7.5 - Decay

How has decay in taphonomy changed in the last 40ish year?

transition from regular observations of decay, now experients occurs within labs and can have control over the environments in which an organism decays

What patterns can decay experiments observe?

changes and loss of morphology at different levels can be done by puttin thins in brines to see decay, inlcuding:

• sub-cellular (melanosomes)

• cellular (embryos)

• whole bodies (anatomy)

• tissues/ structures (muscles)

• communities (brine seeps)

What variables need to be considered when testing a hypothesis in decay experiments?

Phylogeny, ontogeny, physical, chemcal, biological, history

What can decay experiments be used to inform?

interpretations of geology, this works both ways round

Discuss the Melanosome Shape experiment (McNamara et al, 2013)

Experiment = muturation of feathers for implications of fossil feather colour reconstructions

Aim = test feasibility of interpretations

Hypotheis = taphonomic porcesses do not alter geometry of melanosomes

Organismal variables = feathers from range of modern birds

Environmental variables = high temp, high pressure

Output = measuring geometry

Result = shape change, thus implication taphonomy does alter feather geometry

Discuss the Chordate Decay experiment (Sansom et al, 2010,2011)

Experiment = non-random decay of chordates causes biases in fossil interpretation, discussions around chordate ancestry is highly disbuted

Aim = assess interpretations of controversial fossil chordates

Hypotheis = chordate characters decay in random order with respect to informativeness

Organismal variables = hagfish, amphioxus, lamprey

Environmental variables = artifical seawater, bacteria

Output = quantative charcater scores

Result = charcater type correlated with order of loss during decay, thus implication slippage is stem-ward

in some species, the look more primitive than actual form when decayed (what does this say about biases in fossil interpretation?)