Seeds transfer their microbes to the next generation

Scientists have been pondering if the microbiome of plants is due to nature or nurture. Research at Stockholm University, published in Environmental Microbiology, showed that oak acorns contain a large diversity of microbes, ...

Accounting for the gaps in ancient food webs

If you want to understand an ecosystem, look at what the species within it eat. In studying food webs—how animals and plants in a community are connected through their dietary preferences—ecologists can piece together ...

Researchers uncover unequal effects of human activity on mammals

Walking along the Tech Green, you are likely to see squirrels, birds, and the occasional chipmunk scurrying along among passing students. These small critters seem to be thriving in urban environments across the world, but ...

Researchers discover 16 million-year-old bat fossil

A new species of bat that is 16 million years old has been discovered by an international group that includes University of Valencia lecturers Francisco J. Ruiz Sánchez and Plini Montoya. The finding was made at the palaeontologic ...

Brains 'primed' for life on land

A new study adds another layer to the remarkable evolutionary transition of life from water to land on Earth.

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Fossil

Fossils (from Latin fossus, literally "having been dug up") are the preserved remains or traces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous (fossil-containing) rock formations and sedimentary layers (strata) is known as the fossil record. The study of fossils across geological time, how they were formed, and the evolutionary relationships between taxa (phylogeny) are some of the most important functions of the science of paleontology. Such a preserved specimen is called a "fossil" if it is older than some minimum age, most often the arbitrary date of 10,000 years ago. Hence, fossils range in age from the youngest at the start of the Holocene Epoch to the oldest from the Archaean Eon several billion years old. The observations that certain fossils were associated with certain rock strata led early geologists to recognize a geological timescale in the 19th century. The development of radiometric dating techniques in the early 20th century allowed geologists to determine the numerical or "absolute" age of the various strata and thereby the included fossils.

Like extant organisms, fossils vary in size from microscopic, such as single bacterial cells only one micrometer in diameter, to gigantic, such as dinosaurs and trees many meters long and weighing many tons. A fossil normally preserves only a portion of the deceased organism, usually that portion that was partially mineralized during life, such as the bones and teeth of vertebrates, or the chitinous exoskeletons of invertebrates. Preservation of soft tissues is rare in the fossil record. Fossils may also consist of the marks left behind by the organism while it was alive, such as the footprint or feces (coprolites) of a reptile. These types of fossil are called trace fossils (or ichnofossils), as opposed to body fossils. Finally, past life leaves some markers that cannot be seen but can be detected in the form of biochemical signals; these are known as chemofossils or biomarkers.

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