Taphonomy Flashcards
Taphonomy definition
the process of fossilization
taphonomy depends on
the process of decay and decomposition
transportaion of fossils
potential of fossils
burial of reemains
diagenesis of remains
the process by which sediment becomes a rock
good fossil conditions
environment with little oycgen, ex peat
no microbial decay
taphonomic informationq
life position, clustering
• articulation, breakage, sorting, orientation
• population structure - age and size-frequency
sedimentology
trace fossils
valuable because they give contextual information at the time bcs other thing (shell bone) could have been transported
sorted population
transporting or sorting populations (they then are all the same size)
Types of unaltered remians
ossils that didn’t change much, virtually perfect preservation only mini decay
could get DNA from fossils
rare
through freezing, mummification, amber
the oldest ice usually less than 1mio, maybe 2mio years old
Unaltered Remains: ambeer
tree resin
rapidly buries animal, cuts off oxygen, stops decomposition → perfect preservations
however rather small
insects don’t have great fossil record except for amber deposits
extreme good quality
Altered Fossils are
petrification, have been changed
Perminerealization (altereed fossils)
uids and minerals soaks body → soaks pores with precipitated minerals → soft tissues no longer there but minerals preserved in gaps (cells)
coommon in fossil wood
Recrystallization (altered fossil)
originally mineralized so shells or bones
the shell form is unchanged but fabric changes because of recrystallization
because lithification creates fluids that carry minerals that react with shells/bone
Replacement (altered fossil)
shell looks same but mineralogy has been replaced (similar to recrystallisation)
ex. Ammonite shell from aragonite to calcite
also completely replaced from aragonite to pyrite
chemistry been altered still useful telltale signs but mineralogy changed
Carvonization ( altered fossil)
flattened and carbonized
volatile organic carbon molecules gone → carbon film as print
Imprint ( altered fossil)
moulds and casts
through process of lithification → recrystallized → shell no longer there → impression of outre and inner shell (moulds) → preserveed in the rock (casts)
Trace Fossils ( altered fossils)
Tracks or footprints
• Trails or paths made by a moving body/ organism
• Burrows or borings
• Coprolites and fecal pellets
• Gastroliths
• Body imprints, e.g., resting marks
• Root marks
• Represent activity
• Provide information about behaviour and environment
• Usually in situ
• Classified by shape or by mode of behaviour
Quality of fossil depends on chances of fossilization ie. soft/ hardbody
soft vs. hard body (shell or skeleton) effects fossil record
ex jellyfish not well preserved because of soft body
chances of fossilization organisms
scavenged within hours of decaying on land → no fossil
ex. decomposition through recycling organic matter (hunting scavenging)
Lagerstätten
large deposits of fossils
Lagerstätten examples
conservation and preservation of 100s of fossils
ex lagoon in southern germany has big diversity, then buried in lagoon (dragonflies, reptiles, birds)
ex. Messel clay pit, Lake overcome by Co2 poisining, killed all animals and perserved them (Bates, turtles, fish)
lagerstätten environment
often anoxic environemnt ( mud bath etc)
Fossils are
fossils are the remains or traces of organisms that lived in the past and have been buried and preserved in rocks
Traces and complete skeletons
can be used to understand and reconstruct behaviour and biology
ex. teeth marks, insect damage etc. interactions as fossils
Fragmentary skeletons
ex. sharks tooth (bcs they don’t mineralize), bivalve shell (clam)
can use this to reconstruct habitats and ecosystems