types of fossilization

replacement

The original shell or bone dissolves and is replaced by a different mineral. For example, calcite shells may be replaced by dolomite, quartz, or pyrite. If a fossil that has been replace by quartz is surrounded by a calcite matrix, mildly acidic water may dissolve the calcite and leave behind an exquisitely preserved quartz fossil.

compression

Some fossils form when their remains are compressed by high pressure, leaving behind a dark imprint. Compression is most common for fossils of leaves and ferns, but can occur with other organisms. Click image to the left or use the URL below. URL: Click image to the left or use the URL below. URL:

permineralization

The most common method of fossilization is permineralization. After a bone, wood fragment, or shell is buried in sediment, mineral-rich water moves through the sediment. This water deposits minerals into empty spaces and Five types of fossils: (a) insect preserved in amber, (b) petrified wood (permineralization), (c) cast and mold of a clam shell, (d) pyritized ammonite, and (e) compression fossil of a fern. produces a fossil. Fossil dinosaur bones, petrified wood, and many marine fossils were formed by permineralization.

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molds and casts

When the original bone or shell dissolves and leaves behind an empty space in the shape of the material, the depression is called a mold. The space is later filled with other sediments to form a matching cast within the mold that is the shape of the original organism or part. Many mollusks (clams, snails, octopi, and squid) are found as molds and casts because their shells dissolve easily.

types of fossilization

Most fossils are preserved by one of five processes outlined below (Figure 1.1):

preserved remains

Most uncommon is the preservation of soft-tissue original material. Insects have been preserved perfectly in amber, which is ancient tree sap. Mammoths and a Neanderthal hunter were frozen in glaciers, allowing scientists the rare opportunity to examine their skin, hair, and organs. Scientists collect DNA from these remains and compare the DNA sequences to those of modern counterparts.

instructional diagrams

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questions

when insects are fossilized, it is usually in

a) glacial ice

b) soft sediment

c) volcanic ash

-->  d) amber

a fossil frozen into glacial ice may include

a) only bones and teeth.

b) bones and teeth, plus skin and hair.

-->  c) bones, teeth, skin, hair, plus dna.

d) bones, teeth, skin, hair, dna, plus liquid blood.

when water deposits minerals into empty spaces to produce a fossil, it is called

a) petrified wood.

-->  b) permineralization.

c) replacement.

d) compression.

a bone dissolves and leaves behind a space called a _. that space is filled with other materials to form a _ in the shape of the original organism.

-->  a) mold, cast

b) cast, mold

c) trace fossil, body fossil

d) body fossil, trace fossil

permineralization is the most common method of fossilization.

-->  a) true

b) false

a large mammal fossil that is complete must have formed in exceptional circumstances.

-->  a) true

b) false

when the original shell or bone dissolves and the material is substituted for by a different mineral, this is called

-->  a) replacement

b) molds and casts

c) permineralization

d) none of the above

the most common way that fossil leaves are made is by

a) replacement

b) amber

-->  c) compression

d) permineralization

there are many fossils of bacteria and jellyfish.

a) true

-->  b) false

to create petrified wood

a) a piece of wood is compressed by the weight of overlying sediments.

b) a piece of wood dissolves and the hole is filled with sediments that resemble it.

c) a piece of wood dissolves and is replaced by a mineral.

-->  d) a buried piece of wood is filled with minerals that are deposited into the empty spaces.

diagram questions

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