Fossiileja

Fossiileja, the Finnish plural term for fossils, are the preserved remains or traces of organisms from past geological periods. They can be found in sedimentary rocks, glacial deposits, amber, ice, or tar, and they provide direct or indirect evidence about ancient life and environments.

Most fossils form when organic material is buried rapidly and protected from decay. Over time, minerals may replace the original tissues (permineralization), or the organism’s shape may be preserved as molds and casts. Some fossils are preserved as carbon outlines, while others record activity, such as footprints, burrows, or fecal remnants known as coprolites. Soft tissues are rarely preserved, but exceptional conditions—often in Lagerstätten—can yield unusually complete preservation.

Fossiileja are categorized as body fossils, which include bones, shells, teeth, and imprints, and as trace fossils, which document behavior rather than anatomy. Preservation varies with environment, burial rate, chemistry, and time, influencing how much information remains about ancient life.

Dating fossils relies on relative dating through stratigraphy and index fossils, alongside absolute dating methods such as radiometric techniques. Carbon-14 dating is applicable for relatively recent specimens, while older fossils commonly require uranium–lead, potassium–argon, or other isotopic methods.

The study of fossiileja, paleontology, sheds light on evolutionary history, past ecosystems, climate change, and geographic distribution of organisms. Notable fossil discoveries and formations contribute to understanding biodiversity across deep time, from ancient marine communities to terrestrial life. Ongoing excavation, preparation, imaging, and comparative analysis continue to refine interpretations of life’s history and its environmental context.