Bryozoa are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about 0.5 millimetres long, they have a special feeding structure called a lophophore, a "crown" of tentacles used for filter feeding. Most marine bryozoans live in tropical waters, but a few are found in oceanic trenches and polar waters. The bryozoans are classified as the marine bryozoans (Stenolaemata), freshwater bryozoans (Phylactolaemata), and mostly-marine bryozoans (Gymnolaemata), a few members of which prefer brackish water. 5,869 living species are known. One genus is solitary; all the rest are colonial.
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.
Stenolaemata are a class of exclusively marine bryozoans. Stenolaemates originated and diversified in the Ordovician, and more than 600 species are still alive today. All extant (living) species are in the order Cyclostomatida, the third-largest order of living bryozoans.
The Late Ordovician mass extinction, sometimes known as the end-Ordovician mass extinction or Ordovician-Silurian Extinction, is the first of the "big five" major mass extinction events in Earth's history. It is often considered to be the second-largest known extinction event, in terms of the percentage of genera that became extinct. Extinction was global during this interval, eliminating 49–60% of marine genera and nearly 85% of marine species. Under most tabulations, only the Permian-Triassic mass extinction exceeds the Late Ordovician mass extinction in 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. Despite its taxonomic severity, the Late Ordovician mass extinction 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.
Stigmatella is an extinct genus of bryozoans in the family Heterotrypidae. It is known from the Ordovician period and found in the U.S. states of Ohio, Kentucky and Indiana. Its colonies can form branches, lobes, or masses made from new layers encrusting upon older ones. In Kentucky, fossil remains of species Stigmatella personata that lived in underwater caves have been found, growing 'upside-down' on the cave ceiling.
Paleontology in Tennessee refers to paleontological research occurring within or conducted by people from the U.S. state of Tennessee. During the early part of the Paleozoic era, Tennessee was covered by a warm, shallow sea. This sea was home to brachiopods, bryozoans, cephalopods, corals, and trilobites. Tennessee is one of the best sources of Early Devonian fossils in North America. During the mid-to-late Carboniferous, the state became a swampy environment, home to a rich variety of plants including ferns and scale trees. A gap in the local rock record spans from the Permian through the Jurassic. During the Cretaceous, the western part of the state was submerged by seawater. The local waters were home to more fossil gastropods than are known from anywhere else in the world. Mosasaurs and sea turtles also inhabited these waters. On land the state was home to dinosaurs. Western Tennessee was still under the sea during the early part of the Cenozoic. Terrestrial portions of the state were swampy. Climate cooled until the Ice Age, when the state was home to Camelops, horses, mammoths, mastodons, and giant ground sloths. The local Yuchi people told myths of giant lizard monsters that may have been inspired by fossils either local or encountered elsewhere. In 1920, after local fossils became a subject of formal scientific study, a significant discovery of a variety of Pleistocene creatures was made near Nashville. The Cretaceous bivalve Pterotrigonia thoracica is the Tennessee state fossil.
Paleontology in Oklahoma refers to paleontological research occurring within or conducted by people from the U.S. state of Oklahoma. Oklahoma has a rich fossil record spanning all three eras of the Phanerozoic Eon. Oklahoma is the best source of Pennsylvanian fossils in the United States due to having an exceptionally complete geologic record of the epoch. From the Cambrian to the Devonian, all of Oklahoma was covered by a sea that would come to be home to creatures like brachiopods, bryozoans, graptolites and trilobites. During the Carboniferous, an expanse of coastal deltaic swamps formed in areas of the state where early tetrapods would leave behind footprints that would later fossilize. The sea withdrew altogether during the Permian period. Oklahoma was home a variety of insects as well as early amphibians and reptiles. Oklahoma stayed dry for most of the Mesozoic. During the Late Triassic, carnivorous dinosaurs left behind footprints that would later fossilize. During the Cretaceous, however, the state was mostly covered by the Western Interior Seaway, which was home to huge ammonites and other marine invertebrates. During the Cenozoic, Oklahoma became home to creatures like bison, camels, creodonts, and horses. During the Ice Age, the state was home to mammoths and mastodons. Local Native Americans are known to have used fossils for medicinal purposes. The Jurassic dinosaur Saurophaganax maximus is the Oklahoma state fossil.
Cystoporata, also known as Cystoporida or cystoporates, are an extinct order of Paleozoic bryozoans in the class Stenolaemata. Their fossils are found from Ordovician to Triassic strata.
Crepipora is an extinct genus of marine bryozoans belonging to the Ceramoporidae family. There are currently 18 collections from Belarus, Sweden, Canada, France and the United States. It was first assigned to Cystoporata by Sepkoski in 2002. The fossil range is from the Middle Ordovician to the Upper Ordovician.
Amplexopora is a genus of bryozoans of the family Amplexoporidae, known in the rock record from the Ordovician to the Permian periods. Species belonging to this genus were stationary epifaunal suspension feeders. Their colonies showed a very great variety in shapes.
The Lexington Limestone is a prominent geologic formation that constitutes a large part of the late Ordovician bedrock of the inner Bluegrass region in Kentucky. Named after the city of Lexington, the geologic formation has heavily influenced both the surface topography and economy of the region.
Madeleine Alberta Fritz was a Canadian palaeontologist. She was a professor at the University of Toronto, where she taught vertebrate studies in the department of Geology. Fritz's writing on the fossil Bryozoa along with her research on the stratigraphy of Toronto and the surrounding areas were major contributions to the geological field.
Histiodella is an extinct genus of conodonts.
Monticulipora is an extinct genus of Ordovician bryozoans belonging to the family Monticuliporidae. It was first named in 1849, and its description was published the following year by French paleontologist Alcide M. d'Orbigny, making it one of the earliest bryozoans to be recognized in science. It is still one of the most widespread fossil bryozoan genera. Though colonies that grow in masses made of multiple layers are characteristic of the genus, its colonies have varying shapes, able to be encrusting, branching, massive, or frond-like, and are covered in monticules (bumps). Most Monticulipora species have distinctively granular walls, and Monticulipora and can be distinguished from Homotrypa by the presence of axial diaphragms.
Dekayia is an extinct genus of Ordovician bryozoans of the family Heterotrypidae. Its colonies can be branching, encrusting, or massive. All species have acanthopores in varying sizes and numbers. The autozooecia appear angular or sub-angular viewed through a cross-section of the colony, and their walls are distinctively undulating or crenulated. Maculae generally protrude from the colony surface very little or at all, and can contain unusually large autozooecia and a cluster of mesozooecia in their centers.
Homotrypa is an extinct genus of bryozoans from the Ordovician and Silurian periods, known from fossils found in the United States. Its colonies are branch-like and have small monticules made of groups of three or four larger zooecia slightly protruding out from the main surface of the colony.In cross section, the zooecia are erect in axis and gently curve toward the surface of the colony.
Mesotrypa is a genus of bryozoans known from the Ordovician period, first described in 1893. Its colonies consist of low masses, wider than they are thick, made of superimposed layers, with small monticules on the surface of the colony.
Eridotrypa is an extinct genus of bryozoans of the family Aisenvergiidae, consistently forming colonies made of thin branches. Diaphragms are very common in colonies. Distinctively, in the exozone there are serrated dark borders separating the autozooecia.
Prasopora is an extinct genus of bryozoan belonging to the family Monticuliporidae, known from the Middle Ordovician. Its colonies were disc-shaped or hemispherical, flat on bottom and convex on top, and had very abundant mesopores; in the case of the species P. insularis its zooecia were isolated from each other by the numerous mesopores surrounding them. It is very similar to the genus Monticulipora, and some bryozoan species have been assigned to both genera at different points in their study, but it is mostly distinguished by having more mesozooecia, rounder autozooecial apertures, relatively few acanthostyles and diaphragms and cystiphragms equally distributed in the autozooecia.
Revalotrypa is an extinct genus of bryozoan of the family Revalotrypidae that lived during the late Ordovician period. It was initially placed within the order Trepostomatida, but later moved to Cystoporida, a classification supported by the discovery of the very similar genus Lynnopora, which possesses lunaria in its autozooidal apertures, a quality distinctive of Cystoporida.
