Laurence is the old man in Parchment Desert, which is unlocked after beating Fossil Fighters. Talking to him will have him reveal that the player will not be able to find any fossils due to the heat affecting sonars. Go to the Fossil Guild and buy an Oasis Seed. Give it to Laurence, and he'll plant it. Wait for 10 minutes, and an oasis will appear, allowing the player to find (some) fossils. Bring another Oasis Seed and wait. After four oases have been added, all Vivosaur fossils will available here, including T-Rex. He also becomes the Area Guide when this is done. He says phrases, such as "Yup" or "Yuppers" frequently.