Fossilization

From CreationWiki, the encyclopedia of creation science

Unreferenced Material This article contains content that requires citations to credible sources. You are encouraged to make this article better by adding references to validate information.

Fish with fossilized fleshy parts

Fossilization is the process by which plant and animal remains are preserved in sedimentary rock. The Earth is covered in layers of fossils, and this record of history helps us understand what types of organisms that lived in the distant past (i.e. before the flood of Noah).

The study of how living organisms become fossilized in known as taphonomy (Greek for "laws of burial"). Under normal conditions, fossilization will rarely take place, and may best be explained through flood geology mechanisms. Nevertheless, there are two main beliefs regarding the formation of sedimentary rock that contain fossils.

• Uniformitarianism: fossils were buried through uniform rates of erosion and deposition, largely consistent with current rates.
• Catastrophism: fossils were buried quickly by one or more major catastrophes.

Conditions for fossilization

For fossilization to occur, certain conditions must be met. It can only happen after death and normally only affects hard tissues such as shells and bones. In the global cataclysm, organisms that became fossils died either before or after they were buried in the flood sediments. Immediately after death, an organism experiences necrolysis (the decay and breakup up of the organism). Under normal circumstances today the organism suffers destruction by three primary agents--biological, mechanical and chemical (diagenesis)—both before and after they are buried.

Some organism were buried intact quickly and their remains are the best preserved. Others, were buried after they had suffered some decay and breakup. Their remains are usually found in beds of jumbled bone of all types and different species.

1. The organism must be buried quickly. For this to happen, the organism normally must die in abnormal conditions such as in a flood, volcano eruption or an earthquake. Otherwise it is near impossible for an animal to be preserved;
2. The organism must be kept from normal decay. If the animal is exposed to oxygen or bacteria, they will quickly start to decay;
3. The organism must be buried in matter that is leached with mineral-rich waters where carbonates are precipitating. These minerals will replace the original tissue, so that a stone remains in the shape of the original tissue.

From all these examples, a general trend emerges. The best fossilization occurs when there is rapid burial and anoxic conditions to prevent scavenging, no reworking by currents, and diagentic alteration which preserves a fossil rather than destroy it. These conditions are what is expected in models of the Flood.

Types of Fossilization

Most fossils have been dramatically altered from the original compsition of the specimen, and often their original shape and tetxture are hard to determine unless one has some idea of what took place.^[1]

Unaltered remains

Exceptional cases: Wolley Mammoth with hard and soft parts preserved; The fossils of the Rancho La Brea tar pits preserved the hard parts including DNA; Amber preserved orgnaisms with many biochemicals still intact.

Permineralization

Buried hard parts--bones or woody tissue--become permeated with groundwater containing dissolved calcium carbonate or silica that flows through porous marrow cavities or wood canals and pores.

Minerals are precipitated in the pores and open spaces encasing the bone or wood within solid rock. In this type of fossilization, new material comes in and joins with the original matter. A dinosaur fossil that has been permineralized has both bone material and rock. This is why soft blood vessel tissue has been found preserved in permineralized T-rex fossils.

Recrystalization

Some shells are made of relatively unstable minerals like aragonite. Once the shell is buried aragonite commonly reverts to the more stable form of calcium carbonate--calcite. In other cases, small crystals of calcite recrystalize into larger crystals.

Dissolution and Replacement

As water seeps through shell or bones or other remains, the original material gets dissolved away. A fossil shaped mold may be left behind that is then filled with sediment, in other cases the original material is immediately replaced by some precipitate. Such fossils may not contain any of the original matter.

Carbonization

In this case, most of the volatile organic materials of an organism disperse, leaving a residue of coal-like carbon, sometimes showing the detailed structure of the organism. Such fossils are commonly fish, insects and leaves.

Factors affecting fossilization

Immediately after death an organism experiences necrolysis (death breakup), which is the decay and breakup up of the organism. The primary agents of destruction are biological, mechanical and chemical.

Biological

In all environments, scavengers quickly eat and destroy carcasses. In the process, hard parts are broken up and scattered. In subaquious conditions, boring algae or sponges, worms, bryozoans and bacteria efficiently continue the destruction, unless the organism ends up in anoxic waters or sediments. On land, termites, ants, beetles, worms, fungi, and bacteria also destroy organisms in a short time. The key factor that prevents biological destruction is rapid burial. ^[2]

Mechanical

Winds, waves and water currents are very effective destructive agents especially in shallow water where they have the highest energy. The shape, density, and thickness of an organisms bone, shell or other hard parts determine survival of these parts under mechanical transport. The less mechanical action that an organism experiences, the greater the chances of it being preserved in whole or in part in the fossil record. Fully articulated fossils did not experience mechanical action as has a jumbled bone beds.

Diagenesis

After burial, a variety of diagentic changes in the rock, especially metamorphism, can easily destroy shells, for example, and prevent preservation. Aragonitic fossils shells are much more prone to dissolution than calcitic fossils. Original composition and groundwater chemistry are the most important factors in determining whether diagentic changes are likely to alter or dissolve a fossil. These chemical changes can destroy or preserve the fossil

Lagerstatten (mother load) fossils

These unique fossils are found around the world that preserve soft tissues and sometimes even skin texture and color patterns. These are found is places such as the Burgess Shale, The Solnhofen Limestone, the Mazon Creek Beds, the Hunsruck Shale, the Posidonienschiefer of Holzmaden, and the Messel oil shale. From all these examples, several general trend emerge. The best fossilization occurs when there is rapid burial and anoxic conditions to prevent scavenging, no rewoking currents, an little or no diagentic alteration to destroy the fossils.

Catastrophism vs. Uniformitarianism

There are two main beliefs regarding the formation of sedimentary rock; uniformitarianism (organisms were buried slowly and gradually), and catastrophism (organisms were buried during catastrophic conditions).

Uniformitarianism

Main Article: Uniformitarianism

Uniformitarians typically describe fossilization as follows:

"There are many ways for an organism to get preserved, but I will explain the general way in which most fossils form. First of all, fossils only occur in sedimentary rock, no others. Here is a basic example of what happens when fossilization occurs. An organism, let's just say, a dinosaur, dies. Their flesh and other tissues is probably eaten by carnivorous animals, leaving just the bones.

Let's say, just by chance, that this whole ordeal took place in an area with lots of sand, very near to a river. Let's also say that the bones were left undisturbed just long enough for the wind to blow sand and sediments over top of them, causing them to lie a little bit underground. Over the years, and I mean thousands of years, the sediments slowly pile up over top of the bones, until they are buried far underneath the ground. Let's say the river floods or changes it's course too, and the land over top gets covered in water."

While this is going on, the minerals in the bones, calciums and hydroxyapatite, get replaced, one by one, with the minerals in the sand. Due to the great pressure over top, the lower levels of sediment get pressed together to form sedimentary rock, with the bones still in it. Eventually, millions of years pass by, and there is no organic material left in the bones, they are now solid rock, and are buried deep below the surface, encased in sedimentary rocks. One day, someone is digging deep into a quarry, and notices these bones, now fossils." ^[3]

Problems with this model:

• "Their flesh and other tissues is [sic] probably eaten by carnivorous animals, leaving just bones." This predicts that the bones would show evidence of bite marks and scavenger damage. In the vast majority of cases, however, there is no evidence of such damage. The animals appear to have been buried quickly, completely, and without any damage from scavengers.
• "Let's also say that the bones were left undisturbed just long enough for the wind to blow sand and sediments over top of them, causing them to lie a little bit underground. Over the years, and I mean thousands of years, the sediments slowly pile up over top of the bones, until they are buried far underneath the ground." Bones buried only "a little underground" would still decay, particularly over the course of thousands of years. Yet in fossils, the decay that would occur in even a year or two is not observed. Instead, the fossils appear undamaged by decay, a fact consistent with rapid fossilization, rather than simply rapid burial.
• "Let's say the river floods or changes it's course too, and the land over top gets covered in water." Indeed, flooding is an essential element of fossilization because sedimentary rock only forms from wet sediments. However, flooding "thousands of years" after the death of the animal will not do the job. The animal must fossilize in wet sediments before it has time to decay; the animal will continue to decay even if incidentally buried, until it is encased in sedimentary rock. Therefore, the animal must be encased in sedimentary rock before more than a few years have passed.

Catastrophism

Main Article: Catastrophism

Those holding to catastrophism assert that most fossilization occurred as a result of a major catastrophe, such as the flood of Noah. In a massive flood of this type, sediments would be torn up in the raging waters, and then laid back down, with organisms buried in them. As the floodwaters receded, these sediments would dry in under a year, leaving the organisms fossilized before they had a chance to be damaged by scavengers or decay under the elements.

In a massive global cataclysm, ecological environments, sediment, and hard rock would be torn up and then deposited in slower and slack water, burying the organisms in layers. Before, during and as floodwaters receded, the sediments would de-water at different rates according to the type of sediment. The organisms could fossilize because they would be within the ideal environments that favor the various types of fossils found

In 1989, there was a massive mortality rate over 98% for urchins through out the Caribbean. Samples show no increase in echinoderm material, hinting that the reefs where incapable of preserving them. Thus fossil urchins and the like should be considered the product of unusual processes. For example catastrophic flooding.^[4]

Flood geology is consistent with the known facts about fossils. Uniformitarianism, on the otherhand, posits that the organisms were incidentally buried in unconsolidated sediments which only later became substantial enough to consolidate into sedimentary rock, which violates the known fact that organisms will continue to decay until the sediments become solid rock. Flood geology provides the superior explanation for fossilization.

Related References

1. ↑ Prothero, Donald. 2004, Bringing Fossils to Life: An Introduction to Paleobiology. Chapter 1
2. ↑ Prothero, Donald. 2004, Bringing Fossils to Life: An Introduction to Paleobiology. Chapter 1
3. ↑ Fossilization
4. ↑ Greenstein, B. J. 1989. Mass mortality of the West-Indian echinoid Diadema antillarum (Echinodermata: Echinoidea): a natural experiment in taphonomy. Palaios 4:487-492.

Browse

See Also

• Global Flood
• Flood Geology