Which of the following geologic and biologic events defined the Carboniferous period?   The age of the dinosaurs, lush vegetation, and abundant ferns. Birds first appeared and Pangaea broke apart.   Modern humans evolved and a major extinction event was ongoing.   The Earth thawed, allowing for an explosion of animal diversity. Most major groups of animals arose in the resultant oceans. which were dominated by trilobites and shelled organisms.   High atmospheric oxygen levels fostered giant arthropods and spore-forming plants such as lycophyte trees dominated.