fossils

what are fossils?

they are any preserved trace left by. an organism that lived long ago

what are some examples of a fossils?

bones, shells, teeth, footprints, burrows, faeces or impressions of all or part of an animal or. plant

fossils do not have to be…

part of an organism

what are the two types of fossils?

body and trace fossils

what are some examples of body fossils?

bones, shells, teeth

what are some examples of trace fossils?

footprints, burrows, faeces or impressions of all or part of an animal or plant

what are most common human fossils found?

bones teeth or footprints

why are fossils important?

they allow scientists to determine exactly what extinct species were like.

what does materials associated with the fossils e.g bones tell us?

the rock they were found tin or fossils of other plants and animals nearby allow scientists to develop a picture of the past. for example, what the organisms ate, what other organisms existed at the rime and sometimes what the climate was like.

what do fossils show us?

fossils can show evolutionary sequence of a plant or animal e.g a horse which can be traced through fossil remains from a small creature (not much bigger than. a small dog to horses that we know today

not all remains/ traces can be…

fossilised

the creation of fossils happens so…

rarely, meaning that there are many extinct creatures where there is no fossil record. (considering billions of organisms that have lived the earth, chances of a plant or animal. will be fossilised is very small.)

normally what happens to dead organisms that means there will be no fossil?

normally dead organisms are decayed by micro organisms and therefore. there is no trace of their existence left.

what are the different types of fossilisation?

Permineralisation, preserved remains, holds and casts.

what is permineralisation fossilisation?

after burial in sediment, minerals are deposited into the remains by water. This. slowly infuses the remains with the minerals from the water, petrifying them.

what minerals petrify the fossils and how?

lime or iron oxide, and they are deposited into the pores of the bone, replacing the organic matter that makes up to 35% by weight of the bone.

what does it mean by the bone becoming petrified?

this means that the bone is turned into rock and the details and structure of the bone are preserved.

what kind of fossils become permineralised?

many fossil bones and petrified wood are fossilised this way.

what is the preserved remains way of fossilisation?

it is when the entire organism and its tissues are preserved, for example insects in amber, mammoths in ice and nealothic humans in peat bogs.

what is the molds and casts way of fossilisation?

is when original remains dissolve leaving a space “mold” that is later filled with other sediments as a “cast”. for example imprints of shells or other soft bodied creatures, footprints etc

what are the conditions that need to be met for fossilisation to occur?

the organism must be buried rapidly, to prevent decomposition or destruction of remains as these conditions are most likely not suitable for activity if decay organisms (decomposers)

what are some different things that can happen (in environment) to cause fossilisation?

parts of organisms may becomes fossilised when burned by drifting sand, deposited by rivers, volcanic ash, or in case of more recent humans (a deliberate burial)

what happens if fossils are burried in wet acidic soils?

minerals in the bone are dissolved ad no fossilisation occurs

what happens if an organism is burried in alkaline soils?

this will produce the best fossils because the minerals in the bone will not be dissolved) mineral deposits replace tissues, often lime or iron oxide, are deposited in the pores of the bone, replacing organic matter that makes up approx 35% by weight. of the bone. Therefore the bone becomes petrified

what happens if an organism is buried in a no/ limited oxygen environment?

(e.g in a peat) complete preservation of the soft tissues and bones of the organism may occur (this slows the decomposition of the soft tissues)

where have the fossils of human ancestors been found?

fossils of human ancestors found at the edges of ancient lakes/ river systems, in caves or volcanically active areas. as the organism must be burried rapidly so decomposition is prevented

why are there fossils found at lakes and rivers?

the build up of sediments when flooding occurs or when the water flow slows rapidly.

why are there. fossils found in caves?

because of the limestone, which consists of calcium carbonate. this chemical may be deposited around dead organisms, or the cave roof walls may collapse, covering the bodies of animals.

why are there fossils around volcanic eruptions?

it is unusual for animals to be preserved near volcanic eruption because the heat from the volcanic material destroys the organism. but for e.g east Africa ash falls have preserved fossils of many human ancestors

how are fossils found?

geological processes such as erosion means that fossils will eventually resurface. But more. often fossils are found by excavation of “likely sites”

scientists. refer to an excavation as a…

dig

what are likely sites

places which indicate “digs” will be more successful, e.g surface discoveries of fossil fragments, or evidence of human occupation

what are the different ways fossils can be found?

by chance, on surface. This is an indication of a good place to look for more a “likely site”. and by geological surveys, looking at rock for indicators that it may have been favourable for fossil formation

what is the process of digging for fossils?

area is first surveyed and marked out in sections, small hand tools remove soil gently as to not damage material, soil removed is sieved to catch any fossil parts, (with human fossils) artefacts are often found in association with the fossils, photos are taken at every stage so that detailed studies of positions of uncovered material can be carried out later, each item is carefully labelled and cataloged for prolonged study that follows the excavation of the site.

what are artefacts?

are objects that have been deliberately made by humans e.g stone tools, beads, carvings, charcoal from cooking/ fires, cave paintings

what do the scientists do once the fossils are in the lab?

the. fossil bones arecarfully s scraped clean, broken parts are pieced together, measurements are taken and plaster casts or later molds may be made.