An Ammonite Fossil Leaves A Trail of Evidence of a Tranquil Jurassic Seafloor

A remarkable trace fossil has given us a glimpse into the environmental conditions of a Jurassic seafloor.   Ammonite fossils are common in Jurassic rocks but one particular ammonite is more unusual than most.  In the horizontal layer of rock where it was found a 28 foot-long line of shallow grooves was found leading right up to the ammonite.

This long line of grooves in the rock has been interpreted as a drag mark because the streaks begins as just two grooves, then widen to become four grooves and then right before reaching the ammonite there are many more grooves before finally 11 grooves can be seen just an inch from the fossil itself.  These grooves have been interpreted as the product of an ammonite shell gently being dragged across an ancient seafloor.

The scenario painted by this fossil and the trace fossil leading to it, is of an ammonite which had died and at first probably floated on the surface buoyed by gasses produced from its rotting flesh.  Eventually the ammonite lost buoyancy and very slowly began to sink until it touched the sea floor.  A very slight current pushed the ammonite along the seafloor while suspended vertically but as it moved along it continued to lose buoyancy and so the it came into increasing contact with the seafloor leaving more grooves in the sand.  Finally there was so much resistance that it came to a stop and then fell over and nestled into the sand in a horizontal position.  Sediments then slowly rained down on the drag marks and the ammonite capturing this long moment in time for us to see today.

Preservation in a calm sea not a chaotic flood

Some may wonder how such fragile marks on the sandy sea floor could be preserved as they have.  The drag marks themselves provide some boundaries on the conditions that must have existed during the time of their formation.  Had the waters been moving too swiftly the drag marks would have been easily eroded.   In this case we see an example of how preservation requires a very placid environment.  A fine rain of small particles must have fallen from above over this entire area covering the indentations in the sand. It may have taken days or weeks for enough sediments to be deposited above these traces and the ammonite for them to be protected from other disturbances.

Where does this ammonite fit into a young-earth timeline of earth’s history? 

These simple drag marks are a witness of an ancient environment.  An ancient environment that has no place in the young-earth narrative of earth’s history.   Young earth proponents believe most of the fossil record, including these rocks, was the product of a single short-duration global catastrophe.   To support their assumption , they typically show individual examples of fossils that they believe must have been formed quickly such as fossil of a fish eating another fish, or large jumbles of bones of dinosaurs found together in mass graveyards.   They infer that such fossils must have been produced very quickly by destructive events and infer that the Noahic account of a flood in Genesis provides such an opportunity for fossil preservation.

However, local floods and other catastrophes such as large mudslides, earthquakes and volcanoes can also rapidly preserve large numbers of fossils very quickly.   The young-earth model begins with the assumption that a global flood happened 4500 years ago and thus they feel justified to infer that fossils that have been catastrophically preserved are evidence of more than a local catastrophe but rather could be the result of a global catastrophe.

But quick preservation of fossils provides only an “it’s possible” this could have happened in a global flood interpretation. Such fossils do not prove that a flood was global against being local.  Are there other fossils which might help us distinguish between these very different models of earth’s history?

The fossil discussed above points to one model being far better than the other.  Conventional models of Earth’s history describe a world in which a multitude of environments have existed over time and thus many forms of fossil-preservation are not only likely but expected.  If those models are correct, we should expect to find fossils representing a wide-variety of environment phenomena including catastrophic deposition – mudslides, volcanoes, large floods etc.. – and still and calm depositional environments such as the bottom of deep lakes, continental shelves, muddy edges of lakes  and so forth.

The young-earth model proposes that tens of thousands of feet of sediment were deposited in the space of days or weeks during a world-wide flood which was initiated – in most proponent’s estimations–in a violent manner.  There is no room for placid shallow seas in the young-earth model.  The limestone that this ammonite fossil is found in contains other fossils that represent a diverse community of organisms in an ecological hierarchy.  They are all shallow sea creatures, the vast majority are extinct groups of organisms, and there are many other trace fossils attesting to the quiet conditions in which they produced.   This is not what a global flood model would predict.

These types of calm depositional environments in which fossils are found are not rare. In fact, one could make an argument that most of the fossil record is composed of such sites (see my previous posts: Millions of Fossilized Footprints,  Hiking Through the Jurassic Period in Wyoming). Billions of dinosaur footprints, trace fossils of trilobites, underground insect nests, preserved burrows of animals, etc.. all attest to preservation environments that represent similar environments that we see today.   The global flood model isn’t necessary to explain fast preservation of fossils and is contradicted by the billions of fossils preserved in non-flood environments.

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