Paleontology – An Introduction
- Paleontology is also known as Palaeontology. It is the study of prehistoric life.From the earliest time it has peen known that the paleo-marine animals are preserved under calcium carbonate beds. These calcium carbonate beds are quite abundant in oceanic regions. So the probability of finding marine life preserved is more than terrestrial animals. This there are less cases of terrestrial animals to be preserved.
- The remains of plants and animals of past ages in rocks are called fossils , and the study of these fossils forms the subject of Paleontology.
- The Study of Paleontology is divided into two parts Vertebrate and invertebrate.
- For any plant or animal to be preserved there are some conditions
(A) It must posses a skeleton structure as the soft part decomposes easily. These skeleton will be preserved in the limestone or calcium beds
(B) The organism must be covered with some kind of deposit otherwise the skeleton will crumble into pieces.
- As there are very less places on land where the organisms can be preserved so they will have very less chance to be preserved.
- In calcareous organisms the carbonate of lime is ready to dissolve in water. So the mineral from which the skeleton is made is also of much importance. It is mostly Calcite and Aragonite. Calcite occurs in most of the animals. Calcite is lighter and it has hexagonal structure. The fossil calcite shells are translucent and has specific gravity 2.72. While Aragonite is heavier, its specific gravity is 2.93. It has rhombic system. Aragonite is chalky and opaque.
- The mineral character of the skeleton of chief calcareous organisms.
- Foraminifera – Calcite (vitreous)
- Porifera – Calcareous sponges of calcite.
- Anthozoa – mostly calcite but sometimes also found as aragonite.
- Echinoderma – All of calcite.
- Brachiopoda – All of calcite.
- Polyzoa – Chiefly of calcite.
- Gasteropoda – Majority are formed in aragonite but some spices are of calcite.
- Crustacea – The shell consists of chitinous material usually consists of calcite and some phosphates.
Main conditions in which fossils are preserved.
- The entire organism preserved.
- The skeleton of organism preserved almost unchanged.
- skeleton in pieces.
- Imprints of animal or organism preserved