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Alfred Wagner

1912 theory that continents fit together. Prevailing thought at the time was that land bridges were submerged just below sea level


Plate tectonics

The earth moves, plates shift creating movements of continents by millimetres (can move greater distances because of big events- earthquakes)


Earth layers

Outermost layer = crust, 5-25 km thick
Mantle = mobile flowing layer
Outer core = iron and nickel, liquid
Inner core = solid molten, temperature of the sun
Lithosphere = crust and upper part of mantle
Aesthenosphere = part of mantle that flows like play dough

Crust and inner core are solid layers, mantle and outer core are liquid


Plate movements

Hot materials rise, cool materials sink, which creates slow moving currents. Solid crust plates sink at edges, pulling continents



Earthquake fault lines occur at edges of continental plates, when two plates collide, slip under each other, overlap, ect


Lithosphere movement

Causes earthquakes, volcanoes, oceanic rifts, and mountain formations



Triassic (240 million years ago)
Panthalassa - giant ocean that encompasses the globe



Asia, Europe, and NA (Jurassic 170 million years ago)



South America, Australia, Africa, Madagascar, India, and Antarctica
(India and Asia were originally separate, when it collided with Asian the Himalayas were born)
Broke apart in Cretaceous 100 million years ago


Dinosaurs and movement

First Dino's appeared in Triassic 220 mya, while Pangea still existed. Therefore large mixing of Dino's, where similar types are found all over the world
Once Laurasia and Gondwana split, we see predominant types in each.
Laurasia = tyrannosaurs, pachyceohalosaurs, and ceratopsians
Gondwana = sauropauds, abellasaurs, carcharadontasaurs

Late Cretaceous leads to breakup of continents and further break up of Dino's, and potentially an increase in number of species


Antarctica Dino's

Cryolophosaurus - frozen lizard - has a unique crest that looks like a snow shovel, but lived in warmer climates,

Antarctic climate was warmer due to an altered ocean circulation (transporting warm water from equator down to polar region)

70 million years ago, Antarctica was attached to Australia, and currents had to go around Australia, and warmed up there


Marine fossils on land areas

Sea level was much higher during Mesozoic era (up to 250 meters higher) this created sea ways that spanned areas that are currently covered by land
Sea level was higher because of a lack of glaciation, thermal expansion (warm water takes up more space), and sea floor spreading associated with plate techtonism (basins filling with rock and sediment)
Land area decreased
Interior NA was covered by a seaway
Nearby lakes and oceans create increased precipitation a and smooth out extremes in temperature (decreasing seasonality)

Higher temperatures and sea levels could have increased species diversity


Species diversity

Total number of species in an area
Increased due to increased water levels, increased temperatures, and decreased seasonality



Golden age of sauropods and long necks
Late Jurassic = thriving diplodocus, macronaroans



High browser, robust, long front legs, long necks,
Spoon teeth lining entire jaw
Not pickey, crunched woody vegetation


Ecological niche

How a particular species makes its living, where it fits into the role of an ecosystem



Simple peg teeth, selective nipper, reach high and prune leaves


Niche partitioning

Two competing species occupying slightly different niches, diverging to specialize



Ornithischians with body armour in Jurassic period, grazed in the shadows of sauropauds


Theropod takeover

Late Jurassic, large theropods were common, with stiff spines and long legs (ie allosaurus)
Ornitholesies - Turkey sized coelurosaur, long sacral vertebra, short, fast, small predators hunting small mammals, fish, insects, ect.



Early ancestor of birds



Most robust of sauropods, like argentinosaurus, not easy prey. Largest animal to walk the earth

Preyed on by carcharadontasaurs, named for shark like teeth, had large jaws, largest was giganotosaurus.
Abellasaurs are the last of carcharadontasaurs, they had to adapt a different morphology (short muzzles and small heads, very short arms, wrinkley bone, cranial ornaments for sexual display)

At the end of the Cretaceous period, only Titanosaurs were found in both Gondwana and Laurasia
Abelisaurs = Gondwana,
Stegosaurus = became extinct long before Cretaceous began
Carcharadontasaurs = outcompeted by end of the Cretaceous



In Laurasia, split into 2 groups
-ankylosaurids -tall clubs, backward pointing horns
-nodosaurid -large osteoderm spikes, narrow snouts, no tail club


Hadrosaurs (new iguonodon in late Cretaceous, most successful herbivorous Dino)

Sophisticated dental batteries, 2 groups, most abundant in Laurasia
Lambeosaurine - big crests, nasal passages amplifying their calls
Cranial instruments with complex ears leads to intricate calls
Hadrosaurine - crestless or lessened crested hadrosaurs, no sound amplification



Fringe heads
Pachyceohalosaurs - domed skulls
Ceratopsians - primitive ceratopsians did not look like triceratops, but still had beaks



Ornitomimides similar to emus but with long claws
Maniraptors had a semlilunate carpal allowing delicate folding of limbs
Oviraptors - veggie life, no teeth
Therizinosaurs - very long claws, mistaken for turtle, small skull and long neck
Tyrannosaurus - strongest jaws, social, take extreme adaptations like longer legs and stiff vertebral column. Big heads added weight, compensated by reducing arm size
All of the above are only known from Laurasia