Final answer:
Caviar is traditionally harvested from the sturgeon, an ancient fish dating back to the Late Cretaceous period, and not from salmon, tuna, or trout.
Step-by-step explanation:
Caviar is traditionally harvested from the sturgeon, whose earliest fossils date to the Late Cretaceous period. This period is well-known for being around 100 million years ago. Not to be confused, the coelacanth is also an ancient fish from the Late Cretaceous, but it is not the source of caviar. Sturgeons are renowned for their roe, which is processed into caviar. It has been a prized delicacy for centuries and is known for its unique flavor and texture.