Changes In Biodiversity Overtime Flashcards
Archaean eon
Life first appeared on earth. Earth’s first life forms with prokaryotes. Stromatolites.
Proterozoic eon
Eukaryotes appeared. Algae. Earliest evidence of multicellular animals called ediacaran fauna.
Cambrian period
Dramatic increase in number of complex marine life forms.
Ordovician period
The emergence of first vetebrates.
Silurian period
Air- breathing animals first emerged (anthropoids)
Devonian period
Jawed marine fishes first evolved, along with armoured placoderms, ray-finned and lobe-finned and sharks.
Carboniferous period
Evolution of reptiles and amphibian-like ancestors. Formation of forests.
Permian period
Pangea was formed, reptiles diversified, and there was a mass extinction of 90% of the species in that time.
Mesozoic era
Triassic period,Jurassic period and the Cretaceous period.
Triassic period
Reptiles dominant and have diversified into the first dinosaurs, crocodiles and pterosaurs.
Jurassic period
Mammals begun to diversify and birds.
Cretaceous period
Small marsupials and insectivores are abundant. First flowering plants (angiosperms).
Paleogene period
Placental mammals, birds abundant, primates evolved.
Neogene period
First homo species (h. Habillis) evolved.
Quaternary period
Change in environment from cold,dry glacial period to wetter and warmer interglacial period. Megafauna existed and then became extinct.
Palaeontology
Study of fossils.
Fossilisation process
- Death of an organism.
- Decay of soft tissues and burial.
- Sediment accumulation.
- Uplift and erosion and exposure.
- Discovery.
Types of fossils
- impression
- mineralised
- trace fossils
- mummified
Relative dating
Is based of stratigraphy (placed on position of fossil with the strata of rock with the use of index fossils).
Radiometric methods in absolute dating
Measures the proportions of naturally occurring isotopes (carbon-14 to carbon-12).
Methods in absolute dating
- thhermoluminescene
- radiometric methods
- electron spin resonance
Information from examining fossils
- appearance
- structure of the organism
- behaviour
Transitional fossils
Any fossils that show intermediate traits and evidence of major change.
Biogeography
Study of the distribution of organisms.
Homologous features
Fundamental similarity of features of different species due to a common ancestor.
Analogous structures
Features of different species have the same function but have evolved separately due to similar selection pressures.
Vestigial structures
A reduced structure with no real function but acts as evidence of emergence from a species in which has use of the structure.
Development biology
Field of biology that studies the process of growth and development of a zygote to an adult.
Natural selection
Process by which individuals that have certain inherited traits are better suited to their environment and thus more likely to survive and produce more offspring
Coevolution
Occurs when two interacting species evolve together in a reciprocal response to selection pressures.
Mass extinction
Large-scale extinctions
Divergent evolution
Spitting of an ancestral species into two different species.
Convergent evolution
Independent development of analogous features in unrelated species.
Adaptive radiation
From of divergent evolution in which a common ancestor gives rise to a number of new species rapidly.
