quantitatively measure the absolute ages of rocks and the fossils they host. There are many processes that lead to fossilization, including permineralization, casts A fossil (from Classical Latin fossilis, lit. 'obtained by digging') is 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 and DNA remnants. The totality of fossils is known as the fossil record. Though the fossil record A fossil (from Classical Latin fossilis, lit. 'obtained by digging') is 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 and DNA remnants. The totality of fossils is known as the fossil record. Though the fossil record is incomplete, numerous studies have demonstrated that there is enough information available to give a good understanding of the pattern of diversification of life on Earth, and it can fill gaps in our understanding of the sequence of evolution on earth. Paleontology includes the study of fossils: their age, method of formation, and evolutionary significance. Specimens are sometimes considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years to 4.1 billion years old. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the absolute ages of rocks and the fossils they host. There are many processes that lead to fossilization, including permineralization, casts and molds, authigenic mineralization, replacement and recrystallization, adpression, carbonization, and bioimmuration. Fossils vary in size from one-micrometre (1 μm) bacteria to dinosaurs and trees, many meters long and weighing many tons. The largest presently known is a Sequoia sp. measuring 88 m (289 ft) in length at Coaldale, Nevada. 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 or calcareous exoskeletons of invertebrates. Fossils may also consist of the marks left behind by the organism while it was alive, such as animal tracks or feces (coprolites). These types of fossil are called trace fossils or ichnofossils, as opposed to body fossils. Some fossils are…

Studies on the allergenicity of Baltic amber. Baltic amber is a fossil resin deposited 36-7 million years ago and one source may be the extinct tree Pinites (Pinus) succinifer. Palaeobotanical studies of amber have an extensive literature, but the aspect of allergenicity has not been addressed before. The aim of our study was to present the results from sensitization studies with Baltic amber and to discuss these in view of possible cross-reactivity with contact allergens in colophony. It is concluded that allergens found in colophony can also be present in Baltic amber. The main resin acids were identified in an ether-soluble extract of amber. Amber suspended in petrolatum caused positive patch test reactions in patients with contact allergy to colophony. Furthermore, animals sensitized to colophony showed positive reactions to amber, but animals induced with amber did not react when challenged with amber. A use test with an amber necklace in patients with positive test reactions to amber and colophony was negative, which supports the view that amber in personal ornaments is not a clinical problem. Published in Contact dermatitis (1992)

Fossilized plant resins, or ambers, offer a unique paleontological window into the history of life. A natural polymer, amber can preserve aspects of ancient environments, including whole organisms, for tens or even hundreds of millions of years. While most amber research involves imaging with visual light, other spectra are increasingly used to characterize both organismal inclusions as well as amber matrix. Terahertz (THz) radiation, which occupies the electromagnetic band between microwave and infrared light wavelengths, is non-ionizing and frequently used in polymer spectroscopy. Here, we e

diversified group of the Arachnida; about 2000 species are known. No noteworthy fossil spiders are known; the best-preserved are in amber of Oligocene age