More Fabulous Fossils

Public summary: 

Travel back in time through millions of years of Earth's history! If you've ever wanted to see what strange creatures lived in the past then take a look at these fabulous fossil!

A collection of various fossils (Sedgwick Musum Fossil Set 29)

A collection of various fossils (Sedgwick Musum Fossil Set 29)
Useful information
Kit List: 

Large ammonite (partially broken)
Slab of smaller ammonites
Irregular Echinoid (sea urchin)
Two trilobites, one on the top surface, the other in the middle of two slabs of rock
Large fish
Shark Tooth
Laminated pictures
Form to fill in about usage

Packing Away: 

Place all fossils carefully inside the relevant foam slots.

Frequency of use: 


This box of fossils (on loan from the Sedgwick Museum, called Fossil Set 29) has a variety of different invertebrate and plant fossils from different periods of Earth's history. This box can work well in conjunction with the Rocks and Fossils experiment. Emphasise the different morphological features of the fossils and what the creatures were like when they were alive. Possibly talk about how fossils can help you travel back in time and see what was living millions of years ago. If they seem to be old enough you should let them hold the fossils, but tell them to be very careful as they are very old.

At some point it is a good idea to ask children if they know what fossils are and how they form. If they aren’t too sure, explain how hard parts of animals – teeth, bones, shells – can be buried under layers of sediments, and eventually become fossilised. However, plants, footprints, tree sap and excrement can all be fossilised too. The fossil we see may be as it originally was, it may have recrystallised, or it may be an imprint. The details of fossilisation processes are actually very complicated, but fortunately a general idea of what happens is sufficient. The book in the box explains this for a general audience, so it's probably worth a look through.

Wikipedia says that:
"Fossils (from Latin fossus, literally "having been dug up") are the preserved remains or traces of animals (also known as zoolites), plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous (fossil-containing) rock formations and sedimentary layers (strata) is known as the fossil record. The study of fossils across geological time, how they were formed, and the evolutionary relationships between taxa (phylogeny) are some of the most important functions of the science of paleontology. Such a preserved specimen is called a "fossil" if it is older than some minimum age, most often the arbitrary date of 10,000 years ago.

Hence, fossils range in age from the youngest at the start of the Holocene Epoch to the oldest from the Archean Eon several billion years old. The observations that certain fossils were associated with certain rock strata led early geologists to recognize a geological timescale in the 19th century. The development of radiometric dating techniques in the early 20th century allowed geologists to determine the numerical or "absolute" age of the various strata and thereby the included fossils.

Like extant organisms, fossils vary in size from microscopic, such as single bacterial cells only one micrometer in diameter, to gigantic, such as dinosaurs and trees many meters long and weighing many tons. A fossil normally preserves only a portion of the deceased organism, usually that portion that was partially mineralized during life, such as the bones and teeth of vertebrates, or the chitinous or calcareous exoskeletons of invertebrates. Preservation of soft tissues is rare in the fossil record. Fossils may also consist of the marks left behind by the organism while it was alive, such as the footprint or faeces (coprolites) of a reptile. These types of fossil are called trace fossils (or ichnofossils), as opposed to body fossils. Finally, past life leaves some markers that cannot be seen but can be detected in the form of biochemical signals; these are known as chemofossils or biomarkers."

An awkward question I have been asked a few times is how do we know that a given fossil is 50 million years old? This is a hard one to answer, since most of the fossils are old enough to be dated using Uranium decay series. If children are old enough to understand Carbon-dating, you can make an analogy with this, otherwise you may have to make do with talking about relative dating using layers of sedimentary rocks.
The timeline should be useful for talking about ages of various fossils, since large numbers of years become a bit meaningless, but saying that something lived twice as long ago as the first dinosaurs impresses most children.

EduF64(large) and EduF65(small): Ammonites
These marine molluscs had spiral shells and were alive during the Mesozoic- the same time as the dinosaurs. These should not be confused with Nautilus, an animal with a spiral shell more closely related to the straight Nautiloids. They can be told apart by the position of the siphuncle – a tube used to move water between the shell’s chambers and control buoyancy – which runs along the outer edge of ammonites’ (and all ammonoids’) chambers, but through the centre of Nautiloids’. Ammonites vary in size from a couple centimetres to a couple metres, and are commonly found on the Dorset and Yorkshire coastlines.

Be careful of the broken part of the large ammonite. Compare the sizes of the group of small ammonites, the large ammonite and the picture of the gigantic ammonite.

EduF66: Irregular Echinoid (sea urchin)
The sea urchin is a member of a class of animals called echinoids. Echinoids are related to star-fish and tend to have a similar five-fold symmetry, though this may be less obvious depending on the specimen. During life, sea urchins are colourful balls of spikes that live on the sea-bed, feed mainly on algae, and can be found shallowly enough in warm seas such as the Caribbean that people occasionally step on their spines (which can hurt a lot!). The spines are designed to protect sea urchins against predators. They fall out within several days of the animal dying, leaving fossil sea urchins with tiny holes where each of their spines were attached during life.

EduF67a&b and EduF70: Trilobite
These are an extinct class of arthropods which lived during the Paleozoic, though they declined towards the end of it. Trilobites were some of the first animals to evolve hard parts (which is why they are also some of the earliest fossils that are regularly well-preserved) and eyes. Their hard shell meant that they could roll into a ball to protect themselves (as I think this specimen is doing). Their eyes were made from calcite crystals which had to be orientated correctly to avoid a double-image (you can demonstrate the double-image with the calcite crystal in the minerals box). Some had their eyes on stalks, while others were blind. Most moved over the sea-bed, but some swam, and they could be predators, suspension feeders or scavengers. The name trilobite refers to their three “lobes” – one that resembles a spine down the middle of the trilobite, and one on each side of it. I usually liken trilobites to woodlice to help children to imagine them.

EduF68: Fish
A Jurassic fish with armoured scales. Fish don't have this type of armour today, so what has changed. Think about predation or other factors. This is a good sample to talk about why things are fossilised, and why hard parts (such as the armoured scales) are preferentially preserved. Though there is some crayon on the sample, don't use it for rubbings!

EduF69: Shark Tooth
This is one of the most easily recognisable fossils we have. There is an opportunity here to talk about why sharks have such sharp, and often serrated, teeth, as well as why they are such common fossils (sharks have many sets of teeth and frequently lose and replace them). Sharks have skeletons made from cartilage, which makes them unlikely to be preserved, and have been around for more than 420 million years. The tooth is from a shark related to the Megalodon, which some children may have heard of. It lived roughly 28 to 1.5 million years ago, could grow up to around 20 metres in length, and had huge impressive jaws!

Risk Assessment
Date risk assesment last checked: 
Wed, 11/01/2017
Risk assesment checked by: 
Date risk assesment double checked: 
Tue, 07/02/2017
Risk assesment double-checked by: 
Risk Assessment: 

Plastic box (on loan from Sedgwick Museum) with a variety of fossils, information card with fossil names and box layout.

Possible choke hazard for small children with the smaller fossils.
Dropping fossils could cause injury to feet, and some may be very heavy for small children.
Dropping fossils may cause them to shatter, producing shale dust
Fossils could be sharp and cause cut injury

Ensure that items are not in the reach of small children.
Hold fossils over a table or close to the floor (i.e. when sitting on the floor).
Make sure children check the weight before holding them.
Make sure fossils have no sharp edges.

Contact first aider if injury occurs.