Fossils (from Latin fossilis; literally, “obtained by digging”) are any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood, oil, coal, and DNA remnants. The totality of fossils is known as the fossil record. Paleontology is the study of fossils: their age, method of formation (biomineralization), and evolutionary significance (paleobiogeography). Specimens are usually considered to be fossils if they are over 10 thousand years old.
The oldest fossils date back to the early Cambrian period, some 540 million years ago. However the origin and timing of biomineralization events is not well understood. More than 99% of all species that ever lived on Earth are estimated to be extinct. Non-avian dinosaurs became extinct 66 million years ago in the Cretaceous–Paleogene extinction event, while most mammal groups such as plesiosaurs and saber-toothed cats also died out around this time due to another mass extinction event caused by an asteroid impact known as the Chicxulub impactor.
The study of fossils across geological time—through paleontological analysis—provides information about changes in anatomy through evolution, embryology,, biogeography,, population dynamics,:p44 diet,:p21 pathologies,:p526 behaviour:p183 and rates of molecular evolution. Microfossils include pollen grains which can show whether a plant reproduced sexually or asexually; foraminifera which indicate sea water temperature at deposition; diatoms which indicate salinity; plant spores which give evidence for climatic change; authigenic minerals such as pyrite which show environments that existed when they were formed; micromolds with impressions left behind by other microorganisms; tracks left behind by trilobites etc.; sometimes insects entombed in amber provide information about plants close to where they were found because amber often contains resin from plants..
Fossil evidence has helped scientists piece together information about Martian geologic history , including when water might have flowed on its surface . The term “fossil” comes from the Latin word fossilis (“dug up”), which originally applied only to organic materials such as animal bones or shells. These derive from Greek φώσσις phōssis “that which one digs up”. It has been extended over time however so now includes anything dug up – even rocks!
Fossils range in size from one-micrometre (0.000039 in) bacteria-to giant sequoias 60 metres (200 ft) tall and weighing 180 metric tons (200 short tons). A fossil normally preserves only a portion of the deceased organism:-usually that part most resistant to decay.-Teeth and bone frequently survive time and fossilisation better than other parts.-In many cases however,-the person who discovers them has no idea what sort of creature they belong too! This was certainly true in ancient times when people discovered mammoth teeth thinking they were dragon’s teeth.-It wasn’t until 1677 that Robert Plot correctly identified them as coming from elephants.-Today we have many ways -including carbon dating,-to help us determine how old a specimen is -and what kind it is too.
Although most specimens turn out-to be just broken bits of shell or bone,-on occasion something much more interesting can be found.-A few lucky finds have included whole animals encased in tree sap(amber),tar(asphalt),ice(mummified)-or even iron pyrites!(Petrified Wood) Perhaps one day you will be taking part in an excavation yourself? If you do find something you think might be a fossil make sure:-You don’t damage it further trying to get it out!,-Label it so experts can identify where it was found,-Take lots of pictures before bringing it home with you.(And preferably get someone experienced to come take a look first)