Paleontological Evidences

Paleontology is the scientific study of prehistoric life through fossils, which are often described as the true witnesses or documents of evolutionary history. Fossilization, the process by which plant and animal remains are preserved in sedimentary rock, falls into three broad categories. (i) Actual remains — hard parts such as bones, teeth or shells preserved essentially unchanged, usually because sediments covered and protected them from decay (e.g. a Woolly Mammoth preserved intact in frozen Siberian ground, or victims of the Mount Vesuvius eruption preserved in volcanic ash at Pompeii). (ii) Petrifaction — where the original body material is replaced molecule-for-molecule by minerals such as iron pyrites, silica, or calcium/magnesium carbonates and bicarbonates, while the original substance itself disintegrates and is lost. (iii) Natural moulds and casts — where a disintegrating body leaves an impression in soft mud that later hardens into rock (a mould), which may subsequently be filled by hard minerals to form a cast. A related trace fossil is the coprolite, hardened fossilised faecal matter, whos …