This article examines the many afterlives of the Tendaguru Expedition—a 1909–13 fossil excavation in the colony of German East Africa that unearthed the tallest mounted dinosaur in the world, still on display in Berlin. The long process of dinosaur assembly, which took more than three decades, meant that the Tendaguru project effectively outlived the German empire. Accounts of the expedition alongside the dinosaur exhibitions served as attempts to both theorize prehistoric life and write a history of the empire in terms compatible with the many twentieth-century German regimes that followed. These (re)negotiations of Tendaguru were reckoned with an ever-growing list of lost worlds: the prehistoric, the imperial, the Weimar Republic, the Third Reich, and the postwar Germanies. At stake in these dinosaur stories was not merely the progress of some neutral, apolitical, or abstract paleontological science but rather national pride, international authority, civilizational superiority, and imperial legitimacy.