B-SC 5.5: Students will be able to exemplify evidence in fields of embryology, anatomy, biochemistry, and paleontology that underlies the theories of evolution THE FOSSIL RECORD

PALEONTOLOGY THE STUDY OF FOSSILS FOSSIL RECORD PROVIDES EVIDENCE OF THE HISTORY OF LIFE ON EARTH

The fossil record Shows life on Earth has changed over time. 99% of all species that ever lived on Earth are extinct

Relative Dating Age of a fossil is determined by comparing its placement with that of fossils in other layers of rock

INDEX FOSSILS used to compare relative ages of layers of fossils Needs to have been widespread and only lived for short amount of time

Relative dating does not provide information about a fossil’s absolute age

RADIOACTIVE DATING Use of radioactive decay to assign absolute ages to fossils (& rocks) ½ life = time required for ½ radioactive atoms in a sample to decay ½ life of radioactive elements is constant

Radioactive Dating Age of sample calculated based on amount of radioisotopes it contains

Useful: carbon in all living things ½ life 5730 years Older than 60,000 years Useful: carbon in all living things ½ life 5730 years Fossils > 60,000 yrs unable to detect Use radioisotopes K-40  Ar-40 with a ½ life of 1.26 billion years