Mesozoic Era Age of the Dinosaurs Three Periods

Mesozoic Era (Age of the Dinosaurs) Three Periods Triassic Jurassic Cretaceous

MESOZOIC ERA u KNOWN AS THE MIDDLE ERA u TIMEFRAME: Occurred between 248 to 65 million years ago

IMPORTANT EVENT u Time marked by rapid movements of plates u u A major geologic event of the Mesozoic was the break-up of the super continent of Pangaea into several large continents. u HAD WARM CLIMATE

Mesozoic Era Triassic Period (225 -180 MYA) Pangaea (supercontinent) existed

PANGAEA

¡LAND (GEOLOGICAL) FEATURES THAT FIRST APPEARE:

Mesozoic Era Cretaceous Period (135 -65 MYA) Flower plants CALLED (angiosperms) 1 ST APPEARED

¡ANIMALS/ORGANIS MS (BIOLOGICAL) FEATURES THAT FIRST APPEARED:

Mesozoic Era Triassic Period (225 -180 MYA) First Dinosaurs (small in size) Pisanosaurus Length: 3 feet Height: 1 foot Weight: 15 pounds Eoraptor: Length: 3 feet Height: 1 foot Weight: 20 pounds

Mesozoic Era Jurassic Period (180 -135 MYA) Pangaea starts to separate

Mesozoic Era Jurassic Period (180 -135 MYA) 1 st mammals (small rodents).

Mesozoic Era Jurassic Period (180 -135 MYA) 1 st birds (Archaeopteryx). • Jaws and bone structure like dinosaurs • Bones are hollow, like birds • Had feathers

Mesozoic Era Jurassic Period (180 -135 MYA) Reptiles in the sea - Icthyosaurs – 8 m; Plesiosaurs – 15 m.

¡ ANIMALS/ORGANISMS (BIOLOGICAL) & GEOLOGICAL FEATURES THAT BECAME DOMINANT

Mesozoic Era Jurassic Period (180 -135 MYA) Dinosaurs BECAME DOMINANT

Mesozoic Era Cretaceous Period (135 -65 MYA)

Mesozoic Era Cretaceous Period (135 -65 MYA) Continents in modern positions

Mesozoic Era Triassic Period (225 -180 MYA) GYMNOSPERMS BECAME DOMINANT

¡WHAT CATASTROPHIC EVENT CAUSED THE MASS EXTINCTION?

MASS EXTINCTION ¡ Asteroids, METEORITE, or Comets collided into the Earth AND CAUSED Mass Extinction

How could a meteorite impact cause a mass extinction? The impact caused shock waves, tidal waves, and sent a tremendous amount of dust into the atmosphere p As the dust re-entered the Earth’s atmosphere, it would have instantly heated the atmosphere causing tremendous forest fires p Dust from impact blocked out the sun and caused major climate change and plants to die p Plants, animals, etc. went extinct due to the climate changes and competition between organisms ¡

Mesozoic Era Cretaceous Period (135 -65 MYA) Mass Extinction: 50% of all plant and animal groups die out Alvarez’s Meteor Impact Theory- 10 km wide meteorite hits Earth

Scientists now have fresh evidence that such a cosmic impact ended the age of dinosaurs near what is now the town of Chixculub in Mexico.

Mesozoic Era Cretaceous Period (135 -65 MYA) ¡ Evidence of Impact: Iridium l l l An element that is very rare in Earth rocks and very common in meteorites The layer of rocks above the last dinosaur bones contain ~ 160 x normal levels of iridium Called the K/T Boundary