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My animal is....
My questions are...
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During this investigation, you are like the archaeologist discovering your animal's fossil. What questions do you have about your animal? Write 5 questions below that you would like to answer about your animal. Use your name as the title of the post.

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Let's start off with an explanation that rocks and minerals are different things. Rocks are groups of different minerals pushed together and combined. They don't have easy chemical formulas to describe their makeup. A ruby is considered a mineral. It's a nice pretty crystal with the same compounds throughout the object. But the rock that surrounds that ruby has many many different compounds (and even a few pieces of ruby mixed in). There's an easier example that many people can relate to. Think about quartz. On its own (as a mineral) it's a nice pretty crystal. But a piece of granite often has loads of quartz. It's ground up and crushed, but its still bits of quartz. Granite is a rock and quartz is a mineral.

Igneous rocks are the ones that were superheated and originally liquid. They come from the center of the Earth! Not really the center, but they often start their lives below the crust and then get pumped out. There are two basic types of igneous rocks. There are the rocks that make it to the surface (extrusive) and the ones that are stuck in the crust just below the surface (intrusive). These igneous types have all hardened after being molten rock. If you walk around a volcano, you will find those extrusive types. The intrusive types are usually found in areas called plutons and dikes, big old pools of molten rock that were just beneath the surface. Some examples of igneous rock are granite, all volcanic rock, basalt, and obsidian.

This rock type is created by heat and/or pressure. Even though heat is involved, they didn't start off as molten rock. But. You often find metamorphic rock near volcanoes and sources of super hot rock. The heat from the magma changes all of the rock around it. Try another explanation. Look at the name 'metamorphic.' It looks like the word used to describe insects that go through a metamorphosis. It's the same concept. Some force (heat/pressure) has changed these rocks from one type into a new type. The result is a metamorphic rock. Some examples are marble, jade, slate, and gneiss. Because pressure and heat are involved, these rock types are usually found deep beneath the surface. They are also found near fault lines where plates push against each other and create enormous pressures. Over time, because of the movement of the crust, these metamorphic rocks are pushed to the surface where you can find them every day.

The last of the big three rock types is probably the rarest... unless you live near the coast. Sedimentary rock types are created when sediment compresses. It's pretty simple. Here's the setup... A river flows through a canyon and picks up a bunch of silt. That sediment and silt runs downstream and deposits where the river ends. It could be in a flood plain or a valley, but we're using a coastline as an example. When that material gets to the beach, it sits there. Now if you watch this happen over millions of years, more and more sediment builds up and compacts. That compacted sediment eventually becomes a type of rock. Examples of sedimentary rock include sandstone, amber, anthracite, and limestone.

That's right, not all rocks are from Earth. Sure you can debate whether a meteorite is a rock, but you definitely find them all over the Earth. Some super big ones have created massive craters across the globe. Most scientists now believe that a super-massive meteorite hit the Earth and created an extinction event for the dinosaurs. There are also millions of tiny meteorites. They look just like rocks until you break them open. Meteorites are mainly made of iron and nickel. You will also find many smaller trace elements. The key thing to remember about meteorites is that they have much different percentages of elements than rocks on Earth. Many trace elements found on these space travelers are nearly impossible to find on Earth.

Or search the sites for a specific topic.

Our World: The Rock Cycle (NASA eClips Video)

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Geography4Kids.com: Earth Structure: Rock Types

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Let's start off with an explanation that rocks and minerals are different things. Rocks are groups of different minerals pushed together and combined. They don't have easy chemical formulas to describe their makeup. A ruby is considered a mineral. It's a nice pretty crystal with the same compounds throughout the object.

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Home | Soil By Subject | Around the World | Land & People Soils by Grade Level | Lessons & Activities | Other Resources A Program of the Soil Science Society of America

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Types of Fossils

Fossils can be divided into two categories, fossilized body parts (bones, claws, teeth, skin, embryos, etc.) and fossilized traces, called ichnofossils (which are footprints, nests, dung, toothmarks, etc.), that record the movements and behaviors of the dinosaurs.

The four types of fossils are:

mold fossils (a fossilized impression made in the substrate - a negative image of the organism)

cast fossils (formed when a mold is filled in)

trace fossils = ichnofossils (fossilized nests, gastroliths, burrows, footprints, etc.)

true form fossils (fossils of the actual animal or animal part).

There are six ways that organisms can turn into fossils, including:

unaltered preservation (like insects or plant parts trapped in amber, a hardened form of tree sap)

permineralization=petrification (in which rock-like minerals seep in slowly and replace the original organic tissues with silica, calcite or pyrite, forming a rock-like fossil - can preserve hard and soft parts - most bone and wood fossils are permineralized)

replacement (An organism's hard parts dissolve and are replaced by other minerals, like calcite, silica, pyrite, or iron)

carbonization=coalification (in which only the carbon remains in the specimen - other elements, like hydrogen, oxygen, and nitrogen are removed)

recrystalization (hard parts either revert to more stable minerals or small crystals turn into larger crystals)

authigenic preservation (molds and casts of organisms that have been destroyed or dissolved).

Body Fossils

The most common body fossils found are from the hard parts of the body, including bones, claws and teeth. More rarely, fossils have been found of softer body tissues. Body fossils include:

Bones - these fossils are the main means of learning about dinosaurs. The fossilized bones of a tremendous number of species of dinosaurs have been found since 1818, when the first dinosaur bone was discovered. The first nearly-complete skeleton (of Hadrosaurus foulkii) was found in 1858 in New Jersey, USA.

Teeth and Claws - Sometimes a bit of a broken tooth of a carnivore is found with another dinosaur's bones, especially those of herbivores. Lots of fossilized teeth have been found, including those of Albertosaurus and .

Eggs , Embryos , and Nests - Fossilized dinosaur eggs were first found in France in 1869. Many fossilized dinosaur eggs have been found, at over 200 sites. Sometimes they have preserved parts of embryos, which can help to match an egg with a species of dinosaur. The embryo also sheds light on dinosaur development. The nests and clutches of eggs tells much about dinosaurs' nurturing behavior. A dinosaur egg was found by a 3-year-old child.

Skin - Some dinosaurs had thick, bumpy skin, like that of an alligator . A 12-year-old girl discovered a T. rex's bumpy skin imprint, confirming that it had a "lightly pebbled skin."

Muscles, Tendons, Organs, and Blood Vessels - These are extremely rare because these soft tissues usually decay before fossilization takes place. Recently, a beautiful theropod fossil, Scipionyx, was found with many impressions of soft tissue preserved. Also rare are so-called dinosaur "mummies", fossilized imprints of dinosaur skin and other features. These are not real mummies in which actual animal tissue is preserved, but fossils that look a bit like mummies.

Trace Fossils

Trace fossils (ichnofossils) record the movements and behaviors of the dinosaurs. There are many types of trace fossils. Even the lack of trace fossils can yield information; the lack of tail-furrow fossils indicates an erect tail stance for dinosaurs that were previously believed to have dragged their tails.

A Hadrosaur footprint.

Trackways (sets of footprints) - Dinosaur tracks, usually made in mud or fine sand, have been found at over 1500 sites, including quarries, coal mines, riverbeds, deserts, and mountains. There are so many of these fossils because each dinosaur made many tracks (but had only one skeleton) and because tracks fossilize well.

Fossil footprints have yielded information about:

Speed and length of stride

whether they walked on two or four legs

the bone structure of the foot

stalking behavior (a carnivore hunting a herd of herbivores)

the existence of dinosaur herds and stampedes

how the tail is carried (few tail tracks have been found, so tails were probably held above the ground)

Unfortunately, linking a set of tracks with a particular species is often virtually impossible.

Although there were many more plant-eating dinosaurs (sauropods and ornithopods) than meat-eating dinosaurs (theropods), many more footprints of meat-eaters have been found. This may be because the meat-eaters walked in muddy areas (where footprints are more likely to leave a good impression and fossilize) more frequently than the plant-eaters).

Toothmarks - Toothmarks generally appear in bones .

Gizzard Rocks - Some dinosaurs swallowed stones to help grind their food (modern birds do this also). These stones, called gastroliths (literally meaning stomach-stones), have been found as fossils. They are usually smooth, polished, and rounded (and hard to distinguish from river rocks.)

Coprolites (fossilized feces) - Coprolites yield information about the dinosaurs' diet and habitats. Coprolites up to 40 cm (16 inches) in diameter have been found, probably from a sauropod, considering its size. A huge theropod coprolite was recently found Sasketchewan, Canada. The only meat-eater large enough in that area at that time was Tyrannosaurus rex.

Burrows and Nests - Fossils of dinosaurs' burrows and nests can reveal a lot about their behavior.

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Learn about different types of dinosaur fossils; body fossils and trace fossils.

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Fossils give us information about how animals and plants lived in the past.

Once people began to recognise that some fossils looked like living animals and plants, they gradually began to understand what they were. They realised they were actually the ancestors of today's plants and animals.

Some fossils are easy to identify and look like plants and animals alive today.

While we can easily recognise and identify some fossils, many fossils represent animals that no longer exist on Earth. We only know about extinct groups like dinosaurs, ammonites and trilobites through fossils.

Some animals and plant are only known to us as fossils.

By studying the fossil record we can tell how long life has existed on Earth, and how different plants and animals are related to each other. Often we can work out how and where they lived, and use this information to find out about ancient environments.

Fossils can tell us a lot about the past. Why not find out more about fossils?

If you read these pages you should get a pretty good idea of what a fossil is. Find out more about fossils by visiting

Introducing the basics What can fossils tell us?
How do fossils form? Different types of fossils

Invertebrate I.D. or the History of life

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oxford university museum of natural history

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Fossils give us information about how animals and plants lived in the past. Once people began to recognise that some fossils looked like living animals and plants, they gradually began to understand what they were. They realised they were actually the ancestors of today's plants and animals.

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Choose one, and confirm with your teacher!

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extinct animal extinct animals dinosaurs