changes in biodiversity over time Flashcards
steps in fossilisation
organism dies and is rapidly buried in sediment
oxygen poor and alkaline conditions contribute
either minerals in surrounding rock enter the hard tissues, forming mineralised fossils, or organism decays, leaving a mould in the rock.
when did life first form
around 3.7 billion years ago
what eon did prokaryotes arise
archean
when was the great oxygenation event and what happened
2.4 billion years ago (beggining of the proterozoic eon), occurred when bacteria in the oceans evolved the ability to photosynthesise, and oxygen began accumulating in the atmosphere, killing off obligate anaerobes
what are obligate anaerobes
microorganisms that are killed by normal atmospheric concentrations of oxygen
when did eukaryotic and multicellular organisms arise
Proterozoic eon
when did animals become terrestrial
around 400 mya
what was the period called where organisms rapidly began to diversify
the Cambrian explosion
examples of organism from the Cambrian explosion
trilobites and brachiopods
two types of dating
relative and absolute
what is the principle of superposition
rocks at the top layers are younger, while deeper rock are older (used for relative dating)
what is an index fossil
fossils used to define and identify geologic period
requirements for an index fossil
must be widely distributed, abundant, distinctive, and must have existed for a short and know period of time
methods of absolute dating
radiometric dating (carbon 14 - nitrogen 14, and potassium 40 - argon 40) and electron spin resonance
paleontology is the study of
ancient life represented by fossils
define fossil
the preserved remains, impressions or traces of a once living organism
types of fossils
mineralised, impression/trace, mould, cast and biosignature
what is a mineralised fossil
when minerals from rocks surrounding fossil replace the organic material of the fossil over time
what is an impression fossil
when a structure leaves an imprint in soft earth, which hardens and forms a fossil in the shape of the original object
what are mould/cast fossils
mould is when the fossil decays and leaves an impression in its shape, while a cast fossil is when something fills this mould to form the shape of the organism
what is a biosignature
chemical signs preserved in rocks that are inferred to be cellular (or the the product of metabolic activities)
what is biogeography
study of the distribution of organisms, can be used to find patterns
what is structural morphology
the study of the body structures and features in organisms
homologous features
features between organisms that have different functions but similar structure
analogous feature
have similar functions but different structures (such as wings)
developmental biology
studies how an organism grows and develops
convergent evolution
when similar features evolve independently in unrelated organisms
divergent evolution
when 2 related organisms become more different over time
adaptive radiation
divergent evolution of a large number of species within a relatively short period of time, from a common ancestor
coevolution
when 2 species evolve together in response to selection pressures (such as flowers and bees)
background extinction
the average rate of natural loss of species
mass extinction
large scale extinctions following a disruptive change to global climate
angiosperms are:
flowering plants
what is the term used to describe the first terrestrial animals and all of their descendants
tetrapods
vestigial structure
homologous structures that were once used in ancestral species, but due to disuse evolve to become smaller and weaker over time
how far back can carbon dating be used
50000 years
which is the correct order:
- angiosperms formed
- terrestrial life formed
- first multicellular organism
- mammals formed
3,2,4,1
