TRILOBITES
Identifing different species of trilobite is very hard, but with some guidance it is possible. You can identify a trilobite from the shape of it's shell, the ribs and the spines.
ACASTE
UPPER SILURIAN TO LOWER DEVONIAN. 430-390 MYA.
Acaste is recognized by it's rounded shell.
2 cm is a decent size for an Acaste.
They have rounded shells but no spines.
2 cm is a decent size for an Acaste.
They have rounded shells but no spines.
AGNOSTID
UPPER CAMBRIAN. 510-500 MYA.
Agnostid is distinct for it's Pygidium and
Cephalon looking very similar.
12 cm is a decent size for an Agnostid.
They have flat shells and only 3 spines.
The Pygidium looks like the Cephalon.
Cephalon looking very similar.
12 cm is a decent size for an Agnostid.
They have flat shells and only 3 spines.
The Pygidium looks like the Cephalon.
ANOMALOCARIS
UPPER CAMBRIAN. 530-525 MYA.
Anomalocaris is recognized by it's lobster-like tail.
8 cm is a decent size for an Anomalocaris.
They have rounded shells, rounded spines and two tails with spines and a ram-like horn (antenna).
8 cm is a decent size for an Anomalocaris.
They have rounded shells, rounded spines and two tails with spines and a ram-like horn (antenna).
ASAPHIDA
MIDDLE CAMBRIAN TO UPPER SILURIAN. 513-420 MYA.
Asaphida is recognized by it's rounded shell.
6 cm is a decent size for an Asaphida.
They have rounded shells but no spines.
Their eyes are on their antennae.
6 cm is a decent size for an Asaphida.
They have rounded shells but no spines.
Their eyes are on their antennae.
CALYMENE
LOWER SILURIAN TO UPPER DEVONIAN. 430-360 MYA.
Calymene is recognized by it's rounded shell.
4 cm is a decent size for a Calymene.
The calymene trilobites found in Britian usually have 19 segments and those found in America usually have 13 segments.
They have rounded shells but no spines.
4 cm is a decent size for a Calymene.
The calymene trilobites found in Britian usually have 19 segments and those found in America usually have 13 segments.
They have rounded shells but no spines.
CORYNEXOCHIDA
LOWER CAMBRIAN TO UPPER DEVONIAN. 518-360 MYA.
Corynexochida is recognized by it's flat shell.
5 cm is a decent size for a Corynexochida.
They have flat shells and short spines on the Thorax.
They have longer and fewer spines on the Pygidium.
5 cm is a decent size for a Corynexochida.
They have flat shells and short spines on the Thorax.
They have longer and fewer spines on the Pygidium.
DIACALYMENE
LOWER SILURIAN TO UPPER DEVONIAN. 430-360 MYA.
Diacalymene is recognized by it's rounded shell.
5 cm is a decent size for a Diacalymene.
They have rounded shells, no spines and a wide head.
5 cm is a decent size for a Diacalymene.
They have rounded shells, no spines and a wide head.
ELLIPSOCEPHALUS
MIDDLE CAMBRIAN TO LOWER CAMBRIAN. 520-510 MYA.
Ellipsocephalus is recognized by it's rounded shell.
18 cm is a decent size for an Ellipsocephalus.
They have rounded shells but no spines.
Their ribs on the lobe cross each other,
forming a unique pattern.
18 cm is a decent size for an Ellipsocephalus.
They have rounded shells but no spines.
Their ribs on the lobe cross each other,
forming a unique pattern.
ENCRINURUS
LOWER ORDOVICIAN TO UPPER SILURIAN. 470-410 MYA.
Encrinurus is recognized by it's rounded shell.
3 cm is a decent size for an Encrinurus.
They have rounded shells and one spine on
the tip of the tail (unclear in image shown).
3 cm is a decent size for an Encrinurus.
They have rounded shells and one spine on
the tip of the tail (unclear in image shown).
HARPETIDA
UPPER CAMBRIAN TO DEVONIAN. 500-360 MYA.
Harpetida is recognized by it's flat shell.
15 cm is a decent size for a Harpetida.
They have flat shells and frontal spines
with flats surounding the Cephalon.
15 cm is a decent size for a Harpetida.
They have flat shells and frontal spines
with flats surounding the Cephalon.
LICHIDA
MIDDLE CAMBRIAN TO MIDDLE SILURIAN. 513-420 MYA.
Lichida is recognized by it's flat shell.
5 cm is a decent size for a Lichida.
They have flat shells and small spines on the Cephalon.
5 cm is a decent size for a Lichida.
They have flat shells and small spines on the Cephalon.
ODONTOPLEURIDA
MIDDLE CAMBRIAN TO UPPER SILURIAN. 513-470 MYA.
Odontopleurida is recognized by it's flat shell.
7 cm is a decent size for an Odontopleurida.
They have flat shells and a long spine on the Cephalon,
smaller spines on the Thorax and tiny spines on the Pygidium.
7 cm is a decent size for an Odontopleurida.
They have flat shells and a long spine on the Cephalon,
smaller spines on the Thorax and tiny spines on the Pygidium.
OGYGIOCARIS
LOWER ORDOVICIAN TO MIDDLE ORDOVICIAN. 490-470 MYA.
Ogygiocaris is recognized by it's flat shell.
20 cm is a decent size for an Ogygiocaris.
They have flat shells, small spines on the
Cephalon and a wide shell.
20 cm is a decent size for an Ogygiocaris.
They have flat shells, small spines on the
Cephalon and a wide shell.
OGYGOPSIS
MIDDLE CAMBRIAN TO LOWER ORDOVICIAN. 520-470 MYA.
Ogygopsis is recognized by it's flat shell.
4 cm is a decent size for an Ogygopsis.
They have flat shells and no spines.
PHACOPIDA
LOWER ORDOVICIAN TO UPPER DEVONIAN. 490-360 MYA.
Phacopida is recognized by it's rounded shell.
6 cm is a decent size for a Phacopida.
They have rounded shells, no spines and are
almost oblong in shape.
6 cm is a decent size for a Phacopida.
They have rounded shells, no spines and are
almost oblong in shape.
PROETIDA
UPPER CAMBRIAN TO UPPER PERMIAN. 500-251 MYA.
Proetida is recognized by it's flat shell.
6 cm is a decent size for a Proetida.
It was the last trilobite on Earth.
They have flat shells and two spines on the Cephalon.
6 cm is a decent size for a Proetida.
It was the last trilobite on Earth.
They have flat shells and two spines on the Cephalon.
PTYCHOPARIIDA
LOWER CAMBRIAN TO UPPER ORDOVICIAN. 521-450 MYA.
Ptychopariida is recognized by it's flat shell.
3 cm is a decent size for a Ptychopariida.
They have flat shells and two spines on it's Cephalon.
3 cm is a decent size for a Ptychopariida.
They have flat shells and two spines on it's Cephalon.
REDLICHIIDA
LOWER CAMBRIAN TO UPPER CAMBRIAN. 521-501 MYA.
Redlichiida is recognized by it's flat shell.
4 cm is a decent size for a Redlichiida.
They have flat shells and two small spines on the Cephalon, larger spines on the Thorax and very long spines on the Pygidium.
4 cm is a decent size for a Redlichiida.
They have flat shells and two small spines on the Cephalon, larger spines on the Thorax and very long spines on the Pygidium.
TRINUCLEUS
MIDDLE ORDOVICIAN TO UPPER ORDOVICIAN. 470-440 MYA.
Trinucleus is recognized by it's flat shell.
2 cm is a decent size for a Trinucleus.
They have flat shells and two very long spines on the Cephalon (these spines rarely fossilise). It has flats around the Cephalon.
