Fossil: what is it?

Fossils are ancient organisms frozen in sedimentary rock that bear witness to past life on the Planet. The process of fossilization allows the preservation of biological structures over geological time.

The different types of fossils 

Fossils come in different categories, each offering distinct information about past eras. Body fossils, such as bones and teeth, are the most common. Fossilized footprints, revealing animal activities, are also crucial. Pollen and spore fossils provide clues about past vegetation, while microfossils reveal minute details about microorganisms.

In paleontology, fossils are grouped into several categories depending on the nature of the preserved remains. Here are some of the main types of fossils:

Body fossils 

Bones and teeth: The hard parts of the skeleton, such as bones and teeth, are often well preserved as fossils.

Shells and shells: the shells of invertebrate marine, such as those of ammonites, and the shells of arthropods may be common fossils. 

Trace fossils

Footprints: Fossilized footprints left by land animals provide information about their locomotion and behavior.

Burrows and nests: Traces left by excavation or nesting activities are also trace fossils.

Plant fossils 

Leaves and drink Fossilized: Plant remains, such as leaves, seeds, and wood, are common plant fossils.

Pollen and spores: Preserved pollen grains and spores provide information about past vegetation.

Microscopic fossils 

Foraminifera And diatoms: microscopic marine organisms whose shells are often well preserved.

Planktonic microfossils: small planktonic organisms preserved in sediment sailors.

Soft remains fossils 

Insects preserved in amber: Some fossils preserve insects trapped in amber, providing precise anatomical details.

Fossilized soft tissues: Under exceptional conditions, soft tissues such as skin, feathers or hair can be fossilized.

Coprolite fossils 

Fossilized feces: Coprolites are fossilized remains of feces, often rich in information about the diet of past organisms.

Fossils of microorganisms 

Stromatolites: rock structures formed by the activity of photosynthetic microorganisms. These rock formations result from the activity of photosynthetic organisms, mainly cyanobacteria, dating back about 3.5 billion years. Stromatolites are made up of successive layers of sediment trapped and cemented by microorganisms. Stromatolites as a structure are not alive, only the bacteria who built them were. 

Formation of fossils

Fossilization begins with the rapid burial of organic remains, often under sediment. Under the effect of the pressure and chemical reactions, the there matter organic transforms into minerals, thus preserving the morphology initial. This process can take millennia and is influenced by various environmental factors. Decomposition, the main enemy of fossil preservation, is avoided when the organism is buried quickly. Subsequent mineralization replaces soft tissue with minerals, thereby preserving anatomical details. Fossils thus formed are often discovered in strata geological, providing unique snapshots of past evolution.

Formation of fossil sites 

Fossil sites often emerge under specific geological conditions. Lakes, swamps, and ocean sediment deposits are ideal places for preservation. Regions, where fossilization processes have been favored over the centuries, become treasures for paleontologists, making it possible to reconstruct the food chains, the climates and the ecosystem disappeared.

The title of the world's oldest fossil goes to microscopic structures called stromatolites. These rock formations result from the activity of photosynthetic microorganisms, mainly cyanobacteria, dating back approximately 3.5 billion years. Their existence provides fascinating evidence of the emergence of life on Earth, and although these structures are not fossils in the traditional sense, they are considered the oldest traces of life on Earth. Their discoveries were made in rock formations in Australia, mainly in the Pilbara greenstone belt region.