Fossils and the Great Mysteries of our Planet

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Updated on: Educator Review By: Michelle Connolly

Fossils are the remains of plants, animals, fungi, bacteria, and single-celled organisms that have been replaced by rock material or impressions of organisms preserved in rock. Palaeontology is the study of the history of life on Earth based on fossils. Palaeontologists have used fossil remains to understand different aspects of extinct and living organisms.

Individual fossils may contain information about the organism’s life and environment, much like the rings of a tree, for example. Each ring on the surface of an oyster shell indicates one year of age. Studying oyster fossils can help palaeontologists discover how long oysters lived and in what conditions.

If the climate was suitable for oysters, the oysters likely grew more quickly and the rings thicker. If the oysters struggled to survive, the rings would be thinner. Thin rings lead to an unfavourable environment for organisms such as oysters that are too warm or cold for oysters, for example, or lack the nutrients needed for their growth.

One of the most useful windows into the evolution of life on Earth is fossils. A fossil is essentially a record of an organism that displays the size, shape, and texture of various body parts. The following are typical fossil examples: teeth, skin, nests, faeces, and tracks. But not every fossil is created according to this, and there are four primary categories of fossils: mould fossils, fossilised fossils, carbon fossils, and true-form fossils.

Each of these sorts of fossils is generated in a unique method and results in the preservation of various kinds of animals. Scientists in part understand the history of the Earth and all life on it because of fossils. The finding of fossils marked the beginning of human knowledge of dinosaurs, species older than humans, and all other extinct species.

Fossils have helped anthropologists learn a lot about the first human migration. The basis for scientists’ understanding of mass extinction Additionally, a big part of their capacity to forecast the future of the planet is dependent on fossils. Fossils come in a variety of forms, and when taken as a whole, they paint an accurate picture of life on Earth before modern humans appeared.

The Role of Palaeontology

Some fossils show how the organism lived, for example, amber, the fossilised resin of trees. Sometimes the sticky resin falls down the trunk of trees and traps air bubbles, as well as small insects and some large organisms such as frogs and lizards. Palaeontologists study amber, called fossil resin, to observe these complete samples.

Amber can preserve delicate tissues like dragonfly wings, and some ants have been trapped in amber while eating leaves, allowing scientists to know precisely what they ate and how they ate. Even the air bubbles trapped in amber are valuable to palaeontologists. By analysing the chemistry of the air, scientists can figure out If there is a volcanic eruption or other weather changes in the vicinity.

The behaviour of organisms can also be inferred from fossil evidence. Palaeontologists suggest that hadrosaurs, or dinosaurs described as ducks, lived in large herds. They made this hypothesis after observing evidence of social behaviour, including one site with about 10,000 skeletons.

Fossils can also provide evidence of the evolutionary history of living organisms. Palaeontologists conclude that whales evolved from land-dwelling animals, for example. Fossils of extinct animals closely related to whales have forelimbs like paddles similar to the front legs. Fossil animals somewhat resemble the legs, but in other ways, they also show strong similarities to the flippers of modern whales.

Why are fossils important?

The English scientist Robert Hooke, who produced a book on the subject in 1665 and began attempting to envision and depict it in its proper shape in his book “Lectures and Articles on Earthquakes,” which was published after his passing in 1705, was the first to be interested in the study of fossils.

By our awareness of the ongoing movement of the continents, the alteration in the form of the Earth’s surface, and temperature variations, fossils have primarily contributed to our understanding of the history of ancient life on Earth. Seeing the rise and tremendous diversification of new species as well as the enormous extinctions of other species has also advanced our understanding of Earth’s biodiversity.

Long before Charles Darwin’s theory of natural selection, which was formally introduced in 1859 and provided causality for the genesis of species, arose, fossils had already begun to demonstrate all of these concepts.

There are many nature museums where dinosaur fossils, in particular, are the main draw to draw people and pique their interest in prehistoric life. Moreover, fossils helped scientists understand that terrestrial rocks are made up of hundreds of feet thick strata and contain a wide diversity of fossil groups.

One of the essential things that fossils teach us is time, that the Earth is ancient at roughly 4.5 billion years old, that it is in a perpetual state of change, that former ocean floors are now mountains like the Alps or the chalk, and that these things are all true.

The creation of tropical coal swamps dating back to the Carboniferous period, the division and movement of the continents, and other significant changes demonstrated the impact of time on the world.

Ultimately, palaeontology is a fascinating and fascinating field of study. Where there are continually more fossils discovered, there is a new tale to be told about the planet. All you have to do is take in these tales; perhaps the fossils will inspire you to start writing a story about events that occurred in the distant past.

Types of Fossils

Before discussing the excavations and how they are conducted, it is important to discuss the many sorts of fossils briefly. The four primary categories of fossils are as follows:

  1. Body fossils:

These are the actual, fully preserved parts of a living thing, such as a skeleton, claws, teeth, pollen, and other structures, whether animal or plant. The process through which the cells of extremely porous organic materials like bone, nuts, and wood are gradually replaced with minerals is known as fossilisation or mineralisation.

Most people tend to think of them as fossils because they are large, hard, and primarily composed of bones found in archaeological fossils. This process occurs in situations like volcanic eruptions when a tree or animal is suddenly buried so that it does not have the opportunity to rot or be eaten by a predator. The ash and heat turn the organism into stone over time, preserving it for thousands of years. Palaeontologists have learned a lot from fossils, which are the most prevalent fossils of prehistoric species, including dinosaurs.

  • Carbon Trace fossils:

These are traces of an organism’s past activity while it was still alive, such as worm digging, footprints, prints on rocks, and other signs of living things. The soft tissues of plants, animals, insects, and fish that have fallen to the bottom of bodies of water and become stuck there are all preserved in minute detail in carbon fossils, which are far smaller than petrified fossils.

Layers of silt, like volcanic ash, shield them from ingesting or decomposing even in the presence of Further sediment layers accumulating on top of it over millions of years. Shale is a rock that is formed over time as ash, or other elements are compressed under the weight of the thickening layers. Fish and insects decompose around this period. Carbon is present in all living things and persists in the rock, leaving a thin layer. Nonetheless, fragments of insects and certain carbon fossils are visible on the rock.

  • Mould fossils:

An exterior stamp fossil is created when an organism is completely dissolved in sedimentary rocks, and its remnants are left on the rock’s surface. As silt or minerals fill the internal cavity of a skeleton, such as a shell or a skull, they cause excavation of the internal character. Fossil moulds, which typically appear in creatures with complex body components like exoskeletons, teeth, or shells, lack many characteristics in carbon fossils.

Internal mould may form with a fossil with an empty cavity, like a shell. Sediment fills and hardens inside the shell as the shell dissolves over time. The creature becomes trapped in porous rock and sediment, where water runs through and dissolves the body’s soft tissues. Similar to internal mould, external mould develops, but the sediment hardens around the solid body parts, which melt and leave an empty space where the creature formerly existed.

When researchers discover mould fossils, they create a void symbolising the formerly inhabited animal. Casting enters the scene either naturally or deliberately. In rare instances, minerals are deposited in the hollow areas left by the mould fossils, creating a mould for an animal or a piece of its body. If it didn’t, palaeontologists could use plaster of Paris or latex to make a fake cast that will allow them to simulate the size, shape, and other characteristics of the animal that produced the fossil.

  • Casts Fossil:

This fossil was produced by putting a mineral substance within the animal’s cavity. It produces a form that resembles the structure of an animal. In that they are, at least in part, the result of an imprint made in rock or sediment, cast fossils are similar to mould fossils.

However, cast fossils go one step further because once the hollow mould is present, it is filled with minerals that harden to form solid rock. The mould fossils occupy negative space, and the casting fossils occupy positive space. Furthermore, skin, leaves, teeth, layers, and embryos are fossilised in castings.

  • Trace fossils

Celestial fossils and traces both lack details about the original organism. Instead, they provide details on the organism’s traces. Burrows, nests, footprints, dung, and tooth marks are typical examples of uncommon fossils. They are the most prevalent fossil and sometimes reveal more about an organism’s lifestyle (such as how it hunted and rested) than fossilised body components.

  • True-form fossils

True fossils completely preserved in their original form are called fossils. Large portions of an organism’s body that have been replaced by minerals are considered true fossils. The formation of true fossils occurs during a process known as fossilisation. Legs, torsos, fingers, and heads are typical examples of these fossils, which, in contrast to casts and gypsum, are not fashioned using an impression; rather, the portion of the organism is displaced by minerals that harden into rock.

There are several methods for this to happen, but often the object becomes trapped and kept. Early Tertiary conifer trees produced amber, which is their resin. Insects get caught in the resin of trees because of adhesion, and when additional resin accumulates on top of them over millions of years, the resin hardens and undergoes a process known as polymerization that transforms it into amber.

  • Drought

Another real morph fossil is mummification, often known as taxidermy. During the Ice Age, some animals entered caves in the southwestern deserts of North America, where they died. The desert air dried the bodies, which were then perfectly preserved for thousands of years. The mummified remains are so well preserved that the colour of the hair and clothing can still be seen, but these Fossils frequently crumble when touched.

  • Freeze

It is one of the finest preserved fossilisation techniques because the body’s soft tissues are fully unharmed. Frequently, an animal gets unexpectedly trapped in a frozen environment, which results in frozen fossils.

Sub-disciplines of palaeontology

Palaeontology is a broad field with several subfields. Within a larger subject or field of study, a sub-discipline is a specialised area of study. Sub-disciplines in palaeontology may concentrate on a particular fossil type or a particular feature of the world, such as its temperature.

1.      Vertebrate Paleontology

Vertebrate palaeontology, or the study of animal fossils with backbones, is an important subdiscipline. To demonstrate how these animals lived and their evolutionary history, vertebrate palaeontologists have found and prepared the skeletons of many other animals, including cats, turtles, and dinosaurs.

Vertebrate palaeontologists have come to the conclusion that pterosaurs, a type of flying reptile, could fly by flapping their wings rather than just gliding in response to fossil evidence. Pterosaur skeleton reconstructions include hollow, light bones similar to modern birds.

One species of the pterodactyl, with a wingspan of 11 metres, is said to be among the largest flying creatures in history. Regarding the Quetzalcoatlus’s ability to fly, palaeontologists have divergent theories. Palaeontologists disagree as to whether it was difficult at all. According to other scientists, Quetzalcoatlus had the strength to fly across short distances swiftly. These hypotheses demonstrate the various ways vertebrate palaeontologists might interpret the fossil record.

2.      Invertebrate Palaeontology

Palaeontologists who specialise in invertebrates study the fossil remains of molluscs, corals, arthropods like crabs and shrimp, and echinoderms like sand dollars and sea stars, sponges, and worms. Invertebrates lack bones, in contrast to vertebrates. They leave behind impressions, fossilised shells, and external skeletal remains as proof of their existence. For its soft body parts and the footprints, it left while moving on the earth or ocean floor.

To research and reconstruct prehistoric aquatic ecosystems, invertebrate fossils are particularly fascinating. For instance, enormous populations of fossilised marine invertebrate communities dating back 200 million years have been discovered in the Nevada desert in the United States, indicating that significant parts of the state were submerged at the time.

3.      Plant Palaeontology

In addition to providing insight into the diversity and evolution of plants, palaeontologists study the fossilised remains of ancient plants. These remains can either be the impressions of plants that were left on the surfaces of rocks, or they can be the parts of the plants themselves, such as leaves and seeds, that were preserved by the rock material. It is acknowledged as playing a significant role in the reconstruction of palaeoecology, palaeoclimates, and the related fields of paleoecology and palaeoclimatology.

Paleobiologists have uncovered fossils of more than 100 plant species dating back 52 million years at a small location in Argentina’s Patagonia region. Patagonian leaf fossils from 2 million years ago may disprove this hypothesis. Archaeologists now have proof that the diversity of plant species on the continent predated the end of the last Ice Age by 50 million years.

Coal balls are large, solid blocks that include some plant remains. A fossil fuel called charcoal is created from the decomposing remnants of plants. The leftovers of swamp and woodland plants can also generate coal balls, but they do not become charcoal. They gradually turned into fossils or were replaced by rocks. The discovery of coal balls in or near coal deposits is crucial for studying paleoenvironments and comprehending a vital energy source since they reveal the existence of several coal-forming plants.

4.      Microbiology

The study of microorganism fossils, such as proteins, algae, tiny crustaceans, and pollen, is known as microbiology. Microbiologists use robust electron microscopes to examine tiny fossils, which are typically less than four millimetres.

In a process known as biomapping, microorganisms help identify layers of rocks that are similar in age because they are typically short-lived and abundant where they are found. Additionally, because the chemical makeup of some microfossils can be used to infer information about the environment the organism was living in, these organisms are crucial in palaeoclimatology.

In order to comprehend how the Earth’s climate has changed, microbiologists examine the shells of bacteria in the deep oceans. They can compare the shells from one time period to another or from one geographic area to another, and differences in the chemical composition of the ocean can be good indicators of differing oceanographic conditions.

Shells accumulate on the ocean floor after organisms die because organisms pull their shells’ components from the ocean water around them. The shells’ formation reflected the ocean’s current composition and the nutrients in the ocean when the shells evolved.

How is Fossilization done?

The preservation of an organism’s remains in sedimentary rocks is known as fossilisation. This process includes many chemical and physical mechanisms that impact living things after death. These are some of the ways that the organism is kept inside sedimentary rocks after it dies:

  • Maintaining the entire organism while maintaining its traits and structure, as in the case of the “Mammoth Elephant,” whose fossils were discovered in their entirety in the freezing wastelands of Siberia. Another illustration is the well-known bug fossils that were preserved entirely in amber.
  • Preserving the structure of a living organism without altering its composition, in which bacteria destroy the organism’s soft copies while leaving behind the remnants of its structure, which are typically made of calcium minerals or other substances that make up solid structures. This process occurs in organisms whose burial in the layers of rocks was postponed.
  • Maintaining the structures after replacing them with metal materials. There are numerous ways to do this, and metals can be used to replace the structural elements in the following ways:

1.  Carbonization: Temperature and pressure are crucial variables in a process that involves replacing carbon in the remains of a live organism with all other elements, such as oxygen and hydrogen.

2. Per-mineralization: This process occurs after the organism dies and the sedimentary rocks destroy the soft tissues—such as the skin or internal organs. The solid portions of the organism, particularly the bones and structures, survive. Mineral crystals are generated when water that has been dissolved in some minerals seeps into the crevices of the solid residue. These crystallised minerals retain the skeletal remains within sedimentary rocks by hardening them.

3. Replacement: In this process, the mineral content of the organism’s skeletal remains is completely replaced by minerals that are dissolved in groundwater. Plants also go through this process; when minerals take the place of organic stuff in a plant, the entire structure of the plant is changed. The most well-known of them is petrified wood, which still has its typical woody appearance but is made of silica instead of organic material.

To conclude, if its three-dimensional integrity is preserved, remnants of extinct organisms, including caves, shells, plants, tunnels, and paths, are considered a sort of fossil cast. Scientists can learn more about an ancient creature’s surface anatomy and activity by using castings that accurately reproduce an organism’s outward shape. Wing impressions can be seen in a typical fossil cast. Palaeontologists can determine the family of insects by looking at the preserved folds on the wings of extinct insects.

If you found this article interesting, you may also like reading about StonesHealing StonesWood Facts, and Facts about Rocks.

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