What Is Taphonomy? Everything That Happens Between Dying and Being Found

An animal dies and a long series of processes acts on the remains, each removing information. Scavengers disarticulate, scatter and destroy bone, with different scavengers producing characteristic damage. Decay removes soft tissue within days to weeks unless conditions prevent it. Weathering cracks and exfoliates exposed bone through a documented sequence of stages that indicates how long it lay on the surface. Transport by water sorts elements by size and density and rounds their edges, and the degree of sorting indicates how far and how energetically they moved. Burial stops most of that and begins another set, since compaction distorts, chemical conditions dissolve or replace, and pressure and heat alter the mineral. Later, uplift and erosion expose the specimen, at which point weathering resumes and a fossil that survived a hundred million years may be destroyed within a decade. Only then does anyone find it, and collection itself is selective.

Every stage filters, and the resulting record is skewed in identifiable directions:

• •Hard parts survive and soft-bodied organisms do not, so groups without skeletons are almost absent except at exceptional sites
• •Large bones survive transport and small ones do not, so small animals are underrepresented unless sediment is screened deliberately
• •Aquatic and lowland environments preserve far better than uplands, so mountain faunas are largely invisible
• •Rapid burial is required, so places with high sedimentation are overrepresented and stable landscapes are not
• •Rock of some ages is exposed at the surface in greater quantity than others, which produces apparent diversity peaks that track rock availability rather than life
• •Collection bias, since large impressive specimens attract effort and accessible countries are sampled far more heavily than remote ones

The field's productive move was to treat the processes as a subject rather than an obstacle. Actualistic studies observe what happens to modern carcasses, with researchers placing animal remains in various environments and recording decay, scavenging, weathering and burial over months and years, which supplies the calibration for interpreting fossil sites. Experimental work rots specimens under controlled conditions to establish what decays first, which produced a substantial result when experiments showed that decaying early chordates lose their distinguishing features in a predictable order, meaning a partially decayed specimen looks more primitive than it was, which affects the interpretation of several important Cambrian fossils. Flume experiments transport bones in moving water to calibrate sorting. Damage patterns are catalogued so that scavenger, predator and trampling marks can be distinguished. The result is that the same features that destroy information about the animal supply information about the environment and the time elapsed.

Reading the processes gives an account of the environment that the bones alone would not:

• •Articulated skeletons indicate rapid burial and minimal transport, so the animal died close to where it was buried and was covered quickly
• •Disarticulated but unsorted material indicates decay in place without strong water movement
• •Bones aligned in a common direction indicate a current, and the direction records which way it flowed
• •Sorting by size and density indicates hydraulic transport, and the degree of sorting indicates how energetic it was
• •Mixed weathering stages within one deposit indicate accumulation over years rather than a single event, which distinguishes a gradual trap from a mass death
• •Abrasion and rounding indicate distance moved, and heavily rounded bone may have been reworked out of an older deposit entirely, which produces specimens far older than the rock containing them

The same reasoning applies wherever a record is incomplete in patterned ways. Archaeology uses it directly, since the survival of artefacts depends on material, and an assemblage of stone tools and pottery from a site that also used wood, textile and basketry describes the preservation conditions as much as the culture. Forensic science applies it to human remains, with decomposition stages and insect succession used to estimate time since death, which is the same calibration problem. Conservation biology uses it when reconstructing past abundance from historical records, since what was recorded reflects who was writing and why. Any historical discipline faces the general version, which is that surviving evidence is a filtered sample and that the filter must be modelled rather than ignored. The distinctive contribution of taphonomy is the insistence that the filter can be studied experimentally rather than merely acknowledged, which converts a caveat into a research programme.

Scavenging, decay, weathering, transport, burial, chemical alteration and re-exposure each remove information, so the record samples what was preservable rather than what lived. Hard parts, large bones, lowland wet environments and rapidly accumulating sediment are all overrepresented. Experiments rotting and transporting modern remains calibrate the interpretation, and decaying specimens can look more primitive than they were.