What are fossils?

Answer 1

Fossils are the petrified remains of living things. There are three types of fossil, and each type is useful in telling us how creatures lived millions of years ago.

The first type of fossil is part of the body of the creature, usually the hard part of the body like the shell or the skeleton, which is preserved as it was originally. The second type is a mould of the creature's body, left in rock after the body itself has decayed, so that we can see exactly how the creature looked. The last type is the imprint of the animal's footprint in the clay or mud which has hardened into rock over the years. All these types of fossil are very useful for telling us what sort of animals lived on the earth millions of years ago, animals which have long since died our or changed slowly as time passed to adapt themselves to different conditions.

Answer 2

Fossils (from Latin fossus, literally "having been dug up") are the mineralized or otherwise preserved remains or traces (such as footprints) of animals, plants, and other organisms. The totality of fossils and their placement in fossiliferous (fossil-containing) rock formations and sedimentary layers (strata) is known as the fossil record. The study of fossils is called paleontology.

Fossilization is actually a rare occurrence because most components of formerly-living things tend to decompose relatively quickly following death. In order for an organism to be fossilized, the remains normally need to be covered by sediment as soon as possible. However there are exceptions to this, such as if an organism becomes frozen, desiccated, or comes to rest in an anoxic (oxygen-free) environment such as at the bottom of a lake. There are several different types of fossils and fossilization processes.

Fossils usually consist of traces of the remains of the organism itself. However, fossils may also consist of the marks left behind by the organism while it was alive, such as the footprint or feces of a dinosaur or 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 chemical signals; these are known as chemical fossils or biomarkers.

Fossil sites with exceptional preservation are known as Lagerstätten. These formations may have resulted from carcass burial in an anoxic environment with minimal bacteria, thus delaying decomposition. Lagerstätten span geological time from the Cambrian. Examples are the Cambrian Maotianshan shales and Burgess Shale, the Devonian Hunsrück Slates, the Jurassic Solnhofen limestone, and the Carboniferous Mazon Creek localities.

The oldest known structured fossils are most likely stromatolites. Now understood to be formed by the entrapment of sediment by mucous-like sheets of cyanobacteria[1], the oldest of these formations dates from 3.5 billion years ago. Even older deposits (3.8 billion years old) of heavy carbon that are indicative of even earlier life are currently proposed as the remains of the earliest known life on Earth.

Answer 3

Fossils are the preserved skeletal outline of a long dead/decomposed living organism onto rock surfaces. Fossils are normally thousands, even billions of years old and are a fascination to the scientific and archaeological academic communities.

Answer 4

Fossils are the mineralized remains of animals or plants or other traces such as footprints. The totality of fossils and their placement in rock formations and sedimentary layers (strata) is known as the fossil record. The study of fossils is called paleontology.
For many people the opportunity to discover more about the earth's fascinating history is right beneath their feet. Fossils reveal a remarkable insight into how life and the environment has evolved through time, from luscious rain forests, to tropical seas, each depicted in the fossil record left behind.
To tell the age of most layered rocks, scientists study the fossils these rocks contain. Fossils provide important evidence to help determine what happened in Earth history and when it happened.
The word fossil makes many people think of dinosaurs. Dinosaurs are now featured in books, movies, and television programs, and the bones of some large dinosaurs are on display in many museums. These reptiles were dominant animals on Earth for well over 100 million years from the Late Triassic through the Late Cretaceous. Many dinosaurs were quite small, but by the middle of the Mesozoic Period, some species weighed as much as 80 tons. By around 65 million years ago all dinosaurs were extinct. The reasons for and the rapidity of their extinction are a matter of intense debate among scientists.
In spite of all of the interest in dinosaurs, they form only a small fraction of the millions of species that live and have lived on Earth. The great bulk of the fossil record is dominated by fossils of animals with shells and microscopic remains of plants and animals, and these remains are widespread in sedimentary rocks. It is these fossils that are studied by most paleontologists.


In the late eighteenth and early nineteenth centuries, the English geologist and engineer William Smith and the French paleontologists Georges Cuvier and Alexandre Brongniart discovered that rocks of the same age may contain the same fossils even when the rocks are separated by long distances. They published the first geologic maps of large areas on which rocks containing similar fossils were shown. By careful observation of the rocks and their fossils, these men and other geologists were able to recognize rocks of the same age on opposite sides of the English Channel.

William Smith was able to apply his knowledge of fossils in a very practical way. He was an engineer building canals in England, which has lots of vegetation and few surface exposures of rock. He needed to know what rocks he could expect to find on the hills through which he had to build a canal. Often he could tell what kind of rock was likely to be below the surface by examining the fossils that had eroded from the rocks of the hillside or by digging a small hole to find fossils. Knowing what rocks to expect allowed Smith to estimate costs and determine what tools were needed for the job.

Smith and others knew that the succession of life forms preserved as fossils is useful for understanding how and when the rocks formed. Only later did scientists develop a theory to explain that succession.

Answer 5

Mineralized bone, usually found embedded in rock. Fossils can persist for hundreds of millions of years.

Answer 6

Fossils are the remains of pre-historic organisms. After millions of years or sedimentation and thermal changes, the remains become fossilised.

Answer 7

1 : a remnant, impression, or trace of an organism of past geologic ages that has been preserved in the earth's crust

2 a : a person whose views are outmoded : FOGY
b : something (as a theory) that has become rigidly fixed

3 : a brand of wristwatch