These fossils are very useful for us because we can use them to date the layers of rock that they are found in. Fossils that can be used in this way are called index fossils, and rock layers with the same index fossils in them can be correlated. Not my answer, link here for full
http://peter-mulroy.squarespace.com/correlating-rock-layers/
Inherited Traits are passed down and are not influenced by organism’s surroundings
Answer is the phylum is Pteridophyta. Pteridophytes are first land plants, examples ferns, <em>Lycopodium, Selaginella. </em>Members have liginified cells and developed conducting tissues called vascular system to conduct water and synthesized food. They reproduce through spores, seeds do not develop in pteridophytes.
