The survival of the biggest and strongest
Elimination of the weakest organisms
The survival of organisms that occupy the largest area
The survival of organisms that have adaptations that make them better suited to their environment
They will be useful some day.
They are useful but we don't know what they're used for.
They were present in an organism's ancestors.
They are the result of random mutations.
Birds and moths are close relatives.
Birds and moths share a common environment.
Birds and moths have different habitats.
Birds and moths do not share a close ancestor.
They share a common ancestor.
They happen to need the same number of bones in those structures.
The same number of bones happened by accident.
The reason is unknown to science.
In the top layer
In the bottom layer
In the middle layers
Scattered evenly throughout all the layers
The most primitive would be on top.
The most primitive would be on the bottom.
All the fossils would be scattered evenly through every rock layer.
There would be no fossils in the rock layers.