Cambrian fossil over 500 million years old - weird! - but clearly a
How do you know it is a fossil - characteristics of
once living things vs. non-living things
How do you know something is a fossil?
Years of practice helps but here are three basic guidelines....
The fossil trilobites below are a a different color than the
surrounding khaki rocks.
This because fossils usually consist of the hardest and most durable
remains of an ancient creature. It is a different material that falls into
the unconsolidated sediment so it has a different colour.
Afterwards, what once might have been bone or shell is often replaced cell
by cell with rock (often the mineral calcite)
So for example fossil bone (now rock) is denser than
weathered modern bone.
Fossils may be lighter than the rocky substrate, or they might be darker –
it all comes down to the weathering process, and the fossil materials. Plant fossils are almost always darker than the rock in which
they’re found probably because they originally contained carbon.
Alternatively, microfossils on the ground, tend to be a lighter,
almost creamy color since they have been exposed to the elements—though
teeth, claws, and scales are dark and glossy.
110Myo schleral (eye support) ring of an ichtthyosaur is a different
colour than the host rock
Fossils have textures that remind us of the textures in living things.
A piece of fossil turtle shell has a distinct, dimpled texture, which
makes it noticeable even though it’s only about 4 cm wide.
Some bone patterns can tell you who the original owner might have been.
Turtle shells have little pits and grooves on one side. Young and old
members of the same species differ in the growth patterns on their bones,
a fact which can help scientists determine the biological age of a fossil.
Sometimes bones even have little marks on them where muscles used to be
texture of a 4.2Myo turtle shell is similar to a modern turtle, pointer
shows tooth mark of a crocodile attack
fossil bones with porous textures
Bones are more porous than rock, and this texture difference makes them
easier to spot. Because of its “spongy” texture, if you touch a fossil to
your tongue it will typically stick, whereas rock and soil won’t. If
you’re not in the mood to do the tongue test, you can also look for pores
through a hand lens.
If you’re lucky, the item’s shape will be an even bigger clue. While many
bone fragments are unidentifiable, there are many bones that are highly
diagnostic for an entire group of animals, if not for a species. These
diagnostic bones tend to be things with complex shapes, like vertebrae,
skull bones, and even teeth and claws. For plants, the diagnostic features
tend to be the leaf edges and bases, as well as the pattern of
Fossils come in a wide variety of shapes, but they pretty well all have
shapes that remind us of shapes in living things. Living things repeat
patterns but each repetition though slightly different can be modeled on a
computer using mathematics called chaos theory.
Distinctive bones aren’t the only fossils with easily identifiable shapes.
Coprolites (fossil poop) look the way you’d expect them to, and tend to be
a little bit lighter than the rocks around them. Casts, molds, and
steinkerns (internal molds) look like the original organism; mollusks and
other animals with shells are often preserved this way. If you spend even
a short time looking for fossils, you’ll learn how to tell that the thing
in your hand is a vertebra or a root. But to know what genus it belongs
to, you’ll have to spend some time handling fossils and doing research.
Generations of scientists have taken the time to describe in detail the
anatomy of animals past and present, and you can compare your fossils to
fossil poo (called a coprolite) looks like modern poo but everything
soft is replaced by rock
Some things look a lot like fossils but are not. We call them
pseudo-fossils (pseudo means fake).
"fern-like" manganese crystals on a rock surface are not a fossil
Some fossils are the actual creature for example an insect in a
piece of amber (fossilised tree sap) is still the original insect!
original text by Juliana Olsson, NMNH Office of Exhibits Writer with
the support of Angela Roberts and Siobhan Starrs - abridged by Earth
Fossils are found in sedimentary rocks most of the time.
Sometimes fossils can be found under volcanic ash or even preserved under
a lava flow, but this is very rare.
NOTE: Sedimentary rocks do not always have fossils in them.
Layers are a characteristic of sedimentary rocks. The bottom layers are
naturally the oldest.
Some types of rocks found in the layers:
Limestone, mainly calcium carbonate, common in warm, shallow seas, often
Shale is a fine grained rock formed from silt and clays. It preserves
Sandstone is widespread in desert deposits and on shallow water sediments.
Ripple marks and Mud cracks are characteristics of many sedimentary rocks
formed in shallow waters. Ripple marks are common in shale. Mud cracks are
form when mud drys quickly. These imply the presence of sunlight, water
and moderate temperature conditions related to the possibilities of life.
Sedimentary is your best bet for finding something. Too find some where
that has fossils is quite hard if you don't already know where a site is.
If you don't know where a site is you could ask the local Rock Club or a
Museum. You could also look in freshly exposed rock, like look in road or
railway cut. Visit mine dumps quarries and places where rocks are being
excavated for new construction. Cliffs, river banks, headlands and other
naturally exposures are also good. Remember that all these places have an
element of danger. Watch for traffic at road cuts and get permission
before entering quarries.
Looking in Creek Beds and Streams...
1.Start at the bottom of the creek
2.Look for fragments of bone
3.Follow them up the creek looking for larger, more angular bits as you go
4.When the bits of bone stop. Look up on the banks for the fossils
5.Find the larger piece of bone and excavate it
The age of the rock is important -
Geological Time Periods
Generally speaking the Age of the Rocks gives you a good idea you what
kinds of fossils you are likely to find
The time periods are very important to a fossil hunter (palaeontologist).
The table below is a very simple Geological Time Line. These are the
older traditional Geological Periods. Click on a geological period below to take you to a description
of life on earth at that time...
The Quaternary Period is a geologic time period that encompasses the most
recent 2.6 million years — including the present day.
Part of the Cenozoic Era, the period is usually divided into two epochs —
the Pleistocene Epoch, which lasted from approximately 2 million years ago
to about 12,000 years ago, and the Holocene Epoch, which began about
12,000 years ago.
The Quaternary Period has involved dramatic climate changes, which
affected food resources and brought about the extinction of many species.
The period also saw the rise of a new predator: man.The Quaternary Period:
A Time Of Giant Mammals or Megafauna The Pleistocene is known for its
megafauna or “giant mammals.” Along with the wooly mammoth and wooly
rhinoceros there were other giants: bison, ground sloths, and deer. There
were giant carnivores as well. The saber tooth tiger, cave bear, and dire
wolf were bigger than their modern counterparts. The megafauna disappeared
at the end of the Pleistocene. All that remains are a few species of
smaller, though still good-sized, animals in Africa: the elephant,
hippopotamus, and rhinoceros. The Rise of Humans For us, the most
important development of the Quaternary Period is the development of the
hominids: Humans. From the first primates in the Tertiary Period to modern
man, the hominid species has evolved amazing abilities. The earliest
hominid fossils found so far date from the late Tertiary Period. They were
found in Africa. As the Pleistocene Epoch continued, hominids spread
throughout the world. Their larger brains allowed a level of thought and
feeling that was, and is, unique among the animals. We think and solve. We
change and control. The future of our planet will be greatly affected by
the Age of Humans.
During the course of the Neogene period, life on earth adapted to new
ecological niches opened up by global cooling--and some mammals, birds and
reptiles evolved to truly impressive sizes in the process. The Neogene is
the second period of the Cenozoic Era (65 million years ago to the
present), preceded by the Paleogene period (65-23 million years ago) and
succeeded by the Quaternary period---and is itself comprised of the
Miocene (23-5 million years ago) and Pliocene (5-2.6 million years ago)
epochs. the Neogene period the golden age of open prairies and savannahs.
These extensive grasslands spurred the evolution of even- and odd-toed
ungulates, including prehistoric horses and camels (especially in North
America), as well as deer, pigs and rhinoceroses. During the later
Neogene, the interconnections between Eurasia, Africa, and North and South
America set the stage for a confusing network of species interchanges,
resulting (for example) in the near extinction of South America's
Australia-like megafauna. From a human perspective, the most important
development of the Neogene period was the evolution of apes and hominids.
There were two major trends in plant life during the Neogene period.
First, plunging global temperatures spurred the rise of massive deciduous
forests, which replaced jungles and rain forests in high northern and
southern latitudes. Second, the worldwide spread of grasses went
hand-in-hand with the evolution of mammalian herbivores, culminating in
today's familiar horses, cows, sheep, deer, and other grazing and ruminant
Mammals began a rapid diversification during this period. After the
Cretaceous–Paleogene extinction event, which saw the demise of the
non-avian dinosaurs, mammals transformed from a few small and generalized
forms that began to evolve into most of the modern varieties we see today.
Some of these mammals would evolve into large forms that would dominate
the land, while others would become capable of living in marine,
specialized terrestrial, and airborne environments. Those that took to the
oceans became modern cetaceans, while those that took to the trees became
primates, the group to which humans belong. Birds, which were already well
established by the end of the Cretaceous, also experienced an adaptive
radiation as they took over the skies left empty by the now extinct
Pterosaurs. In comparison to birds and mammals, most other branches of
life remained relatively unchanged during this period. As the Earth
cooled, tropical plants became less numerous and were now restricted to
equatorial regions. Deciduous plants, which could survive through the
seasonal climates the world was now experiencing, became more common.
This Era started 65 million years ago and finished 2 million years ago.
This Era is split into 5 parts.
This was the Era of mammals.
Life in the Tertiary Era On land, the age of the mammals was beginning.
Rodents evolved, as well as gliding mammals and the early primates. Sharks
and fish took over from marine reptiles. Towards the middle of this Era,
the ancestors of elephants, horses, cattle, pigs, rhinos and deer
appeared. Other mammals such as whales and sea cows took to the water.
Other groups of animals were also evolving, including ants and bees,
starlings and penguins, moles, camels, cats, dogs and bears. Towards the
end of this period , grazing hoofed animals spread and diversified. The
ancestors of humans appeared in Africa.
Plant life in the Tertiary Era In the early parts of this era, flowering
plants continued to spread and diversify. Towards the end of this era the
climate cooled, grasslands took over from the forest
Started 144 million years ago and lasted to 65 million years ago. This was
the period of the explosion of flowers.
The explosion of flowers Up until the beginning of the Cretaceous Period,
the distribution of spores and pollen was a risky business. In the
Cretaceous Period new and more effective ways of spreading pollen
developed. Flowering plants were now evolving with a partnership with the
Life in the Cretaceous Period Giant turtles and marine reptiles dominated
the oceans. On land snakes evolved. There were new kind of dinosaurs.
Insects such as moths and butterflies, got there food from the new
flowers. At the end of the period, there was a mass extinction which saw
ammonites, ichthyosaurs, and many other marine groups to disappear and the
dinosaurs became extinct. Plant life in the Cretaceous Period The
following plants appeared and evolved relationships with insects for
pollination. The flowers spread rapidly over the land.
The Jurassic period started 213 million years ago and lasted until 240
million years ago. This was the first period to have birds.
Life in the Jurassic Period Turtles and crocodiles increased in numbers
and variety. New species of plesiosaur and ichthyosaur arose. On land
insects were thriving including ancestors of modern ants, bees, earwigs,
flies and wasps. The first bird appeared. Dinosaurs ruled the land.
Plant Life in the Jurassic Period Plants spread across the land as the
climate became wetter. The of the modern cypresses, pines and redwoods
appeared in the forests.
This period started 248 million years ago and finished 213 million years.
This period was the beginning of the Mesozoic era.
Life in the Triassic Period Dinosaurs and other reptiles became the
dominate land animals. Frogs appeared and later the first tortoises,
turtles and crocodiles. The first mammals appeared.
Plant Life in the Triassic Period The cone-bearing plants diversified
forming forests of cycads, monkey-puzzle trees, ginkgoes and conifers.
This period started 286 million years ago and went to 248 million years
ago. This period was the period which reptiles took over.
Life in the Permian Period
Ammonities were still very abundant. Modern corals began to take over the
early reefs. In the early part of this period amphibians dominated fresh
water. Aquatic reptiles evolved. Towards the end of this period over 50%
of the animal families disappeared, including many amphibians, ammonities
and trilobites. Reptiles took over from amphibians on land.
Plant Life in the Permian Period
Conifers appeared and spread inland and up mountains. The southern land
mass was dominated by forests of large seeding ferns.
This period went from 360 million years ago to 286 million years ago.
During this period insects were everyware and the decaying trees during
this time produced the coal known today
Life in the Carboniferous Period Ammonites and Brachiopods became more
abundant. The age of amphibians appeared. Insects including grasshoppers,
cockroaches, silverfish, termites, beatles and giant dragonflies also
evolved. In the late part of this period the first reptiles appeared.
Plant Life in the Carboniferous Period Dence forests of giant clubmosses,
horsetails, tree ferns and sead plants up to 45m tall. The undecomposed
remains of these forests develop into coal.
The Devonian period started at about 410 million years ago and ended about
375 million years ago. This period was the age of the fish.
Life in the Devonian Period During this period there was a rapid evolution
of fish, including sharks and rays, lobe finned fish and ray finned fish.
Ammonities increased in population. Giant squid up to two meters long
hunted the seas. Many arthropods including spiders and wingless insects
invaded the land. Plant Life in the Devonian Period Plants spread from the
margins of the water to cover large areas of land in dense forest. Some
trees developing up to 38m high.
These time periods from 500 million years ago to 435 million years ago. In
these periods powerful predators and reefs began to be built.
Life in the Ordovician and Siluran Periods
In these periods there was a great increase in filter feading animals.
These included sea mats, sea lilies, brachiopods, molluscs and graptolites
which all met their peak in the Ordovician period. Durying the Siluran
period rugose corals were very active reef builders. This was the age of
the great preditors including sea scorpions, and the first jawed fish.
Brachiopods and trilobites thrived.
Plant life in the Ordovician and Siluran Periods
The first true plants first apeared in the late Ordovician period. In the
Siluran period plant life surounded the margins around the water.
The Cambrian period began about 570 million years ago. It lasted for about
70 million years. The period began with an astonishing explosion of
evolution, during which most of the major groups of animals we know today
made their first appearances on Earth.
The Cambrian Explosion
The Cambrian explosion is one of the biggest mysteries in the history of
life. It took 2.5 billion years for simple cells to become more complex
cells. It took another 700 million years for multicellular creatures to
appear. Then, in just 100 million years, came a tremendous variety of
multicellular animals. For over 500 million years not a single new basic
body plan was evolved.
The Cambrian period sea level rose and fell making some populations
extinct. As the Cambrian period went on, animals evolved new and more
specialized ways of feeding thus creating a greater variety of animals.
Life in the Cambrian Period
In the huge burst of evolution creatures including microscopic organisms,
sponges, starfish, sea urchins, sea lilies and velvet worms all evolved in
this period. The first shelled animals also appeared; trilobites and
brachiopods who then dominated the seas. Later in the period molluscs and
primitive fish evolved. Trilobites were a major step in the evolution
because they had the first eyes.
Plant Life in the Cambrian Period
In the Cambrian seas the only plant life was primitive algae and seaweeds.
The Precambrian Period starts with the birth of Earth to the appearance of
many-celled animals, about 570 million years ago.
Methane and other gases were the only gases in the Earth primitive
These gases dissolved into the masses of water which covered the Earth,
forming a complex chemical "soup".
Lighting discharges on this soup acted in a way that caused the chemicals
to react, forming more complex chemicals very similar to the ones in
After a few million years these chemicals developed the ability to
reproduce. In the soup there was also fat globules.
If the soup was stirred violently by the wind, the complex chemicals may
have become trapped within the fat globules.
In time these structures evolved into lining cells surrounded by fatty
membranes. Life in the Precambrian seas
Some of the first life in the sea was stromatolites,
which appear to be made up of lots of rings of limestone, with organic
layers in between.
Later life in these sea saw a range of soft body creatures, including
jellyfish, worms and leaf like sea pens.
The only evidice left from that period where trace fossils left by the
Comparing to Index Fossils
An index fossil is a fossil that is useful in working out the age of a bed
of rock. You need several index fossils in combination to got a good date.
A good index fossil needs:
To be easy to identify
Exists over a short geological time range
Has worldwide distribution
Typical index fossils courtesy USGS...
Index fossils in the first area determine the age in the second area.
Find the fossil and look at it, see which way the covered piece of
the fossil is pointing
Start cutting away at the top and at the sides of the fossil. With
the large chisel when the fossil is well below were you are working,
and then use the small chisel when you get closer to the fossil. Use
the screwdriver and then the dental pick to get really close to the
fossil. Use the paintbrush to make sure you can see what you are
doing. While you are doing this cover the end of the fossil with some
newspaper or something to protect it from falling pieces of rock. Keep
digging until the whole topside of the fossil is visible. Put some
wood glue on as soon as you have finished the topside.
Start cutting away from the bottom, be very careful, as there may be
something even better below!Do the same as the topside only starting
below the fossil this time. Apply the wood glue then remove the fossil
carefully putting it on some newspaper. Wrap the fossil tightly in the
newspaper and put it in the packsack and keep it out of the sun.
Take a good close look at the fossil make sure to note the
location of all the pieces of fossil, so that later you can
reassemble it in the correct order. Remember that fossils in
sandstone are not always in good condition. Although they may be
easer to get at they are much harder to get out in one piece.
As a rule any fossil, in loose sand or rock, must be approached
from the top. If you try excavating for the bottom the fossil will
fall out. Before you start digging cover the fossils with some thing
to protect them. Use the shovel first to get started then as you get
closer to the fossil use the screwdriver and the paintbrush. For the
really fine work use the dental pick. As soon as the fossil is
completely visible cover it with the wood glue. The wood glue acts
as the rock around the fossil after it has been removed from the
rock. The glue prevents the fossil from expanding and cracking from
the sudden drop in pressure and change in humidity and temperature.
The first thing you will need
before you excavate anything will be Tools and some basic essentials.
There are a few basic packs you should take for different environments.
If the fossils are in solid rock.
A good pack sack to carry the removed fossil.
Newspaper is used to wrap and protect the fossil after it has
Note books and pens are a good thing to bring along, as you can
make notes of were you found the fossil, it condition and its basic
shape this can then be used later to give some information to help
classify the fossil later. This white wood glue is great because it
dissolves in water so if you need to reassemble or if you mess-up
you can soak the fossil and try again!
A hammer and a large and small cold chisel are used to remove
fossils from the rock.
A steel prying bar may come in handy.
A screwdriver, dentist pick and a paintbrush can be used to do
fine work and brush away dust from the site.
Plaster may be handy if you want make a mould of the fossil.
Aquadhere or similar white wood glue is good for protecting
the fossil as it comes out of the rock. The glue holds all the
little bits on the fossil. It should be the kind of glue that when
you soak it in water it will soften again so if you get the pieces
wrong the first time you can glue them together again. Test it
before you use it in the fiels
A map (detailed topographic or geological),gps, compass(do not
rely on just one device to find your location), magnifying lens
first aid kit
plenty of water
leave a plan of where you are going and when you will get back
with a reliable person and let them know when you are done
a phone or radio check each day is a good idea
check weather forecast and keep an eye on the weather - get
out early if the weather looks like it will go bad
Dinosaur's tracks can be used to find out some things on the dinosaurs
With footprints you can see a bit of the dinosaurs life style like if it
is sitting down, walking, swimming or running.
You can find out how big the dinosaur was by the depth of the
Also you may be able to find out what family it comes from, for example
Sauropods they are the dinosaurs that walk on
4 legs mostly larger then other dinosaurs. Theropods
are bird-like, they walk mainly on 2 legs and eat meat.
Hadrosaurs are also bird-like, walk mainly on 2 legs but they eat
Two legged Dinosaur
Tracks with short distances between footprints indicate dinosaurs at
slow speeds. Running
Tracks with longer distances between footprints indicate dinosaurs at
Incomplete footprints suggest that the dinosaurs swam.
The dinosaurs in this position may have been resting, having a sleep or
rolling in the mud to rid itself of parasites. This is a good example of
4 Legged Dinosaur
Tracks with short distances between footprints indicate dinosaurs at
slow speeds. Slow walking 4 legged dinosaurs, such as Sauropods would
leave a pattern of tracks as shown above.
Dinosaurs are divided into two groups based on hip structure:
There were many kinds of ornithischian dinosaurs, dating back to the
early Jurassic. The Ornithopoda included the hadrosaurs ("duck-billed
dinosaurs"), the iguanodontids, the heterodontosaurs, the
hypsilophodontids, and various other dinosaurs. The Ceratopsia included
the horned dinosaurs, the Ankylosauria and Stegosauria (now usually
grouped together in the Thyreophora) included various types of armored
dinosaurs, and the Pachycephalosauria, the extremely thick-skulled
The Ornithischian dinosaurs had a hip structure similar to that of
birds, but they were not the ancestors of birds. They outnumbered the
Saurischians. The Ornithischians were vegetarian, and included
two-legged, plated, armored, and horned dinosaurs.
Marginocephalia, a group including:
Ceratopsia (horned dinosaurs)
Ornithopoda, a group including:
Hadrosauridae ("duckbilled" dinosaurs) Heterodontosaurus, the "different-tooth" dinosaur.
Certain features distinguish Saurischians (among other major
characteristics; including a grasping hand, asymmetrical fingers, and a
long, mobile neck) is the pubis that points downward and forward at an
angle to the ischium.
The saurischians form two major groups.
Sauropoda were large herbivores such
as Apatosaurus and Diplodocus.
Theropoda were bipedal carnivores
(meat eaters), ranging from the chicken-sized Compsognathus
and the fearsome Deinonychus and Velociraptor to the
crested Dilophosaurus and the gigantic Tyrannosaurus.
The oldest known dinosaurs, from the middle Triassic of South
America, were saurischians.
Living birds had common ancestors on the theropod lineage. Oddly, birds
are derived from the "lizard-hipped" dinosaurs and not from the
"bird-hipped" ornithischian dinosaurs.
The "bird-hipped" condition of a pubis pointing toward the back of the
animal occured twice independently, once in the ornithischians and once
in the lineage leading to birds, an example of convergent evolution.
Thus "ornithischia," taken literally, is a misnomer, since the
ornithischians have ornithischian-like pelves, not bird-like.
Only birds (and their immediate ancestors) have bird-like pelves.