| Acastoides | |
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| Acastoides zguilmensis, Devonian, Morocco. | |
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| Genus: | Acastoides Delo, 1935 |
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Acastoides is an extinct genus of trilobite that lived during the Silurian and Devonian. It has been found in Bolivia, France, Morocco, Poland, Turkey and the United Kingdom.
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.
John William Salter was an English naturalist, geologist, and palaeontologist.
In the geological timescale, the Llandovery Epoch occurred at the beginning of the Silurian Period. The Llandoverian Epoch follows the massive Ordovician-Silurian extinction events, which led to a large decrease in biodiversity and an opening up of ecosystems.
Diacalymene is a genus of trilobite from the order Phacopida, suborder Calymenina. It includes the species D. ouzregui, D. clavicula, D. diademata and D. gabrielsi. It lived in the Ordovician and Silurian periods.
Ampyx is an Ordovician-Silurian genus of Asaphid trilobites of the family Raphiophoridae. Species of Ampyx are characterized by three extended spines on the head-shield, one spine derived from each free cheek, and one spine emanating from the glabellum. Species include Ampyx linleyensis.
Acaste is a genus of extinct trilobite of the order Phacopida which lived throughout the Silurian period. Though many species had been included, it now has only one species, Acaste downingiae. It is characterized by a convex dorsal surface, an absence of spines, a shortening of the head-shield and a general rounding off of all angles.
Sagenocrinites is an extinct genus of crinoid from the Silurian period. During the Silurian period, a sea-covered Britain that was shallower in the south and deeper in the north lay south of the equator with a tropical to sub-tropical climate. Therefore, in the United Kingdom, amongst Silurian fossils, such as brachiopods, trilobites and graptolites, coral-like organisms like sagenocrinites can be found.
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.
Balizoma is a genus of trilobites from the family Encrinuridae established by David J. Holloway in 1980. It has only been found in rocks of Silurian age. Its type species, B. variolaris, is currently the only named species of the genus, and is found in England. The neotype of B. variolaris was collected from the Much Wenlock Limestone Formation at Dudley, West Midlands. That specimen was first illustrated in Sir Roderick Impey Murchison's classic book, The Silurian System. B. variolaris was the original "strawberry-headed" trilobite of Dudley, so-named because of its nodular glabellar tubercles, and well known to early trilobite collectors. Additional species were originally assigned to Balizoma, but were subsequently placed in other encrinurine genera.
Acernaspis is an extinct genus of trilobite that is known from the Silurian. It contains two species, A. elliptifrons, and A. salmoensis. It is sometimes found preserved in burrows of various forms, sometimes in association with multiple moults, suggesting that it used tunnels as refuges whilst in its vulnerable moulting stage.
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..
Acastocephala is a genus of trilobite from the middle Silurian, known from the United Kingdom.
Bumastus is an extinct genus of corynexochid trilobites which existed from the Early Ordovician period to the Late Silurian period. They were relatively large trilobites, reaching a length of 6 in (15 cm). They were distinctive for their highly globular, smooth-surfaced exoskeleton. They possessed well-developed, large compound eyes and were believed to have dwelled in shallow-water sediments in life.
Planiscutellum is a genus of trilobites in the order Corynexochida family Styginidae. These trilobites were nektobenthic detritivore. They lived in the Silurian period in the upper Ludlow epoch, from 422.9 ± 1.5 to 418.7 ± 2.8 million years ago.
Ardeadactylus is an extinct genus of ctenochasmatoid pterosaur known from the Late Jurassic Solnhofen limestone of Bavaria, southern Germany. It contains a single species, Ardeadactylus longicollum, which was originally thought to be a species of Pterodactylus, as P. longicollum.
Illaenus crassicauda is a species of trilobites belonging to the family Illaenidae. These trilobites lived in the middle Ordovician and in the Silurian age. Fossils of this species have been found in the sediments of Sweden and Russia.
Odontopleura is a genus of spinose odontopleurid trilobite in the family Odontopleuridae, and is the type genus of that family and of Odontopleurida. The various species are found in Upper Ordovician to Middle Devonian marine strata throughout the world. The best studied fossils are of the type species, O. ovata, from the Wenlock-aged Liteň Formation in Loděnice, in Bohemia, Czech Republic, and, southeastern Gotland, of Sweden.
The Waukesha Biota refers to a Konservat-Lagerstätte of Early Silurian age found within the Brandon Bridge Formation in Waukesha County and Franklin, Milwaukee County, Wisconsin. It is known for the exceptional preservation of its diverse, soft-bodied and lightly skeletonized taxa, including many major taxa found nowhere else in strata of similar age. The sites discovery was announced in 1985, thus leading to a wide plethora of discoveries being made. This biota is one of the few well studied lagerstättes from the Silurian, making it very important in our understanding of Silurian faunas. Some of the taxa found here are not easily classified into known animal groups, showing that there is a great amount of studying that needs to be done on this site. Other taxa that are normally common in other Silurian deposits are rare here, but Trilobites are still quite common in the area. This site is also important because it shows that while Wisconsin's paleontology is often overlooked, it still provides exceptional insights concerning the history and diversity of life on Earth.
2021 in arthropod palentology is a list of new arthropod fossil taxa, including arachnids, crustaceans, insects, trilobites, and other arthropods that were announced or described, as well as other significant arthropod paleontological discoveries and events which occurred in 2021.
Dudleyaspis is an extinct genus of Lower to Middle Devonian odontopleurid trilobites that lived in a shallow sea that lay between Euramerica and Gondwana. It was named in 1949 by Prantl & Pribyl.
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