Obtained: Speak with the Tourists near Gingertown in West Area during the main story Meeting the Mysterious Monster. You will need to have completed the sub story Tourists in Trouble on planet Namek during the Frieza Saga for them to show up.
Objective: Collect the durasaurus meat
Travel to Gingertown on the World Map to find the alien couple a short distance away. Speak with couple and offer to find the durasaurus meat for them. Travel to the Gizard Wasteland in the Central Plains Area from the World Map. This will put you near the search area for the sub story. Look for the dino in the search area and defeat it using Ki blasts. Once the dino is down for the count, Piccolo will head back to the couple only to discover them being threatened by one of Frieza’s soldiers. Defeat him to trigger a cutscene completing the story.