Unit 6 Lesson 2 https://youtu.be/O21VOcLIb3M I. Evidence of Evolution

I. Evidence of Change Over Time A. Fossils fossils= remains or imprints of once-living organisms https://youtu.be/VVadWrsHtJM Usually form in sedimentary rock after years of mud and sediments layering on top of an organism or remains of the organism cast fossil= minerals from the environment replace the parts of the organism that decomposed leaving a hard “cast” fossil record= all of the fossils that have been found provides evidence about the order of species and how they change overtime transitional fossils= fill in gaps between organisms https://youtu.be/XRW-ATOUJus

B. Common Structures related organisms share structural traits common ancestor= the most recent species from which two different species have evolved from homologous structures= organisms have similar structures to a common ancestor but the structures have a different function ex: whale arm bones and human arm bones analogous structures= organisms have structures that have similar function but the structure is different and they do not come from a common ancestor ex: flippers of a penguin and a whale

vestigial organs: structures that are reduced in size or function that may have had complete function in an earlier ancestor https://youtu.be/0R8XqyHGIaI ex: appendix & coccyx (tail bone)

C. Similar DNA Comparing similarities in an organisms DNA may show that they come from a common ancestor amino acids join together to code for proteins fewer differences may indicate an evolutionary common ancestor

D. Developmental similarities embryology= the study of development comparing the development of embryos of different species may show a common ancestor https://youtu.be/uAZmLYWEPGk