For each animal that dies, its probabilities of becoming fossilised are estimated to be lower than one in a million. However at the Cradle of Mankind, the chances are higher because the area has the right mixture of conditions that promote fossilisation.
How are fossils formed:
For any fossil to be successfully formed and found several steps have to occur in succession. One overlooked step and the ancient remains of an animal or plant will either not be discovered or not be preserved.
Fossils are created when minerals including replace bones or calcium carbonate envelope along with other organic matter, hardening or casting them in a rock matrix for example breccia that stays unchanged for millions of years.
When many people think of fossils they think of large bones and dinosaur skeletons, but you can find many different types of fossils to be found. Palaeontologists, those who study fossils, separate them into two major types, trace fossils and body fossils.
Body fossils show us what a plant or animal looked like.
The very first type, body fossils, are the fossilised remains of plant or an animal, such as shells, bones and leaves. These can be cast and mould fossils, like the majority of the fossilised dinosaur skeletons and big bones, replacement fossils, like petrified wood, or entire body fossils, mammoths found in ice or insects trapped in amber.
Frozen mammoths, Petrified wood and insects in amber all are body fossils.
The 2nd type of fossil records the activity of an animal. Called trace fossils, these contain trackways, footprints and coprolites.
Footprints and coprolites are trace fossils, they show us how an animal lived.
Fossils are described as the preserved remains of a past geological age. After a living organism died, it became buried below the ground in the layers of sediment. Once these layers become rock, the remains are considered fossilized. Most fossils are of extinct organisms.
1. Fossils also can be the remains of activities of an organism, these are known as trace fossils and contain such things as coprolites (fossilized feces), footprints and burrows.
2. Hard tissues including shells, teeth and bones are more likely to get fossils, because softer materials generally decomposed prior to they became fossilized.
3. The largest dinosaur fossil is Sauroposeidon, which is thought to have stood 60 feet tall and might have weighed as much as 60 tons. That is as tall as a six-story building and as large as a nine elephants.4. The oldest fossil known is of a blue-green algae which lived on some rocks in South Africa 3.2 billion years back.