title: Kennewick, Washington

text: Kennewick lies near the center of Washington's wine country, which stretches from the Yakima Valley through the Columbia Basin and Horse Heaven Hills east to the Walla Walla Valley. There are several American Viticultural Areas near town. Wine tasting is a major part of the Tri-Cities tourism economy, with over 300 wineries and wine bars rooms in the area. The city actively markets this to bring in visitors. Cruises travel up the Columbia from Portland with a stop in the Tri-Cities to tour wineries in the area.


title: Kennewick, Washington

text: Kennewick hosts two professional sports teams, the Tri-City Americans of the Western Hockey League and Tri-Cities Fire of the American West Football Conference. Both teams play at the Toyota Center. The other professional sports team in the Tri-Cities, the Tri-City Dust Devils (a farm team of the San Diego Padres) plays at Gesa Stadium in Pasco.


title: Kennewick, Washington

text: The Tri-City Americans were one of the original teams in the Western Hockey League, starting in Calgary, Alberta in 1966. The team moved a couple times before coming to the Tri-Cities in 1988, most recently being in a suburb of Vancouver, British Columbia. The team's move to the Tri-Cities made them the first professional hockey team to play in the area and was the catalyst for constructing the Toyota Center. The Americans have won the US Division four times, but have not yet won a Western Conference final.


title: Kennewick, Washington

text: The Tri-Cities Fire are an indoor football team playing in a league with three other teams. The team was founded in 2019, bringing indoor football back to the Toyota Center after the Tri-City Fever went dormant in 2016. The Fire finished their first season with an 0-12 record, the worst in the league. The Fever won one National Indoor Football League championship in 2005, beating the Rome Renegades. They went to the Indoor Football League championship game in 2011 and 2012, losing to Sioux Falls Storm both years.


title: Kennewick, Washington

text: While Kennewick does not currently host a professional baseball team, they have a long history of doing so in the past. Professional minor league teams have played in Kennewick starting as early as 1950 with the Tri-City Braves. Other teams included the Tri-City Atoms, the Tri-City A's, the Tri-City Triplets, and the Tri-City Ports. All of these played at Sanders-Jacobs Field, which has since been demolished. The city presently hosts the Atomic City Rollergirls, an amateur roller derby team. Washington State University occasionally plays basketball at the Toyota Center.


title: Kennewick, Washington

text: The only daily newspaper published in the Tri-Cities, the "Tri-City Herald", is based in downtown Kennewick. The "Tri-Cities Journal of Business" is a monthly print publication that is also located in Kennewick and also has a significant online presence. The "Journal of Business" also publishes the "Senior Times", whose target demographic is Tri-Citians who are 60 years or older. The city hosts "Tú Decides", a bilingual weekly news publication that is both in print and online. "Tú Decides" is available in both Spanish and English. Richland based "Tumbleweird" is an alternative newspaper published monthly that covers the Tri-Cities.


title: Kennewick, Washington

text: Kennewick and the Tri-Cities share a television market with Yakima. Because of this, the local affiliates of major national networks are closely linked to the affiliates in Yakima. The studios of the Tri-Cities affiliates of NBC, ABC, and Fox are located in Kennewick. These are KNDU, KVEW, and KFFX respectively. The CBS affiliate, KEPR is in Pasco. KFFX does not produce any local programming, instead it acquires its news from KNDU and its parent station—KHQ in Spokane. Unlike the television market, the Tri-Cities and Yakima have separate radio markets. Sixteen radio stations are licensed in Kennewick by the FCC with others in nearby cities. There are several religious non-commercial radio stations with coverage in Kennewick. The school district operates a student-run station out of Tri-Tech. NPR member stations Northwest Public Radio and Oregon Public Broadcasting also serve Kennewick.


title: Kennewick, Washington

text: Kennewick's low precipitation values and mild-to-warm weather provide opportunities for outdoor recreation throughout much of the year. The city's Parks and Recreation Department operates 27 parks plus other facilities for the public to use. Many parks have shelters that can be reserved for events, with most of them offering playgrounds. There are three athletic complexes throughout the city as well. The Parks and Recreation Department also maintains several hiking and bike trails in the city, including the portion of the Sacagawea Heritage Trail that passes through Kennewick.


title: Kennewick, Washington

text: The largest park in the city's system is Columbia Park, which is a riverfront area to the north of SR 240 from the Richland/Kennewick city line in the west to the Blue Bridge in the east. There are several boat launches here offering access to the Columbia River. Kayaking and canoeing is another popular water activity. The Sacagawea Heritage Trail, a bike path connecting all three of the Tri-Cities, passes through the entire length of the park. The most developed portion of the park is the east end, which has a veterans memorial, golf course, fishing pond, and a large playground. Columbia Park hosts the HAPO Gold Cup, an annual hydroplane race. The part of Richland adjacent to the park is Columbia Park West. Combined, the two form of contiguous public recreation land along the river.


title: Kennewick, Washington

text: In the early 2010s, the city built the Southridge Sports and Events Complex in the quickly growing south end of town along US 395. This property is primarily used for scheduled sporting events, such as baseball, basketball, and volleyball. That said, it also has recreational facilities that don't need to be reserved, such as a playground and open fields. Kennewick was able to secure a piece of the World Trade Center from the Port Authority of New York and New Jersey, which is located in the southeast corner of the complex as a memorial to the victims of the September 11 attacks in 2001. The complex was considered complete when the historic carousel that the city restored was opened on the site.


title: Kennewick, Washington

text: Kennewick is a code city that operates under the council–manager form of government. The city council has seven members, four of which are elected at-large while three are elected by the city's three electoral wards. The mayor is selected by the councilmembers. Kennewick's City Manager serves under the direction of the City Council, and administers and coordinates the delivery of municipal services.


title: Kennewick, Washington

text: The City of Kennewick is a full-service city, providing police, fire prevention and suppression, emergency medical response, water and sewer, parks, public works, planning and zoning, street maintenance, code enforcement, and general administrative services to residents. The city also operations a regional convention center. According to the City's 2018 audited financial report, the cities total annual expenses are $96.6 million, of which $24.2 million is funded by Sales Tax, $13.1 million by Utility Tax and $13.0 million by Property Tax.


title: Kennewick, Washington

text: The citizens of Kennewick are represented in the Washington Senate by Sharon Brown in District 8, and Maureen Walsh in District 16, and in the Washington House of Representatives by Brad Klippert and Matt Boehnke in District 8, and Bill Jenkin and Skyler Rude in District 16. At the national level, Kennewick and the rest of the Tri-Cities are part of the 4th congressional district, has been represented by Republican Dan Newhouse since 2015.


title: Kennewick, Washington

text: Out of the city's residents who are 25 years or older, 88% hold a high school diploma (or equivalent) with 24% holding a bachelor's degree or better. These rates are higher than Pasco, but lower than Richland. Kennewick does not have any post-secondary institutions, but is located near Columbia Basin College in Pasco and Washington State University Tri-Cities in Richland.


title: Kennewick, Washington

text: Public schools located in the city are part of the Kennewick School District (KSD). The Kennewick School District has 17 elementary schools, five middle schools, three high schools serving over 18,000 students. A vocational school is operated by KSD—with funding also coming from other local school districts—named the Tri-Tech Skills Center. Vocational programs at Tri-Tech include firefighting, radio broadcasting, and auto body technology. Similarly, KSD contributes funding to Delta High School in Pasco, which is a STEM-focused school drawing students from around the Tri-Cities. KSD also operates Neil F. Lampson Stadium, located at Kennewick High School, which is used to host football and soccer games for the three high schools in town as well as for special events. Lampson Stadium has a capacity of 6,800 people.


title: Kennewick, Washington

text: There are five private schools for educating children in Kennewick. Many of these are run by Christian churches, including St. Joseph's Catholic School and Bethlehem Lutheran School.


title: Kennewick, Washington

text: The nearest commercial airport to Kennewick is the Tri-Cities Airport in Pasco, with flights to several major international airports in the western part of the country. The busiest route is between Pasco and Seattle–Tacoma. Pasco also has the station for both Amtrak's Portland-Chicago "Empire Builder" and Greyhound Lines. The Port of Kennewick formerly operated Vista Field near the Toyota Center as a general aviation airport, but it closed at the end of 2013. The port plans to turn the land into a mixed-use development.


title: Kennewick, Washington

text: Interstate 82 bypasses Kennewick to the south, connecting to Seattle via Interstate 90 and both Portland and Salt Lake City via Interstate 84. US 395 passes through town from south to north connecting to Spokane, also via Interstate 90. State Route 240 and State Route 397 also pass through Kennewick, but these mostly serve local traffic. SR 240 connects the Hanford Site to Richland and also travels across the Columbia River on the Blue Bridge to Pasco. SR 397 connects both Interstate 82 and Interstate 182 in Pasco (via the Cable Bridge) to Finley, providing a direct route for freight to go to a chemical plant there.


title: Kennewick, Washington

text: Public transportation in Kennewick is provided by Ben Franklin Transit, which runs several bus routes that provide intra-city service as well as connections to Pasco and Richland. There are two transit centers in Kennewick: the Three Rivers Transit Center near the Toyota Center and the Dayton Transfer Point downtown. The transit authority also operates a dial-a-ride service for disabled persons.


title: Kennewick, Washington

text: Water and sewer services are provided by the city, with electricity coming from Benton Public Utility District. Natural gas comes from Cascade Natural Gas. Kennewick contracts with Waste Management for garbage and recycling collection. Many people use irrigation water sourced from nearby rivers to water their lawns. This system is separate from the water provided by the city. Most of Kennewick is part of the Kennewick Irrigation District, with parts of the east side of town being under the Columbia Irrigation District.


title: Kennewick, Washington

text: Nearly 80% of Kennewick's energy is hydroelectric, with another 10% coming from nuclear. Altogether, less than 5% of the city's electricity is sourced from fossil fuels.


title: Kennewick, Washington

text: The largest hospital in Kennewick is Trios, located in the Southridge area. Kennewick General Hospital rebranded to Trios upon the opening of their Southridge hospital. Prior to this, the system's primary hospital was located near Kennewick High School on a campus that continues to be used for medical care. Trios also operates clinics and urgent care facilities throughout the Tri-Cities. The main Trios Hospital has 111 beds for treating patients. Having many clinics around the Tri-Cities, Kadlec Regional Medical Center in Richland is another major health care provider in Kennewick with Miramar Health Center, a Yakima Valley focused provider, also having a clinic.


title: Kennewick, Washington

text: Trios is a Level III trauma center and is the only hospital in the Tri-Cities that is a designated as a pediatric trauma center. Kadlec is a Level II trauma center and often receives victims from car accidents. Patients needing further care are often transported to Harborview Medical Center in Seattle, which is the only Level I trauma center in the Pacific Northwest. Children with significant medical needs are often treated at Seattle Children's. Seattle Children's operates a clinic in Kennewick.


title: Language model

text: A language model is a probability distribution over sequences of words. Given any sequence of words of length , a language model assigns a probability formula_1 to the whole sequence. Language models generate probabilities by training on text corpora in one or many languages. Given that languages can be used to express an infinite variety of valid sentences (the property of digital infinity), language modeling faces the problem of assigning non-zero probabilities to linguistically valid sequences that may never be encountered in the training data. Several modelling approaches have been designed to surmount this problem, such as applying the Markov assumption or using neural architectures such as recurrent neural networks or transformers.


title: Language model

text: Language models are useful for a variety of problems in computational linguistics; from initial applications in speech recognition to ensure nonsensical (i.e. low-probability) word sequences are not predicted, to wider use in machine translation (e.g. scoring candidate translations), natural language generation (generating more human-like text), part-of-speech tagging, parsing, Optical Character Recognition, handwriting recognition, grammar induction, information retrieval, and other applications.


title: Language model

text: Language models are used in information retrieval in the query likelihood model. There, a separate language model is associated with each document in a collection. Documents are ranked based on the probability of the query "Q" in the document's language model formula_2: formula_3. Commonly, the unigram language model is used for this purpose.


title: Language model

text: A unigram model can be treated as the combination of several one-state finite automata. It assumes that the probabilities of tokens in a sequence are independent, e.g.:


title: Language model

text: In this model, the probability of each word only depends on that word's own probability in the document, so we only have one-state finite automata as units. The automaton itself has a probability distribution over the entire vocabulary of the model, summing to 1. The following is an illustration of a unigram model of a document.


title: Language model

text: Different documents have unigram models, with different hit probabilities of words in it. The probability distributions from different documents are used to generate hit probabilities for each query. Documents can be ranked for a query according to the probabilities. Example of unigram models of two documents:


title: Language model

text: In information retrieval contexts, unigram language models are often smoothed to avoid instances where "P"(term) = 0. A common approach is to generate a maximum-likelihood model for the entire collection and linearly interpolate the collection model with a maximum-likelihood model for each document to smooth the model.


title: Language model

text: In an "n"-gram model, the probability formula_1 of observing the sentence formula_8 is approximated as


title: Language model

text: It is assumed that the probability of observing the "i" word "w" in the context history of the preceding "i" − 1 words can be approximated by the probability of observing it in the shortened context history of the preceding "n" − 1 words ("n" order Markov property). To clarify, for "n=3" and "i=2" we have formula_10.


title: Language model

text: The terms bigram and trigram language models denote "n"-gram models with "n" = 2 and "n" = 3, respectively.


title: Language model

text: Typically, the "n"-gram model probabilities are not derived directly from frequency counts, because models derived this way have severe problems when confronted with any "n"-grams that have not been explicitly seen before. Instead, some form of smoothing is necessary, assigning some of the total probability mass to unseen words or "n"-grams. Various methods are used, from simple "add-one" smoothing (assign a count of 1 to unseen "n"-grams, as an uninformative prior) to more sophisticated models, such as Good-Turing discounting or back-off models.


title: Language model

text: In a bigram ("n" = 2) language model, the probability of the sentence "I saw the red house" is approximated as


title: Language model

text: Note that the context of the first "n" – 1 "n"-grams is filled with start-of-sentence markers, typically denoted <nowiki></nowiki>.


title: Language model

text: Additionally, without an end-of-sentence marker, the probability of an ungrammatical sequence "*I saw the" would always be higher than that of the longer sentence "I saw the red house."


title: Language model

text: Maximum entropy language models encode the relationship between a word and the n-gram history using feature functions. The equation is


title: Language model

text: where formula_15 is the partition function, formula_16 is the parameter vector, and formula_17 is the feature function. In the simplest case, the feature function is just an indicator of the presence of a certain n-gram. It is helpful to use a prior on formula_16 or some form of regularization.


title: Language model

text: Neural language models (or "continuous space language models") use continuous representations or embeddings of words to make their predictions. These models make use of Neural networks.


title: Language model

text: Continuous space embeddings help to alleviate the curse of dimensionality in language modeling: as language models are trained on larger and larger texts, the number of unique words (the vocabulary) increases. The number of possible sequences of words increases exponentially with the size of the vocabulary, causing a data sparsity problem because of the exponentially many sequences. Thus, statistics are needed to properly estimate probabilities. Neural networks avoid this problem by representing words in a distributed way, as non-linear combinations of weights in a neural net. An alternate description is that a neural net approximates the language function. The neural net architecture might be feed-forward or recurrent, and while the former is simpler the latter is more common.


title: Language model

text: Typically, neural net language models are constructed and trained as probabilistic classifiers that learn to predict a probability distribution


title: Language model

text: I.e., the network is trained to predict a probability distribution over the vocabulary, given some linguistic context. This is done using standard neural net training algorithms such as stochastic gradient descent with backpropagation. The context might be a fixed-size window of previous words, so that the network predicts


title: Language model

text: from a feature vector representing the previous words. Another option is to use "future" words as well as "past" words as features, so that the estimated probability is


title: Language model

text: This is called a bag-of-words model. When the feature vectors for the words in the context are combined by a continuous operation, this model is referred to as the continuous bag-of-words architecture (CBOW).


title: Language model

text: A third option that trains slower than the CBOW but performs slightly better is to invert the previous problem and make a neural network learn the context, given a word. More formally, given a sequence of training words formula_22, one maximizes the average log-probability


title: Language model

text: where , the size of the training context, can be a function of the center word formula_24. This is called a skip-gram language model. Bag-of-words and skip-gram models are the basis of the word2vec program.


title: Language model

text: Instead of using neural net language models to produce actual probabilities, it is common to instead use the distributed representation encoded in the networks' "hidden" layers as representations of words; each word is then mapped onto an -dimensional real vector called the word embedding, where is the size of the layer just before the output layer. The representations in skip-gram models have the distinct characteristic that they model semantic relations between words as linear combinations, capturing a form of compositionality. For example, in some such models, if is the function that maps a word to its -d vector representation, then


title: Language model

text: where ≈ is made precise by stipulating that its right-hand side must be the nearest neighbor of the value of the left-hand side.


title: Language model

text: A positional language model assesses the probability of given words occurring close to one another in a text, not necessarily immediately adjacent. Similarly, bag-of-concepts models leverage the semantics associated with multi-word expressions such as "buy_christmas_present", even when they are used in information-rich sentences like "today I bought a lot of very nice Christmas presents".


title: Language model

text: Despite the limited successes in using neural networks, authors acknowledge the need for other techniques when modelling sign languages.


title: Language model

text: Hugging Face hosts a set of publicly available language models for developers to build applications using machine learning.


title: Language model

text: Evaluation of the quality of language models is mostly done by comparison to human created sample benchmarks created from typical language-oriented tasks. Other, less established, quality tests examine the intrinsic character of a language model or compare two such models. Since language models are typically intended to be dynamic and to learn from data it sees, some proposed models investigate the rate of learning, e.g. through inspection of learning curves.


title: Language model

text: Although contemporary language models, such as GPT-2, can be shown to match human performance on some tasks, it is not clear they are plausible cognitive models. For instance, recurrent neural networks have been shown to learn patterns humans do not learn and fail to learn patterns that humans do learn.


title: Tylosaurus

text: Tylosaurus (from the ancient Greek (') 'protuberance, knob' + Greek (') 'lizard') is a genus of mosasaur, a large, predatory marine reptile closely related to modern monitor lizards and to snakes, from the Late Cretaceous.


title: Tylosaurus

text: A distinguishing characteristic of "Tylosaurus" is the elongated conical rostrum that protrudes from its snout, from which the genus is named. Unlike typical mosasaurs, "Tylosaurus" did not have teeth up to the end of the snout nor on the bony protuberance that is the rostrum, and scientists believe that this feature was primarily used for combative purposes such as ramming. This is supported with a uniquely broad and somewhat rectangular internarial bar (the extension of the premaxilla on the top of the skull that held together the nasal and upper jaws) that provided high cranial stability and resistance to stress forces. In addition, the development of the elongated rostrum in infant "Tylosaurus" rules out the alternative explanation that it was developed as a function of sexual behavior. "Tylosaurus" also had 24 to 26 teeth in the upper jaw, 20 to 22 teeth on the palate, 26 teeth on the lower jaw, 29 to 30 vertebrate between the skull and hip, 6 to 7 vertebrae in the hip, 33 to 34 vertebrae in the tail with chevrons, and a further 56 to 58 vertebrae making up the tip of the tail.


title: Tylosaurus

text: "Tylosaurus" was one of the largest mosasaurs of all time. The largest known specimen, a skeleton of "T. proriger" from the University of Kansas Natural History Museum nicknamed "Bunker" (KUVP 5033), has been estimated to measure between long. The genus exhibits Cope's rule, in which its body size has been observed to generally increase over geologic time. In North America, the earliest representatives of "Tylosaurus" during the Turonian and Coniacian (90-86 mya), which included early "T. nepaeolicus" and its precursors, typically measured long and weighed between . During the Santonian (86-83 mya), "T. nepaeolicus" and newly-appearing "T. proriger" were long and weighed around . By the Early Campanian, "T. proriger" attained sizes of in length and in body mass. Other species of "Tylosaurus" were smaller. "T. saskatchewanensis" reached in length and in body mass, while "T. bernardi" reached in length and in body mass.


title: Tylosaurus

text: Commenting on the maximum sizes of large mosasaurs, paleontologist Mike Everhart, a leading expert on mosasaurs, speculated that it would be possible for some extremely old "Tylosaurus" individuals to reach in absolute maximum length. However, this is with awareness that there is no fossil evidence suggesting such sizes and that the odds of preserving such a rare individual are "far too great."


title: Tylosaurus

text: In 2014, the Guinness World Records awarded the Canadian Fossil Discovery Centre a record for "Largest mosasaur on display," specifically, a long skeleton of "T. pembinensis" nicknamed "Bruce." However, the skeleton was assembled for display prior to a 2010 reassessment of the species that found its original number of vertebrae to be exaggerated, implying that the actual size of the animal was likely smaller. Paul (2022) suggested a smaller length of and a body mass of for the maximum adult size of "T. pembinensis".


title: Tylosaurus

text: Fossil evidence of the skin of "Tylosaurus" in the form of scales has been described since the late 1870s. These scales were small and diamond-shaped and were arranged in oblique rows, comparable to that found in modern rattlesnakes and other related reptiles. However, the scales in the mosasaur were much smaller in proportion to the whole body. An individual measuring in total body length had dermal scales measuring , and in each square inch (2.54 cm) of the mosasaur's underside an average of ninety scales were present. Each scale was keeled in a form resembling that of a shark's denticles, suggesting that they functioned in reducing underwater drag.


title: Tylosaurus

text: Microscopic analysis of 86 million-year-old fossil scales of a "T. nepaeolicus" in a 2014 study detected high traces of the pigment eumelanin, indicating that the species possessed a dark coloration similar to the leatherback sea turtle in life. This may have also been complemented with countershading, which is present in many aquatic animals, but the distribution of dark and light pigments in the species remains unknown. In addition, the presence of keeled scales in the genus would have reduced reflection on the skin. A dark-colored form would have provided several evolutionary advantages for "Tylosaurus". Dark coloration increases absorption of heat, allowing the animal to maintain elevated body temperatures in colder environments. Possession of this trait during infancy would in turn facilitate fast growth rates. Additionally, unreflective dark coloring and countershading would have provided the mosasaur with increased camouflage. Several speculative functions have also been proposed, such as increased tolerance to solar UV radiation, strengthened integuments, and increased aggressiveness (certain genes that code for high melanin may also have side influences promoting this trait).


title: Tylosaurus

text: "Tylosaurus" was the third new genus of mosasaur to be described from North America behind "Clidastes" and "Platecarpus" and the first in Kansas. The early history of the genus as a taxon was subject to complications spurred by the infamous rivalry between American paleontologists Edward Drinker Cope and Othniel Charles Marsh during the Bone Wars. The type specimen was described by Cope in 1869 based on a fragmentary skull measuring nearly in length and thirteen vertebrae lent to him by Louis Agassiz of the Harvard Museum of Comparative Zoology. The fossil, which remains in the same museum under the catalog number MCZ 4374, was recovered from a deposit of the Niobrara Formation located in the vicinity of Monument Rocks near the Union Pacific Railroad at Fort Hays, Kansas. Cope's first publication of the fossil was very brief and was named "Macrosaurus proriger", the genus being a preexisting European mosasaur taxon. The specific epithet "proriger" means "prow-bearing", which is in reference to the specimen's unique prow-like elongated rostrum and is derived from the Latin word "prōra" (prow) and suffix "-gero" (I bear). In 1870, Cope published a more thorough description of MCZ 4374. Without explanation, he moved the species into another European genus "Liodon" and declared his original "Macrosaurus proriger" a synonym.


title: Tylosaurus

text: In 1871, Cope identified a second species of North American "Liodon" based on several vertebrae and limb fragments, which he named "Liodon dyspelor". The fossils came to Cope under the label as having been collected by an army doctor named William B. Lyon at Fort McRae, New Mexico. However, a 1997 study led by David C. Parris of the New Jersey State Museum found that the chemical composition of the fossil did not match any known geological deposit in New Mexico and is instead identical to that of the Niobrara Formation; the study speculated from examinations of multiple letters between Lyon and the Smithsonian Institution that the "Liodon dyspelor" fossils were actually recovered from somewhere in Western Kansas and were mislabeled as being collected by Lyon in New Mexico (who was shipping a different fossil from Fort McRae around the same time) during transit. The type specimen of the taxon is split between two museums; some of the vertebrae went to Cope's American Museum of Natural History as AMNH 1580 while the rest were sent to the Smithsonian as USNM 41.


title: Tylosaurus

text: In 1872, Marsh argued that "Liodon proriger" and "Liodon dyspelor" are taxonomically distinct from the European genus and must be assigned a new one. For this, he erected the genus "Rhinosaurus", which means "nose lizard" and is a portmanteau derived from the Ancient Greek words (', meaning "nose") and (', meaning "lizard"). Marsh also described a third species based on a partial skeleton he collected near the southern portion of the Smoky Hill River that is now in the Yale Peabody Museum as YPM 1268, which Marsh named "Rhinosaurus micromus". Cope responded by arguing that "Rhinosaurus" was already a preoccupied synonym of "Liodon". He disagreed with Marsh's arguments but proposed that in case Marsh was indeed correct, the genus name "Rhamphosaurus" should be used. Marsh later discovered that the taxon "Rhamphosaurus" was preoccupied as a genus of lizard named in 1843. As a result, he suggested a move to a newly erected genus named "Tylosaurus". This name means "knob lizard" in another reference to the elongated rostrum characteristic of the genus. It is derived from the Latin "tylos" (knob) and Ancient Greek . Despite coining the new genus, Marsh never formally transferred the "Rhinosaurus" species to "Tylosaurus"; this was first done in 1873 by Joseph Leidy of the University of Pennsylvania by transferring "Rhinosaurus proriger" and "Rhinosaurus dyspelor" to "Tylosaurus". "Rhinosaurus micromus" was formally transferred to the same genus in 1894 by John Campbell Merriam, a paleontologist of the University of Munich at the time.


title: Tylosaurus

text: "Tylosaurus" subsequently became the near-universally accepted genus for "T. proriger", "T. dyspelor", and "T. micromus". An exception to this adoption was Cope, who refused to accept Marsh's new genus and continued to refer to its species as "Liodon". Cope also insisted that "Rhamphosaurus" was not preoccupied, arguing that while it was indeed used as a genus of lizard, it was subsequently synonymized with other genera before 1872 and was thus a vacant taxon. Cope's persistence can be seen in his 1874 description of the fourth described species of "Tylosaurus", which he named "Liodon nepaeolicus". This type specimen of this species consists of a right lower jaw, a partial upper jaw, a quadrate bone, and a dorsal vertebra and was discovered by geologist Benjamin Franklin Mudge in an unspecified deposit of Cretaceous grey shale about a half-mile south of the Solomon River. The fossils are stored in the American Museum of Natural History under the catalog number AMNH 1565. The specific epithet "nepaeolicus" is in reference to the Nepaholla, the Native American name for the Solomon River. "Liodon nepaeolicus" was formally transferred to the genus "Tylosaurus" in Merriam's 1894 publication.


title: Tylosaurus

text: The earliest depictions of "Tylosaurus" can be traced back to Cope's 1870 description of MCZ 4374. He suggested that "Tylosaurus" was an "excessively elongate reptile" because four of the back tail vertebrae of the specimen were less than a fifth in diameter than one more proximal, or closer to, the base of the tail, and there was little dimensional variation between the four back tail vertebrae. To Cope, this indicated that the enormous decrease in the size of the tail vertebrae from the base to the tip of the tail was minimal between vertebrae; thus, in order for the vertebrae in the column to approach the size of the tail vertebrae based on the observed rate of size decrease per vertebrae, plentiful amounts of vertebrae would have been needed. By measuring the proportions of the change in dimensions between the vertebrae, Cope estimated that "Tylosaurus" had at minimum over sixty vertebrae between the described proximal tail vertebra and a hypothetical vertebra measuring half the diameter of the four back tail vertebrae. Cope speculated that there were even more tail vertebrae ahead of the proximal vertebra, justified by the small transverse process it possessed, which would increase the vertebral count in the tail to an unknown but monstrous amount. The resulting animal became that akin to an enormous sea serpent-like reptile reaching lengths rivaling that of the largest whales. In an 1872 publication, Cope described in detail his imagination of the appearance of "Tylosaurus". He depicted the head as akin to a giant flat cone supporting eyes directed partially upwards that is capable of swallowing entire prey whole like a snake, with a loose and baggy pelican-like throat to allow entry of such prey. Like a whale, one pair of paddle-like flippers was described to be present in the animal and functional hind limbs were thought to be absent. The tail was imagined as long and flat, propelling "Tylosaurus" forward via an anguilliform locomotion. Cope estimated that "T. proriger" measured at minimum in length. "T. dyspelor" was the largest species of the genus was also described as the longest of all reptiles. Its maximum length was estimated to equal that of the blue whale, which reaches lengths of up to nearly or more. One "T. dyspelor" specimen with fossils relatively smaller than that of the taxon's type specimen had a skull measuring about in length; the whole animal was estimated to measure in total length. In 1874, Cope estimated that "T. nepaeolicus" was around one-third the length of "T. proriger", which would translate to around when using his 1872 estimates.


title: Tylosaurus

text: One of the earliest restorations of "Tylosaurus" comes from an illustration by a popular artist named Henry Worrall for paleontologist William E. Webb's 1872 fictional book "Buffalo Land". This illustration, which is titled "The sea which once covered the plains", represents one of the first paleoart of marine reptiles and pterosaurs from the Niobrara Formation. At the center of the illustration rises a giant "Tylosaurus" (identified as "Liodon proriger"). The appearance of this mosasaur was influenced by Cope, who was an acquaintance of Webb, as evidenced by its excessively elongated tail and serpentine appearance. Additionally, the "Tylosaurus" was given a rather long neck. Although not as long as those of plesiosaurs like "Elasmosaurus", this detail would influence subsequent depictions of "Tylosaurus" in art. An example of this can be seen in the famous fossil collector Charles Hazelius Sternberg's 1889 fictional narrative "The Young Fossil Hunters: A True Story of Western Exploration and Adventure", which contains a scene where a giant "Tylosaurus" skeleton measuring in total length with a long and slender neck that is long is uncovered.


title: Tylosaurus

text: Paleontologists began to understand "Tylosaurus" as scientists do today beginning with Samuel Wendell Williston's 1898 publication of a comprehensive study of the skeletal anatomy of Kansas mosasaurs, which among many things corrected many of the erroneous beliefs held by earlier paleontologists about "Tylosaurus". A central component of the publication was a rigorous skeletal reconstruction of "T. proriger", which was drawn by paleoartist Sydney Prentice under Williston's instructions. This reconstruction was almost entirely informed by three specimens in the collections of the University of Kansas Natural History Museum, but they nevertheless provided enough material to represent nearly an entire skeleton. These three specimens include one consisting of a posterior fragment of the skull and an "absolute complete series of vertebrae, connected from head to tip of tail" collected in an unspecified date by a fossil collector named Elias Putnam West (KUVP 1048); one containing a complete skull and cervical vertebrae collected in 1898 by colleague Handel T. Martin (KUVP 28705); and one collected in 1877 by university chancellor Francis H. Snow that contains a near-complete set of front paddles along with some ribs, vertebrae, and shoulder girdles (KUVP 1075). Various additional "Tylosaurus" specimens informed minor missing body parts such as the hind limbs. The resulting animal was correctly depicted as a four-flipper reptile with a short neck and a tail making up around half the body length. Rather unrealistically, the vertebral column was drawn straight and lacking in structural curves that "Tylosaurus" would have possessed in life. Commentating on this issue, Everhart noted that Williston was already aware of the curvature of a mosasaur's spinal column and suggested that he had a straight spine drawn to save space on the plate the reconstruction was published on. Nevertheless, apart from the straight spine, Williston's century-old skeletal reconstruction of "T. proriger" is still considered accurate by modern standards, and adaptations of the skeleton remain in use by paleontologists and museum workers. In his own interpretation of the available fossil evidence, Williston proposed that "Tylosaurus" grew no larger than in length and lived as a highly mobile predator "at the expense of strength" that was best adapted for preying on small fish and occasionally an "animal of their own kind". In a review of the taxonomy of the "Tylosaurus" genus, Williston (1898) expressed doubt regarding the validity of "T. micromus" and "T. nepaeolicus" and went as far as to suggest the latter species was merely a juvenile representative of "T. proriger". He also remarked that there exist little anatomical differences between "T. proriger" and "T. dyspelor"; the only real distinction between the two species being in size.


title: Tylosaurus

text: In 1899, Henry Fairfield Osborn described the first complete skeleton of "Tylosaurus", a specimen measuring long that resides in the American Museum of Natural History as AMNH FR 221. Discovered in Kansas by a local named W. O. Bourne and initially identified as "T. dyspelor", the fossil has been considered remarkable in that it contained not only every bone apart from a few in the tail's tip, but also had exceptional preservation of the animal's soft tissue, including the larynx, trachea, bronchi, and cartilage in the throat, chest, and shoulders. This was due to calcification, a condition in a calcium-rich environment like the Kansas chalk that causes soft tissue to harden, allowing it to better fossilize. The completeness of AMNH FR 221 allowed Osborn to accurately measure the proportions of each body part; these ratios remain in use by modern paleontologists when extrapolating "Tylosaurus" fossils. Osborn (1899) included a life impression of AMNH FR 221 by paleoartist Charles R. Knight. The restoration carried a number of erroneous features, such as a baggy throat, bloated belly, and inaccurate paddles and dorsal fin. But a seminal feature was the addition of a dorsal crest (known as a fringe) lining the mosasaur's back. This was based on another 1898 description of a mosasaur fossil by Williston that erroneously identified tracheal rings as remains of a dorsal fringe, which he corrected in 1902. Knight updated his "Tylosaurus" restorations with the dorsal fringes removed to reflect this correction. However, his original depiction of a fringe was picked up as a meme, and many subsequent illustrations of the mosasaur continued to portray this inaccuracy.


title: Tylosaurus

text: Additional largely complete skeletons of "T. proriger" and "T. dyspelor" were uncovered from the Niobrara Formation between the 1900s to 1920s by Charles Sternberg and his son George, which were sold to museums in the United States and Germany. A particular find was a "T. proriger" skeleton collected by C. Sternberg from Smoky Hill Chalk deposits in Logan County, Kansas in 1917, which contained digested remains of a plesiosaur within its ribcage. The specimen was sold the following year to the Smithsonian, and the mosasaur has been permanently displayed as USNM 8898. The plesiosaur remains, despite their significance, were stashed as a separate specimen and promptly forgotten until their redescription by Everhart in 2004. This rediscovery formed the basis for the plot of the 2007 National Geographic film "". George Sternberg attempted to sell another complete "T. proriger" skeleton he found to the Smithsonian 1926, but the museum was satisfied with his father's earlier specimen and declined the offer. This skeleton was ultimately transferred to the Sternberg Museum as FHSM VP-3.


title: Tylosaurus

text: In his landmark 1967 work "Systematics and Morphology of American Mosasaurs", Dale Russell performed a complete review and redescription of "Tylosaurus". In a taxonomic examination, Russell found little justification for recognizing the validity of "T. dyspelor" and declared it a "nomem vanum", along with recognizing "T. micromus" as a junior synonym of "T. proriger". Many of the complete skeletons formerly assigned to the former taxon were reassigned to the type species. "T. nepaeolicus" was affirmed as a distinct species. Russell (1967) provided extensive diagnoses of "Tylosaurus" that are still used by scientists today, and Everhart remarked that the work "remains the single best reference regarding the skeletons of the various mosasaur genera" like "Tylosaurus".


title: Tylosaurus

text: By Russell (1967), the only recognized valid species of "Tylosaurus" were "T. proriger" and "T. nepaeolicus". However, throughout the 19th and 20th centuries, numerous species of mosasaurs were described from around the world that are now recognized within the genus "Tylosaurus". These additional species were identified as different genera during their times of discovery and it was not until the early 21st century when they were reclassified as "Tylosaurus".


title: Tylosaurus

text: In 1885, Louis Dollo described the genus "Hainosaurus" from a near-complete but poorly preserved skeleton excavated from a phosphate quarry in the Ciply Basin near the town of Mesvin, Belgium. The fossil was initially discovered as eight vertebrae by a worker in the January of the same year, who sold them to the Royal Belgian Institute of Natural Sciences. Based on information about the circumstances and locality of the discovery given the museum, it was recognized that the rest of the skeleton may have remained intact. In February, excavations were made under the authorization of an industrialist named Leopold Bernard, who managed the quarry the fossil resided in. The rest of the skeleton was recovered after a month of excavating between of phosphate, although a section of the tail was found to have been destroyed by erosion from an overlying deposit. The skeleton went to the museum, which was subsequently studied by Dollo, who recognized that it belonged to a new type of mosasaur. By instruction of the museum, he named it "Hainosaurus bernardi". The prefix "Haino"- in the generic name refers to the Haine, a river located nearby the Ciply Basin, and thus combined with means "lizard from the Haine"; Dollo wrote that this was erected specifically to complement the etymology of "Mosasaurus", which was similarly named in reference to a river near its type locality. The specific epithet "bernardi" was in recognition of Bernard, who made the excavation of the skeleton possible. The skeleton is now on display at the Royal Belgian Institute under the catalog number IRSNB R23.


title: Tylosaurus

text: A second species historically pertained to "Hainosaurus" was described by in 1988 by Elizabeth Nicholls based on a partial skeleton consisting of a partial skull, lower jaw, a near-complete vertebral column, and some limb bones recovered from the Pembina Member of the Pierre Shale in Manitoba, Canada. This skeleton resides in the Miami Museum in Miami, Manitoba cataloged as MT 2. Although "Hainosaurus" was previously only known in Europe, Nicholls (1988) argued that the new species differed from the more locally known "Tylosaurus" based on a higher count of pygal vertebrae, longer external nares, and femur longer than the humerus. The species was named "Hainosaurus pembinensis", the specific epithet referring to the Pembina Member the skeleton was found in.


title: Tylosaurus

text: In 2005, paleontologist Johan Lindgren suspected that "Hainosaurus pembinensis" was actually a species of "Tylosaurus" but stated that a better description of MT 2 was needed to be certain. In 2010, paleontologists Timon Bullard and Michael Caldwell redescribed such specimen. They argued that the pygal vertebrae reported by Nicholls (1988) actually belonged to another individual mosasaur, reducing the vertebral count in MT 2 to one that was indistinguishable with "Tylosaurus". They also noted that the length of the external nares was within the known range of "Tylosaurus" and additionally argued that the femur being longer than the humerus was an insufficient characteristic to diagnose the species at the generic level. Based on these and other characteristics, the study found that the species cannot be referred to "Hainosaurus" and renamed it to "Tylosaurus pembinensis". With this rediagnosis, the study also noted that the only confirmed characteristic that distinguished "Hainosaurus" from "Tylosaurus" at the time was a higher count of pygal vertebrae. It was doubted as to if this would be sufficient enough for "Hainosaurus" to be a distinct genus but acknowledged that further research may provide additional characteristics. This further research was done in 2016 by Paulina Jimenez-Huidobro and Caldwell, which reexamined "H. bernardi". They found that the unique characteristics of the type species are indeed insufficient to warrant a distinction between "Hainosaurus" and "Tylosaurus" and declared the former as a junior synonym of the latter, thus renaming "H. bernardi" to "Tylosaurus bernardi". However, some scientists argue that "Hainosaurus" should remain a distinct genus, justified by differences in tooth morphology unexplored by Jimenez-Huidobro & Caldwell (2016) such as the presence of an advanced cutting-based dentition in "T. bernardi" as opposed to a more general smashing-based dentition seen in other "Tylosaurus" species.


title: Tylosaurus

text: In 1896, paleontologist Armand Thevenin published a formal description of a poorly-preserved skull consisting of the majority of the maxilla, premaxilla, and dentary bones that was found in a phosphate deposit in Eclusier-Vaux, France during an earlier unspecified date. Thevenin wrote that the skull was first described by Jean Albert Gaudry, who initially thought that it belonged to a species of "Liodon". However, Dollo thought that the characteristics of skull supported an alternative placement as a species of "Mosasaurus". Through correspondence with Dollo and a reexamination of the skull, Thevenin noted that the rostrum was more elongated than those found in typical "Mosasaurus" skulls but not as long as those in the skulls of "Tylosaurus" or "Hainosaurus". He suggested that this represented an intermediate trait for a new species, which he subsequently named "Mosasaurus gaudryi"; the specific epithet recognizing Gaudry's previous work on the fossil skull. The skull is now on display at the French National Museum of Natural History as MNHN 1896–15. In 1990, paleontologist Theagarten Lingham-Soliar proposed reassignment of "M. gaudryi" to a possible species of "H. bernardi" based on the discovery of a double buttress supporting the suture between the premaxilla and maxilla in MNHN 1896–15, a trait he claimed that was unique to the latter species, and estimations that the rostrum may have been more elongated than preserved. This was elaborated on a publication of the same year by Nathalie Bardet of the Natural History Museum, who concluded that MNHN 1896-15 belongs to the genus "Hainosaurus" but as a separate species, thus changing the skull's scientific name to "Hainosaurus gaudryi". This was agreed on by Lingham-Soliar in a 1992 publication. In 2005, Lindgren pointed out that the characteristics used to justify the placement in "Hainosaurus", such as the double buttress, can also be found in "Tylosaurus". He also noted that the dentition of MNHN 1896-15 morphologically overlaps more with "T. ivoensis" and "T. pembinensis" than "H. bernardi". With these characteristics, Lindgren concluded that "H. gaudryi" is most certainly a species of "Tylosaurus", renaming it to "Tylosaurus gaudryi".


title: Tylosaurus

text: In 1963, paleontologist Per Ove Persson identified a new taxon of mosasaur based on isolated teeth from a deposit located in an area called Ivö Klack near Ivö Lake in the Kristianstad Basin in Scania, Sweden. Such teeth and various other teeth pertaining to the same taxon were recovered and described from this area numerous times in the past since 1836, but they have always been misidentified as either an ichthyosaur or "Mosasaurus hoffmannii". Persson proposed that the teeth belonged to a new subspecies of "M. hoffmannii" and gave it the name "Mosasaurus hoffmannii ivoensis", the prefix "ivo"- in the species name referring to Ivö Klack. Russell (1967) amended this identification by elevating the taxon to a distinct species. He also identified a mosasaur fossil from the Niobrara Formation in Kansas consisting of a partial skull, some vertebrae, and a coracoid bone as being of "Mosasaurus ivoensis". In an abstract presented in 1998, Lindgren doubted if "M. ivoensis" was a species of "Mosasaurus". He instead proposed that the species was actually of "Hainosaurus". The next year in 1999, Lindgren amended this in another abstract and instead suggested that the species should be moved to "Tylosaurus". In 2002, he co-authored a study with paleontologist which examined the fossils referred to the species as well as new material consisting of pterygoid teeth, partial jawbones, and some vertebrae. It was found that the Niobrara fossil identified as "M. ivoensis" by Russell (1967) is actually of a different species. Examinations of the Swedish teeth found possible similarities with that of "Taniwhasaurus", but due to the poor representation of the genus and the sheer distance between the two taxa ("Taniwhasaurus" was primarily known from New Zealand at the time), it was expressed that it is unlikely that "M. ivoensis" belongs to it. Instead, the study concluded that the species should belong to "Tylosaurus" and thus renamed it "Tylosaurus ivoensis". However, a 2008 study led by Caldwell discovered "Taniwhasaurus" in northern Japan, which was of similar latitude with Ivö Klack during the Cretaceous, and reasserted dental similarities between "T. ivoensis" and the genus. This opened the possibility that the species could be reassigned to "Taniwhasaurus", but the authors considered this to be a topic for a different study.


title: Tylosaurus

text: In 1964, Miguel Telles Antunes described "Mosasaurus iembeensis" from a partial skull excavated from the Itombe Formation near the town of Iembe, Angola. As the deposit was of the Turonian age, this discovery represented one of the oldest derived mosasaurs. In 1992, Lingham-Soliar argued that the features of the skull disagreed with those of "Mosasaurus" and were instead characteristic of "Tylosaurus". He subsequently moved the species into the genus, becoming "Tylosaurus iembeensis". However, Lingham-Soliar did not figure the holotype skull, which he identified as residing in the collections of NOVA University Lisbon without a catalog number, and it was later reported in 2006 that the specimen may have been lost during a fire. In a 2012 multi-author study led by Octávio Mateus, it was reported that an additional "T. iembeensis" fossil consisting of fragmentary skull elements was recovered during an expedition to the lost holotype's locality, although the specimen was not figured or formally described.


title: Tylosaurus

text: In November 2022, a paper describing a purpoted new species, ""Hainosaurus boubker"", from the Sidi Chennane phosphate quarry in Morocco from several partial skulls and skeletal elements argues for the distinction of the genus "Hainosaurus" from "Tylosaurus" based on its dental morphology and a higher precaudal vertebral count, among other suggested autapomorphies. The description of ""H. boubker"" was, however, published by a known predatory journal, Scientific Research Publishing, which places the validity of the publication and this taxon in questionable status. Regardless of their taxonomic status, these specimens, along with teeth referred to "Hainosaurus" from Europe, represent one of the youngest records of Tylosaurinae, as the quarry is dated to be late Maastrichtian in age.


title: Tylosaurus

text: In the 1990s, a well-preserved mosasaur skull of uncertain identity, which was discovered in an outcrop of the Niobrara Formation in the northwestern part of Ellis County, Kansas in 1968 and cataloged in the Sternberg Museum as FHSM VP-2295, was recognized by multiple authors as being a new species of "Tylosaurus". Despite such recognition, however, no paleontologist investigated this further and the fossil remained undescribed during the remainder of the 20th century. In a 2004 meeting, Everhart suggested that the new species should finally be given a scientific name and formal description, to which paleontologist Louis L. Jacobs responded with "Well, get it done." In 2005, Everhart published a formal description of the new species represented by FHSM VP-2295. Thirteen different "Tylosaurus" specimens also from Kansas were identified as conspecific with FHSM VP-2295, and in reference to their shared localities the new species was given the name "Tylosaurus kansasensis". However, during a 2007 meeting, Caldwell approached Everhart and suggested that his description of "T. kansasensis" was not adequate enough and should be readdressed in a followup paper. In 2013, Caldwell and Jiménez-Huidobro presented an abstract at the annual Society of Vertebrate Paleontology meeting casting doubt on the distinction of the species from "T. nepaeolicus" and in 2016 the two and paleontologist Tiago Simões published a study arguing that "T. kansasensis" was merely a juvenile form of "T. nepaeolicus", thus making the former a junior synonym of the latter. This was criticized by Everhart, who in his 2017 book "Oceans of Kansas" claimed that the study was "poorly researched and written". However, he did not provide any comments on the topic, claiming that such would merely be considered "sour grapes". Nevertheless, Everhart maintained that "T. kansasensis" remains a distinct species "until proven otherwise". A 2018 study by Robert F. Stewart and Jordan Mallon also rejected the synonymy based on inconsistencies when comparing the ontogenetic trends of "T. kansasensis" and "T. nepaeolicus" between the better-understood "T. proriger". Another ontogenetic study published in 2020 by Amelia R. Zietlow came in support of the synonymy based on results from ontograms constructed from a cladistical analysis.


title: Tylosaurus

text: In 1995, the Royal Saskatchewan Museum excavated a partial skeleton first discovered a year prior by a local farmer from a hill located northwest of Herbert Ferry, Saskatchewan. The skeleton was found articulated and consists of a "moderately complete" skull, a largely complete vertebral column, limb bones, and bones of a smaller mosasaur as stomach content; it was curated into the museum as RSM P2588.1 and nicknamed "Omācīw" (meaning "hunter" in Cree). In 2006, Timon Bullard of the University of Alberta studied the specimen in his Master of Science thesis. At the time, the Omācīw fossil was still in preparation and Bullard was only able to examine the right side of the skull. However, he identified that the fossil represented a new species of "Tylosaurus" and suggested that it be named "Tylosaurus saskatchewanensis" in reference to its type locality. Bullard's thesis was never published but subsequently published studies recognized "T. saskatchewanensis" as a valid species despite technically never having been formally described. In 2018, Bullard co-authored a multi-author study led by Jiménez-Huidobro which formally described Omācīw, which by then was more fully prepared, and confirmed its identity as a distinct species.


title: Tylosaurus

text: In 2020, the MS thesis of Samuel Garvey of the University of Cincinnati was published. The thesis focused on TMP 2014.011.0001, a "Tylosaurus" fossil in the collections of the Royal Tyrrell Museum consisting of a partial snout and a fragment of the right mandible. The specimen was found around northeast of Grande Prairie, Alberta; during the Cretaceous this locality was located at around 62° N, making the fossil the northernmost known occurrence of "Tylosaurus" and one of the few known occasions of a mosasaur existing in boreal climates. Moreover, the morphology of TMP 2014.011.0001 was recognized as very distinct from other "Tylosaurus" species. For example, it exhibited paedomorphosis in its teeth, which were slender and designed for piercing prey (contrary to the more robust cutting-specialized teeth of typical "Tylosaurus" species), a trait likely retained from juveniles. The uniqueness of the specimen led to the conclusion that it was a new species, which Garvey subsequently proposed that it be named "Tylosaurus borealis" in reference to its northernly occurrence.


title: Tylosaurus

text: As a mosasaur, "Tylosaurus" is classified within the family Mosasauridae in the superfamily Mosasauroidea. The genus is the type genus of its own subfamily, the Tylosaurinae. Other members of this group include "Taniwhasaurus" and possibly "Kaikaifilu", and the subfamily is defined by a shared feature of an elongated conical rostrum that does not bear teeth. The closest relatives of the Tylosaurinae include the Plioplatecarpinae and the primitive subfamilies Tethysaurinae and Yaguarasaurinae; together they are members of one of three possible major lineages of mosasaurs (the others being the Mosasaurinae subfamily and Halisauromorpha group) that was first recognized in 1993. This clade was named the Russellosaurina by Polcyn and Bell in 2005.


title: Tylosaurus

text: "Tylosaurus" was among the earliest known derived mosasaurs. The oldest fossil attributed to the genus is of a skull (SGM-M1) recovered from Upper Turonian deposits of Ojinaga Formation in Chihuahua, Mexico, which may date around 90 million years old at earliest based on correlations with index fossils. This skull has been identified as an indeterminate species with significant affinities with "T. kansasensis", which was previously considered the most primitive species. A tooth from a Late Maastrichtian deposit in Nasiłów, Poland dating close to the Cretaceous–Paleogene boundary has been attributed to "Hainosaurus sp." With the incorporation of "Hainosaurus" as a synonym of "Tylosaurus", this also makes the genus one of the last mosasaurs. Currently, eight species of "Tylosaurus" are recognized by scientists as taxonomically valid. They are as follow: "T. proriger", "T. nepaeolicus", "T. bernardi", "T. gaudryi", "T. ivoensis", "T. iembeensis", "T. pembinensis", and "T. saskatchewanensis". The validity of two additional taxa remain unsettled; there is still debate whether "T. kansasensis" is synonymous with "T. nepaeolicus", and "T. borealis" has yet to be described in a formal publication.


title: Tylosaurus

text: In 2020, Madzia and Cau performed a Bayesian analysis to better understand the evolutionary influence on early mosasaurs by contemporaneous pliosaurs and polycotylids by examining the rates of evolution in mosasauroids like "Tylosaurus" (specifically "T. proriger", "T. nepaeolicus", and "T. bernardi"). A Bayesian analysis in the study's implementation can approximate numerically-defined rates of morphological evolution and ages of divergence of clades. The Tylosaurinae was approximated to have diverged from the Plioplatecarpinae around 93 million years ago; the divergence was characterized by the highest rate of evolution among all mosasaurid lineages. This trend of rapid evolution coincided with the extinction of the pliosaurs and a decrease in polycotylid diversity. The study noted converging traits between "Tylosaurus", pliosaurs, and some polycotylids in tooth morphology and body size. However, there was no evidence to suggest that "Tylosaurus" or its precursors evolved as a result of out-competing and/or driving to extinction the pliosaurs and polycotylids. Instead, Madiza and Cau proposed that "Tylosaurus" may have taken advantage of the extinction of the pliosaurs and decline of polycotylids to quickly fill the ecological void they left behind. The Bayesian analysis also approximated a divergence of "T. nepaeolicus" from the rest of the genus around 86.88 million years ago and a divergence between "T. proriger" and "T. bernardi" around 83.16 million years ago. The analysis also generated a paraphyletic status of the genus, approximating "Taniwhasaurus" to have diverged from "Tylosaurus" around 84.65 million years ago, but this result is not consistent with previous phylogenetic analyses.


title: Tylosaurus

text: In the Western Interior Seaway, two species—"T. nepaeolicus" and "T. proriger"—represent a chronospecies, in which they make up a single lineage that continuously evolves without branching off in a process known as anagenesis. This is evident by how the two species do not stratigraphically overlap, are sister species, share minor and intermediate morphological differences such as a gradual change in the development of the quadrate bone, and lived in the same locations. The means by which this lineage evolved has been hypothesized to be through one of two evolutionary mechanisms related to changes in ontogeny. First, Jiménez-Huidobro, Simões, and Caldwell proposed in 2016 that "T. proriger" evolved as a paedomorph of "T. nepaeolicus", in which the descendant arose as a result of morphological changes through the retention of juvenile features of the ancestor in adulthood. This was based on the presence of a frontal crest and convex borders of the parietal bone of the skull shared in both juvenile "T. nepaeolicus" and all "T. proriger" but lost in adult "T. nepaeolicus". However, an ontogenetic study by Zietlow (2020) found that it was unclear whether this observation was a result of paedomorphosis, although this uncertainty may have been due that the sample size of mature "T. nepaeolicus" was too low to determine statistical significance. Second, the same study proposed an alternative hypothesis of peramorphosis, in which "T. proriger" evolved by developing traits found in mature "T. nepaeolicus" during immaturity. Based on results from a cladistical ontogram developed using data from 74 "Tylosaurus" specimens, the study identified a multitude of traits that were present in all "T. proriger" and mature "T. nepaeolicus" but absent in juvenile "T. nepaeolicus": the skull size and depth are large, the length of the elongated rostrum exceeds 5% of the total skull length, the quadrate suprastapedial processes are thick, the overall quadrate shape converges, and the posteroventral process is fan-like.


title: Tylosaurus

text: The following cladogram is modified from a phylogenetic analysis by Jiménez-Huidobro & Caldwell (2019) using "Tylosaurus" species with sufficiently known material to model accurate relationships; "T. gaudryi", "T. ivoensis", and "T. iembeensis" were too poorly understood to be added into the analysis.


title: Tylosaurus

text: Konishi and colleagues in 2018 assigned specimen FHSM VP-14845, a small juvenile with an estimated skull length of , to "Tylosaurus" based on the proportions of the braincase and the arrangement of the teeth in the snout and on the palate. However, the specimen lacks the characteristic snout projection of other "Tylosaurus", which is present in juveniles of "T. nepaeolicus" and "T. proriger" with skull lengths of . This suggests that "Tylosaurus" acquired the snout projection rapidly at an early stage in life, and also suggests that it did not develop due to sexual selection. Konishi and colleagues suggested a function in ramming prey, as employed by the modern orca.


title: Tylosaurus

text: Nearly all squamates are characterized by their cold-blooded ectothermic metabolism, but mosasaurs like "Tylosaurus" are unique in that they were likely endothermic, or warm-blooded. The only other known lizard with such a trait is the Argentine black and white tegu, though only partially. Endothermy in "Tylosaurus" was demonstrated in a 2016 study by Harrell, Pérez‐Huerta, and Suarez by examining "δ"O isotopes in "Tylosaurus" bones. "δ"O levels can be used to calculate the internal body temperature of animals, and by comparing such calculated temperatures between coexisting cold-blooded and warm-blooded animals, the type of metabolism can be inferred. The study used the body temperatures of the cold-blooded fish "Enchodus" and sea turtle "Toxochelys" (correlated with ocean temperatures) and warm-blooded seabird "Ichthyornis" from the Mooreville Chalk as a proxy. Analyzing the isotope levels of eleven "Tylosaurus" specimens an average internal body temperature of was calculated. This was much higher than the body temperature of "Enchodus" and "Toxochelys" ( and respectively) and similar to that of "Ichthyornis" (). Harrell, Pérez‐Huerta, and Suarez also calculated the body temperatures of "Platecarpus" and "Clidastes" with similar numbers, and respectively. The fact that the other mosasaurs were much smaller in size than "Tylosaurus" and yet maintained similar body temperatures made it unlikely that "Tylosaurus"s body temperature was the result of another metabolic type like gigantothermy. Endothermy would have provided several advantages to "Tylosaurus" such as increased stamina for foraging larger areas and pursuing prey, the ability to access colder waters, and better adaptation to withstand the gradual cooling of global temperatures during the Late Cretaceous.


title: Tylosaurus

text: Scientists previously interpreted "Tylosaurus" as an anguilliform swimmer that moved by undulating its entire body like a snake due to its close relationship with the animal. However, it is now understood that "Tylosaurus" actually used carangiform locomotion, meaning that the upper body was less flexible and movement was largely concentrated at the tail like in mackerels. A BS thesis by Jesse Carpenter published in 2017 examined the vertebral mobility of "T. proriger" spinal columns and found that the dorsal vertebrae were relatively rigid but the cervical, pygal, and caudal vertebrae were more liberal in movement, indicating flexibility in the neck, hip, and tail regions. This contrasted with more derived mosasaurs like "Plotosaurus", whose vertebral column was stiff up to the hip. Interestingly, an examination of a juvenile "T. proriger" found that its cervical and dorsal vertebrae were much stiffer than those in adult specimens. This may have been an evolutionary adaptation among young individuals; a more rigid tail-based locomotion is associated with faster speed, and this would allow vulnerable juveniles to better escape predators or catch prey. Older individuals would see their spine grow in flexibility as predator evasion becomes less important for survival.


title: Tylosaurus

text: "Tylosaurus" likely specialized as an ambush predator. It was lightweight for a mosasaur of its size, having a morphological build designed to vastly reduce body mass and density. Its pectoral and pelvic girdles and paddles, which are associated with weight, are proportionally small. Its bones were highly cancellous and were likely filled with fat cells in life, which also increased buoyancy. It is unlikely that the latter trait was evolved in response to increasing body size as the similarly-sized "Mosasaurus hoffmannii" lacked highly cancellous bone. These traits allowed "Tylosaurus" to be more conservative in its energy requirements, which is useful when traveling between ambush sites over large distances or through stealth. In addition, a reduced body density likely helped "Tylosaurus" to rapidly accelerate during an attack, assisted with the long and powerful tail of the mosasaur.


title: Tylosaurus

text: A 1988 study by Judith Massare attempted to calculate the sustained swimming speed, the speed at which the animal moves without tiring, of "Tylosaurus" through a series of mathematical models incorporating hydrodynamic characteristics and estimations of locomotive efficiency and metabolic costs. Using two "T. proriger" specimens, one long and the other , she calculated a consistent average maximum sustained swimming speed of . However, when testing whether the models represented an accurate framework, they were found to exaggerated. This was primarily because the variables accounting for drag may have been underestimated; estimation of drag coefficients for an extinct species can be difficult as it requires a hypothetical reconstruction of the morphological dimensions of the animal. Massare predicted that the actual sustained swimming speed of "Tylosaurus" was somewhere near half the calculated speed. The mathematical framework was subsequently corrected and modified for accuracy in 2002 by Ryosuke Motani, but "Tylosaurus" was not examined in the study.


title: Tylosaurus

text: One of the largest marine carnivores of its time, "Tylosaurus" was an apex predator that exploited the wide variety of marine fauna in its ecosystem. Stomach contents are well documented in the genus, which includes other mosasaurs, plesiosaurs, turtles, birds, bony fish, and sharks. Additional evidence from bite marks suggests the animal also preyed on giant squid and ammonites.


title: Tylosaurus

text: The enormous and varied appetite of "Tylosaurus" can be demonstrated in a 1987 find that identified fossils of a mosasaur measuring or longer, the diving bird "Hesperornis", a "Bananogmius" fish, and possibly a shark all within the stomach of a single "T. proriger" skeleton (SDSM 10439) recovered from the Pierre Shale of South Dakota. Other records of stomach contents include a sea turtle in a "T. bernardi"-like species, a long "Dolichorhynchops" in another "T. proriger", partially digested bones and scales of a "Cimolichthys" in a third "T. proriger", partially digested vertebrae of a "Clidastes" in a fourth "T. proriger", remains of three "Platecarpus" individuals in a "T. nepaeolicus", and "Plioplatecarpus" bones in a "T. saskatchewanensis". Puncture marks on fossils of ammonites, the carapace of a "Protostega", and the gladius of an "Enchoteuthis" have been attributed to "Tylosaurus".


title: Tylosaurus

text: Pasch and May (2001) reported bite marks from a dinosaur skeleton known as the Talkeetna Mountains Hadrosaur, which was found in marine strata of the Turonian-age Matanuska Formation in Alaska. The features of these marks were found to closely match that of the teeth of "T. proriger". Because the fossil's locality was of marine deposits, the study reasoned that the dinosaur must have drifted offshore as a bloat-and-float carcass that was subsequently scavenged by the mosasaur. It was unlikely that the marks were a result of predation, as that would have led to a puncture, preventing the buildup of the bloating gases that allowed the corpse to drift out to sea in the first place. Garvey (2020) criticized the lack of conclusive evidence to support this hypothesis and ruled out "T. proriger" as a possible culprit, given that the species did not appear until the Santonian and is exclusive to the Western Interior Seaway. However, close relatives did maintain a presence nearby, evidenced by fragmentary fossils of an indeterminate tylosaurine from Turonian deposits in the Russian Chukotsky District.


title: Tylosaurus

text: The behavior of "Tylosaurus" towards each other may have been mostly aggressive, evidenced by fossils with injuries inflicted by another of their own kind. Such remains were frequently reported by fossil hunters during the late 19th and early 20th centuries, but few examples reside as specimens in scientific collections. Many of these fossils consist of healed bite marks and wounds that are concentrated around or near the head region, implying that there were the result of non-lethal interaction, but the motives of such contact remain speculative. In 1993, Rothschild and Martin noted that some modern lizards affectionately bite their mate's head during courtship, which can sometimes result in injuries. Alternatively, they also observed that some males lizards also employ head-biting as territorial behavior against rivals in a show of dominance by grappling the head to turn over the other on its back. It is possible that "Tylosaurus" behaved in similar ways.


title: Tylosaurus

text: Lingham-Soliar (1992) mentioned the consideration that the use of the combat-oriented elongated rostrum of "Tylosaurus" was not exclusive to hunting and that it may have also been applied in sexual behavior through battles over female mates between males. However, the study observed the elongated rostrum was invariably present in all individuals regardless of sex, and subsequent studies by Konishi "et al." (2018) and Zietlow (2020) confirmed this pattern. This would imply that sexual selection was not a driver in its evolution and instead refined through sex-independent means.


title: Tylosaurus

text: At least one fatal instance of intraspecific combat among "Tylosaurus" is documented. This can be seen in the "T. kansasensis" holotype FHSM VP-2295, representing a long animal, which possesses numerous injuries that indicate it was killed by a larger "Tylosaurus". The skull roof and surrounding areas exhibit signs of trauma in the form of four massive gouges, and the dentary contains at least seven puncture wounds and gouges. These pathologies are unequivocally characteristic of bite marks from a larger "Tylosaurus" that measured around in length. The largest of the marks are about in length, matching the size of large mosasaur teeth, and they are positioned along two lines that converge close to 30°, matching the angle that each jaw converges towards in a mosasaur skull. In addition, FHSM VP-2295 suffered damage to the sclerotic ring, a detached quadrate, and an articulation of the cervical vertebrae at an unnatural angle of 40° to the skull's long axis. The pattern of preservation makes it unlikely that the condition of the vertebrae was a result of disturbances by scavengers and instead indicates damage caused by a violently twisted neck during life. In a reconstructed scenario, the larger "Tylosaurus" would have first attacked at an angle slightly below the left side of the victim's head. This impact would cause the victim's skull to roll to the right side, allowing the aggressor to sink its teeth into the skull roof and right lower jaw, the latter crushing the jawbone and causing further breaks of nearby bones such as the pterygoid, a break in the right eye, and the twisting of the jawbone outwards. This would subsequently cause the quadrate to detach from its position and the spinal cord to twist and sever at the skull's base, leading to a swift death.


title: Tylosaurus

text: Examining 12 North American "Tylosaurus" skeletons and one "T. bernardi" skeleton, Rothschild and Martin (2005) identified evidence of avascular necrosis in every individual. For aquatic animals, this condition is often a result of decompression illness, which is caused when bone-damaging nitrogen bubbles build up in inhaled air that is decompressed either by frequent deep-diving trips or by intervals of repetitive diving and short breathing. The studied mosasaurs likely gained avascular necrosis through such behaviors, and given its invariable presence in "Tylosaurus" it is likely that deep or repetitive diving was a general behavioral trait of the genus. The study observed that between 3-15% of vertebrae in the spinal column of North American "Tylosaurus" and 16% of vertebrae in "T. bernardi" were affected by avascular necrosis. Carlsen (2017) considered it frugal to presume that "Tylosaurus" gained avascular necrosis because it lacked the necessary adaptations for deep or repetitive diving, noting that the genus had well-developed eardrums that could protect themselves from rapid changes in pressure.


title: Tylosaurus

text: Unnatural fusion of some vertebrae in the tail has been reported in some "Tylosaurus" skeletons. A variation of these fusions may concentrate near the end of the tail to form a single mass of multiple fused vertebrae called a "club tail." Rothschild and Everhart (2015) surveyed 23 North American "Tylosaurus" skeletons and one "T. bernardi" skeleton and found that five of the North American skeletons exhibited fused tail vertebrae. The condition was not found in "T. bernardi", but this does not rule out its presence due to the low sample size. Vertebral fusion occurs when the bones remodel themselves after damage from trauma or disease. However, the cause of such events can vary between individuals and/or remain hypothetical. One juvenile specimen with the club tail condition was found with a shark tooth embedded in the fusion, which confirms that at least some cases were caused by infections inflicted by predator attacks. The majority of vertebral fusion cases in "Tylosaurus" were caused by bone infections, but some cases may have alternatively been caused by any type of joint disease such as arthritis. However, evidence of joint disease was rare in "Tylosaurus" when compared to mosasaurs such as "Plioplatecarpus" and "Clidastes".


title: Forbes list of Australia's 50 richest people

text: The "Forbes" list of Australia's 50 richest people is a list of Australia's fifty wealthiest individuals and families, ranked by personal net worth published annually by "Forbes Asia" magazine. The list provides a short summary on some of the known business activities of the individuals and families, together with commentary on how their ranking has changed from the previous year, if listed. The list is published annually in January in an online format and updated daily, also online.


text: In 2019, the entry mark for the 50th richest individual was 750 million. The wealthiest individual in the 2019 list was Gina Rinehart, estimated to have a personal net worth of 14.8 billion; a 2.6 billion decrease in her personal net worth of 17.4 billion, as estimated by "Forbes" in 2018. 2019 marked the eighth time that Rinehart had headed the list.


text: Prior to 2013, the list included the forty richest people in Australia; expanded to Australia's fifty wealthiest individuals and families in 2013.


text: The table below is an extract from the list compiled by "Forbes Asia" showing individuals who were once on the list yet are not on the current list. Where appropriate, the list compares movement from previous years:


title: Samba (software)

text: Samba is a free software re-implementation of the SMB networking protocol, and was originally developed by Andrew Tridgell. Samba provides file and print services for various Microsoft Windows clients and can integrate with a Microsoft Windows Server domain, either as a Domain Controller (DC) or as a domain member. As of version 4, it supports Active Directory and Microsoft Windows NT domains.


title: Samba (software)

text: Samba runs on most Unix-like systems, such as Linux, Solaris, AIX and the BSD variants, including Apple's macOS Server, and macOS client (Mac OS X 10.2 and greater). Samba also runs on a number of other operating systems such as OpenVMS and IBM i. Samba is standard on nearly all distributions of Linux and is commonly included as a basic system service on other Unix-based operating systems as well. Samba is released under the terms of the GNU General Public License. The name "Samba" comes from SMB (Server Message Block), the name of the proprietary protocol used by the Microsoft Windows network file system.


title: Samba (software)

text: Andrew Tridgell developed the first version of Samba Unix in December 1991 and January 1992, as a PhD student at the Australian National University, using a packet sniffer to do of the protocol used by DEC Pathworks server software. At the time of the first releases, versions 0.1, 0.5 and 1.0, all from the first half of January 1992, it did not have a proper name, and Tridgell just called it "a Unix file server for Dos Pathworks". At the time of version 1.0, he realized that he "had in fact implemented the netbios protocol" and that "this software could be used with other PC clients".


title: Samba (software)

text: With a focus on interoperability with Microsoft's LAN Manager, Tridgell released "netbios for unix", observer, version 1.5 in December 1993. This release was the first to include client-software as well as a server. Also, at this time GPL2 was chosen as license.


title: Samba (software)

text: Midway through the 1.5-series, the name was changed to "smbserver". However, Tridgell got a trademark notice from the company "Syntax", who sold a product named "TotalNet Advanced Server" and owned the trademark for "SMBserver". The name "Samba" was derived by running the Unix command grep through the system dictionary looking for words that contained the letters S, M, and B, in that order (i.e. ).


title: Samba (software)

text: Versions 1.6, 1.7, 1.8, and 1.9 followed relatively quickly, with the latter being released in January 1995. Tridgell considers the adoption of CVS in May 1996 to mark the birth of the Samba Team, though there had been contributions from other people, especially Jeremy Allison, previously.


title: Samba (software)

text: Version 3.0.0, released on 23 September 2003, was a major upgrade. Samba gained the ability to join Active Directory as a member, though not as a domain controller. Subsequent point-releases to 3.0 have added minor new features. Currently, the latest release in this series is 3.0.37, released 1 October 2009, and shipped on a voluntary basis. The 3.0.x series officially reached end-of-life on 5 August 2009.


title: Samba (software)

text: With version 3.2, the project decided to move to time-based releases. New major releases, such as 3.3, 3.4, etc. will appear every six months. New features will only be added when a major release is done, point-releases will be only for bug fixes. Also, 3.2 marked a change of license from GPL2 to GPL3, with some parts released under LGPL3. The main technical change in version 3.2 was to autogenerate much of the DCE/RPC-code that used to be handcrafted. Version 3.2.0 was released on 1 July 2008. and its current release is 3.2.15 from 1 October 2009. The 3.2.x series officially reached end-of-life on 1 March 2010.


title: Samba (software)

text: Some versions of Samba 3.6.3 and lower suffer serious security issues which can allow anonymous users to gain root access to a system from an anonymous connection, through the exploitation of an error in Samba's remote procedure call.


title: Samba (software)

text: On 12 April 2016, Badlock, a crucial security bug in Windows and Samba, was disclosed. Badlock for Samba is referenced by (SAMR and LSA man in the middle attacks possible).


title: Samba (software)

text: On 24 May 2017, it was announced that a remote code execution vulnerability had been found in Samba named "EternalRed" or "SambaCry", affecting all versions since 3.5.0. This vulnerability was assigned identifier .


title: Samba (software)

text: On 14 September 2020, a proof-of-concept exploit for the netlogon vulnerability called "Zerologon" () for which a patch exists since August was published. Some federal agencies using the software have been ordered to install the patch.


title: Samba (software)

text: Samba allows file and print sharing between computers running Microsoft Windows and computers running Unix. It is an implementation of dozens of services and a dozen protocols, including:


title: Samba (software)

text: All these services and protocols are frequently incorrectly referred to as just NetBIOS or SMB. The NBT (NetBIOS over TCP/IP) and WINS protocols, and their underlying SMB version 1 protocol, are deprecated on Windows. Since Windows Vista the WS-Discovery protocol has been included along with SMB2 and its successors, which supersede these. (WS-Discovery is implemented on Unix-like platforms by third party daemons which allow Samba shares to be discovered when the deprecated protocols are disabled).


title: Samba (software)

text: Samba sets up network shares for chosen Unix directories (including all contained subdirectories). These appear to Microsoft Windows users as normal Windows folders accessible via the network. Unix users can either mount the shares directly as part of their file structure using the mount.cifs command or, alternatively, can use a utility, smbclient (libsmb) installed with Samba to read the shares with a similar interface to a standard command line FTP program. Each directory can have different access privileges overlaid on top of the normal Unix file protections. For example: home directories would have read/write access for all known users, allowing each to access their own files. However they would still not have access to the files of others unless that permission would normally exist. Note that the netlogon share, typically distributed as a read only share from codice_1, is the logon directory for user logon scripts.


title: Samba (software)

text: Samba configuration is achieved by editing a single file (typically installed as codice_2 or codice_3). Samba can also provide user logon scripts and group policy implementation through codice_4.


title: Samba (software)

text: Samba is included in most Linux distributions and is started during the boot process. On Red Hat, for instance, the codice_5 script runs at boot time, and starts both daemons. Samba is not included in Solaris 8, but a Solaris 8-compatible version is available from the Samba website. The OS/2-based ArcaOS includes Samba to replace the old IBM LAN Server software.


title: Samba (software)

text: Samba TNG (The Next Generation) was forked in late 1999, after disagreements between the Samba Team leaders and Luke Leighton about the directions of the Samba project. They failed to come to an agreement on a development transition path which allowed the research version of Samba he was developing (known at the time as Samba-NTDOM) to slowly be integrated into Samba. Development has been minimal, due to a lack of developers. The Samba TNG team frequently directed potential users towards Samba because of its better support and development.


title: Samba (software)

text: A key goal of the Samba TNG project was to rewrite all of the NT Domains services as FreeDCE projects. This was made difficult as the services were developed manually through network reverse-engineering, with limited or no reference to DCE/RPC documentation.


title: Samba (software)

text: A key difference from Samba was in the implementation of the NT Domains suite of protocols and MSRPC services. Samba makes all the NT Domains services available from a single place, whereas Samba TNG separated each service into its own program.


title: Samba (software)

text: ReactOS started using Samba TNG services for its SMB implementation. The developers of both projects were interested in seeing the Samba TNG design used to help get ReactOS talking to Windows networks. They worked together to adapt the network code and build system. The multi-layered and modular approach made it easy to port each service to ReactOS.


title: HIV/AIDS denialism

text: HIV/AIDS denialism is the belief, despite conclusive evidence to the contrary, that the human immunodeficiency virus (HIV) does not cause acquired immune deficiency syndrome (AIDS). Some of its proponents reject the existence of HIV, while others accept that HIV exists but argue that it is a harmless passenger virus and not the cause of AIDS. Insofar as they acknowledge AIDS as a real disease, they attribute it to some combination of sexual behavior, recreational drugs, malnutrition, poor sanitation, haemophilia, or the effects of the medications used to treat HIV infection (antiretrovirals).


title: HIV/AIDS denialism

text: The scientific consensus is that the evidence showing HIV to be the cause of AIDS is conclusive and that HIV/AIDS denialist claims are pseudoscience based on conspiracy theories, faulty reasoning, cherry picking, and misrepresentation of mainly outdated scientific data. With the rejection of these arguments by the scientific community, HIV/AIDS denialist material is now targeted at less scientifically sophisticated audiences and spread mainly through the Internet.


title: HIV/AIDS denialism

text: Despite its lack of scientific acceptance, HIV/AIDS denialism has had a significant political impact, especially in South Africa under the presidency of Thabo Mbeki. Scientists and physicians have raised alarm at the human cost of HIV/AIDS denialism, which discourages HIV-positive people from using proven treatments. Public health researchers have attributed 330,000 to 340,000 AIDS-related deaths, along with 171,000 other HIV infections and 35,000 infant HIV infections, to the South African government's former embrace of HIV/AIDS denialism. The interrupted use of antiretroviral treatments is also a major global concern as it potentially increases the likelihood of the emergence of antiretroviral-resistant strains of the virus.


title: HIV/AIDS denialism

text: A constellation of symptoms named "gay-related immune deficiency" was noted in 1982. In 1983, a group of scientists and doctors at the Pasteur Institute in France, led by Luc Montagnier, discovered a new virus in a patient with signs and symptoms that often preceded AIDS. They named the virus "lymphadenopathy-associated virus", or LAV, and sent samples to Robert Gallo's team in the United States. Their findings were peer reviewed and slated for publication in "Science".


title: HIV/AIDS denialism

text: At a 23 April 1984 press conference in Washington, D.C., Margaret Heckler, Secretary of Health and Human Services, announced that Gallo and his co-workers had discovered a virus that was the "probable" cause of AIDS. This virus was initially named HTLV-III. In the same year, Casper Schmidt responded to Gallo's papers with "The Group-Fantasy Origins of AIDS", published in the "Journal of Psychohistory". Schmidt posited that AIDS was not an actual disease, but rather an example of "epidemic hysteria", in which groups of people subconsciously act out social conflicts. Schmidt compared AIDS to documented cases of epidemic hysteria in the past which were mistakenly thought to be infectious. (Schmidt himself later died of AIDS in 1994.)


title: HIV/AIDS denialism

text: In 1986, the viruses discovered by Montagnier and Gallo, found to be genetically indistinguishable, were renamed HIV.


title: HIV/AIDS denialism

text: In 1987, molecular biologist Peter Duesberg questioned the link between HIV and AIDS in the journal "Cancer Research". Duesberg's publication coincided with the start of major public health campaigns and the development of zidovudine (AZT) as a treatment for HIV/AIDS.


title: HIV/AIDS denialism

text: In 1988, a panel of the Institute of Medicine of the U.S. National Academy of Sciences found that "the evidence that HIV causes AIDS is scientifically conclusive." That same year, "Science" published Blattner, Gallo, and Temin's "HIV causes AIDS", and Duesberg's "HIV is not the cause of AIDS". Also that same year, the Perth Group, a group of denialists based in Perth, Western Australia, led by Eleni Papadopulos-Eleopulos, published in the non-peer-reviewed journal "Medical Hypotheses" their first article questioning aspects of HIV/AIDS research, arguing that there was "no compelling reason for preferring the viral hypothesis of AIDS to one based on the activity of oxidising agents."


title: HIV/AIDS denialism

text: In 1989, Duesberg exercised his right as a member of the National Academy of Sciences to bypass the peer review process and published his arguments in "Proceedings of the National Academy of Sciences of the United States of America" ("PNAS") unreviewed. The editor of "PNAS" initially resisted, but ultimately allowed Duesberg to publish, saying, "If you wish to make these unsupported, vague, and prejudicial statements in print, so be it. But I cannot see how this would be convincing to any scientifically trained reader."


title: HIV/AIDS denialism

text: In 1990, the physiologist Robert Root-Bernstein published his first peer-reviewed article detailing his objections to the mainstream view of AIDS and HIV. In it, he questioned both the mainstream view and the "dissident" view as potentially inaccurate.


title: HIV/AIDS denialism

text: In 1991, The Group for the Scientific Reappraisal of the HIV-AIDS Hypothesis, comprising twelve scientists, doctors, and activists, submitted a short letter to various journals, but the letter was rejected.


title: HIV/AIDS denialism

text: In 1993, "Nature" published an editorial arguing that Duesberg had forfeited his right of reply by engaging in disingenuous rhetorical techniques and ignoring any evidence that conflicted with his claims. That same year, Papadopulos-Eleopulos and coauthors from the Perth Group alleged in the journal "Nature Biotechnology" (then edited by fellow denialist Harvey Bialy) that the western blot test for HIV was not standardized, non-reproducible, and of unknown specificity due to a claimed lack of a "gold standard".


title: HIV/AIDS denialism

text: On 28 October 1994, Robert Willner, a physician whose medical license had been revoked for, among other things, treating an AIDS patient with ozone therapy, publicly jabbed his finger with blood he said was from an HIV-infected patient. Willner died in 1995 of a heart attack.


title: HIV/AIDS denialism

text: In 1995, The Group for the Scientific Reappraisal of the HIV-AIDS Hypothesis in 1991 published a letter in "Science" similar to the one they had attempted to publish in 1991. That same year, Continuum, a denialist group, placed an advertisement in the British gay and lesbian magazine "The Pink Paper" offering a £1,000 reward to "the first person finding one scientific paper establishing actual isolation of HIV", according to a set of seven steps they claimed to have been drawn up by the Pasteur Institute in 1973. The challenge was later dismissed by various scientists, including Duesberg, asserting that HIV undoubtedly exists. Stefan Lanka argued in the same year that HIV does not exist. Also that year, the National Institute of Allergy and Infectious Diseases released a report concluding that "abundant epidemiologic, virologic and immunologic data support the conclusion that infection with the human immunodeficiency virus (HIV) is the underlying cause of AIDS."


title: HIV/AIDS denialism

text: In 1996, the "British Medical Journal" published "Response: arguments contradict the "foreign protein-zidovudine" hypothesis" as a response to a petition by Duesberg: "In 1991 Duesberg challenged researchers… We and Darby et al. have provided that evidence". The paper argued that Duesberg was wrong regarding the cause of AIDS in haemophiliacs.


title: HIV/AIDS denialism

text: In 1997, The Perth Group questioned the existence of HIV, and speculated that the production of antibodies recognizing HIV proteins can be caused by allogenic stimuli and autoimmune disorders. They continued to repeat this speculation through at least 2006.


title: HIV/AIDS denialism

text: In 1998, Joan Shenton published the book "Positively False – Exposing the Myths Around HIV and AIDS", which promotes AIDS denialism. In the book, Shenton claims that AIDS is a conspiracy created by pharmaceutical companies to make money from selling antiretroviral drugs.


title: HIV/AIDS denialism

text: In 2006, Celia Farber, a journalist and prominent HIV/AIDS denialist, published an essay in the March issue of "Harper's Magazine" entitled "Out of Control: AIDS and the Corruption of Medical Science", in which she summarized a number of arguments for HIV/AIDS denialism and alleged incompetence, conspiracy, and fraud on the part of the medical community. Scientists and AIDS activists extensively criticized the article as inaccurate, misleading, and poorly fact-checked.


title: HIV/AIDS denialism

text: In 2007, members of the Perth Group testified at an appeals hearing for Andre Chad Parenzee, asserting that HIV could not be transmitted by heterosexual sex. The judge concluded, "I reject the evidence of Ms Papadopulos-Eleopulos and Dr Turner. I conclude… that they are not qualified to give expert opinions."