Term
| The Cambrian saw an explosion in biodiversity. Why? |
|
Definition
| The evolution of predators and skeletons started an arms race which drove evolution |
|
|
Term
| Organisms with bilateral symmetry flourished and superseded other body plans in the Cambrian. What makes bilateral symmetry so useful? |
|
Definition
| It alows easy movement away from predators and competition, and separates food intake from waste disposal |
|
|
Term
| What caused the demise of stromatolites? |
|
Definition
| They had no defense against grazers |
|
|
Term
| What feature marks the beginning of the Cambrian? |
|
Definition
| The appearance of complex burows in ocean sediment |
|
|
Term
| How did ocean chemistry shift early in the Cambrian? |
|
Definition
| Aragonite seas shifted to Calcite seas, low in Mg, and high in Ca |
|
|
Term
| What imortant feature did trilobites evolve in the Ordovician? |
|
Definition
| complex eyes with calcite lenses |
|
|
Term
| What major evolutionary change occured in the Ordovician? |
|
Definition
| The appearance of floaters and swimmers, including specialized predators |
|
|
Term
| What caused sevral trilobite extinctions in the late Ordovician? |
|
Definition
| Glaciation killed tropical species, then melting and rising sea levels killed shallow-water species. |
|
|
Term
| What did the continents look like in the cambrian? |
|
Definition
| High sea levels flooded much of the cratons, Laurentia (N. America & Greenland) were near the equator, and Gondwanaland sat over the south pole, and started glaciation; sea level dropped sharply. |
|
|
