Here's a list of hypothetical Ancient Devil Fruits, each based on extinct or mythical animals:
1. **Ryu Ryu no Mi, Model: Dragon (Dragon-Dragon Fruit, Model: Dragon)**
2. **Tori Tori no Mi, Model: Phoenix (Bird-Bird Fruit, Model: Phoenix)**
3. **Inu Inu no Mi, Model: Dire Wolf (Dog-Dog Fruit, Model: Dire Wolf)**
4. **Ushi Ushi no Mi, Model: Mammoth (Ox-Ox Fruit, Model: Mammoth)**
5. **Kame Kame no Mi, Model: Megalochelys (Turtle-Turtle Fruit, Model: Megalochelys)**
6. **Kuma Kuma no Mi, Model: Cave Bear (Bear-Bear Fruit, Model: Cave Bear)**
7. **Mushi Mushi no Mi, Model: Meganeura (Bug-Bug Fruit, Model: Meganeura)**
8. **Hebi Hebi no Mi, Model: Titanoboa (Snake-Snake Fruit, Model: Titanoboa)**
9. **Tori Tori no Mi, Model: Archaeopteryx (Bird-Bird Fruit, Model: Archaeopteryx)**
10. **Uma Uma no Mi, Model: Brontosaurus (Horse-Horse Fruit, Model: Brontosaurus)**
11. **Ryu Ryu no Mi, Model: Hydra (Dragon-Dragon Fruit, Model: Hydra)**
12. **Tori Tori no Mi, Model: Roc (Bird-Bird Fruit, Model: Roc)**
13. **Inu Inu no Mi, Model: Sabre-Toothed Tiger (Dog-Dog Fruit, Model: Sabre-Toothed Tiger)**
14. **Ushi Ushi no Mi, Model: Aurochs (Ox-Ox Fruit, Model: Aurochs)**
15. **Kame Kame no Mi, Model: Archelon (Turtle-Turtle Fruit, Model: Archelon)**
16. **Kuma Kuma no Mi, Model: Short-faced Bear (Bear-Bear Fruit, Model: Short-faced Bear)**
17. **Mushi Mushi no Mi, Model: Titan Beetle (Bug-Bug Fruit, Model: Titan Beetle)**
18. **Hebi Hebi no Mi, Model: Megalania (Snake-Snake Fruit, Model: Megalania)**
19. **Tori Tori no Mi, Model: Hesperornis (Bird-Bird Fruit, Model: Hesperornis)**
20. **Uma Uma no Mi, Model: Iguanodon (Horse-Horse Fruit, Model: Iguanodon)**
21. **Ryu Ryu no Mi, Model: Wyvern (Dragon-Dragon Fruit, Model: Wyvern)**
22. **Tori Tori no Mi, Model: Dodo (Bird-Bird Fruit, Model: Dodo)**
23. **Inu Inu no Mi, Model: Thylacine (Dog-Dog Fruit, Model: Thylacine)**
24. **Ushi Ushi no Mi, Model: Indricotherium (Ox-Ox Fruit, Model: Indricotherium)**
25. **Kame Kame no Mi, Model: Plesiosaurus (Turtle-Turtle Fruit, Model: Plesiosaurus)**
26. **Kuma Kuma no Mi, Model: Giant Panda (Bear-Bear Fruit, Model: Giant Panda)**
27. **Mushi Mushi no Mi, Model: Megatherium (Bug-Bug Fruit, Model: Megatherium)**
28. **Hebi Hebi no Mi, Model: Boasaurus (Snake-Snake Fruit, Model: Boasaurus)**
29. **Tori Tori no Mi, Model: Argentavis (Bird-Bird Fruit, Model: Argentavis)**
30. **Uma Uma no Mi, Model: Eohippus (Horse-Horse Fruit, Model: Eohippus)**
31. **Ryu Ryu no Mi, Model: Quetzalcoatl (Dragon-Dragon Fruit, Model: Quetzalcoatl)**
32. **Tori Tori no Mi, Model: Ichthyornis (Bird-Bird Fruit, Model: Ichthyornis)**
33. **Inu Inu no Mi, Model: Hyaenodon (Dog-Dog Fruit, Model: Hyaenodon)**
34. **Ushi Ushi no Mi, Model: Hyracodon (Ox-Ox Fruit, Model: Hyracodon)**
35. **Kame Kame no Mi, Model: Toxochelys (Turtle-Turtle Fruit, Model: Toxochelys)**
36. **Kuma Kuma no Mi, Model: Arctotherium (Bear-Bear Fruit, Model: Arctotherium)**
37. **Mushi Mushi no Mi, Model: Lethocerus (Bug-Bug Fruit, Model: Lethocerus)**
38. **Hebi Hebi no Mi, Model: Eryx (Snake-Snake Fruit, Model: Eryx)**
39. **Tori Tori no Mi, Model: Enantiornis (Bird-Bird Fruit, Model: Enantiornis)**
40. **Uma Uma no Mi, Model: Megaloceros (Horse-Horse Fruit, Model: Megaloceros)**
41. **Ryu Ryu no Mi, Model: Fafnir (Dragon-Dragon Fruit, Model: Fafnir)**
42. **Tori Tori no Mi, Model: Hesperornithes (Bird-Bird Fruit, Model: Hesperornithes)**
43. **Inu Inu no Mi, Model: Andrewsarchus (Dog-Dog Fruit, Model: Andrewsarchus)**
44. **Ushi Ushi no Mi, Model: Paraceratherium (Ox-Ox Fruit, Model: Paraceratherium)**
45. **Kame Kame no Mi, Model: Proganochelys (Turtle-Turtle Fruit, Model: Proganochelys)**
46. **Kuma Kuma no Mi, Model: Tremarctos (Bear-Bear Fruit, Model: Tremarctos)**
47. **Mushi Mushi no Mi, Model: Meganeura (Bug-Bug Fruit, Model: Meganeura)**
48. **Hebi Hebi no Mi, Model: Mosasaurus (Snake-Snake Fruit, Model: Mosasaurus)**
49. **Tori Tori no Mi, Model: Dodo (Bird-Bird Fruit, Model: Dodo)**
50. **Uma Uma no Mi, Model: Chalicotherium (Horse-Horse Fruit, Model: Chalicotherium)**
These Ancient Devil Fruits are based on extinct or legendary creatures, with unique powers and transformations corresponding to their mythical or ancient origins.