Fossils Flashcards
what is paleoecology?
understanding fossil species in their environments
i. interpretation
ii. life cycles
iii. paleo and evolution: biostratigraphy
iv. bench mark for today’s systems!
whats taphonomy?
what happens between death and fossilization (DECAY)
what is comparative anatomy and examples of it
finding bones and comparing them to organisms we have today.
george CUVIERS idea when people brought him mammoth bones - looked like elephant bones!
came up with the idea of extinction
fragments can tell us what a whole organism would have looked like (tooth to tiger)
some are obvious and some look nothing like organisms we have today (hallucigenia)
what is sexual/developmental/environmental factors?
things that look different even if theyre from the same species . can be sexual dimorphism
think: human beings!
i. e. ostracods: thought to be different species but their size is sporadic and changes quickly so that they look like they are “clusters” but are actually a line of growing organisms.
what are interactions between organisms?
mutualism: +/+ chinoid and platyceras (free meal and waste disposal)
commensalism: +/0 brachopod that spreads out to keep afloat on sediments and the worm that lives on it
parasitism: galls on chrinoid stems that parasites would live in
predation: mosasaur and the placenticeras
what is the story between the mosasaurus and the placeticeras?
the mosa is a big boy ocean swimmer that eats places. its an ambush predator when its small
the places. is a fast swimmer, siphening water and then using it as a jet stream, and using gas filled chambers to change its buoyancy.
the mosa would bite it first from behind (puncturing gas chambers) and then swim around and lazily suck it out of its shell like calamari
what are the limiting factors when talking about biological distribution in fossils? “why do we find them here’
i. water turbulence (i.e. Zieglar and Brachiopod work: fossil assemblages specifically track sea level)
ii. nature of the substance (what do they live in? Borings and trace fossils of thalessenoides)
iii. oxygen, temperature, salinety
what is the paleoenvironment?
the mode of life! the biases we face in the fossil record.
where you are matters (marine vs. land)
best fossilization is when you are covered by sedimetns
what is benthic vs netktonic and planktonic?
benthic (on surface of sea (on the ground/seafloor))
- epifaunal: on the floor
- infaunal: IN the floor
nektonic: swimming
planktonic: floating!
what is necrolysis?
the decay that happens after death
what influences necrolysis?
a) supply of oxygen (i.e. in swamps, oxygen at the bottom is scarce, so fewer organisms live down there and fewer microbes) when its warm out, the top layer forms a “cap” and prevents circulation of oxygen down below
b) ph extremees (i.e. lindow man: leather skin and no bones from high acidity)
c) nature of organic carbon (high in volitlies: fats/muslces: fast decay, low in volitiles: cellulose): slow decay
what is biostratinomy? what are the types?
not biostratigraphy!!!
how you have been moved after death
- life assemblage (you havent moved)
- death assemblage indigenous (you moved within your own region
- death assemblage exotic (you moved out of your native region
- remanie: from other strata you have displaced yourself AFTER fossilization has occured -reworked into another rock
what is the burgess shale?
a place where turbidity currents bring life in the shallows down to be buried in deep sediements
also: part of the cambrian period, rapid burial occurs and its low in oxygen!
what contributes to fossilization?
a) flattening (layers of sediments squish you)
b) diagenesis (chemical process of transferring sediment to rock) i.e. calcite’s 3 ice cream flavours !!
i. aragonite (internals lost)
ii. hi mg calcite (moderate recovery)
iii. low mg calcite (good recovery)
all turn into low mg calcite rock ^^^
what is lagerstatte?
awesome fossil preservations :))
- burgess shale: cambrian period
- rhynie chert: devonian period: silica rich water, gyzers that coat plants in mineral mater (fine)
- santana formation: crestaceous, phosphate ground water, gives early replacement of materials
- solnhofen limestone: jurrassic: saline anoxic lagoons and fine carbonate sediments (super salty and low in oxygen)
