World Paleogeography: During the Carboniferous, small oceans began to close, bringing together the western half of Pangea. These continental collisions resulted in several mountain-building episodes. Gondwana rotated clockwise relative to Euramerica, deforming the terranes in between that would form much of Central and Southern Europe. Siberia split from the northern margin of Euramerica and picked up the island arcs of Kazakhstan as it approached the eastern margin of Baltica. North American Paleontology:The word “Carboniferous” comes from the Latin, meaning “coal-bearing.” In the United States, the Carboniferous Period is commonly divided into the Mississippian (Early Carboniferous), 360 to 325 million years ago (mya), and the Pennsylvanian (Late Carboniferous), 325 to 286 mya. During the Early Carboniferous (Mississippian), limestones, shales, sandstones, and evaporites were deposited in the shallow sea that covered most of North America. The highlands along our modern East Coast were being eroded until the Late Carboniferous (Pennsylvanian), when North America started to collide with Gondwana. The collision uplifted the ancestral Rocky Mountains, the Ouachita Mountains of Oklahoma, the Appalachians, and much of present-day eastern Canada and the East Coast from Maine to Alabama. Paleoclimate and Paleontology: Crinoids covered huge areas of the seabed, leaving behind their remains as limestones. By the mid-Carboniferous, the emergence of the continents and proliferation of land plants created large seasonal and latitudinal temperature gradients. Vast swamps formed over low-lying areas of North America, northern Europe, and Asia during the Late Carboniferous. The lush vegetation of these swamps became coal through chemical and physical processes associated with low-oxygen conditions, rapid burial, and subsequent metamorphism. One of the greatest evolutionary innovations of the Carboniferous was the amniote egg, which allowed the ancestors of birds, mammals, and reptiles to reproduce on land.