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Fossil

earth science Maturity 7-9 Next article →

A fossil is any preserved remains, impression, or trace of a once-living organism from a past geological age. These remnants provide a vital window into the history of life on Earth. The collection of all these remains is known as the fossil record. While this record is incomplete, it contains enough information to reveal patterns of biological diversification. It can even help scientists predict where to find missing links in history. A famous example is the discovery of Tiktaalik in the Canadian Arctic.

Fossil Diversity
Fossil Diversity

Fossils form through many complex geological processes. One method is permineralization, where minerals fill the spaces within organic tissues. Other processes include the creation of casts and molds, which preserve the shape of an organism. There is also authigenic mineralization, replacement, recrystallization, adpression, and carbonization. Some fossils are biochemical in nature, known as chemofossils or biosignatures.

Permineralized bryozoan
Permineralized bryozoan

Fossils vary wildly in scale. They range from one-micrometre bacteria to massive Sequoia trees. The largest known fossil is a Sequoia specimen located in Coaldale, Nevada.

Scientists categorize fossils into different types based on what they preserve. Body fossils consist of the actual parts of an organism. This often includes bones or teeth in vertebrates, or the chitinous and calcareous exoskeletons of invertebrates. In contrast, trace fossils, or ichnofossils, are marks left by a living creature. These include animal tracks or coprolites, which are fossilized feces.

Microfossils
Microfossils

Some specimens are only considered fossils if they are over 10,000 years old.

Humanity has interacted with fossils since the beginning of recorded history. Ancient civilizations often used them to support their mythologies. In Egypt, fossilized bones resembling hippopotamuses were kept in temples for the god Set. In China, the bones of ancient mammals like Homo erectus were often mistaken for "dragon bones." These were sometimes used as medicine or kept as art. One Song dynasty scholar, Huang Tingjian, even engraved a poem on a seashell fossil.

hyperborean-gryphon-persepolis-protoceratops-psittacosaurus-skeletons
hyperborean-gryphon-persepolis-protoceratops-psittacosaurus-skeletons

Early thinkers struggled to explain these strange objects. The Greek philosopher Xenophanes suggested a great flood had buried creatures in mud. The Roman naturalist Pliny the Elder wrote about "tongue stones," which were actually fossil shark teeth. He also noted "horns of Ammon," which we now know are fossil ammonites. In the 13th century, scholars suggested that fossil skulls of Deinotherium giganteum might be the origin of the Cyclops myth. These skulls have a single large hole that looks like one eye.

Anoplotherium 1812 Skeleton Sketch
Anoplotherium 1812 Skeleton Sketch

Scientific understanding changed greatly during the 19th and 20th centuries. In the 1800s, observers noticed that specific fossils were associated with certain rock strata. This led to the creation of a geological timescale. William Smith developed the principle of faunal succession, noting that fossils succeed one another in a regular order. This helped prove that rocks from different places could be correlated. Georges Cuvier used fossils to support the idea of extinction and the theory of catastrophism.

Rozprawa o přewratech kůry zemnj, Ichthyosaurus and Plesiosaurus
Rozprawa o přewratech kůry zemnj, Ichthyosaurus and Plesiosaurus

Today, paleontology is a precise science used to study evolution. Scientists use radiometric dating to measure the absolute age of rocks and fossils. This allows them to place life forms accurately on a timeline. The oldest fossils discovered are between 3.48 billion and 4.1 billion years old. By examining the fossil record, researchers can trace how species have changed over eons. This work connects the ancient biological past to the living world we see today.

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🖼️ Images & Media (17)
File:Fossil Diversity.png
Fossil Diversity.png
File:hyperborean-gryphon-persepolis-protoceratops-psittacosaurus-skeletons.jpg
hyperborean-gryphon-persepolis-protocerato...
File:Micraster coranguinum.4 - Cretacico superior.JPG
Micraster coranguinum.4 - Cretacico superior.JPG
File:Anoplotherium 1812 Skeleton Sketch.jpg
Anoplotherium 1812 Skeleton Sketch.jpg
File:Rozprawa o přewratech kůry zemnj, Ichthyosaurus and Plesiosaurus.jpg
Rozprawa o přewratech kůry zemnj,...
File:Eldredgeops-rana-crassituberculata.jpg
Eldredgeops-rana-crassituberculata.jpg
File:Montañita-Olón locality (stratigraphy) - Dos Bocas Formation.png
Montañita-Olón locality (stratigraphy) -...
File:Permineralized bryozoan.jpg
Permineralized bryozoan.jpg
File:Catellocaula.jpg
Catellocaula.jpg
File:Index fossils.gif
Index fossils.gif
File:Microfossils.JPG
Microfossils.JPG
File:Leptofoenus pittfieldae (male) rotated.JPG
Leptofoenus pittfieldae (male) rotated.JPG

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