After midterm Flashcards
French developments
George Cuvier and Alexander brongniart developed ideas of faunal succession
Who was the first person to go beyond faunal succession and develop a modern concept of biostrigraphy?
Alcide dorbigny
What did dorbigny study?
Studied the Jurassic fossils and strata in southern France
Albert Oppel
Completed the modernization of bio stratigraphy
What makes a good biostratigraphic indicator fossil?
Distinctive Abundant Widespread geological distribution Not facies specific Rapid evolution Short temporal range
Reasons why local first and last appearance data isn’t globl
Biogeopgraphic: all species are geographic in origin, may immigrate to other places, suffer local extinction
Preservation
Facies specificity
Uncomformites: no rocks of that age in local sections
Classification of grace fossils
Ethnologic or taxonomic
Ethologic
Trace fossils are primarily evidence of animal behaviour
Seilacher established a small number of ethologic categories
Categories of ethologics
Resting trace: cubichnia Locomotion trace: Repichnia Grazing trace: pascichnia Feeding traces: Fodinichnia Dwelling traces: domichnia Traps/farming traces: agrichnia Escape traces: Fugichnia Equilibrium traces: equilibrichnia Predation traces: praedichnia Nesting traces: calichnia Fixation/ anchoring traces: fixichnia Death traces: mortichnia
Bio stratigraphy
The art and science of telling time from rocks
Based on faunal succession which was first discovered by William smith
Ichnofacies
Trace fossil association that recurs throughout geologic time in response to a set of paleoenvironmental conditions
Food resource paradigm
Limiting factor of distribution of trace making organisms in shallow marine water
Brackish water trace fossil model
- Reduced diversity of trace fossils in many cases mono specific
- Reduced size of trace fossils compared to their fully marine counterparts
- Predominance of simple trace fossils
- Sparse bioturbation
Ediacaran kimberella
In Russia probably a mollusk
Graphic correlation
Quantitative method of biostratigraphy developed by Alan shaw. Works by correlating multiple stratigraphic sections
If correlation is 45 degrees then sections had identical fossil distribution and rock accumulation
If different then one section had sediment accumulating faster then the other section
Biostratigraphic resolution
Ideally when using biostrigraphy for correlation we would like to do so with the greatest detail. Subdivide rocks into shorter zones this allows us to discriminate between events that happen closer together in time
Precision
+ or - error of an age
Dual biostratigraphy
Attempts to take in the spatial distribution of fossils as well as the temporal distribution
Bio facies
Biotic stratigraphic unit of environmental significance. How these are identified is you look at the different genera in your fossil collection
Paleoecology
Study of the interactions of fossils with each other and with the environment they lived in the geological past
Paleoautecology
Relationships of individual organisms to their environment
Palesynecology
Relationships of groups of organisms to each other and to their environment
Information potential
Life habits of extinct organisms
Nature of ancient communities and ecosystems
Paleoenvironmental reconstruction
Sea level changes
Pelagic
Live in the water column
Can be subdivided into plankton (floaters) and nekton (swimmers)
Plankton
Usually passive and goes where the current takes them
Plant plankton (diatoms) are called phytoplankton and are mostly microscopic
Animal plankton are called zooplankton and are mostly microscopic
Include foraminifera and jellyfish
Nekton
Mostly invertebrates like fish but can also be vertebrates like Cephalopods
Benthos
Epifauna (animals)
Epiflora (plants)
Infauna (living in and moving through the sediment)
Sessile
Stay in one place
Mobile
Move around or in the sea floor
Primary producers
Autotrophs
Manufacture their own food
Consumed by primary consumers which are usually suspension feeders
Secondary consumers
Consumer primary consumers so are predators
Tertiary consumers
Consume secondary consumers
Transformers and decomposers
Break down the dead that haven’t been consumed into organic material that can be recycled
Tiering
Prominent in rain forests. Competition for suspension food leads suspension feeders to grow taller then their substrate
K strategists
Slow reproductive and growth rates
Large bodies
Long lived
R strategists
Fast reproductive and growth rates
Small bodies
Short life spans
Limiting factors in species distribution
Light Food supply Oxygen Salinity Energy Temperature Substrate Water depth
Light
Promotes photosynthesis
Limiting factor in deep sea
Food supply
Food greatest at photic zone or near shorelines
Limiting factor in deep marine environments
Oxygen
Increase in need of oxygen with increase in size almost all metazoans need oxygen
Limiting factor on continental slope and in stagnant zones in the deep ocean
Salinity
Lower diversity with higher salinity
Limiting factor in hypersaline and brackish environments
Energy
High energy conditions promote suspension feeders because the wave currents keep organic material suspended within the water
Limiting factor in subtidal and coastal areas
Temperature
Most fish don’t regulate their body temperature but are the same temperature as the water
Limiting factor for nearshore environments where the water is subject to seasonal changes in temp
Substrate
Composition, mobility, and degree of consolidation play a major role in benthic Faunas
Water depth
Effects experienced through increase in hydrostatic pressure
Limiting factor in deep marine environments
How do trace fossils differ from body fossils
- Trace fossils usually represent evidence of behaviour
- The same organism may produce more then one ichnotaxon
- Same ichnotaxon may be produced by more then one organism
- Multiple arichtects may produce a single structure
- Producers are usually soft bodied animals that don’t preserve as well
- Trace fossils are commonly preserved in rock units that are otherwise unfossiliferous
- The same biogenic structure may be differentially preserved in various substrates
- Trace fossils commonly have long stratigraphic ranges
- Trace fossils commonly have narrow environmental ranges
- Trace fossils are rarely transported
Ichnology
Study of traces produced by organisms on or within a substrate
Cambrian explosion
Raid diversification
Origin of many body plans
Fauna: Arthropods trilobites
But also echinoderms brachiopods and molluscs
Cambrian explosion simple artifact or real event?
Physical changes in the environment
Biological changes
Reflecting intrinsic evolutionary change
