3 Types of Fossils

Cast – a rocklike model of an organism, formed when a mold fills in and hardens

Mold – imprint in rock that is the shape of an organism

Imprint – forms when the body of an organism deteriorates leaving a Carbon outline in the rock

Law of Superposition – states that layers of rock or soil are deposited on top of each other.

The lowest stratum (layer) will be the oldest

The position within the rock will provide a Relative Age

Extinct – No members of a species remain alive anywhere.

Extirpated – All members of a species are gone from an area but exist elsewhere.

Mass Extinctions – Brief periods of time in which large numbers of species disappeared.

Biogeography – the study of the distribution of fossils and living organisms

To Summarize the evidence of evolution observed in living organisms.

Compare Lamark’s theory to the theory proposed by Darwin

Discuss Darwin’s theory of evolution and the evidence that caused the theory.

First Systematic approach to evolution.

French Scientist - 1809

The inheritance of acquired characteristics.

Salamanders that did not use their legs gave birth to Salamanders without legs.

No Experimental evidence or Observations.

Offspring are born without legs.

British Scientist

Disliked School - Preferred bird watching and collecting insects to studying.

Sent to medical school in Scotland at the age of 16.

Found Medicine to be “intolerably dull”

Became interested in attending Natural History Lectures.

Sent to the University at Cambridge, England in 1827 to study for the clergy.

“time was wasted as far as academical studies were concerned”

Developed a friendship with the professor of Botany, John S. Henslow.

Acquired increased knowledge of the natural world.

In 1831 Henslow recommended Darwin as the naturalist on the ship HMS Beagle.

The HMS Beagle embarked on a 5 year mapping and collecting expedition to South America and the South Pacific.

Darwin made collections of specimens, made observations and kept careful records of anything significant.

Darwin read “Principles of Geology” by Charles Lyell

This caused him to develop an interest in landforms.

Darwin suffered from seasickness so he often talked the captain into letting him off of the ship so he could walk through uncharted country.

While on these hikes, Darwin would make collections of plants, animals and fossils.

In Chile Darwin observed fossils of Marine organisms at about 4300m.

This made him realize that Lyell was right and Landforms do change over time.

Darwin took Lyell’s theory one step further and hypothesized that as the land forms change, animals would need to change to adapt to the new habitat.

When Darwin returned to the ‘Beagle’ he catalogued and sorted his collected specimens.

The ‘Beagle’ returned to England in 1836.

Darwin's collections were praised and sent to experts.

The Ornithologist noticed 13 species of Finch collected by Darwin were all closely related.

Other experts noticed the fossils collected resembled some of the live specimens.

In 1837 Darwin began his first notebook on evolution.

This notebook contained facts from fossils, homologous and vestigial organs and structures, embryological development, plant and animal breeders and experiments in breeding and seed dispersal.

In 1838 Darwin read “Essay on the Principle of Population” written by a British Economist, Thomas Malthus.

In this book Malthus states that if unchecked a human population will double every 25 years. Resources

cannot and do not increase at this rate so humans are thrust into an intense

“Struggle For Survival” competing for limited resources. Darwin combined

this idea of competition with his observations.

Darwin gathered evidence for evolution for nearly 20 years. Between 1842-

1844 he wrote a 230 page essay summarizing his theory and giving evidence. In the 1850’s he began

working on a detailed, multivolume book to present his theory to the

Scientific community.

Darwin's theory of Evolution

1)Variation exists among individuals of a species.

2) Scarcity of resources will lead to competition.

3) Individuals with advantageous variations will survive and reproduce.

1858 – Alfred Russel Wallace – While living on the Malay

Archipelago in the Pacific Ocean. Formed an independent theory of evolution and sent it to Darwin.

Darwin's and Russel’s theories were presented jointly at a scientific

conference, but “excited very little attention”

In 1859 Darwin published “The Origin of Species”. The 1st printing sold out in

one day. Today Darwin's theory is a unifying theme for all of Biology.

4 items that are examined in living organisms to find evidence of evolution

1) Common Ancestry

2) Structure

3) Biochemistry

4) Embryological Development

Common Ancestry

Structure

Complex Compounds that are unlikely to have evolved independently in different organisms.

Examples: Cytochrome c (essential for aerobic respiration) and Blood Proteins.

Similarities and Differences can suggest the degree of relatedness.

Embryos of species that develop almost identically infer genetic similarities.

Pg. 224 Figure 15-5