Evidence of Evolution

Bailey DeGroat

Fossil layers

What is it? ... Fossil layers are fossils that form in the sedimentary rock, this is formed by the deposing and pressing of on sediments of top of each other. Over time this sedimentary rock builds up and you are left with multiple layers that have multiple fossils from that era, the deeper you go the older the fossils.

How does it support Evolution? ... Fossil layer have provided clear evidence that evolution has occurred, for example the oldest horse fossil shows that they were about the same size as a fox now and they had for 4 long toes compared to the 4 hoofs they have now. Other found fossils show that they had once lived in wooded marshlands and ate soft leaves and through the decades and as the climate became drier the grasslands have slowly replaced most of the marshes which caused the horses to adapt and over time they became taller (which helped them see predators while in the grass lands), they developed the single toe hoof (which helped them run swiftly to escape predators), And their molars became longer and covered with cement (this allowed them to bring through though grass without wearing out their teeth).

Homologous, Analogous & Vestigial Structures

What is it? ... Homologous structures are structures that are similar in relative organisms due to them inheriting features from common ancestors. These inherited features may or may not have the same function in the descendants.

Analogus structures are structures that are similar in unrelated organism. These similar qualities also have the same function.

Vestigial structures is the reduce in size of structures that are no longer used

How does it support Evolution? ... Due to evolution the size has reduced because certain structures are no longer used. For an example the the human appendix it now a tiny organ which was once a larger organ. In a distant ancestor it was needed to digest food and in modern day it serves no purpose to humans today.


Comparative- The study of the similarities and differences in the embryos of different species.

Similarities- Embryos are evidence of common ancestry.

- Most animals loose some of their features by time they reach adult hood.


Deals with chemical compounds and processes occurring in organisms & chemical characteristics and reactions of a particular living organism or biological substance.

  • Since certain blood proteins are found in most organisms/species, scientists believe that all animals have a common ancestor.