Palaeobiology Yr 1 Flashcards
What is taphonomy?
The postmortem processes and preservation of a fossil that aid in listing the sequence of events that occurred since the death of the organism.
Whats a body fossil?
Partial or complete remains of an organism
Factors controlling decay
Oxygen, pH, temperature
Whats a trace fossil?
Provide ecological anatomical and behavioural information
name the 3 minerals soft tissue can be preserved in?
Pyrite, phosphate, carbonate
What 3 common minerals in fossils?
Calcite, Apatite, Silica
mineralization of soft tissue depends on
rate of burial, organic content, salinity.
What could happen after hard parts are preserved
Unaltered, Recrystalization,Material removed/added
Each mineral relates to an organism give some examples
Aragonite in bivalves and brachiopods, Apatite in worms + conodonts
Name processes after death/burial
- Disarticulation
- Corrosion
- Abrasion
- Fragmentation
- bioerosion
Post Burial - Flattening
- Diagenesis
What processes could occur if material is removed
- Partially
- All Removed - leads to mould and cast
What processes could occur if material is added
- molecular level
- infill (shell) - Internal mould and cast
Factors effecting preservation potential
- Anatomical - hard parts?
- Biological - common animals more likely to be preserved + rate of death
- Ecological - Where they live?
- Sedimentary - site of deposition/erosion
- Preservation - Acidity/chemical conditions + transport
- Tectonic/metamorphic - high pressure/baked
- Anoxic (mineral enhancement) - decay can occur if FeO2/nitrates present
- Human Filters - has to be found
Types of plant preservation:
Petrification, Coalified compression, cementation.
How did life originate
fusion of organic molecules in the first few Ga after Earth was formed.
RNA?
A precursor to living cells, self replicating and can act as a gene/enzyme. If RNA replicase came together with a lipid and function as a proto cell - membrane keeps it together allowing the production of lipids. - cell evolution.
What date did cyanobacteria generate enough O2 to form an atmosphere?
2.4Ga - increase around 0.8 - 0.6Ga
Name the 3 domains
Bacteria, Archaea, Eucarya
When were the earliest fossils
Bacteria (3.2Ga) - stromatolites
Cellular fossils are found in the fossil record dating?
2.5Ga
What is a biomarker?
a naturally occurring molecule / characteristic by which an organism can be identified. - lipids help cyanobacteria and eukaryotes 2.7Ga
Oldest eukaryotes date?
1.9Ga with organelles and nucleus
What shows mitosis and meiosis?
Red Algae 1.2Ga, meiosis is specific to sexual reproduction and multi cellular life.
What is the organic model?
Complex replicating molecules, silicate solution with organic interaction, inorganic became organic (NOT much evidence)
Extra Terrestrial origin:
Seeded from meteorites, specific organic compounds found on carbonaceous chondrites.
Primordial soup - highly radiating UV rays from the sun provided energy
Bio-Chemical Theory:
By Oparin + Haldone, Miller-Urey Experiment proved there are gene + enzymes (60’s) and that a membrane cant be produced with RNA
Hydrothermal model
Energy from oxidation of hot reduced sulfur compounds - Last universal common ancestor (LUCA) was a hyperthermophile 1.5Ga.
What are constraints for the theory’s of the origin of life?
The cosmic bombardment is recorded on the moon which can disprove extra terrestrial theories. Micro fossil evidence as early forms are debatable.
Name the features of a prokaryotic cell:
- No nucleus, just loose DNA
- Ribosomes
- Flagellum
- cell membrane
Name the features of a Eukaryotic cell e.g. plant cell:
- Nucleus containing chromosomes
- mitochondria
- chloroplasts
- endoplasmic recticulum + ribosomes
- cell membrane
- cell wall
- vacuole
Definition of endosymbiosis:
The idea that eukaryotic cells fromed from the fusing of different prokaryotic cells to create a nucleus and organelles.
- mitochondria and chloroplasts are thought to have evolved from bacteria living in large cells.
How did the first multi cellular organisms form?
They formed from eukaryotes, the initial cells were asexual and split via mitosis. When sexual reproduction evolved cells used gametes via meiosis. - Bangiomorpha (1.2Ga)
what did the introduction of sexual reproduction allow?
Diversification of genetics and therefore adaptation and natural selection.
Name all the categories of the tree of life starting with domain:
(Domain) - Kingdom - Phylum - Class - Order (suborder) - Family - Genus - Species
Name the 5 types of organism:
- Rangeomorph (pattern repeats inside itself, charnia)
- Erniettomorphs (range of tubes from a midpoint, Ediacaran)
- Bilateral forms (anterior/posterior, move, kimberella is the oldest known form - ediacaran, most life)
- Discoidal form (polyphletic,derived from more than one common ancestor)
- Radial form (relation to star fish/sea urchin
State the order of the biochemical theory
- Primitive atmosphere (H2O, N2, H2, CO,H2S.
- small molecules (lipids, sugars, amino acids, purines)
- large molecules (proteins, nucleic acids, polysaccharides)
- Protocells (membrane)
(genetic mechanism) - Prokaryotes
(organelles) - Eukaryotes
- Multi cellular organisms
How many mass extinctions have occurred in the past 542Ma?
5 to 20 depending on where you place the threshold for a classified mass extinction.
Whats the background mass extinction rate?
5 - 10% thats 1 mammal species every 200 yrs, 5000 extant.
- 89 in the past 200 yrs and 169 critically endangered.
What classifies a mass extinction?
- 30% extinct
- Rapid
- broad range of ecologies effected (including micro fossils)
- Worldwide
- Extinction rate»_space; background rate/origination rate
What can happen if the fossil record is incomplete?
It can infer a gradual decline of species over time and misjudgement of events, alternatively if its truncated then it can look like a mass extinction.
Diversity equilibrium:
Extinction rate = Diversification rate
Diversity increase:
Extinction rate < origination rate
Extinction rate > origination rate
Mass extinction occurring, only 3 have elevated rate:
- Ordovician
- P/T
- K/T
Why is it difficult to detect mass extinctions in the fossil record?
Sedimentary record is truncated and unconform strata, it could make fossils look like a mass extinction occurred.
Who was the first to argue organisms went extinct?
Cuvier 1796 using mammoth and elephant jaws difference in morphology.
- mass extinction theory in 80’s
When was the Ordovician extinction event and what occurred during it?
~445Ma.
- turnover of marine fauna (3rd of brachiopods and bryozoans, conodonts, trilobites and graptolites)
- major climate change
- south continent drifted over south pole therefore glaciation radiated north.
When was the Devonian extinction event and what occurred during it?
380 - 360Ma - serveral pulses.
- Cephalopods, armoured fish, trilobites and brachiopods
- change in sea level
- ocean anoxia
When was the Permian extinction event and what occurred during it?
251Ma.
- 50% of families and 96% of species gone
- Siberian trapps released 2000 ton of flood basalt
- CO2 outgassing and methane hydrate in the oceans caused runaway greenhouse effect.
- Ocean anoxia
- insect death
When was the Triassic extinction event and what occurred during it?
200Ma.
- conodonts and marine reptiles, ammonoids, on land crocodylomorphs and large amphibians.
- anoxia (global warming)
- flood basalts in pangae due to unzipping of N.Atlantic
When was the K/T extinction event and what occurred during it?
65Ma.
- Non avian dinosaurs, Ammonites, marine reptiles and pterosaurs.
- Extraterrestrial impact at 180km wide, chicxulub crator in the gulf of mexico
- accelerated by deccan trapps (india) release of flood basalts
What is an apomorphy?
A derived characteristic that is phylogenetically informative
what is a convergence?
a convergence in evolution is when two different species evolve the same characteristics due to the environment they live in. Whales and dolphins both have the same fins (arms).
Whats a Plesiomorphy?
Characters shared by an organism of interest. e.g. sharks and salmon both have fins, therefore is not helpful to sort the phylogeny of sharks as all fish have fins.
What is a synapomorphy
An apomorphy shared by two or more species, A characteristic inherited exclusively from their common ancestor.
Apomorphies help identify:
Clades and monophyletic groups
Whats a monophyletic group?
single origin and include all the descendants of that common ancestor
What are the two types of clade?
Paraphyletic and polyphyletic
What does paraphyletic mean?
Of a group descended from a single common evolutionary ancestor but not including all descendant groups.
What does polyphyletic mean?
Of a group derived from more than one common evolutionary ancestor (therefore not suitable to be in the same taxon)
What is the importance of fossil form?
- Evidence to identify species + wide relations to reconstruct the tree of life.
- Can tell us about behaviour and ecology.
- The study in change of form within a species tells us its evolutionary path.
