10: plate tectonics Flashcards
Alfred Wegener
noticed that: the coastlines of south america and africa looked like connectable puzzle pieces; that the fossils of animals that had been found could not have swam the distance; identical geologic formations in south america and africa.
theory of continental drift
but could not explain how continents moved
Layers of the earth
crust
mantle
outer core
inner core
lithosphere
curst and upper solid portion of the mantle
crust
outmost earth layer
consists of the continents and ocean basins
cool
more solid and dense than lower layers
mantle
2, 500 km deep
upper portion is solid
Asthenosphere
below lithosphere
lower portion of mantle
viscous and flowing
not liquid, but viscous solid (like playdoh) under the heat and pressure conditions
extreme heat causes convection currents here
lower portions slowly heat, expand, rise, and then cool and sink
these currents affect the plates
core
below mantle
composed of iron, and nickel
outer core is molten liquid
inner core is solid ball, temp: 5, 700 degrees celsius (same surface temperature of the sun)
Plates
pieces of lithosphere
affected by convection currents in the Asthenosphere, which pull along the plates undersurfaces and cause movement
Because the crust is cool and dense, the plates slowly sink, and melt into the lower layers. This occurs at the edges gradually. As an edge sinks, a gap is created on the opposite edge, where molten rock escapes
the cycle contines
Plate tectonics
movement of the lithosphere
explanation for drifting continents theorized by Wegner
verified in lots of ways: mid-ocean ridges
as plates move, they can collide. The boundary where two plates collide can cause lots of pressure to build > forming volcanoes, earthquakes, mountain ranges
pangea
super continent
end of permian, beginning of the triassic
explains why dinosaurs across the world were similar
panthalassa
super ocean
first true sauropods
appeared late in the triassic, alongside prosauropods
Diplodocids
Jurassic sauropod nipping teeth extremely long necks front legs shorter than hind legs tail whip
Macronarians
jurassic sauropod no whip tails robust bodies front legs not shorter than hind ones powerful muncher less picky eaters
ecological niche
animal’s way of life
niche partitioning
two similar animals avoid direct competition for food resources
ex. diplodocids and macronisans
thyreophorans
jurassic grazer and browser Ornithischians with body armour Stegosaurus widespread
Ornithopods
ornithischian
jurassic
“Jurassic Gazelle”
fast
Allosaurids
Jurassic
theropod
vertebras interlock rigidly
successful carnivore
Coelurosaurs
long sacral vertebrae, narrow heads, tails with skinny back halves
theropod
jurassic
spawned birds
During Jurassic, Pangea
split into two continents: Laurasia, Gondwana
Laurasia
northern
NA, Europe, Asia (not india)
Gondwana
Soutehrn
SA, Australia, Antarctica, Africa, Madagascar, India
Dinosaurs of Early Cretaceous
regional differences in dinos:
Iguanodontians, ankylosaurs, brachiosaurid sauropods in NA and Europe
theropods like spinosaurs in Africa
in Asia, coelurosaurian theropods common, ceratopsians evolved
Late cretaceous
Gondwana breaks apart, except for antarctica and australia
- sauropods thrived here (went extinct in Laurasia) > the Titanosaurs
- theropods
- ankylosaurs and hadrosaurs (thanks to a land bridge from NA)
Titanosaurs
Macronian most robust sauropod Gondwana borad chest, wide hips limbs far apart ex. Argentinosaurus
Carchrodontosaurs
late cretaceous theropods giant slayers teeth like those of great white shark allosaurid descendent, have bigger head and longer jaws big teeth powerful forearms, large hooked claws SA preyed on large titanosaurs
Abelisaurs
late cretaceous SA carnivore last survivors of the ceratosaurid lineage short muzzles, tiny teeth short stubby arms small claws preyed on small titanosaurs
In what is now asia
titanosaurs rare
In NA
not a lot of sauropods
lots of hadrosaurs
Laurasia
ankylosaurs split into two groups
- ankylosaurids
- Nodosaurids narrower and elongated nuts, no tail clubs, large osteoderm spike from shoulders
