Trilobite - SOLD 5.75" Phacops Fossil
Trilobite - SOLD 5.75" Phacops Fossil
This specimen is a complete 5.75" trilobite fossil from the genus Phacops. It comes from Morocco and is dated to be around 350-450 million years old. During the Ordovician, these creatures were unique among other trilobites for their complex eyes. They were comprised of over 700 calcite lenses which can still be observed after millions of years.
📸 A beautiful Phacops trilobite with details eyes and body structure
A complete and detailed fossil
Trilobites exemplify the diverse nature of prehistoric aquatic life. This class of arthropods formed a staggering amount of different species throughout the Cambrian period. Today, over 5,000 different genera of trilobites have been discovered and named, with more surely waiting to be discovered.
This specimen is a member of the Phacops genus, a type of trilobite with specialized eyes made of calcite lenses. The physical eyes that the creature used millions of years ago can still be seen on this specimen, an extreme rarity compared to other fossilized animals.
Trilobites were a common sight on the ocean floor for millions of years. Their adaptability and varied lifestyles helped them survive across multiple environments and niches.
This particular fossil comes from Morocco and is dated to around 350 to 400 million years old. It is one of several large trilobite specimens we have currently available and each ships in a sturdy shipping container along with an information card which serves as a statement of authenticity.
Each trilobite fossil is a unique item and are sold individually by size. Smaller display case specimens are also available. You can find all of our current trilobites in the collection below.
Temporal Range: 521,000,000-251,000,000 years ago
MORE ABOUT TRILOBITES
"We are beginning to understand how a group of animals sometimes regarded as ‘primitive’ were actually sophisticated and varied. Had it not been for the Permian extinction event they might be with us still." ~ Richard Fortey, paleontologist at the Natural History Museum in London.
📸 A sample trilobite fossil
A diverse class of creature
Oceans cover about three quarters of our planet, but much of them remain unexplored and unknown to us. It is here in this mysterious environment that life on Earth first began. Forms were simple at first, with plant life and multicellar organisms only just emerging in complexity.
Then, 540,000,000 years ago, the ocean was host to an incredible event that would change the course of evolution forever: the Cambrian Explosion. This massive acceleration of diverse life gave way to the swift radiation of new species and unique evolutionary traits. One creature that exemplified this principle of change so clearly was the trilobite.
📸 A selection of smaller trilobites
This class of arthropods formed a staggering amount of different species throughout the Cambrian period. While all species shared some common aspects, each would evolve unique adaptations that set them apart. Today, over 5000 different genera of trilobites have been discovered and named, with more surely waiting to be discovered.
The common structure that all trilobites share is rather simple. They had a hard exoskeleton composed of three lobes: left, right, and center. Their bodies are also segmented into a cephalon (head), thorax (body), and pygidium (tail). From this base, trilobites evolved into a myriad of strange and unique forms. Some specimens have even been discovered with fossilized soft tissues such as legs, gills, and antennae, giving us a clearer picture of the trilobite’s form in life.
📸 Trilobites had many varied forms (Source: Smithsonian)
Despite certain commonalities, trilobite species were as varied as could be. Spiny exteriors were a common adaptation and were used by some species to ward off predators while others developed spines as a hunting tool. Compound eyes were found in many species, with some having enormous oculars giving them nearly 360-degree vision. Specialized exoskeleton articulation even allowed them to roll into a ball. Trilobites varied in size as well, from a mere tenth of an inch long to the massive 28 inch Isotelus Rex.
Trilobites had an incredibly varied amount of lifestyles to match their many variations in form. Fossils have been discovered in areas that would have been shallow basins of saltwater as well as the floors of ancient trenches. Ocean floor scavengers, predators, filter feeders, swarming schools, and even open water swimmers have all been suggested modes of survival of different groups. There is even evidence some species made short trips onto dry land.
📸 The head of a Phacops trilobite with eyes on either side
The Phacops Genus
This specimen is a genus of trilobite known as Phacops. Like other members of its class, it boasted a three-lobed symmetry and a hard silicate exoskeleton. Phacops, however, were unique for their strong eyesight, a rarity among all the thousands of species of trilobites. Unlike the fleshy eyeballs we might think of though, these creatures had lenses made of hard calcite. While this restricted their flexibity, the calcite was fantastic for fossilization, which means we can still see them today.
Not all trilobites had eyes, but those that did usually fell into one of two categories. There are holochroal eyes that the majority of trilobites with eyes display, and then there are schizochroal eyes that only appear with Phacops. Both types are compound eyes, meaning they are made up of many different corneas and lenses.
Holochroal eyes had about fifteen thousand lenses covered by a single cornea, while schizochroal eyes had half the number of lenses, but these lenses were much bigger and each had its own cornea. This enhanced eyesight allowed Phacops to evade predation, also aided by their natural camouflage and ability to coil into a tight ball through volvation, like a pillbug insect.
Phacops’ specialization within trilobites is demonstrative of the variation and diversity found within the Cambrian explosion. Trilobite fossils are found all over the world, marking the spaces that once held ancient marine life.
Being widespread through the Cambrian period, they serve as excellent stratigraphic markers and help to date other rocks and specimens found near them. Thanks to this, they're always a welcome site for a paleontologist looking to reconstruct the timeline of a fossil site.
Front of the Specimen Card
Back of the Specimen Card
Fordyce, David, and Thomas W. Cronin. “Trilobite Vision: a Comparison of Schizochroal and Holochroal Eyes with the Compound Eyes of Modern Arthropods.” Paleobiology 19.3 (1993): 288–303. Web.
Marshall, Charles R. “EXPLAINING THE CAMBRIAN ‘EXPLOSION’ OF ANIMALS.” Annual Review of Earth and Planetary Sciences 34.1 (2006): 355–384. Web.
Riding, Robert, and Andrey Zhuravlev. The Ecology of the Cambrian Radiation. Ed. Robert Riding and Andrey Zhuravlev. New York, NY: Columbia University Press, 2000. Web.
Secher, Andy. Travels with Trilobites: Adventures in the Paleozoic. New York: Columbia University Press, 2022. Web.
Fortey, Richard A. “The Lifestyles of the Trilobites: These Denizens of the Paleozoic Era Seas Were Surprisingly Diverse.” American Scientist, vol. 92, no. 5, 2004, pp. 446–453.
Briggs, Derek E. G., et al. "Middle Cambrian Arthropods From Utah." Journal of Paleontology, vol. 82, no. 2, 2008, pp. 238-254.
Chatterton, Brian D. E., and Stacey Gibb. "Latest Early To Early Middle Devonian Trilobites From The Erbenochile Bed, Jbel Issoumour, Southeastern Morocco." Journal of Paleontology, vol. 84, no. 6, 2010, pp. 1188-1205.