Useful Information about Fossils
Silurian Period (about 440 to 415 million years ago)
During this period, the Earth was warm and warm shallow seas covered much of
the land.
Silurian high sea levels and warm shallow continental seas provided a great
environment for marine life of all kinds.
Fish were becoming plentiful and they started to develop movable jaws. There were also
great numbers of Trilobites in this period, which are possibly the second most famous fossil
group, after the dinosaurs.
Devonian Period (about 415 t0 355 million years ago)
During the Devonian Period the first fish evolved legs and started to walk on land.
Earthquakes were very common and it was during this period that Caledonian
Mountains in Great Britain were formed due to the rise of the northern
Appalachian Mountains in North America.
Well into the 20th century, the Devonian was often quoted as being "the age of fishes",
referring to the great diversification of various aquatic groups in the period.
Climatius. Also called the ‘Spiny sharks’. They had a cartilaginous skeleton covered by a
thin film of bone.
Placodermi. The most primitive jawed fish. They had a bony skeleton and ‘armoured’ headshield and plates that covered the front part of their body.
Actinopterygii. Also called the ray-finned fishes and can be found in both fresh water and
marine environments from the deep sea to the highest mountain streams.
Eurypterus. A species of sea scorpion. Its sharp needle-like telson was probably used in
combat.
Sarcopterygii. Bony fish that had paired rounded fins. These fins, being similar to limbs,
suggest that these fish may be ancestors of land vertebrates.
Carboniferous Period (about 355 to 290 million years ago)
The Carboniferous gets its name from the extensive coal
beds found in Western Europe. Carboniferous rocks in
Europe largely consist of limestone, sandstone, shale and coal beds.
Marine life during this time is especially rich in crinoids and other echinoderms.
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Crinoids were sea creatures that fed by filtering small particles of food from the sea water
with their feather-like arms. Many fish also inhabited the Carboniferous seas; predominantly
Stethacanthus, commonly known as sharks. Sharks will often feed on crinoids.
Jurassic Period (about 205 to 145 million years ago)
The Jurassic period is often thought to be the golden age of the
large dinosaurs.
Stegosaurus A large, heavy built dinosaur, about the size of a bus,
with a heavily arched back, short forelimbs, head held low to the
ground and a stiffened tail held high in the air. It is believed to have existed over 130 million
years ago. The spikes were most likely used for defence, while the plates have been
proposed as a defensive mechanism, as well as having display and thermoregulatory (heat
control) functions.
Diplodocus The Diplodocus fossils were first discovered in 1877. Diplodocus is one of the
more common dinosaur fossils found in the Upper Morrison Formation, a sequence of
shallow marine sediments deposited about 150 to 147 million years ago. The long-necked,
long-tailed animal with four sturdy legs has been mechanically compared with a suspension
bridge. In fact, Diplodocus is the longest dinosaur known from a complete skeleton. It may
have been up to 54 m (177.05 ft) long, of which over 6 m (20 ft) was neck! Diplodocus had
an extremely long tail, which may have served as a counterbalance for the neck. The middle
part of the tail had 'double beams' (oddly-shaped bones on the underside), which gave
Diplodocus its name.
Dryosaurus The Dryosaurus (pronounced DRY-oh-SAWR-us) meaning 'oak lizard', got it's
name due to the roughly oak shape of its cheek teeth. It lived in the late Jurassic period,
around 150 million years ago. Some scientists suggest that it stored food in its cheeks. It
was probably a herd animal, which raised and protected its young after hatching. A quick
and agile runner with strong legs, Dryosaurus used its tail as a counter-balance. It probably
relied on its speed as a main defence against carnivorous dinosaurs. The fossils were first
discovered in the late 19th century.
Allosaurus The Allosaurus lived 155 to 145 million years ago. Its first remains were found
in 1877 and as one of the first well-known theropod dinosaurs, it has long attracted attention
outside of paleontological circles, and has been a lead dinosaur in several films and
documentaries. Allosaurus was a predator with a large skull, equipped with dozens of large,
sharp teeth. It averaged 8.5 metres (30 ft) in length, though remains suggest it could have
reached over 12 metres (39 ft). Relative to the large and powerful hind limbs, its threefingered forelimbs were small, and the body was balanced by a long, heavy tail. Allosaurus
was at the top of the food chain, probably preying on other large herbivorous dinosaurs.
Cretaceous Period (about 145 to 65 million years ago)
During the Cretaceous period life on both land and sea was rich and diverse.
Ammonites, which were distant relatives, of the squid flourished in the oceans.
Much of the chalk we have today was created in this period and many
excellent fossils of creatures such as Ammonites can often be found in it.
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