Please enable JavaScript.
Coggle requires JavaScript to display documents.
Vertebrate History in Rocks (What are Fossils (fossils are found most…
Vertebrate History in Rocks
What are Fossils
Fossils are hardened remains or other evidence of a living thing that existed a long time ago
a fossil can be a footprint or the outline of a leaf in some sort of rock.
other fossils can be the remains of bones, shells, skeletons , or other parts of living things.
how are fossils made?
fossils are made when a chemical process takes place over time.
as this happens the organisms tissues are replaced by hard minerals.
fossils are found most frequently in sedimentary rock.
sedimentary rock is hardened lalyers of sediments.
this can happen with muddy water that stays still for a long time or with wind when it blows some dust on some dunes.
over time these sediments will press together and form rock.
sediments contain particles of clay sand, mud, or silt.
Interpretation of Fossils
a fossils age
sediments
the oldest layers settle at the bottom so the higher up a fossil is the younger it is.
this is not always the most reliable form of telling a fossils age, the position of the fossil in the rock plays a key part.
other forms of telling age
chemical elements
chemicals can be found in fossils and will over time decay or change other chemicals in the fossil
the more decayed the fossil is the older it is.
using fossils
paleontologists have used fossils to determine the pattern of how vertebrates have changed over time.