It is distinctive, widespread, abundant and limited in geologic time. Because most fossil<span>-bearing rocks formed in the ocean, the major </span>index fossils<span> are marine organisms. That being said, certain land organisms are useful in young rocks and in specific regions.</span>
A carrier is an individual who carries and is capable of passing on a genetic. Carriers are associated with diseases inherited as recessive traits. An individual having one normal allele and one mutated allele does not have the disease.
