EARTH 7 Lecture Notes - Lecture 15: Hadrosaurid, Pangaea, Iguanodon
11/28/17
● Patterns in the fossil record can be influenced by:
○ Preservation bias
■ Amount of exposed sedimentary rock
■ Differential “”preservability” of remains
● The hollow bones of theropods make them even less likely to be
preserved
○ Collecting bias
● Dinosaur world
○ The triassic: dinosaurs evolve on pangaea, but not very diverse until other groups
to go extinct
○ The jurassic: dinosaurs become dominant on land as pangaea splits
○ The cretaceous: peak of dinosaur diversity: as land masses become ever further
divided
● What caused the end permian mass extinction
1. Formation of pangaea
a. Severe decrease in the extent of shallow marine environments
b. New competition from invaders both on continental shelf and on
continents
c. Lowering of sea level
d. Alteration of oceanic circulation and atmospheric weather patterns
e. Interior of continents much dier
i. Triassic becomes much hotter and generally dry, partly due to the
position of pangaea and the extensive continental interior
● Dinosaurs evolve in triassic and there are fewer barrier to dispersal in the triassic
○ Crocs+kin and other archosaurs and synapsids were dominant in triassic
○ First dinosaurs appear in the mid triassic
● Pangaea splits into northern and southern continent in the jurassic
● Overview of jurassic dinosaurs
○ Stegosaurians were most diverse and abundant during jurassic
○ Most well-known sauropods are from the jurassic
○ Non coelurosaurian theropods
● The cretaceous
○ The cretaceous still relatively warm, with shallow continental seas becoming
widespread
● Endemism
○ Distinct faunas not known from anywhere else in the world
■ “The endemic fauna of australia”
● Late cretaceous no more stegosaurians but more
● Iguanodon and hadrosaurid are exclusively cretaceous
● Pterosaurs
● In the oceans
Document Summary
Patterns in the fossil record can be influenced by: The hollow bones of theropods make them even less likely to be preserved. The triassic: dinosaurs evolve on pangaea, but not very diverse until other groups to go extinct. The jurassic: dinosaurs become dominant on land as pangaea splits. The cretaceous: peak of dinosaur diversity: as land masses become ever further divided. Triassic becomes much hotter and generally dry, partly due to the position of pangaea and the extensive continental interior. Dinosaurs evolve in triassic and there are fewer barrier to dispersal in the triassic. Crocs+kin and other archosaurs and synapsids were dominant in triassic. First dinosaurs appear in the mid triassic. Pangaea splits into northern and southern continent in the jurassic. Stegosaurians were most diverse and abundant during jurassic. Most well-known sauropods are from the jurassic. The cretaceous still relatively warm, with shallow continental seas becoming widespread. Distinct faunas not known from anywhere else in the world.
