The Devonian is a geologic period and system of the Paleozoic, spanning 60.3 million years from the end of the Silurian, 419.2 million years ago (Mya), to the beginning of the Carboniferous, 358.9 Mya. It is named after Devon, England, where rocks from this period were first studied.
Trilobites are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period and they flourished throughout the lower Paleozoic before slipping into a long decline, when, during the Devonian, all trilobite orders except the Proetida died out. The last extant trilobites finally disappeared in the mass extinction at the end of the Permian about 252 million years ago. Trilobites were among the most successful of all early animals, existing in oceans for almost 270 million years, with over 20,000 species having been described.
Eldredgeops rana is a species of trilobite from the middle Devonian period. Their fossils are found chiefly in the northeastern United States, and southwestern Ontario.
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, with a broader time range described from the Late Ordovician. It was a rounded animal, with a globose head and large eyes, and probably fed on detritus. Phacops is often found rolled up ("volvation"), a biological defense mechanism that is widespread among smaller trilobites but further perfected in this genus.
Dalmanites is a genus of trilobite in the order Phacopida. They lived from the Late Ordovician to Middle Devonian.
Greenops is a mid-sized Devonian trilobite of the order Phacopida, subfamily Asteropyginae. They are mainly reported from the mid-Devonian Hamilton Group of upstate New York and southwestern Ontario. A similar-looking trilobite from Morocco is often mis-labelled Greenops. Greenops had schizocroidal eyes, large genal spines and short, sharp spines at the tip of each segment of the pygidium ("tail"). Greenops lived in warm, fairly deep water. In the Hamilton Group of New York, they are found with Eldredgeops, Dipleura and Bellacartwrightia, a trilobite that resembles Greenops but has much larger pygidial spines. In Ontario, they are found in the Widder Formation, which outcrops at Arkona, where they are, by far, the dominant trilobite.
Walliserops is a genus of spinose phacopid trilobite, of the family Acastidae, found in Lower to Middle Devonian age rocks from the Anti-Atlas Mountains of Morocco. All species of Walliserops possess a three-pronged "trident" that protrudes from the glabella. Walliserops is most closely related to the genus Comura.
Flexicalymene Shirley, 1936. is a genus of trilobites belonging to the order Phacopida, suborder Calymenina and Family Calymenidae. Flexicalymene specimens can be mistaken for Calymene, Gravicalymene, Diacalymene and a few other Calymenina genera. They are used as an index fossil in the Ordovician. Ohio and North America are particularly known for being rich with Flexicalymene fossils.
Kainops is a genus of trilobites from the family Phacopidae, order Phacopida. It can be distinguished from Paciphacops by the greater number of facets to the eye. The form of the furrow between the palpebral area and the palpebral lobe also distinguishes Kainops from the genera Paciphacops and Viaphacops.
Eldredgeops is a genus of trilobites in the order Phacopida, family Phacopidae, known from the late Middle and earliest Upper Devonian of Morocco and the USA.
Trimerocephalus is a genus of eyeless trilobites from the order Phacopida, family Phacopidae. It lived during the final stage of the Devonian, the Famennian, and became extinct at the end of this stage, together with all other trilobites with the exception of some Proetida. It can be found in Australia, the Czech Republic, France, Germany, Iran, Kazakhstan, Morocco, Poland, the Russian Federation (Urals), Spain, and the United Kingdom (England).
Dicranurus is a genus of Lower to Middle Devonian odontopleurid trilobites that lived in a shallow sea that lay between Euramerica and Gondwana, corresponding to modern-day Oklahoma and New York, and Morocco, respectively. As such, their fossils are found in New York, Oklahoma, and Morocco. Their bodies averaged about 1-inch (25 mm) or so, in length, though their large spines made them at least 2 inches (51 mm) in length. It is speculated that such tremendous spines hampered the ability of predators, such as arthrodire placoderms, to attack them, as well as to help prevent them from sinking into the soft mud of their environment. Dicranurus trilobites are distinguished from other odontopleurids by the pair of large, curled, horn-like spines that emanate from behind the glabellum. The genus name refers to these distinctive horns, in fact.
Erbenochile is a genus of spinose phacopid trilobite, of the family Acastidae, found in Lower to Middle Devonian age rocks from Algeria and Morocco. Originally described from an isolated pygidium, the first complete articulated specimen of E. erbeni revealed the presence of extraordinarily tall eyes:
"Straight-sided towers of lenses... with [up to] 18 lenses in a vertical file"
Cyphaspis is a genus of small trilobite that lived from the Late Ordovician to the Late Devonian. Fossils have been found in marine strata in what is now Europe, Africa and North America. Various species had a compact body, and a large, bulbous glabellum. Many species had long spines arranged similarly to closely related genera, such as Otarian, Otarionella, Chamaeleoaspis, and Namuropyge.
Boeckops is a genus of trilobites in the order Phacopida, which existed in what is now the Czech Republic. It was described by Chlupac in 1972, and the type species is Boeckops boecki, which was originally described as Phacops boecki by Hawle and Corda in 1847. Boeckops is also been discriped from the lower Devonian of Morocco and Algeria. The Genus Boeckops is interpreted as intermediate from between the traditional genus concept of Phacops and Reedops. The Genus Boeckops is regarded as problematic or difficult by McKellar et Chatterton 2009.
Homalonotus is an extinct genus of trilobites in the order Phacopida. It contains several species, including H. armatus and H. roemeri. It is closely related to other trilobites such as Arduennella and Dipleura..
Ceratarges was a genus of lichid Trilobite from the Middle Devonian. It lived in what is now western Europe and Morocco.
Acanthopyge is an extinct genus of lichid trilobite that lived during the Devonian. Very few A. consanguinea from the Devonian of Oklahoma have been found, and only a handful of complete specimens from Morocco, and many so-called Acanthopyge-specimens from Morocco are fake.
Cordania is an extinct genus of trilobites that lived from the Early to Middle Devonian.
Gerastos is a genus of proetid trilobite in the family Proetidae that lived between the Pragian and Eifelian of the Lower-Middle Devonian, spanning approximately 21 million years.
