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