Ice Jeweler/Episodes/OVA Four

Ice Jeweler OVA 4: "The Caveman Who Preceded Link, Oh" (ヒスイの氷、オリジナルアニメーション4(フォア)：オー、穴居人の旅。, Hisui no Kōri, Orijinaru Animēshon Foa: Ō, Kekkyo-jin no Tabi., or "Ice of Hisui, Original Video Animation 4: Oh, a Caveman's Journey.") is a two part OVA that is based on Picha's 1980 film The Missing Link, telling the story of how Oh, Bone and Slick came to be friends, together.
Episode	Episode Title	Plot
1 	The Caveman who Preceded the Missing Link.
(穴居人はミッシング・リンクを先行していた。Kekkyo-jin wa Misshingu Rinku o Senkō Shite Ita.)	In the year 196303 B.C., a group of cavedwellers decide to find food to eat. However, before one of them, an elder caveman, decides to hunt for food, he falls in love with a cavewoman from another tribe. Time passes, and two young babies are born, Oh and Ah. Ah gets all the attention because the cavepeople appreciate him. However, Oh feels neglected and abandoned because of his lighter skin color and red hair. So, Oh decides to leave his cave to seek new environments and feel like he is loved.
Around the same time, a brontosaurus egg bumps into Oh. As soon as the baby brontosaurus Bone hatches, the two instantly become friends.
Some time later, another egg falls from the sky. Oh and Bone decide to eat the egg, but it hatches into a baby pterodactyl. Oh decides to name the pterodactyl "Slick," and the two become friends. Bone, however, becomes a little jealous, and tells Oh not to come within a few feet of Slick.
A lot of time passes by, and Oh becomes an adult. Despite Bone's plea, Oh decides to see Slick, and he wants to fly. However, Bone sees Oh and Slick together and takes Oh away.
The following morning, Oh looks into a reflection at a pool of water, and discovers that he is a caveman, not a brontosaurus. Wanting to know some answers, he decides to search for his own kind. However, Bone doesn't want Oh to go alone, so Bone decides to give Oh a ride, and the search begins...
2 	Brother Against Brother. Oh vs. Ah!
(兄に対する兄。オー対アー！, Ani Nitaisuru Ani. Ō tai Ā!)	The caveman Oh has begun his quest to find his tribe, with the help of his brontosaurus friend Bone. Throughout his quest, he felt thirsty, and wanted to have a drink of water. So, Bone took Oh to a lake to have a drink. Unfortunately, that lake belongs to a red dragon. The dragon agrees to take Oh to a nearby lake that isn't inhabited. However, Oh is accidentally dropped off into an Arctic zone, and he almost drowns. However, he is saved by his pterodactyl friend Slick.
Finally, with his quest complete, he finally reaches his home tribe. The leader of the tribe, Oh's father, the elder caveman, quickly recognizes Oh before passing on. Soon after, Oh becomes the tribe's new leader, and he teaches the tribe all that he has learned throughout his quest. However, Oh is a bit angry at Bone for abandoning him.
Meanwhile, Ah, Oh's twin brother, decides to take over as leader. However, Oh challenges him to a contest to show him who leads the best.
Unfortunately, Oh put up a good fight against his brother, but lost. Ah throws Oh into the fire pit. Oh would have died if not for Bone's rescuing him.
As Ah declares a takeover, Oh, Bone and Slick get abandoned on an uncharted island. Oh thought that he and his friends would spend the rest of their days on the island, but Oh sees an unidentified flying object entering the earth's atmosphere. After the object crashlands, three familiar figures emerge from it and introduce themselves to Oh, Bone and Slick.