Unit 1 Study Guide Test Date: ____________________Fossil Record & the Principle of Superposition

The fossil record contains information about every fossil discovered around the world. Studying these fossils from oldest to youngest give us information about how living things have changed over time.

Relative-age dating uses information we know from the fossil record to determine the approximate age of fossils and compare older fossils to younger fossils. We can also determine which organisms lived at the same time and when organisms went extinct.The Principle of Superposition-

Younger rock layers are on top of older rock layers

Fossils found in the same layer are the same age

Layer E is the youngest layer of rock according to the Principle of Superposition because it is the top layer of rock.

Layer A is the oldest layer of rock according to the Principle of Superposition because it is the bottom layer of rock. The Trilobite fossils found in the oldest rock layer are the oldest fossils shown.

The younger fossils are more complex than the older fossils.

Comparative AnatomyComparative Anatomy: comparing similar

structures among species

Homologous structures: similar structures in organisms each with different function

Example: the bones of a human arm, whale fin, and cat leg are all homologous structures

A

B

C

D

E

Analogous structures: same function but different structures

Example: An insect wing and bird wing are both used for flying through the air, but they do not have similar internal structures.

Vestigial structures: structure in an organism that has lost its function over time

Examples: appendix in humans, pelvis bone in whales, eyes in cave fish, wisdom teeth in humans, tailbone in humans

Embryology

Embryology: study of the development of an organism from one cell to birth

Comparing an embryo’s development before birth can show similarities between organisms.

Using the diagram to the right, we can tell a human, monkey, and pig are closely related because they have very similar embryonic development. Human embryonic development is most similar to a monkey.

The salamander is the least complex organism. Its development and adult structure are very simple compared to the other organisms in the diagram.

Evidence of Evolution: Whales vs. HumansEvolution: the process by which organisms have developed and changed over time

There are 4 types of evidence to support evolutions:

1. Comparative Anatomy2. Embryology: 3. Fossil Record4. DNA

Claim: A whale is more closely related to a human than a

shark.

Evidence:1. Comparative Anatomy

a. Dolphin fin and human arm have similar bone structure

b. Similar nasal passages in skullc. Lungsd. Leg bones present

2. Embryologya. Both embryos develop arm and leg budsb. Nasal passages first appear in the front of the

dolphins face, like a human face3. Fossil Record

a. Whales evolved from land mammalsb. Evidence of strong leg and hip bones found in

an early species of whale4. DNA

a. Whale is closest to hippopotamus (land mammal)

i. Both have multi-chambered stomachsii. Both nurse under water

iii. Both lack full body hair