Deep Dive: Mass Extinctions

DEEP DIVE: MASS EXTINCTIONS World Science Festival BY JULIE ROSSMAN & CLARE SMITH-MARASH worldsciencefestival.com 6? 2) 3 600 M YEARS AGO 300 M YEARS AGO PRESENT TIME 1. 35% of living organisms lost WHAT HAPPENED: rebound of a greenhouse climate. Glaciation followed by a HARD-HIT GROUPS: TRILOBITES BRACHIOPODS BRYOZOANS ECHINODERMS GRAPTOLITES 0% of all marine WHAT HAPPENED: rising sea levels, and global cooling. Lack of oxygen in the oceans, species lost HARD-HIT GROUPS: REEF ENVIRONMENTS OSTRACODERMS STROMATOPOROIDS & PLACODERMS RUGOSA & TABULATA TRILOBITES (AGAIN) 3 96% of all species lost WHAT Extremely dry, hot conditions led to animal and plant decline, and HAPPENED: a large volcanic eruption pushed carbon dioxide into the atmosphere, raising temperatures and lowering oxygen in the ocean. It took 10-20 million years for life to recover its diversity after this event. HARD-HIT GROUPS: TRILOBITES EURYPTERIDS FUSULINID FORAMINIFERA ACANTHODIANS MONURA (YET AGAIN!) AND OTHER INSECTS 76% 4 of all species lost WHAT Extreme volcanic activity, which would eventually break apart HAPPENED: the supercontinent of Pangaea, raised global temperatures and acidified the ocean. There is still a great deal of controversy surrounding the main cause of extinction during this period. HARD-HIT GROUPS: THRINAXODON MASTODONSAURUS BRACHIOPODS AMMONITES CONODONTS & OTHER MAMMAL-LIKE REPTILES & OTHER AMPHIBIANS 5 70% of all species lost WHAT After millions of years of animal and plant decline due HAPPENED: to dropping sea levels and intensifying volcanic activity, which caused acid rain and cooling temperatures, a gigantic asteroid struck Earth, causing further devastation. HARD-HIT GROUPS: DINOSAURS PTEROSAURS MOSASAURS PLESIOSAURS RUDISTID & OTHER MOLLUSKS 6? of all species lost WHAT'S Some scientists think the sixth major extinction event started HAPPENING: 10,000 years ago when humankind began to dominate the Earth, with extinctions tied to a wide array of causes including hunting, habitat destruction, pollution, and global climate change. HARD-HIT GROUPS: WOOLY MAMMOTH DODO PASSENGER PIGEON GOLDEN TOAD GREAT AUK & OTHER AMPHIBIANS NUMBER OF TAXANOMIC FAMILIES HOLOCENE (PROPOSED) END CRETACEOUS END TRIASSIC END PERMIAN (THE GREAT DYING) LATE DEVONIAN END ORDOVICIAN 007 008 PRECAMBRIAN CAMBRIAN ORDOVICIAN SILURIAN DEVONIAN CARBONIFEROUS PERMIAN TRIASSIC JURASSIC CRETACEOUS TERTIARY QUATERNARY