Fossils and Evolution

By Lauren Raynault

1/7/09

Science, Mr. Civita

WHAT IS ATRANSITIONAL FOSSIL?

TRANSITIONAL FOSSIL- Fossilized remains that illustrate an evolutionary transition- Evolutionary bridge between two groups- These fossils are the strongest evidence of Darwin’s theory of evolution

Example:Dinosaur to Bird

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WHAT IS ANARCHAEOPTERYX?

ARCHAEOPTERYX (ancient wing)

Some Facts:- A dinosaur- Dates back to 150 million years ago- An example of a transitional fossil because it is believed to be an intermediate between dinosaur and bird.- The archaeopteryx is closer to coelurosaurian (Suh-Loor-Oh-Saur) theropods, Velociraptor is an example.

ARCHAEOPTERYX (image)

ARCHAEOPTERYX (ancient wing)-

Characteristics:The Archaeopteryx shows characteristics from both dinosaur and bird

Archaeopteryx Dinosaur

√ Teeth

√ Claws (on wings)

√ Breastbones

√ Belly ribs

√ Long bony tails

Archaeopteryx Birds

√ Feathers

√ Wings

√ Wishbone

√ Reduced fingers

√ Light built body

√ Hollow bones

ARCHAEOPTERYX (ancient wing)

Some More Facts:- The first found fossil was a feather found in Jurassic limestone in southern Germany (1860)- Complete skeleton found (1862)- There have only been eight specimen found and the feather

Why do you think there have only been a few specimen found?

Bird fossils are more difficult to find because their bones are hallow and fragile.

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ARCHAEOPTERYX Fossil

OTHER EXAMPLES OF

TRANSITIONAL FOSSILS

Tiktaalik

Some Facts:- Transitional fossil from fish to land animals, or in other words, tetra pod to fish (fishapod). -375 million years old. - Fossil found in Canadian artic (2004)Tiktaalik Fish

√ Fins

√ Gills

√ Scales

Tiktaalik Land Animal (Tetrapod)

√ Flat body

√ Eyes on the top of skull (like a crocodile)

√ A functional neck (which fish lack)

√ Ribs (support body and aid breathing)

Acanthostega

Some Facts:- Transitional fossil from fish to land animals-400 million years old -Devonian period

Land Animal Acanthostega Fish

Lungs √ Internal Gills

“Tiny fingers” √ Paddle-like limbs

Bony legs arms and digits

√ Fish-like tail

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Acanthostega model

Acanthostega skeleton model

Acanthostega finger model

Acanthostega

Do you think these changes happened in the water or on land?

It is believed that the changes happened in water. The purpose of these changes was to help navigate through swampy wetlands, not to move onto land, but later proved to be a survival advantage on land.

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Water

ARE TRANSITIONAL FOSSILS THE ONLY WAY TO SHOW EVOLUTION?

NO!NO!

Non-transitional fossil evolution:

An example: Horses- There are Fossils that have been found of early horses. - These can be compared with fossils of horses up until today.

Does anyone know what some early horses were like?

One early horse from 60 million years ago, was called Hyracotheriun

This horse was small and dog-like and lived in forests.

Early Horses and Present-day Horse