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What’s a fossil and how are they formed?

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Presentation on theme: "What’s a fossil and how are they formed?"— Presentation transcript:

1 What’s a fossil and how are they formed?
Fossilization What’s a fossil and how are they formed?

2 I. Fossilization A. The four types of fossils
1. mold fossils=a fossilized impression made in the substrate - a negative image of the organism.

3 2. cast fossils =formed when a mold is filled in.

4 3. trace fossils = fossilized nests,
gastroliths, burrows, footprints, etc. 1. Signs that a living thing was present 4. true form fossils = fossils of the actual animal or an animal part

5 B. True form and trace fossils
1. True form fossils a. Commonly come from hard parts of the body b. Bones-The fossilized bones of a tremendous number of species of dinosaurs have been found since 1818, when the first dinosaur bone was discovered.

6 c. Teeth and Claws- a broken tooth of a carnivore is found with another dinosaur's bones, especially those of herbivores. Lots of fossilized teeth have been found, including those of Albertosaurus and Iguanodon

7 d. Eggs Embryos and Nests-
1. first found in France in 1869 2. over 200 sites 3. nests and clutches of eggs tells much about dinosaurs' nurturing behavior

8 e. Skin 1. had thick, bumpy skin 2. A 12-year-old girl discovered a T. rex's bumpy skin imprint f. Muscles, Tendons, Organs, Blood Vessels 1. dinosaur "mummies", fossilized imprints of dinosaur skin and other features 2. extremely rare because these soft tissues usually decay

9 2. Trace Fossils a. Trackways (sets of footprints) - usually made in mud or fine sand sites

10 Fossil footprints have yielded information about:
* Speed and length of stride * two or four legs * stalking behavior * existence of dinosaur herds and stampedes * how the tail is carried

11 b. Toothmarks=generally appear on
bones c. Gizzard Rocks = Gastroliths - swallowed stones to help grind their food - Coprolite = fossilized feces * up to 40 cm (16 inches) in diameter

12 d. Burrows and Nests - considered trace fossils of the animal that laid them


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