Download Fossil Evidence

Fossil Evidence
Palaeontology
Palaeontology is the study of __________.
Fossil
A fossil is any sort of ________ of an ________ that lived in a past ___________.
In order for fossils to form, there must be a way to _________ the dead remains of
animals and plants for a time so that they do not _________ completely. The most
common way that this occurs is on the bottom of bodies of __________.
When an animal or plant dies and falls into the water, ___________ sometimes cover
up the remains quickly. The layers of sediment form a _________________ to slow
the process of decay. Over thousands of years, the sediments around the remains
harden into _______. The dead animal or plant remains eventually decay leaving an
___________ inside the sedimentary rock. __________ filter down into this space
and harden into rock, forming a shape just like the __________ or _______. This
process is called ________________. The mineral remains are called _______.
Sometimes there are no minerals that filter down into the empty space in the rock.
The _______ that is left is called an _________. Some common fossil imprints are
dinosaur tracks, which are formed when the large animals left their tracks on the
bottom of shallow seas or rivers.
There are other ways that fossils can be preserved. Many animals have been found
preserved in ____ in Siberia. Freezing preserves a fossil of the highest quality. It
preserves the organism with little alteration to the ___________________. Other
fossils, especially insects, are found imbedded in _______ (a sticky sap from trees
that covers the insects and then hardens).
There are four main types of fossils:
1. Whole Animal/Plant
 Preservation of soft and hard body parts
 Very rare
 Insects entombed in amber (preserved so well, to be studied as though they
had just died)
 Frozen Mammoth carcass and human remains (even after 40 000 years)
2. Petrifaction/Replaced Remains
 Remains of the organism are turned to stone
 Organic substances (soft parts) decay, but water containing
Minerals soak into the cavities and pores of hard structures (bones, shells,
eggs etc…)
 Water slowly dissolves original hard parts
3. Imprints
 Outlines of leaves, feathers, footprints etc…
 Carbon print – transfer of atoms to rock (painting a picture)
 Significance of footprints: depth, size and distance between provide
information about weight, length and bone structure
4.
Mould/Casts
 Living organism is buried in mud/clay, which eventually hardens
 Body dissolves away, leaving a cavity within the hard material
 Cavity is filled with rock in the shape of the original creature
The __________ reveals a history of ____ on Earth and shows the kind of organism
that were alive in the _____. The millions of species on Earth today are only a small
fraction of the species that have ever lived. In fact, it is estimated that ____ of all
species that have ever lived are now ____________.
One of the largest collections of fossils unearthed is in the _____________ – a rich
fossil bed in the Rocky Mountains of Yoho National Park, ______________, shows a
time (about ____________ years ago during the _________ period) in which a
stunning burst of ____________ occurred. A large number of the fossils are unlike
anything in our modern oceans.
Fossils from more recent geological periods are much more _______ to species alive
today. A fact that supports the idea that life has _______ over time. Species that
were alive long ago have had a longer time to __________.