History Of Life Flashcards
(21 cards)
How many mass extinctions have occurred?
There have been five mass extinctions.
What caused the Ordovician mass extinction?
The Ordovician mass extinction (444 million years ago) was caused by climate changes, leading to the extinction of many trilobites.
What were the main factors behind the Devonian mass extinction?
The Devonian mass extinction (383-359 million years ago) was caused by ice ages, global cooling, and glaciations, resulting in almost all life forms dying out.
What was the most severe mass extinction and its cause?
The Permian mass extinction (252 million years ago) was the most severe, caused by volcanic eruptions, leading to the death of reptiles and frogs.
What caused the Triassic mass extinction?
The Triassic mass extinction (201 million years ago) was caused by acid rain and a drop in oxygen in water, destroying more marine life forms.
What led to the Cretaceous mass extinction?
The Cretaceous mass extinction (66 million years ago) led to the extinction of all dinosaurs, caused by an asteroid impact that blotted out sunlight.
What is the current mass extinction crisis caused by?
We are in the crisis of the sixth mass extinction caused by human activities such as illegal veld-fires, illegal hunting, and habitat destruction.
What are the two theories on the causes of mass extinctions?
The two theories are: 1) Environmental disasters (meteor impacts, severe volcanism, radiation, or killer diseases) and 2) Organisms failing to adapt to habitat or environmental changes.
What is the most recent eon in the Geological Time Scale?
Quaternary (Recent)
0.01 mya
What era comes after the Quaternary?
Tertiary
6 mya
What period is known for the rise of angiosperms?
Cretaceous
65 mya
Which period is characterized by the dominance of gymnosperms?
Jurassic
145 mya
What significant event occurred during the Triassic period?
First dinosaurs and egg-laying mammals appeared.
245 mya
What is the date range for the Devonian period?
419 - 359 mya
Age of fishes; amphibians; wingless insects.
What major development occurred in the Silurian period?
Vascular plants appeared, algae were dominant.
443 - 419 mya
What is the significance of the Ordovician period?
Invertebrates were dominant, and the first fishes appeared.
485 - 443 mya
What major event is associated with the Cambrian period?
Origin of marine invertebrates.
541 - 485 mya
What marks the beginning of the age of mammals?
The extinction of dinosaurs.
66 mya
What significant evolutionary event occurred around 570 mya?
Bacterial cells, then primitive algae and fungal marine protozoans emerged.
570 mya
What does the term ‘mya’ stand for?
Million years ago.
What is the age of Homo sapiens?
Humans dominate the current geological epoch.
0.01 mya
