were conjoint or combined together regardless of punctuation.
These are also called fused sentences.
