Fossils

Sedimentary rocks show fossils, because of pre-existing life forms.

They also show ripple marks due to weathering and erosion...

Imprint

Many fossils are actually far older; some going back 5 or 6 times as far in history.

However, trilobites are some of the oldest 'macroscopic fossils' (fossils of bigger things than bacteria and single-celled organisms) simply because they were there in large enough numbers and in the right conditions to be fossilised first too.

Without rapid burial decay will take place and you will not be left with a fossil. In the same way coalification requires rapid burial of organic material. A good example of this is spirit lake in Washington state.

A body fossil would be in the form, or part of, the organism that has fossilized. A trace fossil indicates evidences other than a fossilized body part, that indicates the existence of an organism, such as burrows, trails, eggs, nests, and fecal matter.

balls

Most fossils are found in sedimentary rock, because igneous and metamorphic rock undergo great heat and pressure when forming, where as sedimentary rocks undergo much less pressure and heat to form, better preserving the fossil

Traditionally the earliest dinosaur was considered Eorapter. Examples have been found in the Ischigualasto Basin in Argentina dating from 230 million years ago.

A recent discovery of a pro-sauropod was found possibly predating this discovery in Madagascar.

We have an incomplete fossil record because the earth is continually re-cycling its' crust.

The oldest oceanic crust is less than 200 million years old and as most fossils are found in sediments deposited at the bottom of seas and oceans, this means that only the small amounts pushed up onto the edge of continents, when oceanic crust is subducted, are preserved.

Fossilization is only a very rare occurrence so many species of animals and plants never get the chance to become fossils.

There are other reasons; when an earthquake pushes up a part of the crust it disturbs the cycle of deposition of sediment. A drop in sea level would also do something similar. This means that if organisms were previously buried, a change of deposition could mean whole sections of sediment being washed away, along with the potential fossils.

Any internal organs. Only bones become fossils.

== == They are both composed of minerals. They both occur from natural processes. They are both solid. Both types have rocks that have varied chemical compositions. Either would tend to cause damage when thrown at an object with some energy.

They are dissimilar in their method of formation. Sedimentary rocks are formed by processes that usually involve the compaction and cementation of sediment particles over geologic time spans. Igneous rocks are those that have solidified from magma, either below, at, or above the surface.

They would look for evidence of index fossils, those of certain rapidly evolving creatures that lived during a specific time period. This method is called relative dating. For a closer estimation they would be able to date the rock using radiometric techniques that base its age on the degree of isotope decay . This method would reveal the much more specific absolute age.

A Geologist.

Fossils are proof of organisms that lived long ago

Microscopic fossils are also known as microfossils.

If the fossils that the scientists find are very evolutionarily similar, for example, if they are the same species or genus, then that means that the sedimentary rock layers have some correlation to each other since the two extinct animals that turned into the fossils most likely lived during the same time period. This hints that the two rock layers were both exposed to the atmosphere during the same time period.

The name "Lucy" is supposedly inspired by the Beatles song "Lucy in the Sky with Diamonds" a track which the team who found the fossil were listening to on the evening of the discovery.

Using methods such as radioactive dating, scientists can determine the approximate age of a fossil or the rock in which it was found. Utilizing this knowledge of approximate age, scientists can compare progressive fossils, and identify changes. Changes are often minimal, and sometimes organisms do not change at all for large amounts of time, making comparative analysis of fossils a tedious task.

Some eras produced better fossils than others. This can have several causes, such as particularly prolific habitation of environments that more easily produce fossils, general population booms, certain mass extinction events, and even happenstance. Because some eras produce better or more fossils, and some produce few to almost none, the fossil record can sometimes falter. In such cases, scientific investigations may be forced to fill in blanks between species using genetic analysis of preceding and proceeding species or groups within species, if the fossil(s) contain(s) any remaining genetic material. In other cases, computers will be used to recreate images of the species based on fossils, and identify progression between species. In any case, the fossil record is often used as a base off of which to obtain or recreate further information about an organism's evolutionary history.

Fossils are depositions of dead animal imprints and/or bones. When an animal or plant dies, its skin rots away, leaving behind the bone or imprint.

The ocean floor

Think of the layers like leaves of a book. The further you go back in the book is farther back in time. The layers show drought, floods, fires, and other things that happened in time. They are piled on top of each other. So, the further back you go the more apt you are to find fossils. Location also has a great deal to do with it.

horse

They are used to determine the relative ages of rocks by stating that younger rocks lie above older rocks, and that rocks that cut through a layer are younger than the existing layer.