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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 __________.