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Movements, leaders, victories and the continuing fight for equality.
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Meet the people whose lives, choices and achievements shaped the journey.
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In August 1908, a white mob attacked Springfield, Illinois’s Black community, destroying homes and businesses and lynching two Black men. National outrage over the violence helped spur the movement that created the NAACP the following year.
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 hyomandibula, commonly referred to as hyomandibular [bone] (Latin: os hyomandibulare, from Greek: hyoeides, "upsilon-shaped" (υ), and Latin: mandibula, "jawbone"), is a set of bones that is found in the hyoid region in most fishes. It usually plays a role in suspending the jaws and/or operculum (teleostomi only). It is commonly suggested that in tetrapods (land animals), the hyomandibula evolved into the columella (stapes).[1][2]
In jawless fishes, a series of gills opened behind the mouth, and these gills became supported by cartilaginous elements. The first set of these elements surrounded the mouth to form the jaw. There is ample evidence[3] that vertebrate jaws are homologous to the gill arches of jawless fishes. The upper portion of the second embryonic arch supporting the gill became the hyomandibular bone of jawed fishes, which supports the skull and therefore links the jaw to the cranium. [4]
When vertebrates found their way onto land, the hyomandibula, with its location near the ear, began to function as a sound amplifier beside its function to support the skull. As evolution later attached the cranium of terrestrial vertebrates to the rest of the skull, the hyomandibula lost its supportive function and became an interior organ, the stapes, and thus its secondary function had become its primary function. [4]
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Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
The hyomandibula, commonly referred to as hyomandibular [bone] (Latin: os hyomandibulare, from Greek: hyoeides, "upsilon-shaped" (υ), and Latin: mandibula, "jawbone"), is a set of bones that is found in the hyoid region in most fishes. It usually plays a role in suspending the jaws and/or operculum (teleostomi only). It is commonly suggested that in tetrapods (land animals), the hyomandibula evolved into the columella (stapes).
Squalus is a genus of dogfish sharks in the family Squalidae. Commonly known as spurdogs, these sharks are characterized by smooth dorsal fin spines, teeth in upper and lower jaws similar in size, caudal peduncle with lateral keels; upper precaudal pit usually present, and caudal fin without subterminal notch. In spurdogs, the hyomandibula (the bone connecting the braincase to the jaws) is oriented at a right angle to the neurocranium, while in other sharks, the hyomandibula runs more parallel to the body. This led some to think that the upper jaw of Squalus would not be as protractile as the jaws of other sharks. However, a study that compared different jaw suspension types in sharks showed that this is not the case and that Squalus is quite capable of protruding its upper jaw during feeding. The name comes from squalus, the Latin for shark; this word is the root for numerous words related to sharks such as squaline and scientific names for sharks, such as the order Squaliformes.
Branchial arches or gill arches are a series of paired bony/cartilaginous "loops" behind the throat (pharyngeal cavity) of fish, which support the fish gills. As chordates, all vertebrate embryos develop pharyngeal arches, though the eventual fate of these arches varies between taxa. In all jawed fish (gnathostomes), the first arch pair (mandibular arches) develops into the jaw, the second gill arches (the hyoid arches) develop into the hyomandibular complex (which supports the back of the jaw and the front of the gill series), and the remaining posterior arches (simply called branchial arches) support the gills. In tetrapods, a mostly terrestrial clade evolved from lobe-finned fish, many pharyngeal arch elements are lost, including the gill arches. In amphibians and reptiles, only the oral jaws and a hyoid apparatus remains, and in mammals and birds the hyoid is simplified further to support the tongue and floor of the mouth. In mammals, the first and second pharyngeal arches also give rise to the auditory ossicles. Most vertebrates are aquatic and breathe with gills, where water comes in contact for exchanging dissolved oxygen before flowing out through a series of openings (gill slits) to the outside. Each gill is supported by a cartilaginous or bony gill arch, which helps to maintain the gill's surface area. Bony fish (osteichthyans, mostly teleost ray-finned fish) have four pairs of arches, cartilaginous fish (chondrichthyans) have five to seven pairs, and the more basal jawless fish ("agnathans") have up to seven. The Cambrian ancestors of vertebrates no doubt had more gill arches, as some of their chordate relatives have more than 50 pairs of gills. In amphibians and some primitive bony fish, the larvae bear external gills branching out from the gill arches. These regress upon adulthood, their function taken over by the gills proper in fish, or by lungs (which are homologous to swim bladders) and cutaneous respiration in most amphibians. Some neotenic amphibians (such as the axolotl) retain the external larval gills in adulthood, the complex internal gill system as seen in fish apparently being irrevocably lost very early in the evolution of tetrapods.
The garfish (Belone belone), also known as the garpike, needlefish or sea needle, is a pelagic, oceanodromous needlefish found in brackish and marine waters of the Atlantic Ocean and the Mediterranean, Caribbean, Black, and Baltic Seas.
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 →Joe Louis.
