Answer:
This means that the two separate rocks were once part of one piece of rock. These layers got separated most probably by continental drift as a result of tectonic plate movements. An example of such a fossil is the Mesosaurus, a freshwater crocodile-like reptile, that is found in Southern Africa and Eastern South America continents- that means they were once one land mass.
The environment in these two separate layers would most likely be different. As the layers drift apart from each other , they drift across latitudes that are determinants of climate in a region. Therefore, even the organisms in these two rock layers will evolve differently (even though they will share a common ancestor) in adaptation to respective environments – this is called allopatric speciation.
Answer:
From what I remember in my 9th grade biology class, it's usually half that amount.
Grasshoppers have no ears, instead they use an organ called the tympanum located in the first segment of their abdomen, whereas humans take in sound waves through the ear canal until they reach the eardrum. The eardrum picks up the vibrations and then transmits them to tiny bones in the middle of the ear, the bones pass the vibrations to the inner ear (which is filled with liquid) and the cochlea.
Hope I could help.