Fascinating Facts About Trilobite Fossils

Fossils are a fascinating glimpse into a world that once was. Animal and plant life that once flourished is reduced to mineral form, revealing clues about what existed on our planet millions of years ago. Trilobite fossils are one fossil type that offers a peek at a world before dinosaurs.

Trilobites are part of the earliest known group of arthropods. Primarily marine animals, they dominated the seas over 542 million years ago before dinosaurs roamed the earth. Trilobite fossils range in size, with the largest recorded one measuring eighteen inches long and weighing almost ten pounds. 

Trilobites are Survivors

Before trilobites appeared in historical records, they were already widely dispersed across the globe. They left an extensive fossil record due to their easily fossilized exoskeleton. Trilobites were among the most successful early animals, existing in the oceans for over 270 million years.

It is important to note that trilobites lived longer than dinosaurs. They were predators of the deep for hundreds of years, burrowing into the sediment to feed or avoid becoming prey. The bottom-feeding trilobites would rest with their head above the sediment, filtering the water for plankton while hiding their bodies under the sand or mud. Their diversity of body types and ability to adapt to their environment are what made them successful for so long.

The Body of a Trilobite

The name “trilobite” originates from the body, divided into three main sections running its length– a central lobe and two pleural lobes. These are hard-shelled creatures with jointed legs, although the legs, antennae, and more delicate structures are rarely preserved.

The body of the trilobite is what made this arthropod a survivalist. Made of three primary body parts, its simplicity is key to its longevity. The flexibility of the trio of lobes protected with the hard shell allowed it to roll into the defensive position.

Trilobite Body Parts

• cephalon (head)
• thorax
• pygidium (tail piece)

The successful survival of the trilobite is attributed to its defense mechanism of rolling into a ball. Consequently, trilobite fossils are often found well-preserved, with the body rolled into this defensive position. 

How Did Trilobites Defend Themselves?

Most trilobites could defend themselves by rolling into a ball. Their flexible thoracic segments allowed them to bring their cephalon and pygidium together to create a closed capsule to protect their vulnerable antennae, legs, and soft ventral surface. Some trilobites developed special features that aided this enrollment, including interlocking cephalon and pygidium, allowing for a tighter match.

Though trilobites are known mainly to be sea dwellers, trilobite fossils have been found in various locations worldwide. Based on these findings, it is safe to assume that they experienced several different lifestyles, including: 

Four Surprising Lifestyles of Trilobites

• seabed predators
• scavengers
• swimmers
• land crawlers

As seabed predators, trilobites traveled the ocean floors to find and feast on parasites and other small organisms. Fossils and other markings have shown that trilobites used their endites (an appendage of the inner side of a limb) to excavate nests or probe for prey. They scavenged the floors to feed on the prey of others and even swam to devour plankton and other tiny parasites they could filter. It is even believed that trilobites ventured beyond the ocean to make a meal, crawling onto land to find food.

Earlier trilobites lived in shallow waters, walking on the bottom, feeding on detritus. A few orders may have been pelagic (floaters) and fed in a water column. After the Ordovician period, trilobite groups declined and became extinct, forcing survivors to move to deeper waters for survival. 

How Many Types of Trilobites are There?

There are ten recognized orders of trilobite into which 20,000 species are placed. Thus, trilobites are the most diverse group of extinct animals recorded. You can explore the many species by studying aspects of their biology, orders, constituent suborders, and superfamilies. New species are discovered in the form of trilobite fossils and recorded every year! 

10 Recognized Orders of Trilobites

1. Agnostida
2. Redlichiida
3. Corynexochida
4. Odontopleurida
5. Lichida
6. Phacopida
7. Proetida
8. Asaphida
9. Trinucleida
10. Harpida 

How do Trilobites Help with History?

Trilobite fossils are an educational window to the past. Because they are widely found across the world and at various geographical strata, trilobite fossils have played a significant role in determining the order and age of many other fossils and geological strata.

By studying preserved remains to determine the relative age of geological strata (called biostratigraphy), trilobites help date other plants and animals living at the same time. Simply put, trilobite fossils serve as index fossils, allowing geologists to date the rocks in which they are found.

Based on biostratigraphy, we know that trilobites were first recorded in the Early Cambrian period (521 million years ago). Some existed and became extinct within the same period. By the end of the Devonian period (359 million years ago), all the orders of the trilobites were no longer found, except the Proetida, which persisted until the end of the Paleozoic period (251 million years ago).

The Permian Extinction is the End of Trilobites

The last finding of trilobites corresponds with the event that eliminated over ninety percent of life on the earth at the end of the Permian system, which is the last period of the Paleozoic (251 million years ago). Often called The Permian Extinction, this event eliminated all but five percent of the animal species in the seas and on land. Less than a third of the animals survived.

Where is the Best Place to See a Trilobite Fossil Collection?

Let’s be honest – a wooly mammoth display or the fearsome, towering bones of a tyrannosaurus rex are a bit more exciting than the tiny remnants of trilobites from millions of years ago. However, it is vital to give these fossilized remains their due. So, next time you want to celebrate the little species that outlived the dinosaur, check out one of these fine establishments.

Best Places to See Trilobite Fossil Exhibits

• American Museum of Natural History, New York
• Natural History Museum, London
• Royal Ontario Museum, Ontario
• Houston Museum of Natural Science, Texas
• Field Museum, Chicago
• Smithsonian Institute, Washington, D.C.
• Czech National Museum, Prague
• Museum of Comparative Biology, Boston
• Hunterian Museum & Art Gallery, Glasgow

Each of these displays takes the tiny trilobite and makes it the hero in their space. These exhibits amplify the significance of this fossilized legend in our modern world. Each one is worth the trip! 

The Importance of Collecting Trilobite Fossils

Collecting fossils is a meaningful way to respect the history of our planet. As a window to the past, fossils tell stories of how life looked and behaved in centuries past. Fossils mostly tell the stories of species that are no longer alive, leaving only the imprint of their skeleton or the minerals from their remains.

Trilobite fossils are especially important because they show us what the ocean was like over 250 million years ago. They have been instrumental in biostratigraphy, paleontology, and plate tectonics.

Finding a fossil species on several modern continents gives us a glimpse into the fact that these landmasses were previously unified, likely as the supercontinent known as Pangea. This is incredibly useful for studying tectonics, the long history of life, and the past and current evolution processes of Earth. In addition, collecting these little storytellers is a glimpse into the evolution of life on our planet. 

Which Trilobite Fossils are Special to Find?

As tectonic shelves in the oceans moved and volcanos rose to erupt and become dormant, trilobites moved along the ever-changing sea beds, geographically disbursing themselves throughout the world. While there are many trilobite fossils to be found, a few genera are particularly special.

Four Phenomenal Trilobite Fossils

1. Cyphaspis
2. Hollardops
3. Cornuproetus
4. Phacops

1. The Cyphaspis Trilobite

The extinct marine arthropod species lived through the middle Devonian age approximately 380 million years ago. Fossils have been found in what is now Europe, Africa, and North America. This species had a compact body and a round glabellum, or area of bone between the eyebrows, along the cranium. 

2. The Hollardops Trilobite

Hollardops is a genus of trilobite in the order Phacopida that lived during the Eifelian of the Middle Devonian. Hollardops have schizocroal eyes (all-around vision), and its glabella is slightly raised on its head. This trilobite fossil has 15 thoracic segments and five pairs of spines.

3. The Cornuproetus Trilobite

Cornuproetus is a genus of trilobite in the family Tropidocoryphidae. This species lived throughout the middle Devonian age, around 380 million years ago. These trilobites are identified by the genal spines extending from the cephalon (arthropod head) through the entire length of their body. 

4. The Phacops Trilobite

Phacops is a genus of trilobites in the order Phacopida, family Phacopidae, that lived in Europe, northwestern Africa, North and South America, and China from the Late Ordovician until the very end of the Devonian. This trilobite dates to the middle Devonian age, around 380 million years ago.  

Finding these trilobite fossils is a dynamic beginning or addition to any fossil collection. A collection of trilobite fossils can be quite expansive, extending over several periods, from the time of their discovery until the age of their extinction. A collector may choose to display their fossils in a timeline, using the evolution of the trilobite fossils as a baseline for the display.

How to Display Trilobite Fossils

Trilobite fossils are known to be some of the most unique and beautiful fossils to display. There are countless species, and each one is guaranteed to be a conversation starter. Even the most common trilobite fossil can make an exceptional gift for a fossil collector or paleontologist.

While some might simply see a rock, others will see the history waiting to be discovered. Much like Michelangelo believed the sculpture was already in the stone, waiting to be let out, trilobites are in the stone, waiting to be carefully and meticulously revealed. With careful skill and observation, the trilobite fossil can be seen in the rock and transformed into something special that all can see. 

Why You Want to Collect High-Quality Trilobite Fossils

It is essential to inquire with a reputable purveyor of high-quality fossils when exploring the purchase of a trilobite fossil. With the prevalence of fake fossils in the marketplace, you will want to educate yourself on a few clues for identifying a fake trilobite fossil.

Signs of a Fake Trilobite Fossil

• Air bubbles are a sign of resins
• Cast trilobites often exhibit differences in color
• Devonian trilobites often have cracks
• Characteristics (like color) of the exoskeleton may indicate a fake
• UV lights and solvents identify the resin

For both amateur and seasoned fossil collectors, it is a tough lesson to invest in a fake specimen. However, developing a relationship with a trusted retailer or collector will not only ensure a quality collection, but it will also be the beginning of a beautiful relationship between people with mutual respect and interest in the beginning of the world as we know it now. 

Consider Joining a Fossil Collecting Club

There is a club or society for every past time you can think of! This includes lapidary clubs for rock collecting, which includes collecting fossils. In addition, you might consider a paleontology club or a club that overlaps with fossil collecting, mineral collecting, and amateur geology. Each of these is sure to put you in contact with people who will fan the flames of your interest in trilobite fossils and the organisms they came from.

As you develop your collection and increase your knowledge base regarding fossils, you will begin to appreciate even more that fossils are a tangible connection to life, landscapes, and climates of the past. They show us how things have changed over time and how living things responded to those changes.

Each of us is affected daily by the impacts fossils tell us about. It is proven, once again, that fossils are fascinating and irreplaceable!