GEOLOGIC TIMESCALE MESOZOIC ERA The Age of Reptiles

GEOLOGIC TIMESCALE MESOZOIC ERA The Age of Reptiles!

The Breakup of Pangaea

The Breakup of Pangaea � Affects global & continental climates, as well as oceanic circulation � Climate sensitive deposits offer clues to past climates � Oceans absorb 90% of solar radiation � Continents absorb 50% � Global temperatures remain relatively equable through the end of the Cretaceous.

TRIASSIC (251 -200 Ma) � Seas repopulated by survivors from the Permian � 1 st dinosaurs emerge from ancestral archosaurs 1 st mammals emerge from cynodonts �

Extinction Event! Over half of the known living species were wiped out � Vacated ecological niches � Happened in around 10, 000 years � Possible Causes � Asteroid impact � Volcanic Eruption � Climate change

Jurassic (200 -146 Ma) � Dinosaurs fill vacant niches and begin to dominate � Time of the giant sauropod dinosaurs � 1 st birds emerge

DINOSAUR MYTHS All dinosaurs were big � Dinosaurs could swim and fly � Dinosaurs were a failure (165 million years versus 1 million years) � Why were dinosaurs so successful? �

Jurassic-Cretaceous Boundary � No major extinction event � Instead, boundary is defined by geologic deposits.

Cretaceous (146 -66 Ma) Placental and marsupial mammals diverge � Angiosperms evolve and diversify rapidly �

Angiosperms (flowering plants) � Adapted to every terrestrial habitat � Enclosed seeds � How might this have contributed to their success?

K/T Extinction Event Dinosaurs, flying reptiles and marine reptiles all went extinct � 50% off all marine invertebrates, as well � � What could have caused this?

Asteroid impact? � What evidence would you look for? � What effects would an impact have on the environment and life?

Evidence Yucatan Peninsula of Mexico High Iridium Levels � Soot � Shocked quartz � Huge wave deposits �