title: Nikita Khrushchev

text: There were multiple reasons for Khrushchev's sudden downfall. It was not a coup, because it followed the Central Committee procedures for naming leadership that Khrushchev had himself introduced. As William Tompson has noted, there were no show trials, no ritual attacks, no public confessions, and no executions. For most members of the Central Committee, there was growing annoyance with his arbitrary decision-making and lack of collegiality. They complained about the unwieldy bureaucracy that Khrushchev had fostered. These bureaucrats were now making the real decisions leaving the Party much less important, especially when Khrushchev circumvented local party leaders with his own specialized troubleshooters. Many were angry with his high-handed disregard for Central Committee procedures, including those he himself had been responsible for introducing. Foreign policy issues were not a major factor in his removal because the leadership agreed with his policies. The military was not involved in the removal but the KGB was a key center of opposition. Agriculture was his signature field and the glaring failure of massive efforts to improve agriculture was the most serious domestic issue, and resulted in hostile public opinion regarding food shortages. In the end Khrushchev was too old and tired, and paid less and less attention to maintaining his political base, while his enemies carefully and systematically assembled their irresistible coalition in the Party's Central Committee.


title: Nikita Khrushchev

text: Khrushchev was granted a pension of 500 rubles per month and was given a house, a dacha and a car. Following his removal, he fell into deep depression. He received few visitors, especially since his security guards kept track of all guests and reported their comings and goings. His pension was reduced to 400 rubles per month, though his retirement remained comfortable by Soviet standards. One of his grandsons was asked what the ex-premier was doing in retirement, and the boy replied, "Grandfather cries." Khrushchev was made a non-person to such an extent that the thirty-volume "Great Soviet Encyclopedia" omitted his name from the list of prominent political commissars during the Great Patriotic War.


title: Nikita Khrushchev

text: As the new rulers made known their conservatism in artistic matters, Khrushchev came to be more favorably viewed by artists and writers, some of whom visited him. One visitor whom Khrushchev regretted not seeing was former U.S. Vice President Nixon, then in his "wilderness years" before his election to the presidency, who went to Khrushchev's Moscow apartment while the former premier was at his dacha.


title: Nikita Khrushchev

text: Beginning in 1966, Khrushchev began his memoirs. He initially tried to dictate them into a tape recorder while outdoors, in an attempt to avoid eavesdropping by the KGB. These attempts failed due to background noise, so he switched to recording indoors. The KGB made no attempt to interfere until 1968, when Khrushchev was ordered to hand over his tapes, which he refused to do. While Khrushchev was hospitalized with heart ailments, his son Sergei was approached by the KGB in July 1970 and told that there was a plot afoot by foreign agents to steal the memoirs. Sergei Khrushchev handed over the materials to the KGB since the KGB could steal the originals anyway, but copies had been made, some of which had been transmitted to a Western publisher. Sergei instructed that the smuggled memoirs should be published, which they were in 1970 under the title "Khrushchev Remembers". Under some pressure, Nikita Khrushchev signed a statement that he had not given the materials to any publisher, and his son was transferred to a less desirable job. Upon publication of the memoirs in the West, "Izvestia" denounced them as a fraud. Soviet state radio carried the announcement of Khrushchev's statement, and it was the first time in six years that he had been mentioned in that medium. In the "Great Soviet Encyclopedia", Khrushchev was given a short characterization: "As a leader, Khrushchev showed signs of subjectivism and voluntarism".


title: Nikita Khrushchev

text: In his final days, Khrushchev visited his son-in-law and former aide Alexei Adzhubei (1924–1993) and told him, "Never regret that you lived in stormy times and worked with me in the Central Committee. We will yet be remembered!"


title: Nikita Khrushchev

text: Khrushchev died of a heart attack around noon in the Kremlin hospital in Moscow on 11 September 1971, at the age of 77. He was denied a state funeral with interment in the Kremlin Wall and was instead buried in the Novodevichy Cemetery in Moscow. Fearing demonstrations, the authorities did not announce Khrushchev's death until the hour of his wake and surrounded the cemetery with troops. Even so, some artists and writers joined the family at the graveside for the interment.


title: Nikita Khrushchev

text: "Pravda" ran a one-sentence announcement of the former premier's death; Western newspapers contained considerable coverage. Veteran "New York Times" Moscow correspondent Harry Schwartz wrote of Khrushchev, "Mr. Khrushchev opened the doors and windows of a petrified structure. He let in fresh air and fresh ideas, producing changes which time already has shown are irreversible and fundamental."


title: Nikita Khrushchev

text: Many of Khrushchev's innovations were reversed after his fall. The requirement that one-third of officials be replaced at each election was overturned, as was the division in the Party structure between industrial and agricultural sectors. His vocational education program for high school students was also dropped, and his plan for sending existing agricultural institutions out to the land was ended. However, new agricultural or vocational institutions thereafter were located outside major cities. When new housing was built, much of it was in the form of high rises rather than Khrushchev's low-rise structures, which lacked elevators or balconies.


title: Nikita Khrushchev

text: Historian Robert Service summarizes Khrushchev's contradictory personality traits. According to him, Khrushchev was:


title: Nikita Khrushchev

text: at once a Stalinist and an anti-Stalinist, a communist believer and a cynic, a self-publicizing poltroon and a crusty philanthropist, a trouble-maker and a peacemaker, a stimulating colleague and a domineering boor, a statesman and a politicker who was out of his intellectual depth.


title: Nikita Khrushchev

text: Some of Khrushchev's agricultural projects were also easily overturned. Corn became so unpopular in 1965 that its planting fell to the lowest level in the postwar period, as even "kolkhozes" which had been successful with it in Ukraine and other southern portions of the USSR refused to plant it. Lysenko was stripped of his policy-making positions. However, the MTS stations remained closed, and the basic agricultural problems, which Khrushchev had tried to address, remained. While the Soviet standard of living increased greatly in the ten years after Khrushchev's fall, much of the increase was due to industrial progress; agriculture continued to lag far behind, resulting in regular agricultural crises, especially in 1972 and 1975. Brezhnev and his successors continued Khrushchev's precedent of buying grain from the West rather than suffer shortfalls and starvation. Neither Brezhnev nor his colleagues were personally popular, and the new government relied on authoritarian power to assure its continuation. The KGB and Red Army were given increasing powers. The government's conservative tendencies would lead to the crushing of the "Prague Spring" of 1968.


title: Nikita Khrushchev

text: Though Khrushchev's strategy failed to achieve the major goals he sought, Aleksandr Fursenko, who wrote a book analyzing Khrushchev's foreign and military policies, argued that the strategy did coerce the West in a limited manner. The agreement that the United States would not invade Cuba has been adhered to. The refusal of the western world to acknowledge East Germany was gradually eroded, and, in 1975, the United States and other NATO members signed the Helsinki Agreement with the USSR and Warsaw Pact nations, including East Germany, setting human rights standards in Europe.


title: Nikita Khrushchev

text: The Russian public's view of Khrushchev remains mixed. According to a major Russian pollster, the only eras of the 20th century that Russians in the 21st century evaluate positively are those under Nicholas II, and under Khrushchev. A poll in 1998 of young Russians found that they felt Nicholas II had done more good than harm, and all other 20th-century Russian leaders more harm than good—except Khrushchev, about whom they were evenly divided. Khrushchev biographer William Tompson related the former premier's reforms to those which occurred later:


title: Nikita Khrushchev

text: Throughout the Brezhnev years and the lengthy interregnum that followed, the generation which had come of age during the 'first Russian spring' of the 1950s awaited its turn in power. As Brezhnev and his colleagues died or were pensioned off, they were replaced by men and women for whom the Secret Speech and the first wave of de-Stalinization had been a formative experience, and these 'Children of Twentieth Congress' took up the reins of power under the leadership of Mikhail Gorbachev and his colleagues. The Khrushchev era provided this second generation of reformers with both an inspiration and a cautionary tale.


title: Transformers (film series)

text: Transformers is a series of American science fiction action films based on the "Transformers" franchise, which began in the 1980s. Michael Bay directed the first five films: "Transformers" (2007), "" (2009), "" (2011), "" (2014), and "" (2017), and has served as a producer for subsequent films. A spin-off film "Bumblebee", directed by Travis Knight and produced by Bay, was released on December 21, 2018. A seventh film, "", directed by Steven Caple Jr., is to be released in 2023.


title: Transformers (film series)

text: The series has been distributed by Paramount Pictures and, for the first two films, DreamWorks Pictures. The original "Transformers" series has received negative to mixed reception, except for "Bumblebee", which received positive reviews. It is the 13th-highest-grossing film series, with a total of $4.8 billion; two films in the series have grossed over $1 billion each.


title: Transformers (film series)

text: For the first film, producer Don Murphy was planning a , but when the U.S. launched the invasion of Iraq in March 2003, Hasbro suggested adapting the Transformers franchise instead. Tom DeSanto joined Murphy because he was a fan of the series. They met with comic book writer Simon Furman, and cited the cartoon and comics as their main influence. They made the Creation Matrix their plot device, though Murphy had it renamed because of the film series "The Matrix". DeSanto chose to write the treatment from a human point of view to engage the audience, while Murphy wanted it to have a realistic tone, reminiscent of a disaster film. The treatment featured the Autobots Optimus Prime, Ironhide, Jazz, Prowl, Arcee, Ratchet, Wheeljack, and Bumblebee, and the Decepticons Megatron, Starscream, Soundwave, Ravage, Laserbeak, Rumble, Skywarp and Shockwave.


title: Transformers (film series)

text: Steven Spielberg, a fan of the comics and toys, signed on as executive producer in 2004. John Rogers wrote the first draft, which pitted four Autobots against four Decepticons, and featured the Ark spaceship. Roberto Orci and Alex Kurtzman, fans of the cartoon, were hired to rewrite the script in February 2005. Spielberg suggested that "a boy and his car" should be the focus. This appealed to Orci and Kurtzman because it conveyed themes of adulthood and responsibility, "the things that a car represents in the United States". The characters of Sam and Mikaela were the sole point of view given in Orci and Kurtzman's first draft. The Transformers had no dialogue, as the producers feared talking robots would look ridiculous. The writers felt that even if it would look silly, not having the robots speak would betray the fanbase. The first draft also had a battle scene in the Grand Canyon. Spielberg read each of Orci and Kurtzman's drafts and gave notes for improvement. The writers remained involved throughout production, adding additional dialogue for the robots during the sound mixing (although none of this was kept in the final film, which ran fifteen minutes shorter than the initial edit). Furman's "The Ultimate Guide", published by Dorling Kindersley, remained as a resource to the writers throughout production. "Prime Directive" was used as a fake working title. This was also the name of Dreamwave Productions' first .


title: Transformers (film series)

text: Michael Bay was asked to direct by Spielberg on July 30, 2005, but he dismissed the film as a "stupid toy movie". Nonetheless, he wanted to work with Spielberg, and gained a new respect for the mythology upon visiting Hasbro. Bay considered the first draft "too kiddie", so he increased the military's role in the story. The writers sought inspiration from G.I. Joe for the soldier characters, being careful not to mix the brands. Because Orci and Kurtzman were concerned the film could feel like a military recruitment commercial, they chose to make the military believe nations like Iran were behind the Decepticon attack as well as making the Decepticons primarily military vehicles. Bay based Lennox's struggle to get to the Pentagon phone line while struggling with an unhelpful operator from a real account he was given by a soldier when working on another film.


title: Transformers (film series)

text: Orci and Kurtzman experimented with numerous robots from the franchise, ultimately selecting the characters most popular among the filmmakers to form the final cast. Bay acknowledged that most of the Decepticons were selected before their names or roles were developed, as Hasbro had to start designing the toys. Some of their names were changed because Bay was upset that they had been leaked. Optimus, Megatron, Bumblebee and Starscream were the only characters present in each version of the script. Arcee was a female Transformer introduced by Orci and Kurtzman, but she was cut because they found it difficult to explain robotic gender; Bay also disliked her motorcycle form, which he found too small. An early idea to have the Decepticons simultaneously strike multiple places around the world was also dropped, being used later in the film's sequels.


title: Transformers (film series)

text: In September 2007, Paramount announced a late June 2009 release date for the sequel to "Transformers". A major hurdle that was overcome during the film's production was the 2007–2008 Writers Guild of America strike, as well as possible strikes by the Directors Guild of America and the Screen Actors Guild. Bay began creating animatics of action sequences featuring characters rejected for the 2007 film; this would allow animators to complete sequences if the Directors Guild of America went on strike in July 2008, which ultimately did not happen. The director considered making a small project in between "Transformers" and its sequel, but knew "you have your baby and you don't want someone else to take it". The film was given a $200 million budget, which was $50 million more than the 2007 film, and some of the action scenes rejected for the original were written into the sequel, such as the way Optimus is reintroduced in this film. Lorenzo di Bonaventura said the studio proposed filming two sequels simultaneously, but he and Bay concurred that was not the right direction for the series.


title: Transformers (film series)

text: Writers Roberto Orci and Alex Kurtzman originally passed on the sequel because of a busy schedule. The studio began courting other writers in May 2007, but as they were unimpressed with their pitches, they convinced Orci and Kurtzman to return. The studio also signed on Ehren Kruger, as he impressed Bay and Hasbro president Brian Goldner with his knowledge of the Transformers mythology, and because he was friends with Orci and Kurtzman. The writing trio were paid $8 million. Screenwriting was interrupted by the 2007–2008 Writers Guild of America strike, but to avoid production delays the writers spent two weeks writing a treatment, which they handed in the night before the strike began, and Bay expanded the outline into a sixty-page scriptment, fleshing out the action, adding more jokes, as well as selecting the majority of new characters. The three writers spent four months finishing the screenplay while "locked" in two hotel rooms by Bay: Kruger wrote in his own room and the trio would check on each other's work twice a day.


title: Transformers (film series)

text: Orci described the film's theme as "being away from home", with the Autobots contemplating living on Earth as they cannot restore Cybertron, while Sam goes to college. He wanted the focus between the robots and humans "much more evenly balanced", "the stakes [to] be higher", and the science fiction elements more prominent. Lorenzo di Bonaventura said that in total, there are around forty robots in the film, while ILM's Scott Farrar has said there are actually sixty. Orci added that he wanted to "modulate" the humor more, and felt he managed the more "outrageous" jokes by balancing them with a more serious plot approach to the Transformers' mythology. Bay concurred that he wanted to please fans by making the tone darker, and that "moms will think its safe enough to bring the kids back out to the movies" despite his trademark sense of humor.


title: Transformers (film series)

text: Before "Transformers" was released, producer DeSanto had "a very cool idea" to introduce the Dinobots, while Bay was interested in an aircraft carrier, which was dropped from the 2007 film. Orci claimed they did not incorporate these characters into "Revenge of the Fallen" because they could not think of a way to justify the Dinobots' choice of form, and were unable to fit in the aircraft carrier. Orci also admitted he was also dismissive of the Dinobots because he does not like dinosaurs. "I recognize I am weird in that department", he said, but he became fonder of them during filming because of their popularity with fans. He added "I couldn't see why a Transformer would feel the need to disguise himself in front of a bunch of lizards. Movie-wise, I mean. Once the general audience is fully on board with the whole thing, maybe Dinobots in the future." However, Michael Bay said he hated the Dinobots and they had never been in consideration for being featured in the movies. It is the last film in the series to be distributed by DreamWorks.


title: Transformers (film series)

text: For the third film, as a preemptive measure before the release of "Revenge of the Fallen", Michael Lucchi and Paramount announced on March 16, 2009, that a third film would be released in IMAX 3-D on July 1, 2011, which earned a surprised response from director Bay:


title: Transformers (film series)

text: Screenwriters Roberto Orci and Alex Kurtzman, who had worked on the two previous "Transformers" films, declined to return for the third film, with Kurtzman declaring that "the franchise is so wonderful that it deserves to be fresh, all the time. We just felt like we'd given it a lot and didn't have an insight for where to go with it next". "Revenge of the Fallen"s co-writer Ehren Kruger became the sole screenwriter for "Dark of the Moon". Kruger had frequent meetings with Industrial Light & Magic's (ILM) CGI visual effects producers, who suggested plot points such as the scenes in Chernobyl.


title: Transformers (film series)

text: On October 1, 2009, Bay revealed that "Dark of the Moon" had already gone into pre-production, and its planned release was back to its originally intended date of July 1, 2011, rather than 2012. Due to the revived interest in 3-D technology brought in by the success of "Avatar", talks between Paramount, ILM, and Bay had considered the possibility of the next "Transformers" film being filmed in 3-D, and testing was performed to bring the technology into Bay's work. Bay originally was not much interested in the format as he felt it did not fit his "aggressive style" of filmmaking, but he was convinced after talks with "Avatar" director James Cameron, who even offered the technical crew from that film. Cameron reportedly told Bay about 3-D, "You gotta look at it as a toy, it's another fun tool to help get emotion and character and create an experience." Bay was reluctant to film with 3-D cameras since in test he found them to be too cumbersome for his filming style, but he did not want to implement the technology in post production either since he was not pleased with the results. In addition to using the 3-D Fusion camera rigs developed by Cameron's team, Bay and the team spent nine months developing a more portable 3-D camera that could be brought into location. On the day of the film's release, Shia LaBeouf announced that "Dark of the Moon" will be his last "Transformers" film.


title: Transformers (film series)

text: In a hidden extra for the Blu-ray release of "Revenge of the Fallen", Bay expressed his intention to make "Transformers 3" not necessarily larger than "Revenge of the Fallen", but instead deeper into the mythology, to give it more character development, and to make it darker and more emotional. Having been called "Transformers 3" up to that point, the film's final title was revealed to be "Dark of the Moon" in October 2010. After "Revenge of the Fallen" was almost universally panned by critics, Bay acknowledged the general flaws of the script, having blamed the 2007–2008 Writers Guild of America strike prior to the film for many problems. Bay promised to not have the "dorky comedy" from the last film.


title: Transformers (film series)

text: In February 2012, producer di Bonaventura stated that a fourth film was in the works, aiming for a 2014 release, with Michael Bay to direct and produce. On the same day, Paramount Pictures and Michael Bay announced a June 27, 2014 release date for a fourth film. Ehren Kruger would pen the script and Steve Jablonsky would score the film, as each had for the previous film. The film is set five years after the events in "Transformers: Dark of the Moon". Shia LaBeouf did not return in any future installments. Mark Wahlberg was instead cast in the lead role as new character, Cade Yeager. In November 2012, casting began to search for two more leads. Isabelle Cornish, Nicola Peltz, Gabriella Wilde, and Margaret Qualley were all considered to play Cade's daughter Tessa Yeager, while Luke Grimes, Landon Liboiron, Brenton Thwaites, Jack Reynor, and Hunter Parrish were all considered to play Tessa's race-car-driving boyfriend, Shane Dyson. Bay announced on his website that Reynor would portray Shane and that the fourth film would start the next installment in the overall series; the film was to be a darker sequel to "Dark of the Moon" and have a different feeling. Peter Cullen, who voiced Optimus Prime in the films, was to reprise his role. Tyrese Gibson was in talks to reprise his role as Sgt. Robert Epps from the original trilogy. Glenn Morshower stated that he was contracted for two films and he was to reprise his role. It was later announced that he would not be return until the next film. With a budget of $165 million, filming was expected to take place in London between April and November 2013—once "Pain & Gain", another film that Bay was directing, had finished editing.


title: Transformers (film series)

text: On January 8, 2013, it was announced that Reynor was joining Wahlberg in the lead. On March 26, 2013, Nicola Peltz was cast as the female lead. Bay confirmed that the movie was to be in 3D. Bay revealed to Collider that actor Stanley Tucci had joined the cast, and that the film would be the first feature film to be shot using smaller digital IMAX 3D cameras. On May 1, 2013, actor Kelsey Grammer was cast as the lead human villain named "Harold Attinger". On May 6, 2013, actress Sophia Myles was cast in a major supporting role. That same month, Chinese actress Li Bingbing and comedian T. J. Miller joined the cast.


title: Transformers (film series)

text: Actor T.J. Miller would be playing the best friend of Wahlberg's character who is a mechanic. Also revealed were two Autobots who would have the following alternate modes—a black-and-blue 2013 Bugatti Veyron Grand Sport Vitesse  named "Drift", and a green 2014 C7 Corvette Stingray concept named Crosshairs. A truck from Western Star Trucks would be Optimus Prime's new alternate mode for the movie. Bumblebee's new alternate mode was revealed to be a modified vintage 1967 Chevrolet Camaro, which later transforms into a 2014 Chevrolet Camaro concept. A green military vehicle (later confirmed to be Hound) and a white emergency response vehicle were also revealed.


title: Transformers (film series)

text: Filming began in June 2013, in Detroit, Chicago, Austin, Los Angeles, and Hong Kong. The film was released on June 27, 2014.


title: Transformers (film series)

text: In March 2015, Deadline Hollywood reported that Paramount Pictures was in talks with Akiva Goldsman to pitch new ideas for the "Transformers" franchise's future installments. The studio intends to do what James Cameron and 20th Century Fox have been doing in planning three "Avatar" sequels, and what Disney has done to revive "Star Wars", with sequels and spin-offs. Paramount wants to have their own cinematic universe for "Transformers", similar to Marvel's/Disney's Marvel Cinematic Universe (which had been one of Paramount's previous film series), and DC Comics/Warner Bros.' DC Extended Universe. Goldsman is the head of the future projects, and worked with franchise director Michael Bay, executive producer Steven Spielberg, and producer Lorenzo di Bonaventura to organize a "writers' room" that incubates ideas for potential "Transformers" sequels, prequels and spin-offs. The writers' room members include: Christina Hodson, Lindsey Beer, Andrew Barrer, and Gabriel Ferrari ("Ant-Man"), Robert Kirkman ("The Walking Dead"), Art Marcum & Matt Holloway, Zak Penn ("Pacific Rim Uprising"), Jeff Pinkner ("The Amazing Spider-Man 2"), Ken Nolan, and Geneva Robertson-Dworet. Kirkman left the room after just one day to undergo throat surgery. In July 2015, Akiva Goldsman and Jeff Pinkner were announced as the fifth "Transformers" film's screenwriters. However, on November 20, due to Goldsman's commitments creating a writers' room for "G.I. Joe" and "Micronauts" properties, Paramount began to negotiate with Art Marcum and Matt Holloway ("Iron Man"), as well as Ken Nolan ("Black Hawk Down"), to write the film. Lindsey Beer and Geneva Robertson-Dworet were also brought aboard for writing duties.


title: Transformers (film series)

text: After "", Bay had decided not to direct any future "Transformers" films. But in early January 2016, in an interview with "Rolling Stone", he stated that he would return to direct the fifth film, and that it will be his last "Transformers" film. Paramount Pictures spent $80 million on production in Michigan, in return for $21 million in state incentives, under agreements entered into before the state legislature eliminated the film office incentive program in July 2015. In April 2016, Paramount hired cinematographer Jonathan Sela. On May 17, Bay revealed the official title of the film to be "The Last Knight" on his Instagram account, where he also posted a production video showing a close-up of Optimus Prime's face with purple eyes instead of blue, and his face mostly discolored. The official Twitter account showed a 19-second short video in morse code that translates to "I'm coming for you May 31". On May 31, it was revealed that Megatron would return in the sequel.


title: Transformers (film series)

text: "Bumblebee" is a spin-off film centered on the "Transformers" character of the same name. It was to be a prequel to the film series, then it was later declared a reboot of the franchise. The design and style of the film included both elements from the existing franchise as well as influences from "" franchise of toys.


title: Transformers (film series)

text: Principal photography on the film began in July 2017, in Los Angeles and San Francisco, California. It was released on December 21, 2018, to positive reviews. Following the film's critical success, Hasbro intends to continue and evolve the franchise similar to "Bumblebee".


title: Transformers (film series)

text: In March 2019, producer Lorenzo di Bonaventura announced ongoing developments for a follow-up to "Bumblebee". By January 2020, it was officially announced that a sequel to "Bumblebee" was in development with a script written by Joby Harold, alongside an adaptation of "" with a script written by James Vanderbilt. The film was then scheduled for release on June 24, 2022, that May, while in November, Steven Caple Jr. was hired to serve as director on the project, which serves as both a "Bumblebee" sequel and "Beast Wars" adaptation. In April 2021, Anthony Ramos was cast in one of the lead roles for the film, with Dominique Fishback in final talks to play the lead role. The project will be a joint-venture production between Hasbro, eOne, and Paramount Pictures.


title: Transformers (film series)

text: Principal photography began in June 2021, with the official title announced as "Transformers: Rise of the Beasts", confirmed to be set after the events of "Bumblebee". "Rise of the Beasts" was scheduled to be release on June 24, 2022, but was delayed to June 9, 2023.


title: Transformers (film series)

text: In September 2015, Andrew Barrer and Gabriel Ferrari, who were previously a part of the shared universe writers' room, were hired to write a film that will explore the origins of Cybertron with a working title of "Transformers One". In April 2020, Josh Cooley signed on to direct the animated prequel film. Barrer and Ferrari will co-write a new draft of their previous script, with Cooley. Lorenzo di Bonaventura and Mark Vahradian will serve as producers. The story will take place entirely on Cybertron, and will explore the relationship between Optimus Prime and Megatron, "separate and apart" from what has been portrayed in the live-action films. The project will be a joint-venture production between Hasbro Entertainment, eOne, Paramount Animation, and Paramount Pictures. The film is scheduled for release on July 19, 2024.


title: Transformers (film series)

text: In March 2013, during the release of "", producer di Bonaventura announced the studio's plans to develop a "G.I. Joe/Transformers" crossover. On July 26, 2013, "G.I. Joe: Retaliation" director Jon M. Chu stated that he is also interested in directing a "Transformers/G.I. Joe" crossover film. Despite di Bonaventura stating that a crossover was not in the immediate plans for the franchises, he acknowledged that it is something they intended to do. In July 2021, producer Di Bonaventura and actor Henry Golding expressed interest in the possibility of doing the crossover film.


title: Transformers (film series)

text: In March 2015, Paramount hired Academy Award-winning screenwriter Akiva Goldsman to oversee and compile a team of writers, to pitch ideas for future films with the intention of expanding the franchise into a cinematic universe. Twelve individual stories were written and pitched for the cinematic universe. Goldsman was tasked with developing a multi-part sequel storyline, along with prequels and spin-off films. A "brain-trust" was commissioned to guide the productions of these stories, including Goldsman, Michael Bay, and producers Steven Spielberg and Lorenzo di Bonaventura. The team of writers who were hired included: Robert Kirkman, Art Marcum, Matt Holloway, Zak Penn, Jeff Pinkner, Andrew Barrer, Gabriel Ferrari, Christina Hodson, Lindsey Beer, Ken Nolan, Geneva Robertson-Dworet, and Steven DeKnight. Goldsman described the writer's room collaboration process, as a way to map out stories that can be further developed by the projects that are green-lit by the brain trust; stating: "...if one of the writers discovers an affinity for [a particular story], they can drive forward on treatments that will have been fleshed out by the whole room." In August 2017, following the poor reception of "The Last Knight" which Goldsman co-wrote, the filmmaker officially left the franchise.


title: Transformers (film series)

text: In December 2018, di Bonaventura stated that there will be further films in the series, while also acknowledging that the franchise will make some changes in tone and style due to the success of "Bumblebee".


title: Transformers (film series)

text: Released separately from the first film on home release in October 2007, on DVD as a Walmart Exclusive; the short is an animated prequel, presented in the form of a motion comic, with narration from the character Bumblebee. Mark Ryan provides the voice-over work for the role, while the short depicts Megatron's arrival on Earth, as well as Archibald Witwicky's discovery 4 million years later. The short skips to 2003 with Bumblebee arriving on Earth, and Sector 7's pursuit of him.


title: Transformers (film series)

text: Released on the home video release of "Bumblebee", two short films under a "Sector 7 Archive" label were released.


title: Transformers (film series)

text: A short film, released in the form of a motion comic, taking place two years after the events of "Bumblebee" which depicts a fight between Bumblebee and Soundwave. When Sector 7 is attacked by Soundwave, Bumblebee arrives to protect them. During the ensuing battle, Soundwave demands that Sector 7 give back what belongs to the Decepticons.


title: Transformers (film series)

text: A 13 episode long web mini series released in 2010 and set within and using the Transformers design from the continuity of the live action movies. It was released on Hasbro's website and in 2011 re-released on Transformers official YouTube channel. The series was made by TG Studios in only three months. It is set between the events of "Revenge of the Fallen" and "Dark of the Moon".


title: Transformers (film series)

text: is a 3-episode long retelling of the first half of the "Bumblebee" film with no spoilers. The series was released on Paramount Pictures' Japanese Twitter account.


title: Transformers (film series)

text: With the exception of "Bumblebee", common elements of the original film series received negative reception, such as the repeated formulaic plots, acting, dialogue, filming, Transformer redesigns, sophomoric and toilet humor, female character objectification, the Transformers being reduced to secondary characters in their own films, clichéd and controversial characterizations, aimless story arcs, lack of character development, inconsistent tone, incoherent action, questionable marketing, poor writing, racial and cultural stereotypes, overuse of MacGuffins, product placement, CGI, long running times, and excessive retroactive continuity changes.


title: Transformers (film series)

text: The first "Transformers" film received mixed reviews, with praise for the groundbreaking visual effects, musical score, action sequences, Labeouf's performance, and Peter Cullen's return as Optimus Prime. There was some criticism of the Transformer redesigns, the screen time for certain characters, and the product placement. Film critic Roger Ebert gave the film three stars, writing "It's goofy fun with a lot of stuff that blows up real good, and it has the grace not only to realize how preposterous it is, but to make that into an asset."


title: Transformers (film series)

text: The second film, "Revenge of the Fallen", received mostly negative reviews. Roger Ebert gave the film one star, calling it "a horrible experience of unbearable length, punctuated by three or four amusing moments." The characterization of the Autobot twins, Skids and Mudflap, was heavily criticized. Peter Travers of "Rolling Stone" magazine labeled them: "two of the most offensive bots in screen history...who do black stereotypes in ways that would shame Jar Jar Binks" and concluded the film "has a shot at the title Worst Movie of the Decade." Others described them as "something out of an old minstrel show" with "conspicuously cartoonish, so-called black voices that indicate that minstrelsy remains as much in fashion in Hollywood as when, well, Jar Jar Binks was set loose by George Lucas." Reviews also criticized the excessive running time, inappropriate humor, the rehashing of the MacGuffin-focused plot, nonsensical dialogue, heavy focus on the humans, and indistinguishable robots crashing into each other. Positive aspects noted by critics include Peter Cullen's voiceover work, the visual effects, music, and action.


title: Transformers (film series)

text: The third film, "Dark of the Moon", received mixed reviews but was considered an improvement over the second film. Praise was directed toward the visuals, editing, music, and the voicework of Peter Cullen and Leonard Nimoy, while the acting and story were criticized. Peter Bradshaw of "The Guardian" gave the film a mixed review, saying, "It is as if Bay, perhaps influenced by some stinging critiques, has made an aesthetic policy decision. Because this film is not quite as stupid as the others...But let's face it, these touches are atypical. After half an hour it turns into the same headbanging, eardrum-brutalising action-fest as the other two films." Bradshaw also notes the impressive effects in the Battle of Chicago at the climax and how the September 11 attacks inspired it. A. O. Scott of "The New York Times" called "Dark of the Moon" among Michael Bay's best films but said, "I can't decide if this movie is so spectacularly, breathtakingly dumb as to induce stupidity in anyone who watches, or so brutally brilliant that it disarms all reason. What's the difference?" Scott also criticized the film for continuing the series' pattern of "tongue-in-cheek revisionist history" by using the Space Race as the catalyst for the film's events. Dan Kois of "The Village Voice" also criticized Michael Bay's continuation of "exploiting America's iconic tragedies for maximum impact." He emphasized the 9/11 comparison by noting Chicago being declared "Ground Zero" and pointing out the "re-creation of the 1986 "Challenger" disaster, right down to that lopsided fireball blooming over the ocean." Chris Hewitt of "Empire Online" gave the film 2 out of 5 stars, saying that "Dark of the Moon" is better than "Revenge of the Fallen" but not by much. Hewitt praised the last 45 minutes and the best use of 3D since "Avatar" but panned the choppy editing, lazy writing, the slow first hour, the level of violence in the robot fights, and considered Bay's use of the Chernobyl disaster as a plot device as being in poor taste. Also criticized were Josh Duhamel and Tyrese Gibson for being reduced to needless supporting characters, Shia LaBeouf's Sam Witwicky being an unlikable character, and actors John Malkovich, Alan Tudyk, and Ken Jeong for being used as "cheap-seats comedy relief." Rosie Huntington-Whiteley's Carly was criticized for being an undeveloped female lead with no purpose in the plot except to be a sex object and damsel with Tom Charity of "CNN Entertainment" claiming that she "makes Megan Fox look like Meryl Streep." Roger Ebert rated the film 1 out of 4 stars, and Peter Travers of "Rolling Stones" called it "a movie bereft of wit, wonder, imagination, and any genuine reason for being." Christopher Orr of "The Atlantic" said "Dark of the Moon" is an improvement over the previous film in almost every way apart from its length, praising the special effects, 3D usage, and intense action. He criticized the retrograde depiction of the female characters, the September 11 undertones of the Chicago climax, and the uncomfortable level of violence from the Transformers.


title: Transformers (film series)

text: "Age of Extinction" and "The Last Knight" both received negative reviews and are the lowest-rated films in the series. For "Age of Extinction", some praised elements include the visual effects, musical score, serious tone, action sequences, as well as the performances of Mark Wahlberg, Stanley Tucci, Kelsey Grammer, and Peter Cullen. Critics panned it for its excessive product placement, the nearly three-hour runtime, poor writing and editing, the introduction of the "Transformium" element, and the idea of human-made Transformers. Also criticized was the racist stereotypes in the film, with David Edelstein of "Vulture" using actress Li Bingbing as an example of the stereotype of "all Chinese people being adept in the martial arts." Sam Adams of "IndieWire" labeled "Age of Extinction" "a new, terrible kind of cinema" that could have been written by "a high school sophomore with a permanent hard-on." Angela Wattercutter of "Wired" magazine criticized "Age of Extinction"'s insensitive use of the War on Terror and the September 11 aftermath as inspiration with the Transformers treated as "enemy combatants" and "alien terrorists", and being hunted by Kelsey Grammer's xenophobic government agent. Wattercutter even notes that the film has a captive Autobot making an offhanded joke about waterboarding. The designs of the Autobots, such as Hound, Drift, and Crosshairs, drew criticism, with Drift being called a Japanese stereotype and an example of yellowface. The dark depiction of Optimus Prime also drew criticism for being unpleasant and unfaithful to the character. Critics also panned the film for portraying the Dinobots as mindless robots devoid of their personalities and reducing them to a deus ex machina appearing late in the film despite being a focal point in the marketing. Critics noted Nicola Peltz's character as a sexualized underage girl and damsel-in-distress with no sense of agency whose sole purpose is to have the male leads fight over her. Her character's relationship with Jack Reynor also drew backlash as critics accused Michael Bay of treating statutory rape as a joke and attempting to defend it with the Romeo and Juliet law.


title: Transformers (film series)

text: For "The Last Knight", critics criticized the confusing plot, messy narrative, script, characters and screen time for some characters, excessive length and constant format changes throughout the film, while positive elements focused on the visuals, action, music and the performances of Mark Walhberg, Anthony Hopkins, John Goodman and Peter Cullen. Yohana Desta of "Vanity Fair" called the film "an apocalyptic identity crisis come to life" and "an unruly Frankenstein's monster with shoddy stitchwork." Desta noted that despite the film's nonsensical/non-existent plot, the visual effects remain impressive. Christopher Orr of The Atlantic criticized the film for attempting to connect the Transformers to Stonehenge and World War II, and called it the worst retelling of Arthurian legend of the year, even worse than Guy Ritchie's "". Rebecca Farley of "Refinery29" and Dana Schwartz of "Marie Claire" were critical of the underdeveloped female characters. Farley accused the production of trying to insert last-minute "tween girl empowerment" after Millie Bobby Brown's success in "Stranger Things", noting that the marketing made Isabela Moner appear to have a prominent role in the film, when she does not. Farley also labeled Laura Haddock's character the film's "textbook Strong Woman" cliché since she plays a highly educated and athletic woman harassed by female family members for being single and the male protagonist for "wearing a stripper dress." Schwartz cites Wahlberg's character for referring to Moner's as "Little J. Lo" because of her Latina heritage, and Haddock being portrayed as the "British Megan Fox" for their similar appearances. Ian Freer of "Empire" magazine rated the film 2 out of 5 stars. Freer said that like the previous films, it is "bogged down in backstory, lacks a real feel for its characters and still can't find a way to make its robot-on-robot action exhilarating... It is amazing how a series with so much nostalgic goodwill, technical finesse and behind the scenes talent have led so often to experiences that are so joyless."


title: Transformers (film series)

text: The 2018 spin-off film, "Bumblebee", received positive reviews with a Rotten Tomatoes score of 90%, making it the highest-rated film in the series. Critics praised it for its lighter tone, story, visuals, acting, direction, and faithfulness to the 1980s Transformers show. Glenn Kenny of "The New York Times" praised the plot, Christina Hodson's script, and Hailee Steinfeld's performance, calling her possibly the only appealing main human character in the franchise so far. James Dyer of "Empire" magazine gave the film 4 out of 5 stars, praising aspects such as Travis Knight's directing, the screenplay, Steinfield and John Cena's acting, and the film's '80s nostalgia; he praised the film for acting as a love letter to Steven Spielberg's Amblin films. In a review for "The Hollywood Reporter", Justin Lowe praised the improved digital effects, including the "sharp visual details, realistic color shading and seamless transitions between robot and vehicular forms." Lowe also noted the film's focus on a PG tone despite its PG-13 rating, its character-driven story, and its improved humor compared to its predecessors. David Fear of "Rolling Stone" noted the film for borrowing elements from "E.T.", "The Iron Giant", and John Hughes films, and commented: "the usual Americana-on-steroids vibe of the Bay movies are , replaced with a less bombastic combination of bot-outta-water shenanigans... and sensitive, not-at-all sappy drama."


title: Transformers (film series)

text: The franchise has been frequently praised and won awards for its sound design. Michael Bay praised the crew and highlighted the importance of sound saying "I have like 2,000 people — through their artistry — making my dreams a film," Bay said. "The artistry of this sound group is just amazing. I love, love sound. It's 45-50% of the movies."


title: Transformers (film series)

text: In addition to the films, the film series has a promotional expanded series that is set both before and after the events of the films. This includes comic books, video games, and novels. While the novels are partially based on the films themselves, and the video games are not in the same continuity as the films, the comic books and graphic novels are in the same continuity and fill in several parts of the stories from the films. Also, "" is an amusement ride based on the film series. The ride introduced a new character, Autobot Evac, voiced by Dustin James Leighton.


title: Mammal

text: Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or hair, and three middle ear bones. These characteristics distinguish them from reptiles (including birds) from which they diverged in the Carboniferous, over 300 million years ago. Around 6,400 extant species of mammals have been described divided into 29 orders. The largest orders, in terms of number of species, are the rodents, bats, and Eulipotyphla (hedgehogs, moles, shrews, and others). The next three are the Primates (including humans, apes, monkeys, and others), the Artiodactyla (cetaceans and even-toed ungulates), and the Carnivora (cats, dogs, seals, and others).


title: Mammal

text: In terms of cladistics, which reflects evolutionary history, mammals are the only living members of the Synapsida (synapsids); this clade, together with Sauropsida (reptiles and birds), constitutes the larger Amniota clade. The early synapsids were sphenacodonts, a group that included the famous "Dimetrodon". The synapsids split into several diverse groups of non-mammalian synapsids — traditionally and incorrectly referred to as mammal-like reptiles or by the term pelycosaurs, and now known as stem mammals or protomammals — before giving rise to therapsids during the beginning of the Middle Permian period. Mammals originated from cynodonts, an advanced group of therapsids, during the Late Triassic-Early Jurassic. The modern mammalian orders arose in the Paleogene and Neogene periods of the Cenozoic era, after the extinction of non-avian dinosaurs, and have been the dominant terrestrial animal group from 66 million years ago to the present.


title: Mammal

text: The basic body type is quadruped, and most mammals use their four extremities for terrestrial locomotion; but in some, the extremities are adapted for life at sea, in the air, in trees, underground, or on two legs. Mammals range in size from the bumblebee bat to the blue whale—possibly the largest animal to have ever lived. Maximum lifespan varies from two years for the shrew to 211 years for the bowhead whale. All modern mammals give birth to live young, except the five species of monotremes, which are egg-laying mammals. The most species-rich group of mammals, the cohort called placentals, have a placenta, which enables the feeding of the fetus during gestation.


title: Mammal

text: Most mammals are intelligent, with some possessing large brains, self-awareness, and tool use. Mammals can communicate and vocalize in several ways, including the production of ultrasound, scent-marking, alarm signals, singing, and echolocation. Mammals can organize themselves into fission-fusion societies, harems, and hierarchies—but can also be solitary and territorial. Most mammals are polygynous, but some can be monogamous or polyandrous.


title: Mammal

text: Domestication of many types of mammals by humans played a major role in the Neolithic Revolution, and resulted in farming replacing hunting and gathering as the primary source of food for humans. This led to a major restructuring of human societies from nomadic to sedentary, with more co-operation among larger and larger groups, and ultimately the development of the first civilizations. Domesticated mammals provided, and continue to provide, power for transport and agriculture, as well as food (meat and dairy products), fur, and leather. Mammals are also hunted and raced for sport, and are used as model organisms in science. Mammals have been depicted in art since Paleolithic times, and appear in literature, film, mythology, and religion. Decline in numbers and extinction of many mammals is primarily driven by human poaching and habitat destruction, primarily deforestation.


title: Mammal

text: Mammal classification has been through several revisions since Carl Linnaeus initially defined the class, and at present, no classification system is universally accepted. McKenna & Bell (1997) and Wilson & Reeder (2005) provide useful recent compendiums. Simpson (1945) provides systematics of mammal origins and relationships that had been taught universally until the end of the 20th century.


title: Mammal

text: However, since 1945, a large amount of new and more detailed information has gradually been found: The paleontological record has been recalibrated, and the intervening years have seen much debate and progress concerning the theoretical underpinnings of systematization itself, partly through the new concept of cladistics. Though fieldwork and lab work progressively outdated Simpson's classification, it remains the closest thing to an official classification of mammals, despite its known issues.


title: Mammal

text: Most mammals, including the six most species-rich orders, belong to the placental group. The three largest orders in numbers of species are Rodentia: mice, rats, porcupines, beavers, capybaras, and other gnawing mammals; Chiroptera: bats; and Soricomorpha: shrews, moles, and solenodons. The next three biggest orders, depending on the biological classification scheme used, are the Primates: apes, monkeys, and lemurs; the Cetartiodactyla: whales and even-toed ungulates; and the Carnivora which includes cats, dogs, weasels, bears, seals, and allies. According to "Mammal Species of the World", 5,416 species were identified in 2006. These were grouped into 1,229 genera, 153 families and 29 orders. In 2008, the International Union for Conservation of Nature (IUCN) completed a five-year Global Mammal Assessment for its IUCN Red List, which counted 5,488 species. According to research published in the "Journal of Mammalogy" in 2018, the number of recognized mammal species is 6,495, including 96 recently extinct.


title: Mammal

text: The word "mammal" is modern, from the scientific name "Mammalia" coined by Carl Linnaeus in 1758, derived from the Latin "mamma" ("teat, pap"). In an influential 1988 paper, Timothy Rowe defined Mammalia phylogenetically as the crown group of mammals, the clade consisting of the most recent common ancestor of living monotremes (echidnas and platypuses) and Therian mammals (marsupials and placentals) and all descendants of that ancestor. Since this ancestor lived in the Jurassic period, Rowe's definition excludes all animals from the earlier Triassic, despite the fact that Triassic fossils in the Haramiyida have been referred to the Mammalia since the mid-19th century. If Mammalia is considered as the crown group, its origin can be roughly dated as the first known appearance of animals more closely related to some extant mammals than to others. "Ambondro" is more closely related to monotremes than to therian mammals while "Amphilestes" and "Amphitherium" are more closely related to the therians; as fossils of all three genera are dated about in the Middle Jurassic, this is a reasonable estimate for the appearance of the crown group.


title: Mammal

text: T.S. Kemp has provided a more traditional definition: "Synapsids that possess a dentary–squamosal jaw articulation and occlusion between upper and lower molars with a transverse component to the movement" or, equivalently in Kemp's view, the clade originating with the last common ancestor of "Sinoconodon" and living mammals. The earliest known synapsid satisfying Kemp's definitions is "Tikitherium", dated , so the appearance of mammals in this broader sense can be given this Late Triassic date.


title: Mammal

text: In 1997, the mammals were comprehensively revised by Malcolm C. McKenna and Susan K. Bell, which has resulted in the McKenna/Bell classification. The authors worked together as paleontologists at the American Museum of Natural History. McKenna inherited the project from Simpson and, with Bell, constructed a completely updated hierarchical system, covering living and extinct taxa, that reflects the historical genealogy of Mammalia. Their 1997 book, "Classification of Mammals above the Species Level", is a comprehensive work on the systematics, relationships and occurrences of all mammal taxa, living and extinct, down through the rank of genus, though molecular genetic data challenge several of the groupings.


title: Mammal

text: As of the early 21st century, molecular studies based on DNA analysis have suggested new relationships among mammal families. Most of these findings have been independently validated by retrotransposon presence/absence data. Classification systems based on molecular studies reveal three major groups or lineages of placental mammals—Afrotheria, Xenarthra and Boreoeutheria—which diverged in the Cretaceous. The relationships between these three lineages is contentious, and all three possible hypotheses have been proposed with respect to which group is basal. These hypotheses are Atlantogenata (basal Boreoeutheria), Epitheria (basal Xenarthra) and Exafroplacentalia (basal Afrotheria). Boreoeutheria in turn contains two major lineages—Euarchontoglires and Laurasiatheria.


title: Mammal

text: Estimates for the divergence times between these three placental groups range from 105 to 120 million years ago, depending on the type of DNA used (such as nuclear or mitochondrial) and varying interpretations of paleogeographic data.


title: Mammal

text: Synapsida, a clade that contains mammals and their extinct relatives, originated during the Pennsylvanian subperiod (~323 million to ~300 million years ago), when they split from the reptile lineage. Crown group mammals evolved from earlier mammaliaforms during the Early Jurassic. The cladogram takes Mammalia to be the crown group.


title: Mammal

text: The first fully terrestrial vertebrates were amniotes. Like their amphibious early tetrapod predecessors, they had lungs and limbs. Amniotic eggs, however, have internal membranes that allow the developing embryo to breathe but keep water in. Hence, amniotes can lay eggs on dry land, while amphibians generally need to lay their eggs in water.


title: Mammal

text: The first amniotes apparently arose in the Pennsylvanian subperiod of the Carboniferous. They descended from earlier reptiliomorph amphibious tetrapods, which lived on land that was already inhabited by insects and other invertebrates as well as ferns, mosses and other plants. Within a few million years, two important amniote lineages became distinct: the synapsids, which would later include the common ancestor of the mammals; and the sauropsids, which now include turtles, lizards, snakes, crocodilians and dinosaurs (including birds). Synapsids have a single hole (temporal fenestra) low on each side of the skull. Primitive synapsids included the largest and fiercest animals of the early Permian such as Dimetrodon. Nonmammalian synapsids were traditionally – and incorrectly – called "mammal-like reptiles" or pelycosaurs; we now know they were neither reptiles nor part of reptile lineage.


title: Mammal

text: Therapsids, a group of synapsids, evolved in the Middle Permian, about 265 million years ago, and became the dominant land vertebrates. They differ from basal eupelycosaurs in several features of the skull and jaws, including: larger skulls and incisors which are equal in size in therapsids, but not for eupelycosaurs. The therapsid lineage leading to mammals went through a series of stages, beginning with animals that were very similar to their early synapsid ancestors and ending with probainognathian cynodonts, some of which could easily be mistaken for mammals. Those stages were characterized by:


title: Mammal

text: The Permian–Triassic extinction event about 252 million years ago, which was a prolonged event due to the accumulation of several extinction pulses, ended the dominance of carnivorous therapsids. In the early Triassic, most medium to large land carnivore niches were taken over by archosaurs which, over an extended period (35 million years), came to include the crocodylomorphs, the pterosaurs and the dinosaurs; however, large cynodonts like "Trucidocynodon" and traversodontids still occupied large sized carnivorous and herbivorous niches respectively. By the Jurassic, the dinosaurs had come to dominate the large terrestrial herbivore niches as well.


title: Mammal

text: The first mammals (in Kemp's sense) appeared in the Late Triassic epoch (about 225 million years ago), 40 million years after the first therapsids. They expanded out of their nocturnal insectivore niche from the mid-Jurassic onwards; The Jurassic "Castorocauda", for example, was a close relative of true mammals that had adaptations for swimming, digging and catching fish. Most, if not all, are thought to have remained nocturnal (the nocturnal bottleneck), accounting for much of the typical mammalian traits. The majority of the mammal species that existed in the Mesozoic Era were multituberculates, eutriconodonts and spalacotheriids. The earliest known metatherian is "Sinodelphys", found in 125 million-year-old Early Cretaceous shale in China's northeastern Liaoning Province. The fossil is nearly complete and includes tufts of fur and imprints of soft tissues.


title: Mammal

text: The oldest known fossil among the Eutheria ("true beasts") is the small shrewlike "Juramaia sinensis", or "Jurassic mother from China", dated to 160 million years ago in the late Jurassic. A later eutherian relative, "Eomaia", dated to 125 million years ago in the early Cretaceous, possessed some features in common with the marsupials but not with the placentals, evidence that these features were present in the last common ancestor of the two groups but were later lost in the placental lineage. In particular, the epipubic bones extend forwards from the pelvis. These are not found in any modern placental, but they are found in marsupials, monotremes, other nontherian mammals and "Ukhaatherium", an early Cretaceous animal in the eutherian order Asioryctitheria. This also applies to the multituberculates. They are apparently an ancestral feature, which subsequently disappeared in the placental lineage. These epipubic bones seem to function by stiffening the muscles during locomotion, reducing the amount of space being presented, which placentals require to contain their fetus during gestation periods. A narrow pelvic outlet indicates that the young were very small at birth and therefore pregnancy was short, as in modern marsupials. This suggests that the placenta was a later development.


title: Mammal

text: One of the earliest known monotremes was "Teinolophos", which lived about 120 million years ago in Australia. Monotremes have some features which may be inherited from the original amniotes such as the same orifice to urinate, defecate and reproduce (cloaca)—as lizards and birds also do— and they lay eggs which are leathery and uncalcified.


title: Mammal

text: "Hadrocodium", whose fossils date from approximately 195 million years ago, in the early Jurassic, provides the first clear evidence of a jaw joint formed solely by the squamosal and dentary bones; there is no space in the jaw for the articular, a bone involved in the jaws of all early synapsids.


title: Mammal

text: The earliest clear evidence of hair or fur is in fossils of "Castorocauda" and "Megaconus", from 164 million years ago in the mid-Jurassic. In the 1950s, it was suggested that the foramina (passages) in the maxillae and premaxillae (bones in the front of the upper jaw) of cynodonts were channels which supplied blood vessels and nerves to vibrissae (whiskers) and so were evidence of hair or fur; it was soon pointed out, however, that foramina do not necessarily show that an animal had vibrissae, as the modern lizard "Tupinambis" has foramina that are almost identical to those found in the nonmammalian cynodont "Thrinaxodon". Popular sources, nevertheless, continue to attribute whiskers to "Thrinaxodon". Studies on Permian coprolites suggest that non-mammalian synapsids of the epoch already had fur, setting the evolution of hairs possibly as far back as dicynodonts.


title: Mammal

text: When endothermy first appeared in the evolution of mammals is uncertain, though it is generally agreed to have first evolved in non-mammalian therapsids. Modern monotremes have lower body temperatures and more variable metabolic rates than marsupials and placentals, but there is evidence that some of their ancestors, perhaps including ancestors of the therians, may have had body temperatures like those of modern therians. Likewise, some modern therians like afrotheres and xenarthrans have secondarily developed lower body temperatures.


title: Mammal

text: The evolution of erect limbs in mammals is incomplete—living and fossil monotremes have sprawling limbs. The parasagittal (nonsprawling) limb posture appeared sometime in the late Jurassic or early Cretaceous; it is found in the eutherian "Eomaia" and the metatherian "Sinodelphys", both dated to 125 million years ago. Epipubic bones, a feature that strongly influenced the reproduction of most mammal clades, are first found in Tritylodontidae, suggesting that it is a synapomorphy between them and mammaliformes. They are omnipresent in non-placental mammaliformes, though "Megazostrodon" and "Erythrotherium" appear to have lacked them.


title: Mammal

text: It has been suggested that the original function of lactation (milk production) was to keep eggs moist. Much of the argument is based on monotremes, the egg-laying mammals. In human females, mammary glands become fully developed during puberty, regardless of pregnancy.


title: Mammal

text: Therian mammals took over the medium- to large-sized ecological niches in the Cenozoic, after the Cretaceous–Paleogene extinction event approximately 66 million years ago emptied ecological space once filled by non-avian dinosaurs and other groups of reptiles, as well as various other mammal groups, and underwent an exponential increase in body size (megafauna). Then mammals diversified very quickly; both birds and mammals show an exponential rise in diversity. For example, the earliest known bat dates from about 50 million years ago, only 16 million years after the extinction of the non-avian dinosaurs.


title: Mammal

text: Molecular phylogenetic studies initially suggested that most placental orders diverged about 100 to 85 million years ago and that modern families appeared in the period from the late Eocene through the Miocene. However, no placental fossils have been found from before the end of the Cretaceous. The earliest undisputed fossils of placentals comes from the early Paleocene, after the extinction of the non-avian dinosaurs. In particular, scientists have identified an early Paleocene animal named "Protungulatum donnae" as one of the first placental mammals. however it has been reclassified as a non-placental eutherian. Recalibrations of genetic and morphological diversity rates have suggested a Late Cretaceous origin for placentals, and a Paleocene origin for most modern clades.


title: Mammal

text: The earliest known ancestor of primates is "Archicebus achilles" from around 55 million years ago. This tiny primate weighed 20–30 grams (0.7–1.1 ounce) and could fit within a human palm.


title: Mammal

text: Living mammal species can be identified by the presence of sweat glands, including those that are specialized to produce milk to nourish their young. In classifying fossils, however, other features must be used, since soft tissue glands and many other features are not visible in fossils.


title: Mammal

text: For the most part, these characteristics were not present in the Triassic ancestors of the mammals. Nearly all mammaliaforms possess an epipubic bone, the exception being modern placentals.


title: Mammal

text: On average, male mammals are larger than females, with males being at least 10% larger than females in over 45% of investigated species. Most mammalian orders also exhibit male-biased sexual dimorphism, although some orders do not show any bias or are significantly female-biased (Lagomorpha). Sexual size dimorphism increases with body size across mammals (Rensch's rule), suggesting that there are parallel selection pressures on both male and female size. Male-biased dimorphism relates to sexual selection on males through male–male competition for females, as there is a positive correlation between the degree of sexual selection, as indicated by mating systems, and the degree of male-biased size dimorphism. The degree of sexual selection is also positively correlated with male and female size across mammals. Further, parallel selection pressure on female mass is identified in that age at weaning is significantly higher in more polygynous species, even when correcting for body mass. Also, the reproductive rate is lower for larger females, indicating that fecundity selection selects for smaller females in mammals. Although these patterns hold across mammals as a whole, there is considerable variation across orders.


title: Mammal

text: The majority of mammals have seven cervical vertebrae (bones in the neck). The exceptions are the manatee and the two-toed sloth, which have six, and the three-toed sloth which has nine. All mammalian brains possess a neocortex, a brain region unique to mammals. Placental brains have a corpus callosum, unlike monotremes and marsupials.


title: Mammal

text: The lungs of mammals are spongy and honeycombed. Breathing is mainly achieved with the diaphragm, which divides the thorax from the abdominal cavity, forming a dome convex to the thorax. Contraction of the diaphragm flattens the dome, increasing the volume of the lung cavity. Air enters through the oral and nasal cavities, and travels through the larynx, trachea and bronchi, and expands the alveoli. Relaxing the diaphragm has the opposite effect, decreasing the volume of the lung cavity, causing air to be pushed out of the lungs. During exercise, the abdominal wall contracts, increasing pressure on the diaphragm, which forces air out quicker and more forcefully. The rib cage is able to expand and contract the chest cavity through the action of other respiratory muscles. Consequently, air is sucked into or expelled out of the lungs, always moving down its pressure gradient. This type of lung is known as a bellows lung due to its resemblance to blacksmith bellows.


title: Mammal

text: The mammalian heart has four chambers, two upper atria, the receiving chambers, and two lower ventricles, the discharging chambers. The heart has four valves, which separate its chambers and ensures blood flows in the correct direction through the heart (preventing backflow). After gas exchange in the pulmonary capillaries (blood vessels in the lungs), oxygen-rich blood returns to the left atrium via one of the four pulmonary veins. Blood flows nearly continuously back into the atrium, which acts as the receiving chamber, and from here through an opening into the left ventricle. Most blood flows passively into the heart while both the atria and ventricles are relaxed, but toward the end of the ventricular relaxation period, the left atrium will contract, pumping blood into the ventricle. The heart also requires nutrients and oxygen found in blood like other muscles, and is supplied via coronary arteries.


title: Mammal

text: The integumentary system (skin) is made up of three layers: the outermost epidermis, the dermis and the hypodermis. The epidermis is typically 10 to 30 cells thick; its main function is to provide a waterproof layer. Its outermost cells are constantly lost; its bottommost cells are constantly dividing and pushing upward. The middle layer, the dermis, is 15 to 40 times thicker than the epidermis. The dermis is made up of many components, such as bony structures and blood vessels. The hypodermis is made up of adipose tissue, which stores lipids and provides cushioning and insulation. The thickness of this layer varies widely from species to species; marine mammals require a thick hypodermis (blubber) for insulation, and right whales have the thickest blubber at . Although other animals have features such as whiskers, feathers, setae, or cilia that superficially resemble it, no animals other than mammals have hair. It is a definitive characteristic of the class, though some mammals have very little.


title: Mammal

text: Herbivores have developed a diverse range of physical structures to facilitate the consumption of plant material. To break up intact plant tissues, mammals have developed teeth structures that reflect their feeding preferences. For instance, frugivores (animals that feed primarily on fruit) and herbivores that feed on soft foliage have low-crowned teeth specialized for grinding foliage and seeds. Grazing animals that tend to eat hard, silica-rich grasses, have high-crowned teeth, which are capable of grinding tough plant tissues and do not wear down as quickly as low-crowned teeth. Most carnivorous mammals have carnassialiforme teeth (of varying length depending on diet), long canines and similar tooth replacement patterns.


title: Mammal

text: The stomach of even-toed ungulates (Artiodactyla) is divided into four sections: the rumen, the reticulum, the omasum and the abomasum (only ruminants have a rumen). After the plant material is consumed, it is mixed with saliva in the rumen and reticulum and separates into solid and liquid material. The solids lump together to form a bolus (or cud), and is regurgitated. When the bolus enters the mouth, the fluid is squeezed out with the tongue and swallowed again. Ingested food passes to the rumen and reticulum where cellulolytic microbes (bacteria, protozoa and fungi) produce cellulase, which is needed to break down the cellulose in plants. Perissodactyls, in contrast to the ruminants, store digested food that has left the stomach in an enlarged cecum, where it is fermented by bacteria. Carnivora have a simple stomach adapted to digest primarily meat, as compared to the elaborate digestive systems of herbivorous animals, which are necessary to break down tough, complex plant fibers. The caecum is either absent or short and simple, and the large intestine is not sacculated or much wider than the small intestine.


title: Mammal

text: The mammalian excretory system involves many components. Like most other land animals, mammals are ureotelic, and convert ammonia into urea, which is done by the liver as part of the urea cycle. Bilirubin, a waste product derived from blood cells, is passed through bile and urine with the help of enzymes excreted by the liver. The passing of bilirubin via bile through the intestinal tract gives mammalian feces a distinctive brown coloration. Distinctive features of the mammalian kidney include the presence of the renal pelvis and renal pyramids, and of a clearly distinguishable cortex and medulla, which is due to the presence of elongated loops of Henle. Only the mammalian kidney has a bean shape, although there are some exceptions, such as the multilobed reniculate kidneys of pinnipeds, cetaceans and bears. Most adult placental mammals have no remaining trace of the cloaca. In the embryo, the embryonic cloaca divides into a posterior region that becomes part of the anus, and an anterior region that has different fates depending on the sex of the individual: in females, it develops into the vestibule that receives the urethra and vagina, while in males it forms the entirety of the penile urethra. However, the tenrecs, golden moles, and some shrews retain a cloaca as adults. In marsupials, the genital tract is separate from the anus, but a trace of the original cloaca does remain externally. Monotremes, which translates from Greek into "single hole", have a true cloaca.


title: Mammal

text: As in all other tetrapods, mammals have a larynx that can quickly open and close to produce sounds, and a supralaryngeal vocal tract which filters this sound. The lungs and surrounding musculature provide the air stream and pressure required to phonate. The larynx controls the pitch and volume of sound, but the strength the lungs exert to exhale also contributes to volume. More primitive mammals, such as the echidna, can only hiss, as sound is achieved solely through exhaling through a partially closed larynx. Other mammals phonate using vocal folds. The movement or tenseness of the vocal folds can result in many sounds such as purring and screaming. Mammals can change the position of the larynx, allowing them to breathe through the nose while swallowing through the mouth, and to form both oral and nasal sounds; nasal sounds, such as a dog whine, are generally soft sounds, and oral sounds, such as a dog bark, are generally loud.


title: Mammal

text: Some mammals have a large larynx and thus a low-pitched voice, namely the hammer-headed bat ("Hypsignathus monstrosus") where the larynx can take up the entirety of the thoracic cavity while pushing the lungs, heart, and trachea into the abdomen. Large vocal pads can also lower the pitch, as in the low-pitched roars of big cats. The production of infrasound is possible in some mammals such as the African elephant ("Loxodonta" spp.) and baleen whales. Small mammals with small larynxes have the ability to produce ultrasound, which can be detected by modifications to the middle ear and cochlea. Ultrasound is inaudible to birds and reptiles, which might have been important during the Mesozoic, when birds and reptiles were the dominant predators. This private channel is used by some rodents in, for example, mother-to-pup communication, and by bats when echolocating. Toothed whales also use echolocation, but, as opposed to the vocal membrane that extends upward from the vocal folds, they have a melon to manipulate sounds. Some mammals, namely the primates, have air sacs attached to the larynx, which may function to lower the resonances or increase the volume of sound.


title: Mammal

text: The vocal production system is controlled by the cranial nerve nuclei in the brain, and supplied by the recurrent laryngeal nerve and the superior laryngeal nerve, branches of the vagus nerve. The vocal tract is supplied by the hypoglossal nerve and facial nerves. Electrical stimulation of the periaqueductal gray (PEG) region of the mammalian midbrain elicit vocalizations. The ability to learn new vocalizations is only exemplified in humans, seals, cetaceans, elephants and possibly bats; in humans, this is the result of a direct connection between the motor cortex, which controls movement, and the motor neurons in the spinal cord.


title: Mammal

text: The primary function of the fur of mammals is thermoregulation. Others include protection, sensory purposes, waterproofing, and camouflage. Different types of fur serve different purposes:


title: Mammal

text: Hair length is not a factor in thermoregulation: for example, some tropical mammals such as sloths have the same length of fur length as some arctic mammals but with less insulation; and, conversely, other tropical mammals with short hair have the same insulating value as arctic mammals. The denseness of fur can increase an animal's insulation value, and arctic mammals especially have dense fur; for example, the musk ox has guard hairs measuring as well as a dense underfur, which forms an airtight coat, allowing them to survive in temperatures of . Some desert mammals, such as camels, use dense fur to prevent solar heat from reaching their skin, allowing the animal to stay cool; a camel's fur may reach in the summer, but the skin stays at . Aquatic mammals, conversely, trap air in their fur to conserve heat by keeping the skin dry.


title: Mammal

text: Mammalian coats are colored for a variety of reasons, the major selective pressures including camouflage, sexual selection, communication, and thermoregulation. Coloration in both the hair and skin of mammals is mainly determined by the type and amount of melanin; eumelanins for brown and black colors and pheomelanin for a range of yellowish to reddish colors, giving mammals an earth tone. Some mammals have more vibrant colors; certain monkeys such mandrills and vervet monkeys, and opossums such as the Mexican mouse opossums and Derby's woolly opossums, have blue skin due to light diffraction in collagen fibers. Many sloths appear green because their fur hosts green algae; this may be a symbiotic relation that affords camouflage to the sloths.


title: Mammal

text: Camouflage is a powerful influence in a large number of mammals, as it helps to conceal individuals from predators or prey. In arctic and subarctic mammals such as the arctic fox ("Alopex lagopus"), collared lemming ("Dicrostonyx groenlandicus"), stoat ("Mustela erminea"), and snowshoe hare ("Lepus americanus"), seasonal color change between brown in summer and white in winter is driven largely by camouflage. Some arboreal mammals, notably primates and marsupials, have shades of violet, green, or blue skin on parts of their bodies, indicating some distinct advantage in their largely arboreal habitat due to convergent evolution.


title: Mammal

text: Aposematism, warning off possible predators, is the most likely explanation of the black-and-white pelage of many mammals which are able to defend themselves, such as in the foul-smelling skunk and the powerful and aggressive honey badger. Coat color is sometimes sexually dimorphic, as in many primate species. Differences in female and male coat color may indicate nutrition and hormone levels, important in mate selection. Coat color may influence the ability to retain heat, depending on how much light is reflected. Mammals with a darker colored coat can absorb more heat from solar radiation, and stay warmer, and some smaller mammals, such as voles, have darker fur in the winter. The white, pigmentless fur of arctic mammals, such as the polar bear, may reflect more solar radiation directly onto the skin. The dazzling black-and-white striping of zebras appear to provide some protection from biting flies.


title: Mammal

text: Mammals are solely gonochoric (an animal is born with either male or female genitalia, as opposed to hermaphrodites where there is no such schism). In male placentals, the penis is used both for urination and copulation. Depending on the species, an erection may be fueled by blood flow into vascular, spongy tissue or by muscular action. A penis may be contained in a prepuce when not erect, and some placentals also have a penis bone (baculum). Marsupials typically have forked penises, while the echidna penis generally has four heads with only two functioning. The testes of most mammals descend into the scrotum which is typically posterior to the penis but is often anterior in marsupials. Female mammals generally have a clitoris, labia majora and labia minora on the outside, while the internal system contains paired oviducts, 1–2 uteri, 1–2 cervices and a vagina. Marsupials have two lateral vaginas and a medial vagina. The "vagina" of monotremes is better understood as a "urogenital sinus". The uterine systems of placental mammals can vary between a duplex, where there are two uteri and cervices which open into the vagina, a bipartite, where two uterine horns have a single cervix that connects to the vagina, a bicornuate, which consists where two uterine horns that are connected distally but separate medially creating a Y-shape, and a simplex, which has a single uterus.


title: Mammal

text: The ancestral condition for mammal reproduction is the birthing of relatively undeveloped, either through direct vivipary or a short period as soft-shelled eggs. This is likely due to the fact that the torso could not expand due to the presence of epipubic bones. The oldest demonstration of this reproductive style is with "Kayentatherium", which produced undeveloped perinates, but at much higher litter sizes than any modern mammal, 38 specimens. Most modern mammals are viviparous, giving birth to live young. However, the five species of monotreme, the platypus and the four species of echidna, lay eggs. The monotremes have a sex determination system different from that of most other mammals. In particular, the sex chromosomes of a platypus are more like those of a chicken than those of a therian mammal.


title: Mammal

text: Viviparous mammals are in the subclass Theria; those living today are in the marsupial and placental infraclasses. Marsupials have a short gestation period, typically shorter than its estrous cycle and generally giving birth to a number of undeveloped newborns that then undergo further development; in many species, this takes place within a pouch-like sac, the marsupium, located in the front of the mother's abdomen. This is the plesiomorphic condition among viviparous mammals; the presence of epipubic bones in all non-placental mammals prevents the expansion of the torso needed for full pregnancy. Even non-placental eutherians probably reproduced this way. The placentals give birth to relatively complete and developed young, usually after long gestation periods. They get their name from the placenta, which connects the developing fetus to the uterine wall to allow nutrient uptake. In placental mammals, the epipubic is either completely lost or converted into the baculum; allowing the torso to be able to expand and thus birth developed offspring.


title: Mammal

text: The mammary glands of mammals are specialized to produce milk, the primary source of nutrition for newborns. The monotremes branched early from other mammals and do not have the nipples seen in most mammals, but they do have mammary glands. The young lick the milk from a mammary patch on the mother's belly. Compared to placental mammals, the milk of marsupials changes greatly in both production rate and in nutrient composition, due to the underdeveloped young. In addition, the mammary glands have more autonomy allowing them to supply separate milks to young at different development stages. Lactose is the main sugar in placental mammal milk while monotreme and marsupial milk is dominated by oligosaccharides. Weaning is the process in which a mammal becomes less dependent on their mother's milk and more on solid food.


title: Mammal

text: Nearly all mammals are endothermic ("warm-blooded"). Most mammals also have hair to help keep them warm. Like birds, mammals can forage or hunt in weather and climates too cold for ectothermic ("cold-blooded") reptiles and insects. Endothermy requires plenty of food energy, so mammals eat more food per unit of body weight than most reptiles. Small insectivorous mammals eat prodigious amounts for their size. A rare exception, the naked mole-rat produces little metabolic heat, so it is considered an operational poikilotherm. Birds are also endothermic, so endothermy is not unique to mammals.


title: Mammal

text: Among mammals, species maximum lifespan varies significantly (for example the shrew has a lifespan of two years, whereas the oldest bowhead whale is recorded to be 211 years). Although the underlying basis for these lifespan differences is still uncertain, numerous studies indicate that the ability to repair DNA damage is an important determinant of mammalian lifespan. In a 1974 study by Hart and Setlow, it was found that DNA excision repair capability increased systematically with species lifespan among seven mammalian species. Species lifespan was observed to be robustly correlated with the capacity to recognize DNA double-strand breaks as well as the level of the DNA repair protein Ku80. In a study of the cells from sixteen mammalian species, genes employed in DNA repair were found to be up-regulated in the longer-lived species. The cellular level of the DNA repair enzyme poly ADP ribose polymerase was found to correlate with species lifespan in a study of 13 mammalian species. Three additional studies of a variety of mammalian species also reported a correlation between species lifespan and DNA repair capability.


title: Mammal

text: Most vertebrates—the amphibians, the reptiles and some mammals such as humans and bears—are plantigrade, walking on the whole of the underside of the foot. Many mammals, such as cats and dogs, are digitigrade, walking on their toes, the greater stride length allowing more speed. Digitigrade mammals are also often adept at quiet movement. Some animals such as horses are unguligrade, walking on the tips of their toes. This even further increases their stride length and thus their speed. A few mammals, namely the great apes, are also known to walk on their knuckles, at least for their front legs. Giant anteaters and platypuses are also knuckle-walkers. Some mammals are bipeds, using only two limbs for locomotion, which can be seen in, for example, humans and the great apes. Bipedal species have a larger field of vision than quadrupeds, conserve more energy and have the ability to manipulate objects with their hands, which aids in foraging. Instead of walking, some bipeds hop, such as kangaroos and kangaroo rats.


title: Mammal

text: Animals will use different gaits for different speeds, terrain and situations. For example, horses show four natural gaits, the slowest horse gait is the walk, then there are three faster gaits which, from slowest to fastest, are the trot, the canter and the gallop. Animals may also have unusual gaits that are used occasionally, such as for moving sideways or backwards. For example, the main human gaits are bipedal walking and running, but they employ many other gaits occasionally, including a four-legged crawl in tight spaces. Mammals show a vast range of gaits, the order that they place and lift their appendages in locomotion. Gaits can be grouped into categories according to their patterns of support sequence. For quadrupeds, there are three main categories: walking gaits, running gaits and leaping gaits. Walking is the most common gait, where some feet are on the ground at any given time, and found in almost all legged animals. Running is considered to occur when at some points in the stride all feet are off the ground in a moment of suspension.


title: Mammal

text: Arboreal animals frequently have elongated limbs that help them cross gaps, reach fruit or other resources, test the firmness of support ahead and, in some cases, to brachiate (swing between trees). Many arboreal species, such as tree porcupines, silky anteaters, spider monkeys, and possums, use prehensile tails to grasp branches. In the spider monkey, the tip of the tail has either a bare patch or adhesive pad, which provides increased friction. Claws can be used to interact with rough substrates and reorient the direction of forces the animal applies. This is what allows squirrels to climb tree trunks that are so large to be essentially flat from the perspective of such a small animal. However, claws can interfere with an animal's ability to grasp very small branches, as they may wrap too far around and prick the animal's own paw. Frictional gripping is used by primates, relying upon hairless fingertips. Squeezing the branch between the fingertips generates frictional force that holds the animal's hand to the branch. However, this type of grip depends upon the angle of the frictional force, thus upon the diameter of the branch, with larger branches resulting in reduced gripping ability. To control descent, especially down large diameter branches, some arboreal animals such as squirrels have evolved highly mobile ankle joints that permit rotating the foot into a 'reversed' posture. This allows the claws to hook into the rough surface of the bark, opposing the force of gravity. Small size provides many advantages to arboreal species: such as increasing the relative size of branches to the animal, lower center of mass, increased stability, lower mass (allowing movement on smaller branches) and the ability to move through more cluttered habitat. Size relating to weight affects gliding animals such as the sugar glider. Some species of primate, bat and all species of sloth achieve passive stability by hanging beneath the branch. Both pitching and tipping become irrelevant, as the only method of failure would be losing their grip.


title: Mammal

text: Bats are the only mammals that can truly fly. They fly through the air at a constant speed by moving their wings up and down (usually with some fore-aft movement as well). Because the animal is in motion, there is some airflow relative to its body which, combined with the velocity of the wings, generates a faster airflow moving over the wing. This generates a lift force vector pointing forwards and upwards, and a drag force vector pointing rearwards and upwards. The upwards components of these counteract gravity, keeping the body in the air, while the forward component provides thrust to counteract both the drag from the wing and from the body as a whole.


title: Mammal

text: The wings of bats are much thinner and consist of more bones than those of birds, allowing bats to maneuver more accurately and fly with more lift and less drag. By folding the wings inwards towards their body on the upstroke, they use 35% less energy during flight than birds. The membranes are delicate, ripping easily; however, the tissue of the bat's membrane is able to regrow, such that small tears can heal quickly. The surface of their wings is equipped with touch-sensitive receptors on small bumps called Merkel cells, also found on human fingertips. These sensitive areas are different in bats, as each bump has a tiny hair in the center, making it even more sensitive and allowing the bat to detect and collect information about the air flowing over its wings, and to fly more efficiently by changing the shape of its wings in response.


title: Mammal

text: A fossorial (from Latin "fossor", meaning "digger") is an animal adapted to digging which lives primarily, but not solely, underground. Some examples are badgers, and naked mole-rats. Many rodent species are also considered fossorial because they live in burrows for most but not all of the day. Species that live exclusively underground are subterranean, and those with limited adaptations to a fossorial lifestyle sub-fossorial. Some organisms are fossorial to aid in temperature regulation while others use the underground habitat for protection from predators or for food storage.


title: Mammal

text: Fossorial mammals have a fusiform body, thickest at the shoulders and tapering off at the tail and nose. Unable to see in the dark burrows, most have degenerated eyes, but degeneration varies between species; pocket gophers, for example, are only semi-fossorial and have very small yet functional eyes, in the fully fossorial marsupial mole the eyes are degenerated and useless, talpa moles have vestigial eyes and the cape golden mole has a layer of skin covering the eyes. External ears flaps are also very small or absent. Truly fossorial mammals have short, stout legs as strength is more important than speed to a burrowing mammal, but semi-fossorial mammals have cursorial legs. The front paws are broad and have strong claws to help in loosening dirt while excavating burrows, and the back paws have webbing, as well as claws, which aids in throwing loosened dirt backwards. Most have large incisors to prevent dirt from flying into their mouth.


title: Mammal

text: Many fossorial mammals such as shrews, hedgehogs, and moles were classified under the now obsolete order Insectivora.


title: Mammal

text: Fully aquatic mammals, the cetaceans and sirenians, have lost their legs and have a tail fin to propel themselves through the water. Flipper movement is continuous. Whales swim by moving their tail fin and lower body up and down, propelling themselves through vertical movement, while their flippers are mainly used for steering. Their skeletal anatomy allows them to be fast swimmers. Most species have a dorsal fin to prevent themselves from turning upside-down in the water. The flukes of sirenians are raised up and down in long strokes to move the animal forward, and can be twisted to turn. The forelimbs are paddle-like flippers which aid in turning and slowing.


title: Mammal

text: Semi-aquatic mammals, like pinnipeds, have two pairs of flippers on the front and back, the fore-flippers and hind-flippers. The elbows and ankles are enclosed within the body. Pinnipeds have several adaptions for reducing drag. In addition to their streamlined bodies, they have smooth networks of muscle bundles in their skin that may increase laminar flow and make it easier for them to slip through water. They also lack arrector pili, so their fur can be streamlined as they swim. They rely on their fore-flippers for locomotion in a wing-like manner similar to penguins and sea turtles. Fore-flipper movement is not continuous, and the animal glides between each stroke. Compared to terrestrial carnivorans, the fore-limbs are reduced in length, which gives the locomotor muscles at the shoulder and elbow joints greater mechanical advantage; the hind-flippers serve as stabilizers. Other semi-aquatic mammals include beavers, hippopotamuses, otters and platypuses. Hippos are very large semi-aquatic mammals, and their barrel-shaped bodies have graviportal skeletal structures, adapted to carrying their enormous weight, and their specific gravity allows them to sink and move along the bottom of a river.


title: Mammal

text: Many mammals communicate by vocalizing. Vocal communication serves many purposes, including in mating rituals, as warning calls, to indicate food sources, and for social purposes. Males often call during mating rituals to ward off other males and to attract females, as in the roaring of lions and red deer. The songs of the humpback whale may be signals to females; they have different dialects in different regions of the ocean. Social vocalizations include the territorial calls of gibbons, and the use of frequency in greater spear-nosed bats to distinguish between groups. The vervet monkey gives a distinct alarm call for each of at least four different predators, and the reactions of other monkeys vary according to the call. For example, if an alarm call signals a python, the monkeys climb into the trees, whereas the eagle alarm causes monkeys to seek a hiding place on the ground. Prairie dogs similarly have complex calls that signal the type, size, and speed of an approaching predator. Elephants communicate socially with a variety of sounds including snorting, screaming, trumpeting, roaring and rumbling. Some of the rumbling calls are infrasonic, below the hearing range of humans, and can be heard by other elephants up to away at still times near sunrise and sunset.


title: Mammal

text: Mammals signal by a variety of means. Many give visual anti-predator signals, as when deer and gazelle stot, honestly indicating their fit condition and their ability to escape, or when white-tailed deer and other prey mammals flag with conspicuous tail markings when alarmed, informing the predator that it has been detected. Many mammals make use of scent-marking, sometimes possibly to help defend territory, but probably with a range of functions both within and between species. Microbats and toothed whales including oceanic dolphins vocalize both socially and in echolocation.


title: Mammal

text: To maintain a high constant body temperature is energy expensive—mammals therefore need a nutritious and plentiful diet. While the earliest mammals were probably predators, different species have since adapted to meet their dietary requirements in a variety of ways. Some eat other animals—this is a carnivorous diet (and includes insectivorous diets). Other mammals, called herbivores, eat plants, which contain complex carbohydrates such as cellulose. An herbivorous diet includes subtypes such as granivory (seed eating), folivory (leaf eating), frugivory (fruit eating), nectarivory (nectar eating), gummivory (gum eating) and mycophagy (fungus eating). The digestive tract of an herbivore is host to bacteria that ferment these complex substances, and make them available for digestion, which are either housed in the multichambered stomach or in a large cecum. Some mammals are coprophagous, consuming feces to absorb the nutrients not digested when the food was first ingested. An omnivore eats both prey and plants. Carnivorous mammals have a simple digestive tract because the proteins, lipids and minerals found in meat require little in the way of specialized digestion. Exceptions to this include baleen whales who also house gut flora in a multi-chambered stomach, like terrestrial herbivores.