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 22,000 species having been described.
Redlichiida is an order of trilobites, a group of extinct marine arthropods. Species assigned to the order Redlichiida are among the first trilobites to appear in the fossil record, about halfway during the Lower Cambrian. Due to the difficulty to relate sediments in different areas, there remains some discussion, but among the earliest are Fallotaspis, and Lemdadella, both belonging to this order. The first representatives of the orders Corynexochida and Ptychopariida also appear very early on and may prove to be even earlier than any redlichiid species. In terms of anatomical comparison, the earliest redlichiid species are probably ancestral to all other trilobite orders and share many primitive characters. The last redlichiid trilobites died out before the end of the Middle Cambrian.
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.
Redlichia is a genus of redlichiid trilobite in the family Redlichiidae, with large to very large species. Fossils of various species are found in Lower Cambrian (Toyonian)-aged marine strata from China, Korea, Pakistan, the Himalayas, Iran, Spain, southern Siberia, and Antarctica, and from Middle Cambrian (Ordian)-aged marine strata of Australia.
Isotelus is a genus of asaphid trilobites from the middle and upper Ordovician period, fairly common in the Northeastern United States, northwest Manitoba, southwestern Quebec and southeastern Ontario. One species, Isotelus rex, is currently the world's largest trilobite ever found as a complete fossil, and was probably exceeded in size only by Hungioides bohemicus, in which the specimens probably exceeding Isotelus rex in size are only known from partial remains.
Eldredgeia is a genus of trilobites in the order Phacopida, suborder Phacopina, family Calmoniidae. This genus comes from the Devonian of South America and South Africa, usually found in nodules. The trilobite Eldredgeia venusta, from Bolivia, is the most common South American trilobite on today's fossil market, and even then it is not all that common. This genus has a spiny pygidium and usually the eye facets are well preserved.
Ductina is a genus of extinct, small to average sized, eyeless phacopid trilobite, that lived during the Devonian.
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.
Drotops is a genus of trilobites from the order Phacopida, family Phacopidae that lived during the Eifelian of the Middle Devonian. It was described by Struve in 1990 under type species Drotops megalomanicus. Their fossils are found in present-day Morocco, specifically the Maïder Region located South West of Erfoud.
Homosteus is a genus of flattened arthrodire placoderm from the Middle Devonian. Fossils are found primarily in Eifelian-epoch aged strata of Europe, Canada, Greenland, and Estonia. All of the species had comparatively large, flattened heads with, as suggested by the upward opening orbits, upward-pointing eyes. These adaptations suggest that the various species were benthic predators. A study on Titanichthys, in contrast, suggests that species of Homosteus may have been filter-feeders instead.
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"
Calmonia is an extinct genus of trilobites. It contains one species: C. curvioculata. Fossils of Calmonia have been found in the Emsian to Eifelian Ponta Grossa Formation and Chapada Group of Brazil, the Belén and Sica Sica Formations of Bolivia and the Cordobés Formation of Uruguay.
Holonema is an extinct genus of relatively large, barrel-shaped arthrodire placoderms that were found in oceans throughout the world from the Mid to Late Devonian, when the last species perished in the Frasnian-Fammian extinction event. Most species of the genus are known from fragments of their armor, but the Gogo Reef species, H. westolli, is known from whole, articulated specimens.
Aayemenaytcheia paragranulata is a Middle Devonian proetid trilobite.
The Devonian Jeffersonville Limestone is a mapped bedrock unit in Indiana and Kentucky. It is highly fossiliferous.
Paleontology in Wisconsin refers to paleontological research occurring within or conducted by people from the U.S. state of Wisconsin. The state has fossils from the Precambrian, much of the Paleozoic, and the later part of the Cenozoic. Most of the Paleozoic rocks are marine in origin. Because of the thick blanket of Pleistocene glacial sediment that covers the rock strata in most of the state, Wisconsin’s fossil record is relatively sparse. In spite of this, certain Wisconsin paleontological occurrences provide exceptional insights concerning the history and diversity of life on Earth.
Protitanichthys is an extinct genus of comparatively large coccosteid arthrodire placoderms from the Middle Devonian of the eastern United States. Fossils are found primarily in the Eifelian-epoch aged Delaware Limestone of Ohio, and the Lower Givetian-aged Rockport Quarry Limestone of Michigan
Hollardops is a genus of trilobite in the order Phacopida that lived during the Devonian. Their fossils are found in the upper Emsian of western Europe and in the lower Emsian to lowermost Eifelian of North Africa. The type species, Asteropyge mesocristata, was described from Algeria by Le Maître in 1952. The genus Hollardops was erected by Morzadec in 1997. In the same year, Lieberman & Kloc erected Modellops and Philipsmithiana but those genera are regarded as subjective synonyms of Hollardops. The 10-segmented thoracic condition of Hollardops is a rare feature among acastid trilobites that almost always have 11 thorax segments. Van Viersen & Kloc (2022) revisited Hollardops and described a number of new species from the Devonian of Morocco. They also regarded Pennarbedops Bignon & Crônier, 2013 as a synonym of Hollardops. Van Viersen & Kloc construed Hollardops as a scavenger or predator with well-developed eyes, that used its shovel-like cephalon to plough the top layers of the sediment in search of food. Hollardops had small pits horizontally along the fringe of the exoskeleton; these are believed to have housed setae that allowed the trilobite to closely monitor its surroundings.
The Vireux-Molhain national nature reserve (RNN104) is a national nature reserve of geological and paleontological interest. It is located in the Pointe de Givet, department of Ardennes, on the border between France and Belgium. It covers an area of 1.82 ha. The site is known as Customs Wall as it is near an old customs post. This outcrop of Middle Devonian shale is notable for the quantity and good state of preservation of its fossils. Trilobites are well-represented.
