■ Ron Neller
ARECENT Australian research study on how crocodile carcasses decompose in water has important implica- tions for fossilization.1 The researchers were seeking to better understand
the processes operating on a skeleton after the flesh decomposes,
affecting such things as how much of the skeleton remains, and
how much stays articulated (the bones aligned together as in life).
If e.g. the top of the long leg bone or femur is found well away
from its hip socket, that part of the skeleton has become
disarticulated. A fossil skeleton in which the bones were scattered around
would be completely disarticulated.
Crocodiles were chosen as they are commonly found as fossils
worldwide, and are often found to have excellent skeletal articulation and completeness.
For the experiment, eight dead Australian saltwater crocodiles,
Crocodylus porosis, were placed in tanks of fresh water. These
are the largest living reptiles, and can be huge; for this study,
juveniles were used.
Three different treatments were then used to assess how
the rate and timing of burial affected the decomposition
1. Two carcasses were immediately buried under 20 cm
( 8 inches) of fine-grained sand, simulating rapid burial.
2. Three were allowed to ‘bloat and float’ uncovered
until they sank to the bottom weeks later. At this time
they were covered with 20 cm of fine-grained sand,
simulating delayed burial.
3. Three were not buried at any stage.
Some interesting findings
All crocodiles in Treatments 2 and 3 bloated and rose within
3–5 days, and remained afloat on average for 32 days. This
shows how quickly the carcass would have to be buried
after death to be significantly preserved.
At the end of the experiment, for crocodiles in
Treatments 2, and 3 “...most of the axial skeleton, forelimbs, and hindlimbs were either partially articulated
or disarticulated”. 2
The 20 cm of fine-grained sand used to initially bury
the crocodiles in Treatment 1 was insufficient to keep one
of them buried, and on day 12 it made a ‘bloat and float’
escape from the sediment (it was reburied the next day).
The crocodiles which were immediately buried, unlike
the others, stayed in the same position with virtually full
On the basis of these findings, the authors concluded
that “... preservation of articulated skeletons ... is more likely
to result from rapid burial”, 4 and articulation is “... less
likely to result from decay in a low-energy aqueous environment.”. Also, “... if a carcass is inhibited from floating,
the likelihood of articulated preservation increases.”. 2
Given that one of the sand-covered crocodiles in
Treatment 1 made a ‘bloat and float’ escape after burial,
the authors further concluded, “Therefore, burial would not
only have to be rapid enough to occur before the bloated
stage commenced (approximately before 4 days ...), it would
also have to involve enough sediment to continue to negate
the positive buoyancy created by internal gas production”
(emphases added). 5
So to have whole fossil skeletons nicely preserved, they
need to firstly be rapidly buried to provide immediate
protection from scavengers. And the sediment covering
them needs to be deep enough to protect against burrowing
scavengers, and heavy enough to prevent the gas buildup
from decomposition allowing the carcass to ‘escape’.
However, in today’s conditions, where would the sediment needed to cover a crocodile come from? Extensive
deposition of more than 20 cm of sediment is exceptionally rare and/or limited in extent; and even that depth was
apparently insufficient in this experiment. Far more sediment would be needed to bury much larger animals than
How croc decomposition helps confirm
a crucial element of Bible history
CREATION.com 14 Creation 39( 3) 2017