Plant and Planetary Evolution Part II Flashcards
How many mass extinctions events have occurred in the last half billion years?
At least 5 with Each resulting in the loss of more than 3/4s of existing species.
Which was the first mass extinction?
Ordovician Mass Extinction: Climate cooling resulted in 86% of species loss.
What did competition for light lead to?
New developments and innovations such as stems and leaves allowing for plants to take on a more upright and complicated body plan.
What types of stems did early plants have?
Underground stems and anchoring roots that were dichotomously branched (split into two equal parts)
Why was there dichotomous branching?
Because there was a need for communication between upper and lower parts which resulted in early vascular tissue functioned in conduction.
What happened in later evolutionary history?
The vascular tissue became thicker and more important for structural support.
Today it’s even more structural (wood)
What happened 385 myr?
Plants had become abundant and diverse
First trees were in existence
When was the Devonian Mass Extinction
Associated with cooling occurred 359 million years ago
Resulted in around 75 percent species loss
What were some of the first trees?
Ferns
Lycopods
Horsetails
Enormous
What does the size of the plants tell us about the Earth?
Climate must have been pretty warm and wet to support these plants
What are gymnosperms?
Plants with “naked” seeds
What are some modern gymnosperms?
Coniferous trees (ex. pine , firs, etc.)
When was the Permian Mass Extinction?
Occurred 252 myr
Resulted in 96% species loss
Massive volcanic eruptions resulted in the acidification and warming from the release of CO2, SO2, and CH4
What are angiosperms?
Flowering plants
Produce fruit
Vessel elements (specialized for transport)
Fibres (Specialized for support)
When was the last recognized mass extinction?
66myr
A boldie *exploding meteor hit Earth
Caused a short but severe winter
