Civil Rights
Movements, leaders, victories and the continuing fight for equality.
q2K BHP
Black History Portal
THE BHP WIRE —
HIDDEN TRUTHS
What's New!
Explore the people, places, events, achievements, struggles and stories that shaped our journey.
Movements, leaders, victories and the continuing fight for equality.
Innovation, patents, science, technology and world-changing contributions.
Pioneers, champions, Negro Leagues, records, activism and excellence.
Meet the people whose lives, choices and achievements shaped the journey.
Black towns, communities, institutions and places where history happened.
Moments that changed communities, movements, institutions and the nation.
In 1968 Shirley Chisholm became the first Black woman elected to the United States Congress. In 1972 she launched a campaign for the Democratic presidential nomination, breaking another political barrier.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
The cleithrum (pl.: cleithra) is a paired membrane bone which first appears as part of the skeleton in primitive bony fish, where it runs vertically along the scapula.[1] Its name is derived from Greek κλειθρον = "key (lock)", by analogy with "clavicle" from Latin clavicula = "little key".
The cleithrum forms a part of the shoulder girdle. Unlike most bones of the shoulder, but like the clavicle and interclavicle, it develops as dermal bone. It articulates with the clavicle on its ventral side.[2]
In fishes, where it attaches to the rear part of the skull, it articulates anteriorly with the bones of the operculum. It also articulates with the similarly-named postcleithrum (also known as the anocleithrum), supracleithrum, and presupracleithrum.[2]
Ancestrally the cleithrum formed a part of the dermatocranium of the skull, and was attached to the rear part of the head in fishes. It is believed to have evolved from a number of bony plates present in placoderms (namely, the anterior lateral plate, the anterior ventrolateral plate, and the spinal plate).[3]
In modern fishes, the cleithrum is a large bone that extends upwards from the base of the pectoral fin and anchors to the cranium above the gills, forming the posterior edge of the gill chamber.[4] The bone has scientific use as a means to determine the age of fishes.
The lobe-finned fishes share this arrangement. In the earliest tetrapods, however, the cleithrum/clavicle complex came free of the skull roof, allowing for a movable neck. A small cleithrum is present in Triadobatrachus (the earliest known lissamphibian) and in modern frogs, where it forms a vestigial portion of the shoulder girdle attached to the suprascapula.[5][6]
The cleithrum disappeared early in the evolution of reptiles, and in amniotes is very small or absent. It has been argued based on position, muscle connectivity, and developmental origin that the nuchal element of the turtle carapace is formed from fused cleithra.[7]
| About fish |  | ||||
|---|---|---|---|---|---|
| Anatomy and physiology | |||||
| Sensory systems | |||||
| Reproduction | |||||
| Locomotion | |||||
| Other behaviour | |||||
| By habitat | |||||
| Other types | |||||
| Commerce |
| ||||
| Major groups | |||||
| Lists | |||||
Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
The cleithrum (pl.: cleithra) is a paired membrane bone which first appears as part of the skeleton in primitive bony fish, where it runs vertically along the scapula. Its name is derived from Greek κλειθρον = "key (lock)", by analogy with "clavicle" from Latin clavicula = "little key".
Hynerpeton ( lit. 'creeping animal from Hyner') is an extinct genus of early four-limbed vertebrate that lived in the rivers and ponds of Pennsylvania during the Late Devonian period, during the Late Fammenian stage. The only known species of Hynerpeton is H. bassetti, named after the describer's grandfather, city planner Edward Bassett. Hynerpeton is known for being the first Devonian four-limbed vertebrate discovered in the United States, as well as possibly being one of the first to have lost internal (fish-like) gills. This genus is known from few remains discovered at the Red Hill fossil site in Hyner, Pennsylvania. The most notable fossil is a large endochondral shoulder girdle consisting of the cleithrum, scapula, and coracoid (but not the interclavicle and clavicles), all connected into one shoulder bone. The inner surface of this shoulder bone possesses an array of depressions believed to have been attachment points for a unique set of powerful muscles around the chest. This may have given Hynerpeton improved mobility and weight-bearing abilities compared to other Devonian limbed vertebrates such as Ichthyostega and Acanthostega. The cleithrum (upper blade of the shoulder) is fused to the scapulocoracoid (lower plate of the shoulder, in front of the shoulder socket), unlike in most tetrapods. Conversely, the shoulder girdle is independent of the skull, unlike in most fish. Early four-limbed vertebrates are often referred to as tetrapods, according to a trait-based definition of the term as commonly used by most paleontologists. Devonian animals like Hynerpeton, Ichthyostega, and Acanthostega are excluded from the crown group Tetrapoda, since they evolved prior to the common ancestor of modern amphibians (Lissamphibia), reptiles, mammals, and birds. For specialists who prefer a neontological definition of tetrapods (i.e., only in the context of modern life), alternative terms for non-crown tetrapods include "stem-tetrapod" or "stegocephalian". Hynerpeton hails from the Red Hill fossil site, which, during the Late Devonian, was a warm floodplain inhabited by a diverse ecosystem of aquatic fish and terrestrial invertebrates. Hynerpeton was one of several genera of four-limbed vertebrates known from the site, although it was the first to be discovered. Some paleontologists have proposed that animals like Hynerpeton made use their amphibious lifestyle to find shallow pools where they could spawn, isolated from predatory fish which inhabited the deeper rivers.
Platynematichthys notatus, the coroatá or striped catfish, is a species of catfish (order Siluriformes) of the monotypic genus Platynematichthys of the family Pimelodidae. It is native to the Amazon and Orinoco Basins in South America. In the Orinoco this distinctly spotted species reaches up to 1 m (3.3 ft) in standard length, but it reportedly only reaches about half that size in the Amazon. Platynematichthys and its sister group Brachyplatystoma are the only genera in the tribe Brachyplatystomatini. These two genera are characterized by two synapomorphies; these include a gas bladder divided into an anterior portion and a triangular posterior portion, as well as a ventral crest under the cleithrum, the main bone supporting the pectoral fins.
Lophius piscatorius, commonly known as the angler, toadfish, sea frog, fishing frog, frogfish, or sea devil, is a species of Lophius in the family Lophiidae. It occurs in coastal and shelf waters of the northeast Atlantic, ranging from the Barents Sea south to the Strait of Gibraltar, and is also present in the Mediterranean and Black Sea. In parts of its range, including the Irish Sea, it supports an important commercial fishery.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Brown v. Board of Education in 1954.
