Final answer:
Two major fossil collection expeditions in the early 20th century took place in Tanzania and Mongolia, places that were heavily explored during the age of colonization and provided significant contributions to dinosaur paleontology.
Step-by-step explanation:
The student asked which two places were significant in collecting dinosaur fossils in the first half of the 20th Century. The correct answer is C. Tanzania, Mongolia. These regions were part of large expeditions that contributed significantly to paleontology and the study of dinosaurs. Tanzania was part of the colonization efforts in Africa, where European countries claimed territories. Similarly, Mongolia, closely associated with the political interests of Russia and China, saw major paleontological activities. Fossil distribution in these areas can reflect the shifting continents over geological eras, like the division of Pangaea into Laurasia and Gondwanaland during the Triassic Period, which ultimately gave rise to the variety of dinosaurs that once roamed these ancient landscapes. These historical expeditions have helped deepen our understanding of the Mesozoic Era and the fascinating age of dinosaurs.