Dinasours Flashcards
What do fossil in the marine sediment reveal about extinctions ?
Major extinction events occurred numerous times
Give the time period in which dinosaurs first evolved
The Triassic period
What group of organisms lived alongside the dinasours in the Triassic period?
The Crurotarsi
When did the crurotarsi go extinct ?
At the end of the Triassic, whilst the main dinosaur lineages persisted.
Describe the theories of Crurotarsi extinction.
Thought to be outcompeted by dinosaurs
Actually morphologically distinct (D & C) No interspecific competition,
Due to another factor.
When and why did the rapid increase in dinasour occur ?
83 million years, cretaceous
Evolution of flowering plants, new niche
1000 species of dinosaur were thought to exist- actually synonyms,
How many actually exist ?
500
How are the 2 dinosaur clades distinct ?
Due to hip morphology
State the 2 dinosaur clades
Ornithschia
Saurischia
Give the characteristics of the organisms in the Ornithischia.
Bird hipped croppers
All herbivorous
4 legged and bipedal species
Common after the jurasic.
Give the characteristics of the organisms in the Saurischia
Lizard hipped dinosaurs
Theropods and Sauropodomorphs
Define the characteristics of the Theropods
Within the Saurischia
Bipedal carnivores
Define the characteristics of the Sauropodomorphs
Within the Saurischia
Quadrupedal herbivores
Long necked
Which class to birds belong to ?
The Therepods, within the Saurishcia
Give examples of feathered therepods within the fossil record
Microraptor
Archaeopteryx
Confuciusornis
Why was the intital hypothesis of endothermy in dinosaurs unlikely ?
Large dinosaurs would require huge amounts of high quality food source to generate the type of heat required
Wasn’t present
Why was the initial hypothesis of ecothermy in dinosaurs unlikely ?
Would require dinasours to bask as a means of thermoregulation
Could not be done in some habitats they inhabited.
What is the proposed temperature regulation system of dinosaurs ?
Inertial homeothermy
Maintain a body temperature but is dependant on mass
Small- ecothermic
Large- Warmer, endothermic
The larger the dinasour, the …… its body temperature
Warmer, even in same habitat
Gave different behaviours depending on size
Give the main impacts of the meteorite strike
Lack of sunlight due to ash- affecting basking & food supply
Affect productivity of organism
Sex ratios- dependant on temperature In some species
Give the 2 major pieces of evidence for meteorite impact
- 180km wide crater in Mexico, fragments date 65 mya.
2. Global deposits of iridium common in asteroids, between cretaceous and later periods
What occurred at the Deccan traps in India ?
Massive volcanic eruptions
Prevented photosynthesis and caused greenhouse effect altering temperature
The Deccan traps or the Meteorite impact are thought to be the main reason the mass extinction
The Meteorite impact
Did the competition with mammals affect extinction rates ?
No, mammals begun to diversify before extinction occurred. (good relationship)
How did birds, crocodiles and mammals survive ?
Pure chance.
