Lecture17- Dinosaurs Role in Paleogeography .doc

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Lecture 17
Dinosaurs: Their Role in Paleogeography
Late Ordovician
Late Devonian
Late Permian
Late Triassic
Late Cretaceous
We are going through an extinction that it is man made.
In late Triassic - dinosaurs experienced a small extinction
What had contributed to the extinction?
we are looking at plate tectonic were we have continents forming super
continents diversity is on the low side and as the continents separate it creates
diversity is going upward
Dinosaurs achieved a global distribution
successful animals
more diversity more dinosaurs
Vertebrate are rarer than invertebrates
Geographic distribution
Ex. Patagonia have more fossil material that tells us more about dinosaurs
Temporal distribution
Rare fossil of two species together
what do these tell us ?
they lived together and we can reconstruct that ecosystem
Rare fossil of interspecific behavior
Ex. One biting the other, protected themselves from predators
Ex. lived together and died together in combat position
Geographic Distribution
Endemic Taxa
Indigenous Taxa
Continental Separation
Taxa which occur a specific geographic area and are related to certain
Ex. Kangaroo
Why are they endemic to Australia?
The moment Australia separated the animals stayed in Australia and
they evolved. Migration routes are shut down.
Mountain Range forms certain animals are not able to cross over.
Barriers of faunal migration.
What period of the mesozoic has the most endemism ?
Temporal Distribution
A new dinosaur genus occurred every 4-8 Million years
Possibly exceeded at time of mass extinctions
Ceratopsian Dinosaurs
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Relatively complete fossil record
A new species every 1.9 Million years
Stegosaurs produces 1 new species every 5.6 Million years
Minimum Divergence Time: Sedimentary column
one is able to date the sequence
Y=125 Ma to X=100 Ma (eggs) MDT 25
If X and Y are related, there must be an ancestor older than 125 Ma
MDT is as old or older than 125 Ma, if not preserved ghost lineage
Used for estimation of fossil completeness
MDTs in Ceratopsian dinosaurs
Range from 0-30 million years
Average 5 Ma
Good candidate or temporal and geographic distribution studies
North america spread out nicely along the seaway and China
Late Triassic (231-208 Ma)
Time of Pangea
Climate: Heat and aridity
those dinosaurs that managed to survive these extreme conditions they are
forming the assemblages for the late Triassic they are completely different
than dinosaurs from the cretaceous.
Strong seasons (continental climate)
Low endemism
Evolution of Dinosaurs through time
Who was around the Triassic?
early Mammals
Earliest dinosaurs (231-223 Ma)
Ex. Eoraptor
Theropod, Middle to Late Triassic, Argentina
Fossil Localities
China and India
South Africa- Stromberg Series
Ancient fluvial system
Beautifully preserved therapsids
Prosauropod Melanorosaurrus
Several localities in Europe
South America
Chile and Argentina
North America
Chinle Formation
New Mexico, Utah, and Arizona
Ghost Ranch- Coelophysis (Cerapoda)
Early Jurassic 208-178 Ma
Dinosaurs become more dominant
Slow break up of Pangea
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