Science Focus Topic 8 Notes: Fossils |
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Fossils are preserved impressions in rock that tell us when, where, and how living
organisms lived and behaved millions of years ago.
Types of Fossils
Remains of dead plants and animals that have been protected from scavengers can
become fossilized in a number of ways:
- petrified (rock-like) fossils preserve
the bones of dead animals by using silica
- an outline or impression from the carbon residue on rock surfaces can provide a carbonaceous
film
- original remains may be preserved in tar, amber or peat bogs
- trace fossils are evidence of animal
activity, like worm holes, footprints, and burrows
Dinosaur Finds
(Dinosaur Provincial Park is a world UNESCO Heritage site, where over 36 species
of Dinosaur have be found - nearby, Burgess Shale in B.C. is also renowned because of the rich deposits of fossilized
marine animal soft-body parts)
- Trilobites date back before
the dinosaurs roamed the Earth
- Ammonites are common fossils
found in Alberta
- Oviraptor (when a clutch
of eggs were found with a fossil of this dinosaur, it was thought it was a scavenger, but further evidence indicates
it was likely an overprotective parent)
- Gigantosaurus, found in Argentina
is heavier than Tyrannosaurus Rex, a carnivore.
- Seismosaurus, a huge plant
eater, was found in Mexico (its tail could move faster than the speed of sound)
- Bambiraptor, a dinosaur,
found by a 14 year old boy in Glacier National Park, Montana, may help to provide the link between birds and dinosaurs
Fossil Mould and Cast Formation
An animal dies in mud and gets covered by more sediment. The body dissolves, leaving
a mould, which is then filled with
more sediment and hardens into rock, making a cast of the original animal.
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