The age of the earth is something that a lot of scientists, particularly geologists, archaeologists, and paleontologists, have continuously theorized. According to a recent geologic time scale, the earth is estimated to be around four point fifty four billion years old `. There are numerous theories that are currently being studied as to what is the most accurate means of knowing the chronological age of the earth. It is also important to mention that because of the number of theories surrounding the true age of the earth, literatures have been filled with different values. For the purpose of uniformity, however, the rough estimate of 4.5 billion years provided by the International Commission on Stratigraphy will be the one that will be used. Now, the presence of these theories lead us to the question: how many organisms have actually managed to live in this planet, including the ones that came before the earliest humans, such as the dinosaurs and the other plant and animal species that people have not actually seen yet they know existed? One of the hardest and most reliable evidences that scientists look into is the availability of fossils. Fossils can be practically defined as the remains of an animal, a plant, or basically any form of organism that can be used as a solid evidence of its prior existence. They are the preserved remains of often old species, some of which are already extinct. A case in point would be the sabre cat and mammoth fossils that scientists have managed to dig up, majority of which were discovered accidentally, a few years to decades ago. There are numerous ways how fossils are and can be formed and the first and perhaps the most important thing to know about such processes and their associated steps is that they all involve not just a single step but actually a series of it; and that all steps required to fossilize a deceased organism has to be done in the right time and in the right place because otherwise, the subject organism’s remains would fail to turn into a fossil .
For a paleontologist to be able to discover a fossil, he has to have a high level of skill (particularly the skill of knowing where fossils can possibly be found and where and what types of areas to scan and search), but also a certain degree of luck. This is mainly because fossil formation, as mentioned earlier, requires a series of delicate steps and processes and oftentimes, these steps and or processes do not happen.
The most common and perhaps the most popular mechanism of fossil formation is through perimineralization. There are numerous steps or sub-processes involved in this fossil formation mechanism. The first phenomenon that has to happen is the death of the organism. Let us use a medium-sized dinosaur as an example. Once the dinosaur dies, scavengers (often in the form of other organisms) are expected to eat the carcasses or whatever type of soft tissue that may be consumed or eaten.
Whatever remains would later on be decomposed by bacteria and other microorganisms until all that is left is the bone or the exoskeleton. Now, if by any chance a large predator, such as a considerably larger dinosaur or any organism, destroyed the exoskeleton through whatever means, then the dead dinosaur would already be ineligible to proceed to the next steps of fossil formation via perimineralization. This is because there is nothing left to mineralize any longer because the exoskeleton has already been taken away. The same can in fact be true on the succeeding steps of perimineralization.
If the product gets destroyed by any natural or organism-caused action or reaction, the process of fossil formation automatically fails and becomes impossible. Now, assuming that the dead dinosaur’s exoskeleton managed to survive, over the course of many years (thousands or even millions of years), the bones are expected to be buried under sediments (i.e. soil, rock, or minerals). As more and more years pass, the layers of the sediments burying the dead dinosaur’s exoskeleton grow bigger in number. This pushes the exoskeleton down on whichever layer it is underground. Over the course of many more years, minerals from the sediments are expected to engulf the entire exoskeleton.
The reaction of the exoskeleton varies. Some organisms whose fossilized remains have been discovered (via perimineralization) were seen to be completely replaced by minerals, although the figure and shape of the organism can still be recognized. In that case, what happened was that as the exoskeleton remains got buried underground through continuous and repetitive sedimentation processes, it got completely decomposed but was replaced with minerals coming from the sediments which took the shape and figure of the exoskeleton .
The next major step of this fossil formation would involve the natural movement of volcanic plates in the earth’s crust. As another series of thousands or millions of years pass, the already-fossilized but still buried remains of the dead dinosaur will have to be brought back to or near the surface for the next generation of organisms (i.e. the human beings) to discover. Without this last phase of fossilization, the fossil would just remain underground and it will basically be impossible to be discovered .
Works Cited
Australian Museum Organization. "How are Fossils Formed." Australian Museum Organization (2013).
Castro, J. "How do Fossils Form." Live Science (2013): 01.
Cohen, K., S. Finney and P. Gibbard. "International Chronostratigraphic Chart." International Commission on Stratigraphy (2013).
Oxford University Museum of Natural History. "How do Fossils Form: Not many plants and animals are lucky enought to be turned into fossils." Oxford University Museum of Natural History (2006).
