Unit 4 10B: Fossils Flashcards
Fossil
The remains or traces of a preexisting life form
Fossil record
A record of organisms that once lived through geological time, documented by fossils
Palaeontologist
a scientist who studies fossils
Trace Fossil
Fossilised signs or remains of an organism’s activity, e.g. tracks
Petrification
The replacement of an organism’s organic matter with minerals
Mould fossil
An impression that forms from the decay of the organism within a rock
Cast fossil
Fossil formed when an organism decays, leaving an impression, which fills with minerals, resulting in a 3D object of the organism’s external surface
Sedimentary rock
A type of rock that is formed from the accumulation of sediment into layers
Metamorphic rock
A type of rock that arises from the transformation of existing rocks
Sediment
weathering and erosion
Naturally occurring material that is formed through the effects of weathering and erosion
Transitional fossil
A hybrid fossil that shows traits of both an ancestral group and a descendant group, allowing the comparison of structures to determine relatedness
Absolute dating
Determines the actual age of a specimen being analysed
Relative dating
Determines the age of a specimen by comparing its placement with that of other fossils or the rock layers it is found in
Stratigraphy
A branch of geology that uses th principle of rock succession to examine the order and position of strata in connection with fossilised remains
Index fossil
A fossil of organisms that were widespread but only existed for a short period of time, that is used to date and correlate that strata within which it is found
Radiometric dating
A method of absolute dating that uses the concept of the decay of an isotope into its stable daughter isotope at a known rate to determine the age of a geological sample
Isotope
Variant of an element that differes in the number of neutrons in the nucleus
Half-life
The time taken for 50% of an unstable parent isotope to decay into its corresponding stable daughter isotope
What is the half life of Carbon 14
5730 years
Faunal Succession
Is a techinque used to determine the relative age of fossils, through the basis that the deeper the rock strata the older the corresponding fossils
Fossilisation process
1)Organism dies and body is rapidly buried in sediment
2)Soft tissue decomposes
3)Compression increases as layers of sediment form above the organism
4)Original hard structures become porous, minerals from the surrounding sediment seep in and replace to form the fossil.
5)Sediment i hardened into rock from pressure
6)Rock may become eroded, exposing the fossil.
