South America became linked to North America through the Isthmus of Panama during the Pliocene, bringing a nearly complete end to South America's distinctive marsupial faunas. The formation of the Isthmus had major consequences on global temperatures, since warm equatorial ocean currents were cut off and an Atlantic cooling cycle began, with cold Arctic and Antarctic waters dropping temperatures in the now-isolated Atlantic Ocean. Africa's collision with Europe formed the Mediterranean Sea, cutting off the remnants of the Tethys Ocean. Sea level changes exposed the land-bridge between Alaska and Asia. Near the end of the Pliocene, about 2.58 million years ago (the start of the Quaternary Period), the current ice age began. The polar regions have since undergone repeated cycles of glaciation and thaw, repeating every 40,000–100,000 years. COUNT 5
QSN1 What is the link between North and South America called? ANS1 the Isthmus of Panama QSN2 In which period did North and South America become linked? ANS2 Pliocene QSN3 The Mediterranean was created by the collision of Europe and what? ANS3 Africa QSN4 What period came after the Pliocene? ANS4 the Quaternary Period QSN5 The Pliocene saw the end of what fauna in South America? ANS5 marsupial faunas