Planet fish dating
While everybody understands that black bears are related to grizzly bears and we can even figure they are related to extinct bears, lots of people wonder how scientists can be so sure that bears are related to salmon as well.
One evidence is rock layersspecifically, what is called the geologic column.
In addition, research suggests that we’ve already crossed four of nine “Planetary Boundaries” – safe thresholds for critical Earth system processes that maintain life on the planet.All British salmon do not migrate from their home rivers and end up in the same feeding grounds.Different salmon may respond differently to environmental change. Research shows that fish carry natural records of feeding location hidden in the chemistry of their scales.Basically, scientists have learned that rocks are stacked in layers containing fossils with the oldest fossils at the deepest layers, and the youngest, or most recent fossils, near the top. At the bottom of the timeline there are no fossils of modern animals.As you move towards the surface, you find fish, then amphibians, then reptiles, mammals, birds, and finally modern mammals including humans.
Human activities are pushing our planet into uncharted territory.