Why fossils are rare

For long periods of time, most individuals in some species may not have survived long enough after their deaths to become fossils because they were eaten, and the few fossils that were formed may have been destroyed at a high rate by increased erosion in particular regions. Gaps in the fossil record are sometimes due also to the simple fact that we have looked for them in the wrong places.

The climate has dramatically changed many times in the past. When that occurred, members of the same species often died out in one region but flourished in others. Unless we are alert to this possibility and search in different geographic regions, it will look like the fossil record has been abruptly broken, only to begin again thousands or even millions of years later. Eventually , the larger gaps in the fossil record are usually filled through intensive worldwide research.

This has resulted in an ever more accurate picture of the past. What do the Fossils Tell Us? Fossils show us a great deal about earlier life forms.

Not only can we learn about evolutionary processes and trends, but we can also reconstruct body shapes. Most prominent animal fossils displayed in museums usually are mineralized bones. From these skeletons, researchers can often learn about gender, physical capabilities, growth patterns, life expectancies, and pathologies. For instance, by studying muscle attachment points on bones, it is usually possible to make inferences about the size and shape of muscles. This can be an important clue to understanding locomotion.

The relative size, shape, and position of eyes, nose, and ears on a skull can lead to an understanding of the importance and capabilities of these different senses. In humans, gender can often be determined by noting skeletal differences of the pelvis, or hip region. These differences are due to modifications needed for a broad birth canal in females. Brains are virtually never fossilized, but the brain cases often are. These can give us a good idea of the gross structures of brains and their overall mass.

The age at death can be estimated by such things as closure of bone growth plates and skull sutures as well as tooth eruption and wear patterns. Bones sometimes also show evidence of medical abnormalities such as fractures and other injuries as well as specific kinds of diseases such as meningitis and tuberculosis.

How are Fossils Assigned a Species Name? When new fossils are discovered, it is not always clear as to which species they belong. There are two different, opposing approaches to solving this problem. They are commonly known as the typological and the populationist viewpoints. Those who take the typological approach believe that if two fossils look even slightly different, they must be from two distinct species.

This is an emphasis on minor differences. In contrast, those who use the populationist approach accept that individuals in all populations of organisms normally have at least minor differences. Therefore, when they encounter fossils that are similar, but not identical, they tend to lump them into the same species.

They expect that separate species would exhibit major differences. The populationist approach to defining species has become the dominant one in the biological sciences today.

For psychological reasons, however, some important discoverers of fossils have tended to take the typological viewpoint. It is ego boosting to say that you have discovered something new and unknown rather than just another specimen of an already well known species. There probably always will be a heated debate regarding the species identification for new fossil specimens.

W e cannot use the criteria of reproduction to distinguish species from fossils because it is not possible to get two skeletons to breed in order to see if they can produce fertile offspring. Therefore, paleoanthropologists often take a cautious approach and use the term paleospecies instead of species. However, if you want your remains to become a fossil that lasts for millions of years, then you really want minerals to seep through your bones and replace them with harder substances.

It can take millions of years. As a result, you might skip the coffin. Bones permineralise most rapidly when mineral-rich water can flow through them, imbuing them with things like iron and calcium. A coffin might keep the skeleton nicely together, but it would interfere with this process.

There is a way a coffin might work, though. Mike Archer, a palaeontologist at the University of New South Wales, suggests burial in a concrete coffin filled with sand and with hundreds of 5mm holes drilled into the sides.

This then needs to be buried deep enough that groundwater can pass through. In terms of the minerals, calcium ions which can precipitate into calcite, a form of calcium carbonate, are especially good. Deliberately seeding your corpse with the appropriate minerals, such as calcite or gypsum, might be a way to accelerate this.

Encouraging the growth of tough iron-rich minerals would also be sensible as they withstand weathering well in the long run. If you want to personalise your fossil further, add colour with some copper Credit: Alamy. Silicates, from the sand, are also a nice durable mineral to have incorporated. Archer even suggests getting buried with copper strips and nickel pellets if you fancy fossilised bones and teeth with a nice blue-green colour to them. If you made it through the first few hundred thousand years and minerals begin to replace your bones, congratulations!

Steer clear of the edges of tectonic plates, where the crust is going to eventually get sucked under the surface. If you want somebody to chance upon your carefully preserved fossil one day, you need to plan for burial in a spot that currently is low enough to accumulate the necessary sediments for deep burial — but that will eventually be pushed up again.

What are trace fossils and what are some examples? What is permineralization and how is it important for the preservation of fossils? What is a trace fossil and what can be learned from them? Question 6b3d1. Why are fossils important? Why are fossils rare in precambrian rocks?

See all questions in Fossils. In the former case, it is clear that dinosaur remains were rapidly buried before substantial scavenging could take place. Remains of dinosaurs that were washed into the fluvial systems are found buried in actual river channels, whereas others are found out on the former floodplains at the location where they fell and were covered by sediments from floodwaters that breached river banks.

Because river currents tend to scatter and break up bones, remains from river channels are often biased toward certain bones depending on the strength of the current. Such aggregations are called Voorhies groups after one of the first paleontologists to study the phenomenon by which certain bones, such as ribs and vertebrae, tend to readily tumble downstream, leaving behind only partial skeletons.

Dinosaur fossils found on former floodplains also often show bias toward elements such as pelvises and larger long bones that were difficult for scavenging or predaceous theropod dinosaurs to consume. In any event, once bones were entombed in fluvial sediments, not only were they protected from scavengers and many types of bioorganisms, but they could also begin a process known as permineralization. Water percolating through the sands or muds was often rich in silica natural glass and other minerals, which could infill the pores of the bones and make them physically resistant to crushing by the overlying sediment.

At least some minor replacement of the actual bone matrix usually occurred as well, typically by iron-rich minerals, but it should be noted that most dinosaur bones actually retain much of the original calcium and phosphatic minerals they possessed in life. As such, the phrase "turned to stone"--often used to describe fossil bone--is misleading.