Trilobites (pronounced "TRY-luh-BYTS" or "TRIL-uh-BYTS"; meaning "three-lobed entities") are extinct marine arthropods that belong to the class Trilobita. They were among the first arthropods to appear in the fossil record and were some of the most successful early animals. Trilobites lived in oceans for nearly 270 million years, and scientists have identified over 22,000 species. Their wide variety and hard, calcite-based exoskeletons made them easy to fossilize, leaving behind a large number of fossils. Studying these fossils has helped scientists understand important topics such as biostratigraphy, paleontology, evolutionary biology, and plate tectonics. Trilobites are part of the clade Artiopoda, which includes many organisms that look similar to trilobites but lack hard, mineralized parts. Scientists are still unsure how Artiopoda is related to other arthropods.
Trilobites filled many different roles in ancient ecosystems. Some crawled along the ocean floor as predators, scavengers, or filter feeders, while others swam and fed on plankton. A few may have even moved onto land. Most behaviors seen in modern marine arthropods were also present in trilobites, except for parasitism, which is still debated by scientists. Some trilobites, like those in the Olenidae family, may have lived with sulfur-eating bacteria that provided them with food. The largest trilobites were over 70 centimeters (28 inches) long and could weigh up to 4.5 kilograms (9.9 pounds).
The first trilobites appeared in the fossil record around 521 million years ago, marking the start of the Atdabanian/Cambrian Stage 3 in the Early Cambrian period. Soon after their origin, trilobites were already widespread and diverse. Their greatest diversity occurred during the late Cambrian–Ordovician periods, and they remained diverse through the Silurian and early Devonian periods. By the mid- to late Devonian, their diversity dropped sharply due to several extinction events, including the Taghanic event, the Late Devonian mass extinction (Kellwasser event), and the Hangenberg/end-Devonian mass extinction. These events nearly wiped out trilobites, leaving only the Proetida order surviving. Their numbers slightly increased during the Early Carboniferous period but then declined again during the late Carboniferous and Permian periods. Trilobites remained common until their final extinction during the end-Permian mass extinction event about 251.9 million years ago, when only a few species remained.
Evolution
Trilobites are part of the Artiopoda, a group of extinct arthropods that look similar to trilobites. However, only trilobites had hard, mineralized outer shells. Other artiopodans are usually found only in special rock layers that preserve fossils very well, mostly from the Cambrian period.
Scientists are unsure how artiopods are related to other arthropods. Some think they are closely related to chelicerates (like horseshoe crabs, sea spiders, and spiders) as part of a group called Arachnomorpha. Others believe they are more closely related to Mandibulata (which includes insects, crustaceans, and centipedes) as part of a group called Antennulata.
A diagram showing the relationships of Artiopoda, including trilobites, was created by Berks et al. in 2023.
The oldest trilobites found in the fossil record are redlichiids and ptychopariid bigotinids, dating back about 520 million years. Some of the earliest trilobites include Profallotaspis jakutensis (from Siberia), Fritzaspis spp. (from the western US), Hupetina antiqua (from Morocco), and Serrania gordaensis (from Spain). These trilobites appeared at about the same time in Laurentia, Siberia, and West Gondwana.
All Olenellina trilobites lack facial sutures (lines on the head that help the trilobite split during molting), and this is thought to be the original condition. The earliest trilobite with facial sutures, Lemdadella, appeared almost at the same time as the earliest Olenellina, suggesting trilobites may have existed before the Atdabanian period but left no fossils. Other groups, like Agnostina and some Phacopina, later lost their facial sutures. Another feature of Olenellina suggests they are the ancestor of all trilobites: early stages of their development (protaspid stages) are not found, possibly because they were not made of calcium, which is the original condition. Earlier trilobites may still be discovered, which could help scientists learn more about their origins.
Three trilobites from Morocco, called Megistaspis hammondi, are 478 million years old and have fossilized soft parts. In 2024, scientists found soft tissues, including the labrum (a part of the mouth), in well-preserved trilobites from the Cambrian Stage 4 in Morocco. These discoveries provided new information about the trilobites’ anatomy. The excellent preservation is likely due to the trilobites dying quickly after an underwater volcanic event.
Trilobites diversified greatly over time. Because they lived for so long, their history includes many extinction events where some groups died out, and others adapted to fill new roles in their environments. Trilobites remained diverse during the Cambrian and Ordovician periods but gradually declined in the Devonian period. Their final extinction happened at the end of the Permian period.
Key evolutionary changes from early trilobites, like Eoredlichia, include new types of eyes, better mechanisms for curling up and moving, larger pygidium (the tail section), and extreme spines in some groups. Other changes included narrower thoraxes and varying numbers of body segments. The head (cephalon) also changed, with differences in the glabella (a part of the head), eye position, facial sutures, and specialized mouth parts. Some features, like eye reduction or small size, appeared independently in different groups.
Effacement, the loss of surface details on the head, tail, or body segments, is a common trend. Examples include the Agnostida and Asaphida orders and the Illaenina suborder. Effacement may indicate a burrowing or open-ocean lifestyle. This loss of details makes it harder for scientists to classify trilobites and understand their relationships.
Although some scientists once thought trilobites existed before the Cambrian period, this is no longer supported. Instead, trilobites likely appeared just before their fossils were first found in the lower Cambrian. Soon after, they diversified into major groups like Redlichiida, Ptychopariida, Agnostida, and Corynexochida. A major crisis in the Cambrian period led surviving groups to develop stronger defenses, like thicker shells. The Late Cambrian saw the peak of trilobite diversity. The end-Cambrian extinction event wiped out most Redlichi
Fossil distribution
Trilobites were mainly ocean-dwelling creatures, as their fossil remains are always found in rocks that also contain fossils of other sea animals, such as brachiopods, crinoids, and corals. Some evidence suggests that trilobites occasionally moved onto land for short periods. In ancient ocean environments, trilobites lived in a wide range of depths, from very shallow water to the deep sea. Like brachiopods, crinoids, and corals, trilobite fossils are found on all modern continents and in every ancient ocean where Paleozoic fossils have been discovered. Fossil remains of trilobites can include their entire bodies or parts of their hard outer shells, which they shed during a process called ecdysis. Additionally, the tracks trilobites made on the seafloor are often preserved as trace fossils.
Three main types of trace fossils are linked to trilobites: Rusophycus, Cruziana, and Diplichnites. These fossils show the activities of trilobites on the seafloor. Rusophycus, which are resting traces, are shallow pits made by trilobites while resting, hiding, or hunting. Cruziana, which are feeding traces, are furrows in sediment believed to be made by trilobites as they moved while feeding on the seafloor. Diplichnites are tracks left by trilobites walking on the sediment. Care must be taken, as similar trace fossils in freshwater or later geological layers may not be from trilobites.
Trilobite fossils are found worldwide, with thousands of known species. Because they appeared quickly in Earth’s history and shed their shells like other arthropods, trilobites are excellent index fossils, helping scientists determine the age of the rocks they are found in. They were among the first fossils to be widely studied, and new species are still being discovered today.
In the United States, one of the best public trilobite fossil sites is in Hamburg, New York, at a quarry called Penn Dixie. Mining there stopped in the 1960s, and trilobites were discovered in the 1970s by Dan Cooper, a rock collector who raised interest in the site. The fossils are about 387 to 382 million years old, from a time when western New York was near the equator and covered by water. The town of Hamburg purchased the land with help from a natural history society to protect it from development. In 1994, the site became a public park and nature reserve, open for visitors and fossil collecting. The most common trilobite fossils found there are Eldredgeops rana and Greenops.
In the United Kingdom, a famous trilobite site is Wren’s Nest in Dudley, West Midlands, where Calymene blumenbachii is found in Silurian rocks. This trilobite is on the town’s coat of arms and was called the Dudley Bug or Dudley Locust by workers in old limestone quarries. Another notable site is Llandrindod Wells in Powys, Wales, where Elrathia kingi is found in Cambrian rocks in Utah, USA.
Well-preserved trilobite fossils, including soft body parts like legs, gills, and antennae, have been found in places like British Columbia, Canada (Cambrian Burgess Shale), New York, USA (Ordovician Walcott–Rust quarry and Beecher’s Trilobite Bed), China (Lower Cambrian Maotianshan Shales), Germany (Devonian Hunsrück Slates), and, less commonly, in Utah, Ontario, and Manuels River, Newfoundland and Labrador.
In Morocco, trilobites are also found in excellent condition, often preserved in mudslides that buried them alive. This has led to an industry focused on recovering these fossils, but some practices in restoring them have caused controversy. These fossils are especially valuable for studying the variety of eye shapes, body forms, and delicate features, similar to how bodies were preserved in the ancient city of Pompeii.
The French paleontologist Joachim Barrande (1799–1883) conducted groundbreaking research on trilobites in the Cambrian, Ordovician, and Silurian periods in Bohemia. He published the first volume of Système silurien du centre de la Bohême in 1852.
Importance
Niles Eldredge's research on Paleozoic trilobites in the Welsh-English borders helped create and test punctuated equilibrium, a theory about how species change over time.
Finding 'Atlantic' and 'Pacific' trilobite groups in North America and Europe showed that the Iapetus Ocean closed, forming the Iapetus suture. This supported the idea that continents move over time.
Trilobites are important for understanding how quickly new species formed during the Cambrian explosion, as they are the most varied group of animals found in early Cambrian fossils.
Trilobites help scientists identify rock layers from the Cambrian period. Finding trilobites with specific features, like alimentary prosopon and micropygium, means the rocks are from the Early Cambrian. Much of Cambrian rock layer dating relies on these trilobite fossils.
Trilobites are the official state fossils of Ohio (Isotelus), Wisconsin (Calymene celebra), and Pennsylvania (Phacops rana).
Taxonomy
The 10 most commonly recognized trilobite orders are Agnostida, Redlichiida, Corynexochida, Lichida, Odontopleurida, Phacopida, Proetida, Asaphida, Harpetida, and Ptychopariida. In 2020, an 11th order, Trinucleida, was proposed to be moved from the asaphid superfamily Trinucleioidea. Sometimes the Nektaspida are considered trilobites, but these lack a calcified exoskeleton and eyes. Some scholars have proposed that the order Agnostida is polyphyletic, with the suborder Agnostina representing non-trilobite arthropods unrelated to the suborder Eodiscina. Under this hypothesis, Eodiscina would be elevated to a new order, Eodiscida.
Over 22,000 species of trilobite have been described.
Despite their rich fossil record with thousands of described genera found throughout the world, the taxonomy and phylogeny of trilobites have many uncertainties. Except possibly for the members of the orders Phacopida and Lichida (which first appear during the early Ordovician), nine of the eleven trilobite orders appear prior to the end of the Cambrian. Most scientists believe that order Redlichiida, more specifically its suborder Redlichiina, contains a common ancestor of all other orders, with the possible exception of the Agnostina. While many potential phylogenies are found in the literature, most have suborder Redlichiina giving rise to orders Corynexochida and Ptychopariida during the Lower Cambrian, and the Lichida descending from either the Redlichiida or Corynexochida in the Middle Cambrian. Order Ptychopariida is the most problematic order for trilobite classification. In the 1959 Treatise on Invertebrate Paleontology, what are now members of orders Ptychopariida, Asaphida, Proetida, and Harpetida were grouped together as order Ptychopariida; subclass Librostoma was erected in 1990 to encompass all of these orders, based on their shared ancestral character of a natant (unattached) hypostome. The most recently recognized of the nine trilobite orders, Harpetida, was erected in 2002. The progenitor of order Phacopida is unclear.
Morphology
When trilobite fossils are found, only the hard outer shell (exoskeleton) is usually preserved, and it is often incomplete. However, in a few special locations called Lagerstätten, scientists can also find soft body parts like legs, gills, muscles, and the digestive system. These places may also show details of other structures, such as the fine parts of the eyes. Out of the 20,000 known trilobite species, only 38 have fossils that show preserved appendages.
Trilobites varied greatly in size, from as small as less than 1 millimeter (0.039 inches) to as large as over 70 centimeters (28 inches). The smallest known species is Acanthopleurella stipulae, which measured up to 1.5 millimeters (0.059 inches). The largest known trilobite, Isotelus rex, was 72 centimeters (28 inches) long. It was discovered in 1998 by Canadian scientists in Ordovician rocks near Hudson Bay. Another trilobite, Hungioides bohemicus, found in 2009 in Arouca, Portugal, may have measured up to 86.5 centimeters (34.1 inches) when complete.
Only the top part of the trilobite’s exoskeleton is made of minerals like calcite and calcium phosphate, arranged in a chitin framework. This part curves around the bottom edge to form a small fringe called the "doublure." The appendages and soft underside were not made of minerals. The trilobite’s body is divided into three main sections: the cephalon (head), thorax (body), and pygidium (tail).
Trilobites are a diverse group with over 5,000 genera, so their body shapes and features can be complex. Despite this, they have unique traits that set them apart from other arthropods. These include a hard, chitinous exoskeleton shaped like an oval and divided into three distinct lobes (which gives the group its name). The head shield (cephalon) is large and connects to the thorax, which is made of segments that are often fused at the back to form the tail shield (pygidium). When comparing trilobite species, scientists often note the size, shape, and presence of features on the head.
During molting, the exoskeleton usually splits between the head and body, which is why many fossils are missing either the head or body. Facial sutures on the head helped trilobites shed their old exoskeleton. Like lobsters and crabs, trilobites grew between molting and when their new exoskeleton hardened.
The head (cephalon) of a trilobite varies in shape and has complex features. A dome-shaped area called the glabella sits beneath the "crop" or stomach. The exoskeleton on the underside has few features, but the head often shows muscle attachment marks and sometimes a small rigid plate called the hypostome. The mouth and stomach were toothless and sat above the hypostome, with the mouth facing backward at the edge of the hypostome.
The hypostome’s shape and position vary. Sometimes it is supported by a soft membrane, sometimes fused to the front edge of the doublure, and sometimes shaped differently from the glabella. These variations are linked to different lifestyles, diets, and ecological roles.
In some trilobites, like those in the group Harpetida, the front and sides of the head are greatly expanded. In other species, a bulge near the glabella suggests a brood pouch. Complex compound eyes are also a notable feature of the head.
Facial or cephalic sutures are natural lines on the head that helped trilobites shed their old exoskeleton during molting. All species in the suborder Olenellina, which went extinct at the end of the Early Cambrian (like Fallotaspis, Nevadia, Judomia, and Olenellus), lacked facial sutures. These trilobites are considered the earliest ancestors of later species because they predated the evolution of facial sutures.
Some later trilobites also lost facial sutures, and the type of sutures found in different species is used to classify and study their relationships. The top part of the head (cephalon) can be divided into two regions: the cranidium (central part) and the librigena (free cheeks). The cranidium includes the glabella (central lobe) and the fixigena (fixed cheeks). Facial sutures are located at the edge where the cranidium and librigena meet.
Facial sutures on the top of the head can be grouped into five main types based on where they end relative to the genal angle (where the side and back of the head meet). The most basic type is proparian. Opisthoparian sutures evolved independently multiple times, and no proparian sutures are found in species with opisthoparian ancestry. Some trilobites, like Yunnanocephalus and Duyunaspis, have proparian sutures as young individuals but opisthoparian sutures as adults. Hypoparian sutures also evolved independently in several groups.
The path of facial sutures varies, but it is hard to categorize because there is no clear reference point like the genal angle. In some trilobites, like those in the Asaphida, the front of the sutures meet at the middle of the head. In others, like Triarthrus and Phacopidae, the front branches of the sutures meet, creating yoked free cheeks. However, in Phacopidae, the sutures are not functional, as free cheeks are not found separated from the cranidium.
There are two types of sutures related to the compound eyes on the
Soft body parts
Only about 21 species have been described where soft body parts are preserved, so some features, such as the posterior antenniform cerci found only in Olenoides serratus, are hard to study in other trilobites.
Trilobites had one pair of preoral antennae and limbs that were not clearly divided into different types (four pairs on the head, one pair on each thoracic segment, and some on the tail). Each walking leg (endopodite) had six or seven segments, similar to those of other early arthropods. These legs were attached to the coxa, which also had a feathery exopodite, or gill branch, used for breathing and, in some species, swimming. A 2021 study found that the upper limb branch of trilobites acted as a well-developed gill, helping to oxygenate their blood, similar to the book gill in modern horseshoe crabs (Limulus). In Olenoides, the connection between the leg and body was partially joined, different from the exopods of chelicerates or crustaceans. The inside of the coxa (or gnathobase) had spines, likely used to handle prey. The last segment of the exopodite often had claws or spines. Many hairs on the legs suggest adaptations for feeding or sensing movement.
The trilobite mouth, which had no teeth, was located on the back edge of the hypostome (facing backward), in front of the legs attached to the head. The mouth connected to the stomach through a short tube, located below the glabella. The "intestine" extended from the stomach to the tail. Limbs attached to the head may have helped move food into the mouth, possibly cutting food on the hypostome or gnathobases first. A recent study using 3D imaging of a Bohemolichas incola specimen found many undigested pieces of Conchoprimitia osekensis (a small, extinct shelled creature) in its digestive tract.
These fragments suggest B. incola ate hard-shelled prey by crushing their shells. Since the shells’ composition was not taxonomically important but related to their strength and size, B. incola likely ate opportunistically, like scavengers. The presence of undigested shell fragments also suggests B. incola used enzymes to break down food, leaving only shell pieces behind. This supports the idea that early trilobites may have had glands that helped with digestion.
While there is clear evidence for the mouth, stomach, and digestive tract (as described above), the heart, brain, and liver are only implied, with little direct geological proof.
Although rarely preserved, long muscles ran from the head to the middle of the tail, attaching to the axial rings to help the trilobite curl up. Separate muscles on the legs helped move them out of the way during curling.
Sensory organs
Many trilobites had complex eyes and a pair of antennae. Some trilobites were blind, likely because they lived too deep in the ocean where no light reached them. This loss of sight happened over time in some trilobite groups. Other trilobites, like Phacops rana and Erbenochile erbeni, had large eyes that helped them see clearly in bright, dangerous waters filled with predators.
The antennae of most trilobites (found in some fossils) were flexible so they could be pulled back when the trilobite curled into a ball for protection. One species, Olenoides serratus, had antenna-like structures called cerci that extended from the back of its body.
Even the earliest trilobites had compound eyes with lenses made of calcite, a type of mineral found in all trilobite eyes. This shows that eyes in arthropods and possibly other animals may have evolved before the Cambrian period. Improved eyesight in both predators and prey during the Cambrian period is thought to have pushed the rapid development of many new life forms, known as the Cambrian explosion.
Trilobite eyes were usually compound, made of many small, prism-shaped lenses. The number of lenses varied: some had one, while others had thousands. In compound eyes, lenses were often arranged in a hexagonal pattern. Fossils of trilobite eyes are well-preserved, allowing scientists to study their evolution over time, even though soft body parts rarely survive.
The lenses of trilobite eyes were made of calcite (calcium carbonate, CaCO₃). Some trilobites used clear, precisely aligned calcite crystals to form each lens. These rigid lenses could not adjust focus like human eyes, but some trilobites had a special double-layered structure in their lenses, which allowed for better vision. This design follows optical principles discovered by scientists René Descartes and Christiaan Huygens in the 17th century. A modern animal with similar eyes is the brittle star Ophiocoma wendtii.
In other trilobites, lenses lacked a feature called the Huygens interface. Instead, they may have used a gradient-index lens, where the lens’s refractive power changed toward the center.
Some phacopid trilobites had sensory structures under their lenses. These structures included groups of sensory cells around a rhadomeric shape, similar to those found in the eyes of modern arthropods like horseshoe crabs (Limulus).
Secondary blindness, or losing eyes over time, was common in some long-lived trilobite groups, such as Agnostida and Trinucleioidea. In groups like Proetida and Phacopina from western Europe, and especially in Tropidocoryphinae from France, studies show that eye size gradually decreased in related species, eventually leading to blindness.
Other trilobite features, like "macula" (thin areas on the underside of their hypostome), may have acted as simple "ventral eyes" to detect light or help them navigate while swimming upside down.
Some parts of a trilobite’s head, called prosopon, may have acted as sensory tools to detect chemicals or vibrations. For example, the large pitted fringes on the heads of Harpetida and Trinucleoidea, combined with their small or absent eyes, suggest these fringes might have functioned as a type of "compound ear."
Development
Trilobites grew through a series of stages called instars, during which their existing body parts grew larger, and new segments formed in a specific area of the body during the anamorphic phase. After this phase, the epimorphic phase began, where the trilobite continued to grow and molt, but no new segments were added to the exoskeleton. The combination of these two growth phases is called the hemianamorphic mode, which is common in many living arthropods.
Trilobite development was unique because the way their body segments connected changed over time. These changes led to the recognition of three main stages in their life cycle, which are not easily compared to those of other arthropods. Growth and changes in the trilobite’s body shape happened when the trilobite was soft-shelled, after molting and before the new exoskeleton hardened.
Trilobite larvae are known from the Cambrian to the Carboniferous periods and exist in all sub-orders. Instars from closely related trilobite species are more similar than those from unrelated species, making larvae useful for studying the evolutionary relationships among trilobites.
Although no fossil evidence supports it, trilobites are believed to have reproduced sexually and laid eggs. Some species may have carried eggs or larvae in a pouch near the head, especially in challenging environments. The size and shape of the first hard, calcified stage of trilobites vary between species but not within the same species, suggesting some trilobites developed more inside the egg than others. Early stages before the exoskeleton hardened may have existed, but this is not certain.
The earliest known post-embryonic stage of trilobites is the "protaspid" stage, which occurs during the anamorphic phase. These stages begin with a head and tail that are not clearly separated and end with a furrow dividing the head and tail. New segments are added at the back of the tail, but all segments remain fused together.
The "meraspid" stages, also part of the anamorphic phase, are marked by the development of a joint between the head and the fused trunk. Before this stage, the trilobite had a two-part structure: the head and the fused trunk (pygidium). During the meraspid stages, new segments form near the back of the pygidium, and additional joints develop at the front, allowing segments to move freely in the thorax. Segments are typically added one at a time with each molt, though some species added two segments per molt or one every other molt. Growth during this phase was significant, increasing the trilobite’s size by up to 25% to 40%.
The "holaspid" stages, part of the epimorphic phase, begin when the trilobite reaches a stable number of thoracic segments. Moulting continued during this phase, but no new segments were added. Some trilobites may have continued to grow throughout their lives, though at a slower rate after reaching maturity.
Some trilobites showed a major change in body shape at a specific instar, called "trilobite metamorphosis." This change involved the loss or gain of features that reflected a shift in lifestyle. Changes in lifestyle during development affected how trilobites survived and spread, as they could occupy different environments during growth. For example, trilobites that were planktonic as larvae and then became benthic (bottom-dwelling) as adults survived the Ordovician extinctions better than those that remained planktonic longer.
There is no evidence that trilobites reabsorbed their old exoskeletons during molting. Some scientists suggest that trilobites’ inability to reabsorb their hardened exoskeletons made them slower to rebuild their new shells, increasing their vulnerability to predators compared to modern arthropods that can reabsorb their old shells.
History of usage and research
In 1698, Rev. Edward Lhwyd published a letter in The Philosophical Transactions of the Royal Society, the oldest scientific journal in the English language. His letter, titled "Concerning Several Regularly Figured Stones Lately Found by Him," included a page of etchings of fossils. One etching showed a trilobite he found near Llandeilo, likely on the grounds of Lord Dynefor's castle. He described the trilobite as "the skeleton of some flat Fish."
The discovery of Calymene blumenbachii (the Dudley locust) in 1749 by Charles Lyttleton marked the start of trilobite research. In 1750, Lyttleton sent a letter to the Royal Society of London about a "petrified insect" he found in the "limestone pits at Dudley." In 1754, Manuel Mendez da Costa claimed the Dudley locust was not an insect but belonged to "the crustaceous tribe of animals." He suggested naming the Dudley specimens Pediculus marinus major trilobos (large trilobed marine louse), a name used until the 19th century. German naturalist Johann Walch, who conducted the first comprehensive study of this group, proposed the name "trilobite." He chose it because of the three-lobed shape of the central axis and the two pleural zones on either side.
Written descriptions of trilobites may date back to the third century BC, but definite records exist from the fourth century AD. Spanish geologists Eladio Liñán and Rodolfo Gozalo suggest that some fossils described in Greek and Latin lapidaries as "scorpion stone," "beetle stone," and "ant stone" refer to trilobite fossils. More clear references to trilobite fossils appear in Chinese sources. Fossils from the Kushan formation in northeastern China were valued as inkstones and decorative items.
In the New World, American fossil hunters discovered large deposits of Elrathia kingi in western Utah in the 1860s. Until the early 1900s, the Ute Native Americans of Utah wore these trilobites, which they called pachavee (little water bug), as amulets. A hole was drilled in the head of the fossil, and it was worn on a string. According to the Ute, trilobite necklaces protected against bullets and diseases like diphtheria. In 1931, Frank Beckwith found evidence of Ute use of trilobites. During a trip, he photographed two petroglyphs that likely represent trilobites and examined a burial site with a drilled trilobite fossil in the chest cavity of the buried person. Since then, trilobite amulets have been found in the Great Basin, British Columbia, and Australia.
In the 1880s, archaeologists found a much-handled trilobite fossil in the Grotte du Trilobite (Caves of Arcy-sur-Cure, Yonne, France). The fossil had been drilled, as if to be worn as a pendant. The layer of soil where the trilobite was found is dated to 15,000 years ago. Because the pendant was handled so often, the trilobite's species cannot be identified. This type of trilobite is not found near Yonne, so it may have been traded from another region and highly valued.