| Acastidae Temporal range: | |
|---|---|
 | |
| Coltraneia oufatenensis | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | † Trilobita |
| Order: | † Phacopida |
| Superfamily: | † Acastoidea |
| Family: | † Acastidae Delo, 1935 |
| subfamilies [1] | |
| |
Acastidae is a family of trilobites in the order Phacopida, suborder Phacopina, superfamily Acastoidea, containing the following genera: [2]
Phacopida ("lens-face") is an order of trilobites that lived from the Late Cambrian to the Late Devonian. It is made up of a morphologically diverse assemblage of taxa in three related suborders.
Dalmanitoidea is a superfamily of trilobites in the order Phacopida, containing the three families Dalmanitidae, Diaphanometopidae and Prosopiscidae.
Dalmanitidae is a family of trilobites in the order Phacopida that lived from the Floian (Ordovician) to the Devonian and includes 33 genera.
Calymenina is a suborder of the trilobite order Phacopida.
Acastoidea is a superfamily of trilobites from the order Phacopida, suborder Phacopina. This superfamily is divided into two families, Acastidae and Calmoniidae. This superfamily is distinguishable from the Phacopidae in that eyes are closer to the glabella and that the glabella has lobes, unlike the genera in Phacopidae. Acastoidea was first proposed by T.J.A. Reijers in 1972.
Calmoniidae is a family of trilobites from the order Phacopida, suborder Phacopina, superfamily Acastoidea.
Acastava is an extinct genus of trilobite in the order Phacopida, from the upper Pragian to Emsian period of the Devonian.
Ceraurinus is an extinct genus of trilobite in the order Phacopida. It contains one species, C. serratus.
Deltacephalaspis is an extinct genus of trilobites in the order Phacopida. It contains four species, D. comis, D. magister, D. retrospina, and D. tumida. Fossils of the genus have been found in the Belén, Icla and Gamoneda Formations of Bolivia and the Gydo Formation of South Africa.
Gourdonia is a trilobite in the order Phacopida, that existed during the middle Devonian in what is now France. It was described by Pillet in 1954, and the type species is Gourdonia gourdoni, which was originally described under the genus Dalmanites by Barrois in 1883. The generic name is derived from the species epithet. The type locality was the Cathervielle Shale in the Pyrenees mountains.
Hexacosta is a trilobite in the order Phacopida, that existed during the middle Devonian in what is now Afghanistan. It was described by Farsan in 1981, and the type species is Hexacosta zendadjanensis.
Kayserops is a trilobite in the order Phacopida, that existed during the lower Devonian in what is now Germany. It was described by Delo in 1935, and the type species is Kayserops kochi, which was originally described under the genus Cryphaeus by Kayser in 1883. The generic name is derived from the name of the species' author. The type locality was the Rhenish Massif.
Encrinuridae is a family of trilobite within the order Phacopida that lived in what would be Africa, Asia, Australia, Europe, North America, and South America from the middle Ordovician to the early Devonian from 479 to 412.3 million years ago, existing for approximately 66.7 million years.
Calymenidae is a family of trilobites, containing the following genera:
Pilekiidae is a family of trilobites in the order Phacopida, specifically within Suborder Cheirurina. It includes the following genera:
Cheirurina is a suborder of the trilobite order Phacopida. Known representatives range from the uppermost Cambrian to the end of the Middle Devonian (Givetian). Cheirurina is made up of a morphologically diverse group of related families.
Librostoma is a subclass of trilobites defined by having a natant hypostome, which is a hypostome that is free from the anterior doublure and aligned with the anterior of the glabella, this is unlike a conterminant hypostome, which is attached to the exoskeleton.
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.
Gregory Donald Edgecombe is a merit researcher in the department of Earth Sciences at the Natural History Museum, London. He is a leading figure in understanding the evolution of arthropods, their position in animal evolution and the integration of fossil data into analyses of animal phylogeny. As a palaeontologist, he is also an authority on the systematics of centipedes – and a morphologist whose work contributes to the growth and methods of analysis of molecular datasets for inferring evolutionary relationships.
Tolkienia is an extinct genus of trilobite in the family Acastidae. It consists of three species split from Comura based on morphological differences. The genus was present during the Emsian stage of the Early Devonian epoch around 400 Ma.
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