Death March
Horseshoe Crab stopped dead in its tracks
by Tas Walker
This fossil Horseshoe Crab (Mesolimulus walchi) in limestone is exceptionally
well preserved (picture viewable in Creation).1
Its external skeleton (exoskeleton) is still intact. The largest section at
the front, the cephalothorax (combined head and chest), is domed like a helmet.
It looks like a horse’s hoof, giving the crab its name.2
The middle section, the abdomen, still displays a row of spines around its edge.
In living crabs, the abdomen is connected to the cephalothorax by a hinge.
The long spike-like tail, or telson, protrudes the same as it did when the creature
was alive. This fossil is 15 cm (6 inches) from its head to the tip of its
tail. A living crab uses its tail for steering, and to right itself if it
flips upside down.3
Not only is the body preserved, but also its footprints—a series of tiny triangular
impressions to the rear of the animal. Although the crab is benthic (bottom
dwelling), the track is not a record of its normal activities. It is a death
trail—the last steps that the crab took.
Clearly, this crab perished in exceptional conditions.
Normally, when animals die, bacteria destroy the soft tissue (it rots), and the
body falls apart, often within days. Decaying agents and scavengers in living
environments are very efficient, removing all traces of dead animals quickly.
This Horseshoe Crab must have been buried quickly to isolate the body from scavengers
and prevent it disintegrating.
The fossil is from the Solnhofen Limestone, part of the Jurassic geological deposits
of Bavaria, Germany. There fine-grained, flat slabs of rock (called Plattenkalk
in German) have been quarried as tiles and for lithography.4 The fossils it contains (even the delicate, soft-bodied
organisms, which usually leave, at best, only fragmentary traces of their existence)
are exceptionally well preserved.1
Long-age scientists say that this limestone formed over hundreds of thousands of
years in a warm lagoon, isolated from the ocean.4
They need to explain how the animals were preserved on the bottom while they were
covered slowly with sediment. So they hypothesize that the salinity of the
water increased greatly at the bottom of the lagoon, preventing bacterial decay
and scavenging.
But why would crabs want to live in such a hostile environment? They say the
crab must have been washed in. But how could a crab be washed from the bottom
of the ocean and into an isolated lagoon? Why would a storm, severe enough
to lift a crab from the bottom of the deep ocean, not disturb the bottom of the
shallow lagoon? For that matter, how would the delicate footprints be preserved
from water movements produced by such a storm?
The problem gets worse for the long-age explanation. The Solnhofen Limestone
contains an amazing array of different fossil animals. There are bottom dwellers
such as shrimps, lobsters, crabs and even bivalves. There are free-swimming
animals, such as jellyfish, fish, sea lilies, ammonites and squid. There are
animals that inhabit both land and water, such as crocodiles. There are insects,
such as beetles, cicadas and dragonflies. And there are even birds, such as
the famous Archaeopteryx lithographica, which is now extinct.1,5
A hypothetical lagoon lasting for hundreds of thousands of years does not explain
the Horseshoe Crab fossil. Rather, the fossil crab points to rapid burial
in a watery catastrophe that affected the oceans, the land and the atmosphere.
The Bible describes such a global flood in
Genesis chapters 6 to 9. During this event, abnormally high sedimentation,
probably combined with chemical precipitation of limestone, stopped the Horseshoe
Crab dead—even preserving its delicate tracks.
References and notes
- Ching, K., The Jurassic Solnhofen Limestone, Geoscience Reports
33:6–7, 2002. Return to text.
-
The Horseshoe Crab: Anatomy, 3 December 2002. Return to text.
-
Maryland Horseshoe Crabs: Anatomy, 3 December 2002. Return to text.
-
Localities of the Jurassic: The Solnhofen Limestone of Germany, 3 December 2002.
Return to text.
-
The plate limestone from Solnhofen, 3 December 2002. Return to text.
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