History of species
A species is defined as a population with the potential to interbreed that are reproductively isolated form other such groups.
Definition cannot be applied to fossils or to species that do not reproduce sexually.
Collecting evidence of the relationships between extinct species relys on the careful identification of fossils.
System of classification of species
Kingdom , phylum, class, order, family, genus and species.
To find out if a species is at risk of extinction they need to be compared to what has happened in the past. Common structures like limbs, eyes and…