REHASHED FROM THE PREVIOUS FOUR EPISODES: Trini is convinced she has discovered a dinosaur bone. A visit to a American Museum of Natural History shows that she actually has the femur of a horse. Marc visits Miami Seaquarium to see whales trained. At the Bronx Zoo, Lisa goes on the rounds with a young veterinarian feeding baby animals.Fresh items for end of week: Model train built to one-eighth scale. Film insert: New York pizzeria owner bakes the largest pizza ever made (80 feet). ANIMATIONS: The need for a standardized measuring system; a pizza baker's dilemma with a trio of customers.