| Pterygometopidae | |
|---|---|
 | |
| Calliops armatus dorsal view of the cephalon, collected from the Bromide Formation, Sandbian | |
| Scientific classification | |
| Kingdom: | |
| Phylum: | |
| Class: | |
| Order: | |
| Suborder: | |
| Superfamily: | |
| Family: | Pterygometopidae Reed, 1905 |
| subfamilies | |
| |
The Pterygometopidae are a family of trilobites, that is known from the Floian to the Katian (Ordovician), and reappears from the Telychian to the Sheinwoodian (Silurian). As part of the Phacopina suborder, its members have schizochroal eyes.
The Pterygometopinae may be exclusive to Baltica and are known from the Floian to the Upper Katian with 49 species in 14 genera. The 71 species from 8 genera belonging to the Eomonorachinae occur mostly in Laurentia from the Floian. One genus, Podowrinella , is known from the Silurian, and may be the sister taxon of the Phacopidae. 50 species in 8 genera have been assigned to the Chasmopinae. They are exclusive to Baltica from the Darriwilian to the Sandbian. The subfamily spread to Avalonia and Laurentia in the Katian, at the end of which they became extinct. 32 species of Monorachinae in 6 genera occurred on the paleocontinent Siberia, now parts of northeastern Russia and of Alaska, from the Sandbian to the Upper Katian. [1]
The following genera are assigned to the Pterygometopidae: [2]
The Ordovician is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period 485.4 million years ago (Mya) to the start of the Silurian Period 443.8 Mya.
The PaleozoicEra is the earliest of three geologic eras of the Phanerozoic Eon. It is the longest of the Phanerozoic eras, lasting from 541 to 251.902 million years ago, and is subdivided into six geologic periods : the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian. The Paleozoic comes after the Neoproterozoic Era of the Proterozoic Eon and is followed by the Mesozoic Era.
The Silurian is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago (Mya), to the beginning of the Devonian Period, 419.2 Mya. The Silurian is the shortest period of the Paleozoic Era. As with other geologic periods, the rock beds that define the period's start and end are well identified, but the exact dates are uncertain by a few million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when up to 60% of marine genera were wiped out.
The Ordovician–Silurian extinction events, also known as the Late Ordovician mass extinction (LOME), are collectively the second-largest of the five major extinction events in Earth's history in terms of percentage of genera that became extinct. Extinction was global during this period, eliminating 49–60% of marine genera and nearly 85% of marine species. Only the Permian-Triassic mass extinction exceeds the LOME in total biodiversity loss. The extinction event abruptly affected all major taxonomic groups and caused the disappearance of one third of all brachiopod and bryozoan families, as well as numerous groups of conodonts, trilobites, echinoderms, corals, bivalves, and graptolites. This extinction was the first of the "big five" Phanerozoic mass extinction events and was the first to significantly affect animal-based communities. However, the LOME did not produce major changes to ecosystem structures compared to other mass extinctions, nor did it lead to any particular morphological innovations. Diversity gradually recovered to pre-extinction levels over the first 5 million years of the Silurian period.
The Iapetus Ocean was an ocean that existed in the late Neoproterozoic and early Paleozoic eras of the geologic timescale. The Iapetus Ocean was situated in the southern hemisphere, between the paleocontinents of Laurentia, Baltica and Avalonia. The ocean disappeared with the Acadian, Caledonian and Taconic orogenies, when these three continents joined to form one big landmass called Euramerica. The "southern" Iapetus Ocean has been proposed to have closed with the Famatinian and Taconic orogenies, meaning a collision between Western Gondwana and Laurentia.
Baltica is a paleocontinent that formed in the Paleoproterozoic and now constitutes northwestern Eurasia, or Europe north of the Trans-European Suture Zone and west of the Ural Mountains. The thick core of Baltica, the East European Craton, is more than three billion years old and formed part of the Rodinia supercontinent at c. 1 Ga.
Bioerosion describes the breakdown of hard ocean substrates – and less often terrestrial substrates – by living organisms. Marine bioerosion can be caused by mollusks, polychaete worms, phoronids, sponges, crustaceans, echinoids, and fish; it can occur on coastlines, on coral reefs, and on ships; its mechanisms include biotic boring, drilling, rasping, and scraping. On dry land, bioerosion is typically performed by pioneer plants or plant-like organisms such as lichen, and mostly chemical or mechanical in nature.
Phacopidae is a family of phacophid trilobites that ranges from the Lower Ordovician to the Upper Devonian, with representatives in all paleocontinents.
The Caledonian orogeny was a mountain-building era recorded in the northern parts of Ireland and Britain, the Scandinavian Mountains, Svalbard, eastern Greenland and parts of north-central Europe. The Caledonian orogeny encompasses events that occurred from the Ordovician to Early Devonian, roughly 490–390 million years ago (Ma). It was caused by the closure of the Iapetus Ocean when the continents and terranes of Laurentia, Baltica and Avalonia collided.
Tabulata, commonly known as tabulate corals, are an order of extinct forms of coral. They are almost always colonial, forming colonies of individual hexagonal cells known as corallites defined by a skeleton of calcite, similar in appearance to a honeycomb. Adjacent cells are joined by small pores. Their distinguishing feature is their well-developed horizontal internal partitions (tabulae) within each cell, but reduced or absent vertical internal partitions (septa). They are usually smaller than rugose corals, but vary considerably in shape, from flat to conical to spherical.
Cryptospores are fossilised primitive plant spores that first appear in the fossil record during the middle of the Ordovician period.
Cheiruridae is a family of phacopid trilobites of the suborder Cheirurina. Its members, as with other members of the suborder, had distinctive pygidia modified into finger-like spines. They first appeared in the uppermost Cambrian, and persisted until the end of the Middle Devonian (Givetian). Currently about 657 species assigned to 99 genera are included.
Asaphidae is a family of asaphid trilobites. Although the first genera originate in Upper Cambrian marine strata, the family becomes the most widely distributed and most species-rich trilobite family during the Ordovician. 754 species assigned to 146 genera are included in Asaphidae.
Diaphanometopidae is a family of trilobites. Its representatives lived during the Arenig and Llanvirn stages of the Ordovician Period, approximately 479 to 463 million years ago. The Diaphanometopidae are thought to have been an early transitional group between the Ptychopariida ancestors and all other Phacopina. Diaphanometopidae, are found in the Lower and Middle Ordovician of Sweden and Russia. Three species are assigned to this family: Diaphanometopus volborthi that has been found in the Dapingian of Baltica, Gyrometopus lineatus occurring in the Floian of Baltica and Prodalmanitina nikolaevi that is known from the Floian of Kolyma. These species have many ancestral characters compared to other Phacopina, but they do not seem to be each other's nearest relatives, which makes it unlikely this family will be maintained when the phylogeny has been studied in more detail.
Trinodus is a very small to small blind trilobite, a well known group of extinct marine arthropods, which lived during the Ordovician, in what are now the Yukon Territories, Virginia, Italy, Czech Republic, Poland, Denmark, Sweden, Svalbard, Ireland, Scotland, Wales, Iran, Kazakhstan and China. It is one of the last of the Agnostida order to survive.
Raphiophoridae is a family of small to average-sized trilobites that first occurred at the start of the Ordovician and became extinct at the end of the Middle Silurian.
The Illaenidae are a family of trilobites in the order Corynexochida. 223 currently accepted species in 24 genera are known from the Ordovician. Some scholars include the Panderiidae in the Illaenidae, but this is not generally supported.
Telephinidae is a family of pelagic trilobites with large wide-angle eyes, occupying most of the free cheeks, downward directed facial spines and 9-10 thorax segments. The family is known during the entire Ordovician and occurred in deep water around the globe.
Trinucleidae is a family of small to average size asaphid trilobites that first occurred at the start of the Ordovician and became extinct at the end of that period. It contains approximately 227 species divided over 51 genera in 5 subfamilies. The most conspicuous character is the wide perforated fringe of the head.
Diploporita is an extinct class of blastozoan that ranged from the Ordovician to the Devonian. These echinoderms are identified by a specialized respiratory structure, called diplopores. Diplopores are a double pore system that sit within a depression on a single thecal (body) plate; each plate can contain numerous diplopore pairs.
 | This Phacopida-related article is a stub. You can help Wikipedia by expanding it. |