What's the difference between ichthyolite and ichthyology?

Ichthyolite

Definition:

• (n.) A fossil fish, or fragment of a fish.

Example Sentences:

Ichthyology

Definition:

• (n.) The natural history of fishes; that branch of zoology which relates to fishes, including their structure, classification, and habits.

Example Sentences:

• (1) In the course of ichthyological inventory investigations in the main water-course of the Narew River the occurrence of Tracheliastes polycolpus Nordm.