Trilobite Facts and Informaion: What are Trilobites, Where to find fossil Trilobites, Types of fossil Trilobites


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Trilobites
in this Gallery:
Agnostida Trilobites
Asaphiscus Trilobites
Eldredgeops (Phacops) Trilobites
Elrathia Trilobites
Cryptolithus Trilobites
Huntonia Trilobites
Triarthrus Trilobites
What is a Fossil?



Go to the MAIN GALLERY
Go to MAIN FOSSILGUY Page
Go to COLLECTING SITES





Utah Trilobite Hunt
Fossil Hunting Trip Report



Trilobite Collecting Site: North West Ohio is a Great place to find Trilobites!



Trilobite Collecting Site: Western New York has its Share of Trilobites!



The Eurypterid Gallery: Learn about New York's State Fossil!





Trilobite Fossil Gallery: Browse througha sample of trilobite fossils and learn about each one, including trilobite fossil hunting sites
The Trilobite Fossil Gallery
Fossil Hunting for Trilobites in an Ohio quarry! An enrolled fossil phacops trilobite as found We just found a fossil trilobite death plate. It's still in the ground.
Fossil Hunting for Elrathia kingi trilobites - Here is a plate with a couple on. Fossil Hunting for Calymene trilobites in Ohio This is an image of a flagship trilobite, a Huntonia from Oklahoma. It prepped out beutifully,
What is a Fossil Trilobite Trilobite Gallery Where to find Trilobites

Introduction to Trilobite Fossils - Trilobite Fossil Facts and Information

Diagram of trilobite fossils, showing the teminology, and the three lobes. This image shows Elrathia kingi trilobites from Utah
This image shows the three lobes of a trilobite (what they are named after), and also the 3 segments of a trilobite. The specimens pictured here are Elrathia kingi trilobites from Utah.

What is a Trilobite Fossil?

The term Trilobite literally means "Three Lobes." The name references the animal's body plan. All Trilobites have three lobes, a left pleural lobe, Axial lobe, and a right pleural lobe.

Trilobites look like little insects, and are often nicknamed "bugs" by fossil collectors. However, they are not related to insects. Trilobites are an extinct clade of Arthropods (like crustaceans). Nothing like them exists today. They are, however, distantly related to the chelicerates clade. Chelicerates include horseshoe crabs and spiders.

Trilobite Size:

There are many types of trilobites. Trilobites came in a wide array of sizes. Some, such as the Perenopsis trilobites, grew to only a few millimeters in size, and look like flakes of pepper on a rock. The largest, Isotelus rex, from the Upper Ordovician of Manitoba, Canada grew over two feet in length. The worlds largest trilobite specimen of Isotelus rex is recorded at 720 mm, over 2.3 feet in length.

Exoskeleton and Trilobite Enrollment:

Trilobites have a hard calcite shell protecting them, similar to a crab. These exoskeletons are usually the only part of a trilobite that survives fossilization. Their soft parts such as antennae and legs rarely fossilize. A rare example of soft tissue trilobite preservation is shown in the image below.

When a trilobite grew, it molted, i.e. removed it's exoskeleton, again, similar to what a crab does. Molted exoskeletons are by far the most commonly found trilobite fossils, they are usually missing segments, such as the cephalon or pygidium.

One interesting characteristic of trilobites is that many could enroll themselves. This enrollment was probably for defensive purposes, as an enrolled trilobite would have all of it's soft parts protected.

diagram of enrolled trilobites. All of these trilobites were found in various places in Ohio. They include Gravicalymene, flexicalymene, and phacops
This image shows what enrolled trilobites look like. The large white one is a Grvicalymene, the large black one is a Phacops, and the small rollers are Flexicalymene. All are from various places in Ohio.

Pyratized Triarthrus Trilobite showing appendages - By Didier Descouens (Own work)
By Didier Descouens (Own work) [GFDL or CC-BY-SA-3.0-2.5-2.0-1.0], via Wikimedia Commons
This image shows pyritized Triarthrus trilobites with their soft appendages preserved. These amazing fossils come from Beecher' Trilobite Bed in NY.

Trilobite Origins and Extinction

Trilobites probably arose from a soft bodied ancestor in the Pre-Cambrian. The first actual trilobites appear and rapidly diversify in the Cambrian. Once they made their appearance, they dominated the Paleozoic seas, many new orders and families quickly appeared. They were actually the most diverse class of life on the planet, containing thousands of genera, and tens of thousands of species.

However, mass extinctions took their toll on Trilobites. The End Ordovician extinction event took out a few orders of trilobites. Then the End Devonian extinction event removed all but one order of trilobite. When the Great Permian extinction even occurred, which marks the end of the Paleozoic, the last trilobites became extinct. Exactly why one of Earth's most successful and prolific creature could not survive the mass extinctions is still a mystery, and often debated. Fortunately, their hard exoskeletons enabled them to become readily preserved as fossils, and we can enjoy them today.


Where to Find Fossil Trilobites

Trilobite fossils are incredibly abundant in many Paleozoic outcrops across the planet. Unfortunately, almost all of them come in the form of bits and pieces. Some formations, though, were formed in just the right conditions to leave an occasional whole trilobite.

Some of the more famous locations in the United States where whole trilobites can be found include: Oklahoma, Utah, New York, and Ohio.


Oklahoma has the world famous Devonian Haragan and Bois d' Arc Formations. These formations have a similar trilobite fauna as the Morocco Devonian trilobites, however the preservation is similar to the famous St. Petersburg Russian trilobites.
-Oklahoma Trilobite Hunting Trip Report here-

Utah has the famous Cambrian Wheeler and Marjum Formations exposures which have a plethora of beautiful trilobites. Americas famous little trilobite, Elraithi Kingii, is found here en masse.
-Utah Trilobite Hunting Trip Report here-
(Utah Collecting Site Coming Soon)

New York has famous exposures all over the state that contain beautifully preserved trilobites. These exposures also extend through many time periods, including the Devonian and the Ordovician.
-Western New York Trilobite Fossil Site-

Ohio has a world famous Devonian exposure called the Silica Shale. It contains Eldredgeops (Phacops) rana trilobites that tend to be a little larger than other collecting locations.
-Silica Shale of Ohio Trilobite Fossil Site-
Where to Find Fossil Trilobites
Looking for Trilobites in utah. Here is a nice Ausphiscus wheeleri that will prep out beautifully!


Trilobite Fossil Gallery

Browse through the different types of trilobites and learn about each fossil. Each type of Trilobite is linked to facts, collecting sites, trips, images, and additional information.
The fossil trilobites are sorted by geologic time period.

Click on any of the images below to go to the specific trilobite page.


CAMBRIAN
(541 - 485 Million Years Ago)
NAME
LOCATION AGE FORMATIONS TRILOTIBTE
ORDER
asaphiscus trilobite information Ausphiscus wheeleri
Utah Middle
Cambrian
Wheeler Shale Ptychopariida
elrathia trilobite information Elrathia Kingii
Utah Middle
Cambrian
Wheeler Shale Ptychopariida
agnostid trilobite information Agnostid Trilobites
Utah Middle
Cambrian
Wheeler & Marjum Agnostida


ORDOVICIAN
(485 - 443 Million Years Ago)
NAME
LOCATION AGE FORMATIONS TRILOTIBTE
ORDER
cryptolithus trilobite information Cryptolithus Trilobites
Pennsylvania Ordovician Martinsburg Formation Asaphida
triarthrus trilobite information Triarthrus eatoni
New York Ordovician Utica Shale Ptychopariida


DEVONIAN
(419 - 359 Million Years Ago)
NAME
LOCATION AGE FORMATIONS TRILOTIBTE
ORDER
Eldredgeops (Phacops) trilobite information Eldredgeops (Phacops)
Eastern North America Devonian Numerous Formations Phacopida
huntonia trilobite information Huntonia
Oklahoma Devonian Haragan Formation Phacopida


SILURIAN
(443 - 419 Million Years Ago)
NAME
LOCATION AGE FORMATIONS TRILOTIBTE
ORDER
Coming soon Coming Soon
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