TYPES OF FOSSILS -
S.No.
Fossil
Example
Mode of formation
1
Unaltered
(Preservation)
Wooly mammoths, 25,000 years
old, ice in Siberia, mummies, insect.
Whole bodies are found frozen in ice.
2
Altered or
petrified fossils
Bones, shell, teeth, wood etc.
Replacement of organic parts by mineral
deposits is called petrification.
3
Coprolite
Coenozoic mammals
Faecal pellets buried in sediments.
4
Moulds and
Casts
Gastropods (Mullusca)
from Portland
Moulds of hardened and fossilized mud that surround an extinct individual, the burried individuals have been completely destroyed but the moulds retained true
copies of their shape.
5
Impressions
Archaeopteryx feather, leaf
Remains in fine grained sediments on
which organisms died.
6
Imprints
Dinosaur footprints, prints of leaf,
skin, wing etc.
Footprint trails, tract of
organism.
7
Compression
Plants
Main tissues part disappears and only the outer tough parts remains intact covering into rock.