title: Murder of Laci Peterson

text: One day later, a passerby found the body of a recently pregnant woman, wearing beige pants and a maternity bra, washed up on the eastern rocky shoreline of the bay, one mile away from where the baby's body was found. The corpse was decomposed to the point of being almost unrecognizable as a human body. The woman had been decapitated and her limbs were missing, including most of her legs. On April 18, 2003, the results of DNA tests verified that they were the bodies of Laci and her unborn son, who was to be named Conner.


title: Murder of Laci Peterson

text: The autopsies on both bodies were performed by forensic pathologist Dr. Brian Peterson (no relation). Conner's skin was not decomposed at all, though the right side of his body was mutilated. An April 24 ABC News report stated his umbilical cord was still attached, and the "San Francisco Chronicle" reported that it appeared torn, rather than cut or clamped, as is the normal practice following birth. However, ABC News later reported on May 30 that according to the autopsy, the placenta and umbilical cord were "not" found with the body.


title: Murder of Laci Peterson

text: The exact date and cause of Laci's death were never determined. Her cervix was intact. She had suffered two cracked ribs, but Dr. Peterson could not determine if this occurred before or after her death. Laci's upper torso had been emptied of internal organs except for the uterus, which protected the fetus, explaining the lower level of decomposition it experienced. Dr. Peterson concluded that the fetus had died in utero, and determined he had been expelled from Laci's decaying body, though when cross-examined in court, he conceded that he could not determine whether he had been born alive when this occurred. Dr. Peterson also found meconium in the fetus's bowels, which is the first stool passed after birth.


title: Murder of Laci Peterson

text: On January 17, 2003, it became known that Peterson had engaged in two other extramarital affairs prior to an affair with a woman named Amber Frey. Frey informed police of their relationship on December 30, 2002, shortly after discovering he was a person of interest in Peterson's disappearance, She told detectives that she met Peterson on November 20, and that he had initially told her he was single. After they had begun dating, however, she came to suspect that he was married, and confronted him on December 9 about this. Frey said to Brocchini, "He said he lost his wife, this would be the first holiday he was without his wife." She informed police that Scott had told her on December 9, two weeks before Peterson's disappearance, he was a widower, and it would be the first Christmas without his wife. Police considered whether this was an indication that Peterson had already decided to kill Laci, which Sharon Rocha agreed was a possibility.


title: Murder of Laci Peterson

text: Scott was arrested on April 18, 2003, near a La Jolla golf course. He claimed to be meeting his father and brother for a game of golf. His naturally dark brown hair had been dyed blond, and his Mercedes was "overstuffed" with miscellaneous items, including nearly $15,000 in cash, 12 Viagra tablets, survival gear, camping equipment, several changes of clothes, four cell phones, and two driver's licenses, his and his brother's. Scott's father, Lee Peterson, explained that Scott had used his brother's license the day before to get a San Diego resident discount at the golf course, and that Scott had been living out of his car because of the media attention. Police and prosecutors, however, saw these items as an indication that Peterson had planned to flee to Mexico.


title: Murder of Laci Peterson

text: On April 21, 2003, Scott was arraigned in Stanislaus County Superior Court before Judge Nancy Ashley. He was charged with two felony counts of murder with premeditation and special circumstances. He pleaded not guilty. Judge Al Girolami of Stanislaus County Superior Court moved his trial to San Mateo County because so many people in Stanislaus had made up their minds about Peterson's guilt. His trial began on June 1, 2004. On November 12, 2004, Scott Peterson was convicted of first degree murder for his wife's death and second degree murder for Conner's death. Judge Alfred A. Delucchi sentenced Scott to death, calling the murder of Laci "cruel, uncaring, heartless, and callous".


title: Murder of Laci Peterson

text: In March 2019, California Governor Gavin Newsom issued a moratorium for all 737 prisoners on death row in California, including Peterson. The order postponed all executions for the duration of Newsom's tenure as governor. California had not executed a prisoner since 2006 due to legal challenges to the state's execution protocol. Newsom's order spared the approximately 25 prisoners on death row who had exhausted their legal appeals and could have had their executions move forward once the legal challenge was resolved. Peterson's sister-in-law Janey Peterson welcomed Newsom's decision but noted that his case was likely to be unaffected by it, and did not believe Peterson would exhaust all of his legal challenges by January 2027, when Newsom would be leaving office, assuming his re-election in 2022.


title: Murder of Laci Peterson

text: Laci and Conner were buried at Burwood Cemetery on August 30, 2003. The death of Laci and Conner Peterson led to the passage of the Unborn Victims of Violence Act, which is also known as Laci and Conner's Law. On April 1, 2004, Sharon Rocha and her husband Ron Grantski were in attendance at the White House when President George W. Bush signed the bill into law. The Act provides that, under federal law, any person who causes death or injury to an unborn child while in the commission of a crime upon a pregnant woman will be charged with a separate offense.


title: Murder of Laci Peterson

text: On October 21, 2005, Stanislaus County, California, Superior Court Judge Roger Beauchesne ruled that Scott was not entitled to collect on Laci's $250,000 life insurance policy, having been convicted of her murder. Under California state law, criminals may not profit from insurance policies. On December 19, 2005, the money was given to her mother, Sharon Rocha, as the executor of her estate. The California Fifth District Court of Appeals in Fresno later affirmed the trial court's decision on October 31, 2007.


title: Murder of Laci Peterson

text: In 2006, Sharon wrote "For Laci: A Mother's Story of Love, Loss, and Justice", a biography and memoir about Laci's life and death. All proceeds are used to fund the Laci and Conner Search and Rescue Fund, which she had founded. On January 29, 2006, it was listed at No. 1 on "The New York Times" Non-Fiction Best Seller list.


title: Murder of Laci Peterson

text: Laci's stepfather, Ron Grantski, died in his sleep at his Modesto home on April 8, 2018, at age 71, after a lengthy period of failing health. He was buried next to Laci and Conner. Laci's father, Dennis Rocha, died December 9, 2018, at the age of 72.


title: Murder of Laci Peterson

text: On August 24, 2020, in a 7-0 decision, the Supreme Court of California upheld Peterson's conviction, but overturned his death sentence, because Peterson's trial judge, Alfred Delucchi, who had died on February 26, 2008, had dismissed jurors who opposed capital punishment without asking them whether they could put their views aside. Justice Leondra Kruger explained that per U.S. Supreme Court rulings since 1968, "Jurors may not be excused merely for opposition to the death penalty, but only for views rendering them unable to fairly consider imposing that penalty in accordance with their oath. This is the meaning of the guarantee of an impartial jury." Prosecutors initially stated that they would retry the penalty phase, but reversed that decision in June 2021.


title: Murder of Laci Peterson

text: On September 22, 2021, California Superior Court Judge Anne-Christine Massullo scheduled Peterson to be re-sentenced that November to life in prison without the possibility of parole. On December 8, Massullo re-sentenced Peterson to life in prison without the possibility of parole for the first-degree murder of Laci, and a concurrent sentence of 15 years to life for the second-degree murder of Conner.


title: Bodies Bodies Bodies

text: Bodies Bodies Bodies is a 2022 American black comedy slasher film directed by Halina Reijn (in her English-language debut) and written by Sarah DeLappe from a story by Kristen Roupenian. It stars Amandla Stenberg, Maria Bakalova, Myha'la Herrold, Chase Sui Wonders, Rachel Sennott, Lee Pace, and Pete Davidson.


title: Bodies Bodies Bodies

text: "Bodies Bodies Bodies" premiered at South by Southwest on March 14, 2022, and was theatrically released in the United States on August 5, 2022, by A24. The film received generally positive reviews from critics, who praised the humor and the cast's performances—particularly Sennott's.


title: Bodies Bodies Bodies

text: Bee, a working-class young woman from Eastern Europe, travels with her wealthy girlfriend Sophie to a "hurricane party" at a mansion owned by the family of David, Sophie's friend. Other guests include David's actress girlfriend Emma, podcaster Alice, her much-older new boyfriend Greg, and enigmatic Jordan. Max, another guest, left after a fight with David, the night before Sophie and Bee arrived.


title: Bodies Bodies Bodies

text: After drinking, using drugs, and dancing, the group decides to play "Bodies Bodies Bodies", a murder in the dark-style game. Greg goes to bed early due to multiple altercations throughout the game with David, who also leaves soon after another fight with Emma. As the storm worsens, the power goes out and the girls scramble to find a power source. Minutes later, Bee finds David outside with his throat slashed, a blood-stained kukri nearby. Panicked and without reception, the group try to go for help in Sophie's car, but find its battery dead.


title: Bodies Bodies Bodies

text: The group discovers Greg has a go bag with a knife and a map of the area and become suspicious of him. They confront Greg, who returns their hostility. After a struggle, Bee bludgeons him to death with a kettle bell out of self defense.


title: Bodies Bodies Bodies

text: The group doubt that Greg was the killer and Emma theorizes that Max, who had confessed feelings for her the night before, returned to kill David. Sophie, a sober addict, relapses. Emma kisses her, to Sophie's confusion, before accepting drugs. Alice later finds Emma dead from a head wound at the bottom of the stairs, and believes the group is being killed one by one. Jordan and Alice cast suspicion on Bee, revealing that no one with her name is on record as having graduated from her college; they cast Bee out into the hurricane.


title: Bodies Bodies Bodies

text: Returning to Sophie's car, Bee finds underwear that matches Jordan's bra in the backseat. She sees Jordan holding David's father's gun through a window, then crawls back into the mansion through a pet door. Bee confronts the group, revealing that she dropped out of college to take care of her mother, who has borderline personality disorder. A vicious verbal fight ensues between the group. Jordan, revealed to have been the "killer" in the Bodies Bodies Bodies game, expresses resentment for Sophie due to her drug addiction and using David to regain access to her trust fund, and claims Sophie cheated on Bee with Jordan. Sophie expresses why she would not date Jordan, that she avoids her friends because their behavior challenges her sobriety, and reveals that Jordan only "hate-listens" to Alice's podcast. After Alice responds by insulting Jordan's insecurities, Jordan shoots Alice in the leg. A struggle for the gun follows; Alice is fatally shot in the throat. As Sophie and Jordan fight, Bee pushes Jordan over the staircase bannister. With her dying breath, Jordan tells Bee to check Sophie's text messages. Bee hides from Sophie out of distrust.


title: Bodies Bodies Bodies

text: When morning comes and the storm has blown over, Sophie tearfully confesses to Bee that she relapsed and witnessed Emma tripping and falling down the stairs to her death. However, Bee holds her at gunpoint, demanding to see her texts. Sophie tosses her phone away and they struggle, inadvertently picking up David's phone in the process, which shows that David accidentally slashed his own throat trying to use the kukri to open a wine bottle for a TikTok video—revealing there was no real murderer after all. As Bee and Sophie realize the night's bloodshed was all for nothing, a confused Max returns to the mansion, and the power comes back on.


title: Bodies Bodies Bodies

text: In March 2018, A24 acquired "Bodies, Bodies, Bodies", a spec script written by Kristen Roupenian. In September 2019, it was announced Chloe Okuno would re-write the script and direct the film. In April 2021, it was reported that Amandla Stenberg and Maria Bakalova were set to star in the film, while Pete Davidson and Myha'la Herrold were in talks to join the cast, with Halina Reijn now set to direct. Bakalova said she was scared to be in a horror film, having been frightened watching them, but thought that A24 films were deeper; she said that the film was "more like an R-rated comedy." In May 2021, actors Lee Pace, Rachel Sennott, Chase Sui Wonders, and Conner O'Malley joined the film, with Davidson and Herrold's casting also being confirmed.


title: Bodies Bodies Bodies

text: Principal photography began in May 2021, with filming taking place at a Georgian stone manor house in Chappaqua, New York.


title: Bodies Bodies Bodies

text: Ultimately, Roupenian was given a "Story by" credit for her work on the film's screenplay, while "The Wolves" playwright Sarah DeLappe received sole, final "Screenplay by" credit.


title: Bodies Bodies Bodies

text: The film's music score was composed by Disasterpeace in March 2022. Charli XCX performed the song "Hot Girl" for the film, which was released as a single on July 26, 2022. The 9-music scores album was released on August 10, 2022, by A24 Music. Meghan Currier was credited as the music supervisor for the film, and contains 15 credited songs from a wide variety of artists including Shygirl, Kilo Kish, Princess Nokia, Azealia Banks and Tommy Genesis. The music selection features a heavy prominence of female rappers and singer-songwriters.


title: Bodies Bodies Bodies

text: "Bodies Bodies Bodies" has been described as a "satire on class and privilege, all mediated by new technology, the language of progressive politics and youth culture, and Gen Z identity itself". In a piece for "The New York Times", Kalia Richardson writes that the film satirizes Gen-Z’s symbiotic relationship with their cellphones and the internet, using dark humor to illustrate what happens when those two things became inaccessible: "when the Wi-Fi goes out, it’s like they lose oxygen", remarks director Halina Reijn . Richardson notes that despite "the physical danger each character faces, their virtual realities remain central to the plot", recalling the characters' inability to relate to each other in person without the use of the "trauma-centered" jargon of social media such as "gaslight", "trigger", and "toxic".


title: Bodies Bodies Bodies

text: Several critics noted the influence of Agatha Christie or specifically her 1939 mystery novel "And Then There Were None" on the film. In an interview with "Vice", director Halina Reijn cited the many films that influenced "Bodies Bodies Bodies", such as "Heathers" (1988), "Don's Plum" (2001), "Who's Afraid of Virginia Woolf?" (1966), "The Piano Teacher" (2001), "Cries and Whispers" (1972), and the filmography of John Cassavetes.


title: Bodies Bodies Bodies

text: "Bodies Bodies Bodies" premiered at South by Southwest on March 14, 2022. It was theatrically released on August 5, 2022, in select cities, before a nationwide expansion on August 12. Sony Pictures Releasing will distribute the film internationally via the Stage 6 Films banner.


title: Bodies Bodies Bodies

text: The film was released on VOD on September 27, 2022, followed by release on Blu-ray and DVD on October 18, 2022.


title: Bodies Bodies Bodies

text: In its opening weekend, "Bodies Bodies Bodies" made $226,653 from six theaters in Los Angeles and New York City. The $37,775 per-venue average was the second best of 2022 for a limited release, behind "Everything Everywhere All at Once" ($50,130 in March). The film expanded to 1,283 theaters in its second weekend, and was projected to gross $2–3 million. It made $3.1 million, finishing eighth at the box office. Expanding to 2,541 theaters in its third weekend, the film made $2.6 million, finishing tenth. It made $1.1 million the next weekend, finishing fourteenth.


title: Bodies Bodies Bodies

text: On the review aggregator website Rotten Tomatoes, 86% of 217 reviews are positive, with an average rating of 7.1/10. The website's critical consensus reads, "Impeccably cast and smartly written, "Bodies Bodies Bodies" is an uncommonly well-done whodunnit." Metacritic, which uses a weighted average, assigned a score of 69 out of 100 based on 43 critics, indicating "generally favorable reviews." Audiences polled by PostTrak gave the film an average 3 out of 5 stars, with 63% saying they would definitely recommend it.


title: Bodies Bodies Bodies

text: Abby Olcese for "RogerEbert.com" praised the use of music and cinematography to enhance the single-location setting. Bloody Disgusting found the social satire of the movie, and its use of setting to highlight this, to be strong. Lovia Gyarkye for "The Hollywood Reporter" found the film to be a psychological study of the friendship archetypes and the digital age, while also showing an understanding of the anxieties of twenty-somethings, praising the story. IndieWire's Robert Daniels wrote that Reijn's direction was the strongest part of the film, while also praising the script for its social interrogation. Erin Brady of "Little White Lies" instead thought that the film fell apart towards the end because it is "a movie that claims to understand how Gen-Z treats societal topics ... [while] portraying some of those topics so stereotypically." However, she said that the film was well-paced and it was hard to resist the fun of it. "IGN"s Rafael Motamayor wrote that "it does falter somewhat when it comes to Gen Z talk ... like someone had a bunch of placeholders they swapped in with whatever term a teenager told them kids use these days," though also felt it was good overall.


title: Bodies Bodies Bodies

text: Valerie Complex at "Deadline Hollywood" praised the cast, saying "each actor [has] their own style that brings a varied flavor to the film, which makes the cast ... a joy to watch, even if their characters are insufferable," and Owen Glieberman for "Variety" praised the directing for giving the characters and actors room to explore. Complex and Daniels said that the characters as written are weak, but the performances all elevate them. Sennott was consistently named the standout performance of the film, while Brady said this was Herrold. Gyarkye wrote that nobody could deny the acting talent, noting Herrold as well as Stenberg. Daniels highlighted Sennott and Davidson, while Marya E. Gates of "The Playlist" commended the ensemble while noting Davidson and Bakalova. "Paste" Aurora Amidon felt that the cast were all successful, but that Bakalova's comedic talents were wasted by playing a serious character.


title: Bodies Bodies Bodies

text: Glieberman described the film as ""And Then There Were None" staged by John Cassavetes for the age of Instagram." Gates felt that some scenes ran too long, but said that the film is "destined to [take] its place on the mantle with seminal horror-comedy faves like "Jennifer's Body" and "Scream";" Gyarkye instead said that the film may not appeal to slasher genre fans. Eileen Jones of "Jacobin" gave a negative review of the film, summarizing: "Like so many horror films attempting to be subversive, "Bodies Bodies Bodies" tries to satirize the upper class. But all it delivers are tired, lazy tropes about Gen Z."


title: Burnt (film)

text: Burnt is a 2015 American comedy-drama film directed by John Wells and written by Steven Knight, from a story by Michael Kalesniko. The film stars an ensemble cast including Bradley Cooper, Sienna Miller, Omar Sy, Daniel Brühl, Matthew Rhys, Riccardo Scamarcio, Alicia Vikander, Uma Thurman and Emma Thompson. The film was released on October 30, 2015, by The Weinstein Company. The film was not well-received by critics and grossed $36.6 million.


title: Burnt (film)

text: Adam Jones was the chef at a high-class Parisian restaurant owned by his mentor Jean-Luc, until his drug use and temperamental behavior destroyed his career and the restaurant. In the aftermath, Adam went into self-imposed exile in New Orleans by shucking a million oysters to sober up, planning to head to London to restart his career and attempt to earn a third Michelin star.


title: Burnt (film)

text: In London, Adam searches for old colleagues, beginning with his mentor's former maître d'hôtel, Tony Balerdi, now a hotel manager of The Langham Hotel in London, under the ownership of the Balerdi family. Adam checks into one of The Langham's rooms then visits an old friend, Conti, and notes the talent of his sous-chef Helene, but she dislikes his arrogance and dismisses him immediately. A Paris colleague, Michel, whose restaurant Adam had sabotaged out of jealousy, tracks him down. After a brief fistfight, they talk and Michel forgives Adam then asks to work for him. Adam also visits a cutting-edge eatery run by Reece, with whom he has a long-standing rivalry, and the visit ends poorly. Adam's former drug dealer realizes he has returned to Europe and attempts to collect Adam's outstanding debt.


title: Burnt (film)

text: Adam convinces famed restaurant critic Simone to dine at Tony's hotel. Tony realizes that Adam set this up and is reluctant to let him cook, but his kitchen is in such poor condition it would result in Simone shutting his restaurant down. Seeing no other way, he allows Adam to cook. Simone's favorable review convinces Tony to renovate the hotel's kitchen and hire Adam as head chef permanently. He stipulates that Adam must submit to weekly drug tests with Tony's psychiatrist Dr. Rosshilde. Adam agrees to the tests, although he is uninterested in therapy and throws himself into preparations for the grand opening. Another old friend, Max, joins Adam's team after being released from prison. Helene rebuffs further job offers until Conti fires her and sends her to Adam's kitchen. Helene is irate about being fired, but Adam convinces her to work for him by tripling her salary.


title: Burnt (film)

text: Opening night is a disaster, and Adam furiously closes early, blaming Helene. He publicly humiliates her, escalating from verbal to physical aggression, and she quits. Adam goes on a talk show that he previously turned down to drum up publicity for the restaurant. At his second opening, a restaurant critic gives a positive review, enraging Reece. Tony convinces Helene to return with a doubled salary and some insight about Adam's behavior. Adam improves his attitude, but refuses her request for time off for her daughter Lily's birthday. Later, he notices his kitchen acting in a strange manner. Helene reveals that her daughter is at the restaurant under Tony's supervision, since she did not want to spend her birthday at home. Adam is upset, but relents and bakes Lily a birthday cake, which impresses Helene.


title: Burnt (film)

text: With the restaurant's reputation established, Adam sets his sights on three Michelin stars, still avoiding his drug dealer, even after Tony offers to pay off his debt. Adam takes Helene to the reopening of Reece's restaurant. Adam and Reece are civil, but the night derails when Adam spots his ex-girlfriend Anne Marie, the daughter of Jean-Luc. Adam finds Anne Marie surprisingly forgiving after he abandoned her in Paris and missed her father's funeral. The encounter leaves Adam shaken and introspective about his failure in Paris. Early the next morning, Helene finds him at the fish market where they kiss in the alley behind The Langham on the way back to the restaurant. They are interrupted by the drug dealer's thugs, who take Adam away. He returns that night during dinner service beaten and bruised.


title: Burnt (film)

text: Kaitlin, the front of house host, advises Tony that two Michelin reviewers have arrived, and he cooks for them rather than going to the hospital. They send their meals back as it's too spicy, and Michel reveals he sabotaged the sauce with cayenne pepper as revenge for Adam's past cruelty before walking out. On the verge of a breakdown, Adam leaves the restaurant.


title: Burnt (film)

text: He wanders the city, eventually arriving at Reece's restaurant drunk. Once inside, he begins to break down emotionally. Reece soothes him, and they part on better terms the following morning. Adam attends a group therapy session, then returns to the hotel, where he learns that Anne Marie has paid off his debt. She gives him her father's knives and tells him that she approves of Helene. Tony and Helene find Adam and tell him that the two men they thought were Michelin reviewers were actually just businessmen on a trip. Adam rejoices at the opportunity of a second chance, and he and Helene kiss.


title: Burnt (film)

text: Altered by his experiences, Adam changes the way he runs the kitchen. As a result of his improved attitude and teamwork, the restaurant receives its third Michelin star. At the end, he sits down to eat the family meal with the kitchen crew, who are his new family.


title: Burnt (film)

text: In 2013, John Wells was set to direct a cooking comedy film, then titled "Chef", with Bradley Cooper signed to star as a former Paris chef, Adam Jones. Sienna Miller signed as lead actress.


title: Burnt (film)

text: Omar Sy, Jamie Dornan, Emma Thompson, Daniel Brühl, Alicia Vikander and Lily James were also set to star in the film. Dornan's appearance was later removed due to cuts and adjustments in the storyline and Lily James's role revealed to be a cameo. Dornan's scenes were added to the home release.


title: Burnt (film)

text: In July 2014, it was reported that the film's title had been changed from "Chef" to "Adam Jones", to avoid confusion with Jon Favreau's film "Chef". Uma Thurman joined the cast around this time. According to "Deadline Hollywood", as of July 28, 2014, Weinstein was calling the film "Untitled John Wells project", until they could decide on a better title. On August 7, 2014, Matthew Rhys was added to the cast, playing chef Jones' rival, Reece. In July 2015, it was announced that the film had been retitled "Burnt".


title: Burnt (film)

text: Principal photography on the film began July 23, 2014, in New Orleans, Louisiana, filming for two days. Production then moved to London and West London Film Studios.


title: Burnt (film)

text: On October 2, 2014, Nick Moore was hired for the film editing job. During editing of the film, Jamie Dornan's scenes were cut from the finished version.


title: Burnt (film)

text: The first poster, with the new title "Burnt", was released on August 7, 2015. Cooper introduced a sneak peek of the film on the "Today" show on August 10, 2015. The Weinstein Company released the teaser trailer on August 14, 2015. On September 21, 2015, the first international trailer was released. On September 28, 2015, producers released the first full-length trailer for the film and on October 29, 2015, released a clip featuring Vikander and Cooper online.


title: Burnt (film)

text: The film was scheduled to be released on October 2, 2015, but in July 2015, The Weinstein Company moved the release date to October 23, 2015. The plan then was to give the film a limited release on October 23, 2015, before a wide release on October 30, 2015. However, they cancelled the limited release plan and immediately released the film nationwide, on October 30, 2015.


title: Burnt (film)

text: "Burnt" grossed $13.7 million in North America and $23.0 million in other territories, for a worldwide total of $36.6 million, against a budget of $20 million.


title: Burnt (film)

text: The film opened on October 30, 2015, alongside "Our Brand Is Crisis" and "Scouts Guide to the Zombie Apocalypse". In its opening weekend, the film was projected to gross $7–9 million from 3,003 theaters. However, it only ended up grossing $5 million, finishing sixth at the box office, and marking the second straight underperforming opener for Cooper, following "Aloha" ($9.7 million opening against its $37 million budget).


title: Burnt (film)

text: "Burnt" received negative reviews from critics, who praised Cooper's performance but derided the script and storytelling. On Rotten Tomatoes, the film holds a rating of 28%, based on 159 reviews, with an average rating of 4.90/10. The site's critical consensus reads, ""Burnt" offers a few spoonfuls of compelling culinary drama, but they're lost in a watery goulash dominated by an unsavory main character and overdone clichés." On Metacritic, the film has a score of 42 out of 100, based on 28 critics, indicating "mixed or average reviews". Audiences polled by CinemaScore gave the film an average grade of "B−" on an A+ to F scale.


title: Burnt (film)

text: Justin Chang of "Variety" praised Cooper's performance but was critical of the script: "Steven Knight’s script pours on the acid but holds the depth, forcing its fine actors (including Sienna Miller and Daniel Bruhl) to function less as an ensemble than as a motley sort of intervention group."


title: Autumn

text: Autumn, also known as fall in American English and Canadian English, is one of the four temperate seasons on Earth. Outside the tropics, autumn marks the transition from summer to winter, in September (Northern Hemisphere) or March (Southern Hemisphere). Autumn is the season when the duration of daylight becomes noticeably shorter and the temperature cools considerably. Day length decreases and night length increases as the season progresses until the Winter Solstice in December (Northern Hemisphere) and June (Southern Hemisphere). One of its main features in temperate climates is the striking change in colour for the leaves of deciduous trees as they prepare to shed.


title: Autumn

text: Some cultures regard the autumnal equinox as "mid-autumn", while others with a longer temperature lag treat the equinox as the start of autumn. In the English-speaking world of high latitude countries, autumn traditionally began with Lammas Day and ended around Hallowe'en, the approximate mid-points between midsummer, the autumnal equinox, and midwinter. Meteorologists (and Australia and most of the temperate countries in the southern hemisphere) use a definition based on Gregorian calendar months, with autumn being September, October, and November in the northern hemisphere, and March, April, and May in the southern hemisphere.


title: Autumn

text: In the higher latitude countries in the Northern Hemisphere, autumn traditionally starts with the September equinox (21 to 24 September) and ends with the winter solstice (21 or 22 December). Popular culture in the United States associates Labor Day, the first Monday in September, as the end of summer and the start of autumn; certain summer traditions, such as wearing white, are discouraged after that date. As daytime and nighttime temperatures decrease, trees change colour and then shed their leaves.


title: Autumn

text: Under the traditional East Asian solar term system, autumn starts on or around 8 August and ends on or about 7 November. In Ireland, the autumn months according to the national meteorological service, Met Éireann, are September, October, and November. However, according to the Irish Calendar, which is based on ancient Gaelic traditions, autumn lasts throughout the months of August, September, and October, or possibly a few days later, depending on tradition. In the Irish language, September is known as ("middle of autumn") and October as ("end of autumn"). Persians celebrate the beginning of the autumn as Mehregan to honor Mithra (Mehr).


title: Autumn

text: The word "autumn" () is derived from Latin "autumnus", archaic "auctumnus", possibly from the ancient Etruscan root "autu-" and has within it connotations of the passing of the year. Alternative etymologies include Proto-Indo-European ("cold") or ("dry").


title: Autumn

text: After the Greek era, the word continued to be used as the Old French word ' (' in modern French) or "" in Middle English, and was later normalised to the original Latin. In the Medieval period, there are rare examples of its use as early as the 12th century, but by the 16th century, it was in common use.


title: Autumn

text: Before the 16th century, "harvest" was the term usually used to refer to the season, as it is common in other West Germanic languages to this day (cf. Dutch ', German ', and Scots ""). However, as more people gradually moved from working the land to living in towns, the word "harvest" lost its reference to the time of year and came to refer only to the actual activity of reaping, and "autumn", as well as "fall", began to replace it as a reference to the season.


title: Autumn

text: The alternative word "fall" for the season traces its origins to old Germanic languages. The exact derivation is unclear, with the Old English ' or ' and the Old Norse "" all being possible candidates. However, these words all have the meaning "to fall from a height" and are clearly derived either from a common root or from each other. The term came to denote the season in 16th-century England, a contraction of Middle English expressions like "fall of the leaf" and "fall of the year". Compare the origin of "spring" from "spring of the leaf" and "spring of the year".


title: Autumn

text: During the 17th century, Englishmen began emigrating to the new North American colonies, and the settlers took the English language with them. While the term "fall" gradually became nearly obsolete in Britain, it became the more common term in North America.


title: Autumn

text: The name "backend", a once common name for the season in Northern England, has today been largely replaced by the name "autumn".


title: Autumn

text: Association with the transition from warm to cold weather, and its related status as the season of the primary harvest, has dominated its themes and popular images. In Western cultures, personifications of autumn are usually pretty, well-fed females adorned with fruits, vegetables and grains that ripen at this time. Many cultures feature autumnal harvest festivals, often the most important on their calendars.


title: Autumn

text: Still-extant echoes of these celebrations are found in the autumn Thanksgiving holiday of the United States and Canada, and the Jewish Sukkot holiday with its roots as a full-moon harvest festival of "tabernacles" (living in outdoor huts around the time of harvest). There are also the many festivals celebrated by indigenous peoples of the Americas tied to the harvest of ripe foods gathered in the wild, the Chinese Mid-Autumn or Moon festival, and many others. The predominant mood of these autumnal celebrations is a gladness for the fruits of the earth mixed with a certain melancholy linked to the imminent arrival of harsh weather.


title: Autumn

text: This view is presented in English poet John Keats' poem "To Autumn", where he describes the season as a time of bounteous fecundity, a time of 'mellow fruitfulness'.


title: Autumn

text: In North America, while most foods are harvested during the autumn, foods usually associated with the season include pumpkins (which are integral parts of both Thanksgiving and Halloween) and apples, which are used to make the seasonal beverage apple cider.


title: Autumn

text: Autumn, especially in poetry, has often been associated with melancholia. The possibilities and opportunities of summer are gone, and the chill of winter is on the horizon. Skies turn grey, the amount of usable daylight drops rapidly, and many people turn inward, both physically and mentally. It has been referred to as an unhealthy season.


title: Autumn

text: Similar examples may be found in Irish poet W.B. Yeats' poem "The Wild Swans at Coole" where the maturing season that the poet observes symbolically represents his own ageing self. Like the natural world that he observes, he too has reached his prime and now must look forward to the inevitability of old age and death. French poet Paul Verlaine's ""Chanson d'automne"" ("Autumn Song") is likewise characterised by strong, painful feelings of sorrow. Keats' "To Autumn", written in September 1819, echoes this sense of melancholic reflection but also emphasises the lush abundance of the season. The song "Autumn Leaves", based on the French song "Les Feuilles mortes", uses the melancholic atmosphere of the season and the end of summer as a metaphor for the mood of being separated from a loved one.


title: Autumn

text: Autumn is associated with Halloween (influenced by Samhain, a Celtic autumn festival), and with it a widespread marketing campaign that promotes it. The Celtic people also used this time to celebrate the harvest with a time of feasting. At the same time though, it was a celebration of death as well. Crops were harvested, livestock were butchered, and Winter was coming.


title: Autumn

text: Halloween, 31 October, is in autumn in the northern hemisphere. Television, film, book, costume, home decoration, and confectionery businesses use this time of year to promote products closely associated with such a holiday, with promotions going from late August or early September to 31 October, since their themes rapidly lose strength once the holiday ends, and advertising starts concentrating on Christmas.


title: Autumn

text: In some parts of the northern hemisphere, autumn has a strong association with the end of summer holiday and the start of a new school year, particularly for children in primary and secondary education. "Back to School" advertising and preparations usually occurs in the weeks leading to the beginning of autumn.


title: Autumn

text: Thanksgiving Day is a national holiday celebrated in Canada, in the United States, in some of the Caribbean islands and in Liberia. Thanksgiving is celebrated on the second Monday of October in Canada, on the fourth Thursday of November in the United States (where it is commonly regarded as the start of the Christmas and holiday season), and around the same part of the year in other places. Similarly named festival holidays occur in Germany and Japan.


title: Autumn

text: Television stations and networks, particularly in North America, traditionally begin their regular seasons in their autumn, with new series and new episodes of existing series debuting mostly during late September or early October (series that debut outside the autumn season are usually known as mid-season replacements). A sweeps period takes place in November to measure Nielsen Ratings.


title: Autumn

text: American football is played almost exclusively in the autumn months; at the high school level, seasons run from late August through early November, with some playoff games and holiday rivalry contests being played as late as Thanksgiving. In many American states, the championship games take place in early December. College football's regular season runs from September through November, while the main professional circuit, the National Football League, plays from September through to early January.


title: Autumn

text: Summer sports, such as association football (in Northern America, East Asia, Argentina, and South Africa), Canadian football, stock car racing, tennis, golf, cricket, and professional baseball, wrap up their seasons in early to late autumn; Major League Baseball's championship World Series is popularly known as the "Fall Classic". (Amateur baseball is usually finished by August.) Likewise, professional winter sports, such as ice hockey and basketball, and most leagues of association football in Europe, are in the early stages of their seasons during autumn; American college basketball and college ice hockey play teams outside their athletic conferences during the late autumn before their in-conference schedules begin in winter.


title: Autumn

text: The Christian religious holidays of All Saints' Day and All Souls' Day are observed in autumn in the Northern hemisphere. Easter falls in autumn in the southern hemisphere.


title: Autumn

text: The secular celebration of International Workers' Day also falls in autumn in the southern hemisphere.


title: Autumn

text: In Indian mythology, autumn is considered to be the preferred season for the goddess of learning Saraswati, who is also known by the name of "goddess of autumn" (Sharada).


title: Autumn

text: In Asian mysticism, Autumn is associated with the element of metal, and subsequently with the colour white, the White Tiger of the West, and death and mourning.


title: Autumn

text: Although colour change in leaves occurs wherever deciduous trees are found, coloured autumn foliage is noted in various regions of the world: most of North America, Eastern Asia (including China, Korea, and Japan), Europe, southeast, south, and part of the midwest of Brazil, the forest of Patagonia, eastern Australia and New Zealand's South Island.


title: Autumn

text: Eastern Canada and New England are famous for their autumnal foliage, and this attracts major tourism (worth billions of US dollars) for the regions.


title: Superpower

text: A superpower is a state with a dominant position characterized by its extensive ability to exert influence or project power on a global scale. This is done through the combined means of economic, military, technological, political and cultural strength as well as diplomatic and soft power influence. Traditionally, superpowers are preeminent among the great powers. While a great power state is capable of exerting its influence globally, superpowers are states so influential that no significant action can be taken by the global community without first considering the positions of the superpowers on the issue.


title: Superpower

text: The term was first applied in 1944 during World War II to the United States, the United Kingdom, and the Soviet Union. During the Cold War, the British Empire dissolved, leaving the United States and the Soviet Union to dominate world affairs. At the end of the Cold War and the dissolution of the Soviet Union in 1991, the United States became the world's sole superpower.


title: Superpower

text: No agreed definition of what is a superpower exists and may differ between sources. However, a fundamental characteristic that is consistent with all definitions of a superpower is a nation or state that has mastered the seven dimensions of state power, namely geography, population, economy, resources, military, diplomacy and national identity.


title: Superpower

text: The term was first used to describe nations with greater than great power status as early as 1944, but only gained its specific meaning with regard to the United States and the Soviet Union after World War II. This was because the United States and the Soviet Union had proved themselves to be capable of casting great influence in global politics and military dominance. The term in its current political meaning was coined by Dutch-American geostrategist Nicholas Spykman in a series of lectures in 1943 about the potential shape of a new post-war world order. This formed the foundation for the book "The Geography of the Peace", which referred primarily to the unmatched maritime global supremacy of the British Empire and the United States as essential for peace and prosperity in the world.


title: Superpower

text: A year later in 1944, William T. R. Fox, an American foreign policy professor, elaborated on the concept in the book "The Superpowers: The United States, Britain and the Soviet Union — Their Responsibility for Peace" which spoke of the global reach of a super-empowered nation. Fox used the word superpower to identify a new category of power able to occupy the highest status in a world in which—as the war then raging demonstrated—states could challenge and fight each other on a global scale. According to him, at that moment there were three states that were superpowers, namely the United States, the Soviet Union and the United Kingdom. The British Empire was the most extensive empire in world history and considered the foremost great power, holding sway over 25% of the world's population and controlling about 25% of the Earth's total land area, while the United States and the Soviet Union grew in power before and during World War II. The UK would face serious political, financial and colonial issues after World War II that left it unable to match Soviet or American power. Ultimately, Britain's empire would gradually dissolve over the course of the 20th century, sharply reducing its global power projection.


title: Superpower

text: According to Lyman Miller, "[t]he basic components of superpower stature may be measured along four axes of power: military, economic, political, and cultural (or what political scientist Joseph Nye has termed "soft power")".


title: Superpower

text: In the opinion of Kim Richard Nossal of Queen's University in Canada, "generally this term was used to signify a political community that occupied a continental-sized landmass, had a sizable population (relative at least to other major powers); a superordinate economic capacity, including ample indigenous supplies of food and natural resources; enjoyed a high degree of non-dependence on international intercourse; and, most importantly, had a well-developed nuclear capacity (eventually normally defined as second strike capability)".


title: Superpower

text: In the opinion of Professor Paul Dukes, "a superpower must be able to conduct a global strategy including the possibility of destroying the world; to command vast economic potential and influence; and to present a universal ideology". Although "many modifications may be made to this basic definition". According to Professor June Teufel Dreyer, "[a] superpower must be able to project its power, soft and hard, globally". In his book "", Dr. Ian Bremmer, president of the Eurasia Group, argues that a superpower is "a country that can exert enough military, political, and economic power to persuade nations in every region of the world to take important actions they would not otherwise take".


title: Superpower

text: Apart from its common denotation of the foremost post-WWII states, the term "superpower" has colloquially been applied by some authors retrospectively to describe various preeminent ancient great empires or medieval great powers, in works such as Channel 5 (UK)'s documentary "" or the reference in "The New Cambridge Medieval History" to "the other superpower, Sasanian Persia".


title: Superpower

text: The 1956 Suez Crisis suggested that Britain, financially weakened by two world wars, could not then pursue its foreign policy objectives on an equal footing with the new superpowers without sacrificing convertibility of its reserve currency as a central goal of policy. As the majority of World War II had been fought far from its national boundaries, the United States had not suffered the industrial destruction nor massive civilian casualties that marked the wartime situation of the countries in Europe or Asia. The war had reinforced the position of the United States as the world's largest long-term creditor nation and its principal supplier of goods; moreover it had built up a strong industrial and technological infrastructure that had greatly advanced its military strength into a primary position on the global stage. Despite attempts to create multinational coalitions or legislative bodies (such as the United Nations), it became increasingly clear that the superpowers had very different visions about what the post-war world ought to look like and after the withdrawal of British aid to Greece in 1947 the United States took the lead in containing Soviet expansion in the Cold War.


title: Superpower

text: The two countries opposed each other ideologically, politically, militarily, and economically. The Soviet Union promoted the ideology of Marxism–Leninism, planned economy and a one-party state whilst the United States promoted the ideologies of liberal democracy and the free market in a capitalist market economy. This was reflected in the Warsaw Pact and NATO military alliances, respectively, as most of Europe became aligned with either the United States or the Soviet Union. These alliances implied that these two nations were part of an emerging bipolar world, in contrast with a previously multipolar world.


title: Superpower

text: The idea that the Cold War period revolved around only two blocs, or even only two nations, has been challenged by some scholars in the post–Cold War era, who have noted that the bipolar world only exists if one ignores all of the various movements and conflicts that occurred without influence from either of the two superpowers. Additionally, much of the conflict between the superpowers was fought in proxy wars which more often than not involved issues more complex than the standard Cold War oppositions.


title: Superpower

text: After the Soviet Union disintegrated in the early 1990s, the term hyperpower began to be applied to the United States as the sole remaining superpower of the Cold War era. This term, popularized by French foreign minister Hubert Védrine in the late 1990s, is controversial and the validity of classifying the United States in this way is disputed. One notable opponent to this theory is Samuel P. Huntington, who rejects this theory in favor of a multipolar balance of power. Other international relations theorists such as Henry Kissinger theorize that because the threat of the Soviet Union no longer exists to formerly American-dominated regions such as Western Europe and Japan, American influence is only declining since the end of the Cold War because such regions no longer need protection or have necessarily similar foreign policies as the United States.


title: Superpower

text: After the dissolution of the Soviet Union in 1991 which ended the Cold War, the post–Cold War world has in the past been considered by some to be a unipolar world, with the United States as the world's sole remaining superpower. In 1999, Samuel P. Huntington wrote: "The United States, of course, is the sole state with preeminence in every domain of power – economic, military, diplomatic, ideological, technological, and cultural – with the reach and capabilities to promote its interests in virtually every part of the world". However, Huntington rejected the claim that the world was unipolar, arguing: "There is now only one superpower. But that does not mean that the world is unipolar," describing it instead as "a strange hybrid, a uni-multipolar system with one superpower and several major powers". He further wrote that "Washington is blind to the fact that it no longer enjoys the dominance it had at the end of the Cold War. It must relearn the game of international politics as a major power, not a superpower, and make compromises".


title: Superpower

text: Experts argue that this older single-superpower assessment of global politics is too simplified, in part because of the difficulty in classifying the European Union at its current stage of development. Others argue that the notion of a superpower is outdated, considering complex global economic interdependencies and propose that the world is multipolar.


title: Superpower

text: A 2012 report by the National Intelligence Council predicted that the United States superpower status will have eroded to merely being first among equals by 2030, but that it would remain highest among the world's most powerful countries because of its influence in many different fields and global connections that the great regional powers of the time would not match. Additionally, some experts have suggested the possibility of the United States losing its superpower status completely in the future, citing speculation of its decline in power relative to the rest of the world, economic hardships, a declining dollar, Cold War allies becoming less dependent on the United States, and the emergence of future powers around the world.


title: Superpower

text: According to a RAND Corporation paper by American diplomat James Dobbins, Professor Howard J. Shatz, and policy analyst Ali Wyne, Russia in the breakdown of a disintegrating unipolar world order, whilst not a peer competitor to the United States, would still remain a player and a potential rogue state that would undermine global affairs. The West could contain Russia with methods like those employed during the cold war with the Soviet Union, though this would be tested by Russia's overt and covert efforts to destabilize Western alliances and political systems. On the other hand, China is a peer competitor to the United States that cannot be contained, and will be a far more challenging entity for the West to confront. The authors state that China's military dominance in the Asia-Pacific is already eroding American influence at a rapid pace, and the costs for the US to defend its interests there will continue to rise. Moreover, China's economic influence has already broken out of its regional confines long ago and is on track to directly contest the US role as the center for economic trade and commerce.


title: Superpower

text: There have been many attempts by historians to apply the term superpower retrospectively, and sometimes very loosely, to a variety of entities in the past. Recognition by historians of these older states as superpowers may focus on various superlative traits exhibited by them. Examples of these ancient or historical superpowers include the British Empire, Ancient Egypt, the Hittite Empire, the Neo-Assyrian Empire, the Neo-Babylonian Empire, the Achaemenid Empire, the Germanic Kingdoms, Macedonian Empire, the Han Empire, the Roman Empire, the Carthaginian Empire, the Sasanid Empire, the Maurya Empire, the Mughal Empire, the Russian Empire, the Tang Empire, the Umayyad Caliphate, the Mongol Empire, the Ottoman Empire, the Habsburg Empire, the French colonial Empire, the Spanish Empire, the First French Empire of Napoleon, the German Empire, Safavid Iran, Afsharid Iran, and the Parthian Empire.


title: Superpower

text: According to historical statistics and research from the OECD, until the early modern period, Western Europe, China, and India accounted for roughly ⅔ of the world's GDP.


title: Superpower

text: The term potential superpowers has been applied by scholars and other qualified commentators to the possibility of several political entities achieving superpower status in the 21st century. Due to their large markets, growing military strength, economic potential, and influence in international affairs, China, the European Union, India and Russia are among the political entities most cited as having the potential of achieving superpower status in the 21st century. In 2020, a new UBS survey found that 57% of global investors predicted that China would replace the U.S. as the world's biggest superpower by 2030. However, many historians, writers and critics have expressed doubts whether any of these countries would ever emerge as a new superpower. Some political scientists and other commentators have even suggested that such countries might simply be emerging powers, as opposed to potential superpowers.


title: Superpower

text: The record of such predictions has not been perfect. For example, in the 1980s, some commentators thought Japan would become a superpower due to its large GDP and high economic growth at the time. However, Japan's economy crashed in 1991, creating a long period of economic slump in the country which has become known as "The Lost Years".


title: History of Earth

text: The history of Earth concerns the development of planet Earth from its formation to the present day. Nearly all branches of natural science have contributed to understanding of the main events of Earth's past, characterized by constant geological change and biological evolution.


title: History of Earth

text: The geological time scale (GTS), as defined by international convention, depicts the large spans of time from the beginning of the Earth to the present, and its divisions chronicle some definitive events of Earth history. (In the graphic, Ma means "million years ago".) Earth formed around 4.54 billion years ago, approximately one-third the age of the universe, by accretion from the solar nebula. Volcanic outgassing probably created the primordial atmosphere and then the ocean, but the early atmosphere contained almost no oxygen. Much of the Earth was molten because of frequent collisions with other bodies which led to extreme volcanism. While the Earth was in its earliest stage (Early Earth), a giant impact collision with a planet-sized body named Theia is thought to have formed the Moon. Over time, the Earth cooled, causing the formation of a solid crust, and allowing liquid water on the surface.


title: History of Earth

text: The Hadean eon represents the time before a reliable (fossil) record of life; it began with the formation of the planet and ended 4.0 billion years ago. The following Archean and Proterozoic eons produced the beginnings of life on Earth and its earliest evolution. The succeeding eon is the Phanerozoic, divided into three eras: the Palaeozoic, an era of arthropods, fishes, and the first life on land; the Mesozoic, which spanned the rise, reign, and climactic extinction of the non-avian dinosaurs; and the Cenozoic, which saw the rise of mammals. Recognizable humans emerged at most 2 million years ago, a vanishingly small period on the geological scale.


title: History of Earth

text: The earliest undisputed evidence of life on Earth dates at least from 3.5 billion years ago, during the Eoarchean Era, after a geological crust started to solidify following the earlier molten Hadean Eon. There are microbial mat fossils such as stromatolites found in 3.48 billion-year-old sandstone discovered in Western Australia. Other early physical evidence of a biogenic substance is graphite in 3.7 billion-year-old metasedimentary rocks discovered in southwestern Greenland as well as "remains of biotic life" found in 4.1 billion-year-old rocks in Western Australia. According to one of the researchers, "If life arose relatively quickly on Earth … then it could be common in the universe."


title: History of Earth

text: Photosynthetic organisms appeared between 3.2 and 2.4 billion years ago and began enriching the atmosphere with oxygen. Life remained mostly small and microscopic until about 580 million years ago, when complex multicellular life arose, developed over time, and culminated in the Cambrian Explosion about 538.8 million years ago. This sudden diversification of life forms produced most of the major phyla known today, and divided the Proterozoic Eon from the Cambrian Period of the Paleozoic Era. It is estimated that 99 percent of all species that ever lived on Earth, over five billion, have gone extinct. Estimates on the number of Earth's current species range from 10 million to 14 million, of which about 1.2 million are documented, but over 86 percent have not been described. However, it was recently claimed that 1 trillion species currently live on Earth, with only one-thousandth of one percent described.


title: History of Earth

text: The Earth's crust has constantly changed since its formation, as has life since its first appearance. Species continue to evolve, taking on new forms, splitting into daughter species, or going extinct in the face of ever-changing physical environments. The process of plate tectonics continues to shape the Earth's continents and oceans and the life they harbor.


title: History of Earth

text: In geochronology, time is generally measured in mya (million years ago), each unit representing the period of approximately 1,000,000 years in the past. The history of Earth is divided into four great eons, starting 4,540 mya with the formation of the planet. Each eon saw the most significant changes in Earth's composition, climate and life. Each eon is subsequently divided into eras, which in turn are divided into periods, which are further divided into epochs.


title: History of Earth

text: The history of the Earth can be organized chronologically according to the geologic time scale, which is split into intervals based on stratigraphic analysis.


title: History of Earth

text: The standard model for the formation of the Solar System (including the Earth) is the solar nebula hypothesis. In this model, the Solar System formed from a large, rotating cloud of interstellar dust and gas called the solar nebula. It was composed of hydrogen and helium created shortly after the Big Bang 13.8 Ga (billion years ago) and heavier elements ejected by supernovae. About 4.5 Ga, the nebula began a contraction that may have been triggered by the shock wave from a nearby supernova. A shock wave would have also made the nebula rotate. As the cloud began to accelerate, its angular momentum, gravity, and inertia flattened it into a protoplanetary disk perpendicular to its axis of rotation. Small perturbations due to collisions and the angular momentum of other large debris created the means by which kilometer-sized protoplanets began to form, orbiting the nebular center.


title: History of Earth

text: The center of the nebula, not having much angular momentum, collapsed rapidly, the compression heating it until nuclear fusion of hydrogen into helium began. After more contraction, a T Tauri star ignited and evolved into the Sun. Meanwhile, in the outer part of the nebula gravity caused matter to condense around density perturbations and dust particles, and the rest of the protoplanetary disk began separating into rings. In a process known as runaway accretion, successively larger fragments of dust and debris clumped together to form planets. Earth formed in this manner about 4.54 billion years ago (with an uncertainty of 1%) and was largely completed within 10–20 million years. The solar wind of the newly formed T Tauri star cleared out most of the material in the disk that had not already condensed into larger bodies. The same process is expected to produce accretion disks around virtually all newly forming stars in the universe, some of which yield planets.


title: History of Earth

text: The proto-Earth grew by accretion until its interior was hot enough to melt the heavy, siderophile metals. Having higher densities than the silicates, these metals sank. This so-called "iron catastrophe" resulted in the separation of a primitive mantle and a (metallic) core only 10 million years after the Earth began to form, producing the layered structure of Earth and setting up the formation of Earth's magnetic field. J.A. Jacobs was the first to suggest that Earth's inner core—a solid center distinct from the liquid outer core—is freezing and growing out of the liquid outer core due to the gradual cooling of Earth's interior (about 100 degrees Celsius per billion years).


title: History of Earth

text: The first eon in Earth's history, the "Hadean", begins with the Earth's formation and is followed by the "Archean" eon at 3.8 Ga. The oldest rocks found on Earth date to about 4.0 Ga, and the oldest detrital zircon crystals in rocks to about 4.4 Ga, soon after the formation of the Earth's crust and the Earth itself. The giant impact hypothesis for the Moon's formation states that shortly after formation of an initial crust, the proto-Earth was impacted by a smaller protoplanet, which ejected part of the mantle and crust into space and created the Moon.


title: History of Earth

text: From crater counts on other celestial bodies, it is inferred that a period of intense meteorite impacts, called the "Late Heavy Bombardment", began about 4.1 Ga, and concluded around 3.8 Ga, at the end of the Hadean. In addition, volcanism was severe due to the large heat flow and geothermal gradient. Nevertheless, detrital zircon crystals dated to 4.4 Ga show evidence of having undergone contact with liquid water, suggesting that the Earth already had oceans or seas at that time.


title: History of Earth

text: By the beginning of the Archean, the Earth had cooled significantly. Present life forms could not have survived at Earth's surface, because the Archean atmosphere lacked oxygen hence had no ozone layer to block ultraviolet light. Nevertheless, it is believed that primordial life began to evolve by the early Archean, with candidate fossils dated to around 3.5 Ga. Some scientists even speculate that life could have begun during the early Hadean, as far back as 4.4 Ga, surviving the possible Late Heavy Bombardment period in hydrothermal vents below the Earth's surface.


title: History of Earth

text: Earth's only natural satellite, the Moon, is larger relative to its planet than any other satellite in the Solar System. During the Apollo program, rocks from the Moon's surface were brought to Earth. Radiometric dating of these rocks shows that the Moon is 4.53 ± 0.01 billion years old, formed at least 30 million years after the Solar System. New evidence suggests the Moon formed even later, 4.48 ± 0.02 Ga, or 70–110 million years after the start of the Solar System.


title: History of Earth

text: Theories for the formation of the Moon must explain its late formation as well as the following facts. First, the Moon has a low density (3.3 times that of water, compared to 5.5 for the Earth) and a small metallic core. Second, the Earth and Moon have the same oxygen isotopic signature (relative abundance of the oxygen isotopes). Of the theories proposed to account for these phenomena, one is widely accepted: The "giant impact hypothesis" proposes that the Moon originated after a body the size of Mars (sometimes named Theia) struck the proto-Earth a glancing blow.


title: History of Earth

text: The collision released about 100 million times more energy than the more recent Chicxulub impact that is believed to have caused the extinction of the non-avian dinosaurs. It was enough to vaporize some of the Earth's outer layers and melt both bodies. A portion of the mantle material was ejected into orbit around the Earth. The giant impact hypothesis predicts that the Moon was depleted of metallic material, explaining its abnormal composition. The ejecta in orbit around the Earth could have condensed into a single body within a couple of weeks. Under the influence of its own gravity, the ejected material became a more spherical body: the Moon.


title: History of Earth

text: Mantle convection, the process that drives plate tectonics, is a result of heat flow from the Earth's interior to the Earth's surface. It involves the creation of rigid tectonic plates at mid-oceanic ridges. These plates are destroyed by subduction into the mantle at subduction zones. During the early Archean (about 3.0 Ga) the mantle was much hotter than today, probably around , so convection in the mantle was faster. Although a process similar to present-day plate tectonics did occur, this would have gone faster too. It is likely that during the Hadean and Archean, subduction zones were more common, and therefore tectonic plates were smaller.


title: History of Earth

text: The initial crust, formed when the Earth's surface first solidified, totally disappeared from a combination of this fast Hadean plate tectonics and the intense impacts of the Late Heavy Bombardment. However, it is thought that it was basaltic in composition, like today's oceanic crust, because little crustal differentiation had yet taken place. The first larger pieces of continental crust, which is a product of differentiation of lighter elements during partial melting in the lower crust, appeared at the end of the Hadean, about 4.0 Ga. What is left of these first small continents are called cratons. These pieces of late Hadean and early Archean crust form the cores around which today's continents grew.


title: History of Earth

text: The oldest rocks on Earth are found in the North American craton of Canada. They are tonalites from about 4.0 Ga. They show traces of metamorphism by high temperature, but also sedimentary grains that have been rounded by erosion during transport by water, showing that rivers and seas existed then. Cratons consist primarily of two alternating types of terranes. The first are so-called greenstone belts, consisting of low-grade metamorphosed sedimentary rocks. These "greenstones" are similar to the sediments today found in oceanic trenches, above subduction zones. For this reason, greenstones are sometimes seen as evidence for subduction during the Archean. The second type is a complex of felsic magmatic rocks. These rocks are mostly tonalite, trondhjemite or granodiorite, types of rock similar in composition to granite (hence such terranes are called TTG-terranes). TTG-complexes are seen as the relicts of the first continental crust, formed by partial melting in basalt.


title: History of Earth

text: Earth is often described as having had three atmospheres. The first atmosphere, captured from the solar nebula, was composed of light (atmophile) elements from the solar nebula, mostly hydrogen and helium. A combination of the solar wind and Earth's heat would have driven off this atmosphere, as a result of which the atmosphere is now depleted of these elements compared to cosmic abundances. After the impact which created the Moon, the molten Earth released volatile gases; and later more gases were released by volcanoes, completing a second atmosphere rich in greenhouse gases but poor in oxygen. Finally, the third atmosphere, rich in oxygen, emerged when bacteria began to produce oxygen about 2.8 Ga.


title: History of Earth

text: In early models for the formation of the atmosphere and ocean, the second atmosphere was formed by outgassing of volatiles from the Earth's interior. Now it is considered likely that many of the volatiles were delivered during accretion by a process known as "impact degassing" in which incoming bodies vaporize on impact. The ocean and atmosphere would, therefore, have started to form even as the Earth formed. The new atmosphere probably contained water vapor, carbon dioxide, nitrogen, and smaller amounts of other gases.


title: History of Earth

text: Planetesimals at a distance of 1 astronomical unit (AU), the distance of the Earth from the Sun, probably did not contribute any water to the Earth because the solar nebula was too hot for ice to form and the hydration of rocks by water vapor would have taken too long. The water must have been supplied by meteorites from the outer asteroid belt and some large planetary embryos from beyond 2.5 AU. Comets may also have contributed. Though most comets are today in orbits farther away from the Sun than Neptune, computer simulations show that they were originally far more common in the inner parts of the Solar System.


title: History of Earth

text: As the Earth cooled, clouds formed. Rain created the oceans. Recent evidence suggests the oceans may have begun forming as early as 4.4 Ga. By the start of the Archean eon, they already covered much of the Earth. This early formation has been difficult to explain because of a problem known as the faint young Sun paradox. Stars are known to get brighter as they age, and the Sun has become 30% brighter since its formation 4.5 billion years ago. Many models indicate that the early Earth should have been covered in ice. A likely solution is that there was enough carbon dioxide and methane to produce a greenhouse effect. The carbon dioxide would have been produced by volcanoes and the methane by early microbes. It is hypothesized that there also existed an organic haze created from the products of methane photolysis that caused an anti-greenhouse effect as well. Another greenhouse gas, ammonia, would have been ejected by volcanos but quickly destroyed by ultraviolet radiation.


title: History of Earth

text: One of the reasons for interest in the early atmosphere and ocean is that they form the conditions under which life first arose. There are many models, but little consensus, on how life emerged from non-living chemicals; chemical systems created in the laboratory fall well short of the minimum complexity for a living organism.


title: History of Earth

text: The first step in the emergence of life may have been chemical reactions that produced many of the simpler organic compounds, including nucleobases and amino acids, that are the building blocks of life. An experiment in 1953 by Stanley Miller and Harold Urey showed that such molecules could form in an atmosphere of water, methane, ammonia and hydrogen with the aid of sparks to mimic the effect of lightning. Although atmospheric composition was probably different from that used by Miller and Urey, later experiments with more realistic compositions also managed to synthesize organic molecules. Computer simulations show that extraterrestrial organic molecules could have formed in the protoplanetary disk before the formation of the Earth.


title: History of Earth

text: Additional complexity could have been reached from at least three possible starting points: self-replication, an organism's ability to produce offspring that are similar to itself; metabolism, its ability to feed and repair itself; and external cell membranes, which allow food to enter and waste products to leave, but exclude unwanted substances.


title: History of Earth

text: Even the simplest members of the three modern domains of life use DNA to record their "recipes" and a complex array of RNA and protein molecules to "read" these instructions and use them for growth, maintenance, and self-replication.


title: History of Earth

text: The discovery that a kind of RNA molecule called a ribozyme can catalyze both its own replication and the construction of proteins led to the hypothesis that earlier life-forms were based entirely on RNA. They could have formed an RNA world in which there were individuals but no species, as mutations and horizontal gene transfers would have meant that the offspring in each generation were quite likely to have different genomes from those that their parents started with. RNA would later have been replaced by DNA, which is more stable and therefore can build longer genomes, expanding the range of capabilities a single organism can have. Ribozymes remain as the main components of ribosomes, the "protein factories" of modern cells.


title: History of Earth

text: Although short, self-replicating RNA molecules have been artificially produced in laboratories, doubts have been raised about whether natural non-biological synthesis of RNA is possible. The earliest ribozymes may have been formed of simpler nucleic acids such as PNA, TNA or GNA, which would have been replaced later by RNA. Other pre-RNA replicators have been posited, including crystals and even quantum systems.


title: History of Earth

text: In 2003 it was proposed that porous metal sulfide precipitates would assist RNA synthesis at about and at ocean-bottom pressures near hydrothermal vents. In this hypothesis, the proto-cells would be confined in the pores of the metal substrate until the later development of lipid membranes.


title: History of Earth

text: Another long-standing hypothesis is that the first life was composed of protein molecules. Amino acids, the building blocks of proteins, are easily synthesized in plausible prebiotic conditions, as are small peptides (polymers of amino acids) that make good catalysts. A series of experiments starting in 1997 showed that amino acids and peptides could form in the presence of carbon monoxide and hydrogen sulfide with iron sulfide and nickel sulfide as catalysts. Most of the steps in their assembly required temperatures of about and moderate pressures, although one stage required and a pressure equivalent to that found under of rock. Hence, self-sustaining synthesis of proteins could have occurred near hydrothermal vents.


title: History of Earth

text: A difficulty with the metabolism-first scenario is finding a way for organisms to evolve. Without the ability to replicate as individuals, aggregates of molecules would have "compositional genomes" (counts of molecular species in the aggregate) as the target of natural selection. However, a recent model shows that such a system is unable to evolve in response to natural selection.


title: History of Earth

text: It has been suggested that double-walled "bubbles" of lipids like those that form the external membranes of cells may have been an essential first step. Experiments that simulated the conditions of the early Earth have reported the formation of lipids, and these can spontaneously form liposomes, double-walled "bubbles", and then reproduce themselves. Although they are not intrinsically information-carriers as nucleic acids are, they would be subject to natural selection for longevity and reproduction. Nucleic acids such as RNA might then have formed more easily within the liposomes than they would have outside.


title: History of Earth

text: Some clays, notably montmorillonite, have properties that make them plausible accelerators for the emergence of an RNA world: they grow by self-replication of their crystalline pattern, are subject to an analog of natural selection (as the clay "species" that grows fastest in a particular environment rapidly becomes dominant), and can catalyze the formation of RNA molecules. Although this idea has not become the scientific consensus, it still has active supporters.


title: History of Earth

text: Research in 2003 reported that montmorillonite could also accelerate the conversion of fatty acids into "bubbles", and that the bubbles could encapsulate RNA attached to the clay. Bubbles can then grow by absorbing additional lipids and dividing. The formation of the earliest cells may have been aided by similar processes.


title: History of Earth

text: A similar hypothesis presents self-replicating iron-rich clays as the progenitors of nucleotides, lipids and amino acids.


title: History of Earth

text: It is believed that of this multiplicity of protocells, only one line survived. Current phylogenetic evidence suggests that the last universal ancestor (LUA) lived during the early Archean eon, perhaps 3.5 Ga or earlier. This LUA cell is the ancestor of all life on Earth today. It was probably a prokaryote, possessing a cell membrane and probably ribosomes, but lacking a nucleus or membrane-bound organelles such as mitochondria or chloroplasts. Like modern cells, it used DNA as its genetic code, RNA for information transfer and protein synthesis, and enzymes to catalyze reactions. Some scientists believe that instead of a single organism being the last universal common ancestor, there were populations of organisms exchanging genes by lateral gene transfer.


title: History of Earth

text: The Proterozoic eon lasted from 2.5 Ga to 538.8 Ma (million years) ago. In this time span, cratons grew into continents with modern sizes. The change to an oxygen-rich atmosphere was a crucial development. Life developed from prokaryotes into eukaryotes and multicellular forms. The Proterozoic saw a couple of severe ice ages called snowball Earths. After the last Snowball Earth about 600 Ma, the evolution of life on Earth accelerated. About 580 Ma, the Ediacaran biota formed the prelude for the Cambrian Explosion.


title: History of Earth

text: The earliest cells absorbed energy and food from the surrounding environment. They used fermentation, the breakdown of more complex compounds into less complex compounds with less energy, and used the energy so liberated to grow and reproduce. Fermentation can only occur in an "anaerobic" (oxygen-free) environment. The evolution of photosynthesis made it possible for cells to derive energy from the Sun.


title: History of Earth

text: Most of the life that covers the surface of the Earth depends directly or indirectly on photosynthesis. The most common form, oxygenic photosynthesis, turns carbon dioxide, water, and sunlight into food. It captures the energy of sunlight in energy-rich molecules such as ATP, which then provide the energy to make sugars. To supply the electrons in the circuit, hydrogen is stripped from water, leaving oxygen as a waste product. Some organisms, including purple bacteria and green sulfur bacteria, use an anoxygenic form of photosynthesis that uses alternatives to hydrogen stripped from water as electron donors; examples are hydrogen sulfide, sulfur and iron. Such extremophile organisms are restricted to otherwise inhospitable environments such as hot springs and hydrothermal vents.


title: History of Earth

text: The simpler anoxygenic form arose about 3.8 Ga, not long after the appearance of life. The timing of oxygenic photosynthesis is more controversial; it had certainly appeared by about 2.4 Ga, but some researchers put it back as far as 3.2 Ga. The latter "probably increased global productivity by at least two or three orders of magnitude". Among the oldest remnants of oxygen-producing lifeforms are fossil stromatolites.


title: History of Earth

text: At first, the released oxygen was bound up with limestone, iron, and other minerals. The oxidized iron appears as red layers in geological strata called banded iron formations that formed in abundance during the Siderian period (between 2500 Ma and 2300 Ma). When most of the exposed readily reacting minerals were oxidized, oxygen finally began to accumulate in the atmosphere. Though each cell only produced a minute amount of oxygen, the combined metabolism of many cells over a vast time transformed Earth's atmosphere to its current state. This was Earth's third atmosphere.


title: History of Earth

text: Some oxygen was stimulated by solar ultraviolet radiation to form ozone, which collected in a layer near the upper part of the atmosphere. The ozone layer absorbed, and still absorbs, a significant amount of the ultraviolet radiation that once had passed through the atmosphere. It allowed cells to colonize the surface of the ocean and eventually the land: without the ozone layer, ultraviolet radiation bombarding land and sea would have caused unsustainable levels of mutation in exposed cells.


title: History of Earth

text: Photosynthesis had another major impact. Oxygen was toxic; much life on Earth probably died out as its levels rose in what is known as the "oxygen catastrophe". Resistant forms survived and thrived, and some developed the ability to use oxygen to increase their metabolism and obtain more energy from the same food.


title: History of Earth

text: The natural evolution of the Sun made it progressively more luminous during the Archean and Proterozoic eons; the Sun's luminosity increases 6% every billion years. As a result, the Earth began to receive more heat from the Sun in the Proterozoic eon. However, the Earth did not get warmer. Instead, the geological record suggests it cooled dramatically during the early Proterozoic. Glacial deposits found in South Africa date back to 2.2 Ga, at which time, based on paleomagnetic evidence, they must have been located near the equator. Thus, this glaciation, known as the Huronian glaciation, may have been global. Some scientists suggest this was so severe that the Earth was frozen over from the poles to the equator, a hypothesis called Snowball Earth.


title: History of Earth

text: The Huronian ice age might have been caused by the increased oxygen concentration in the atmosphere, which caused the decrease of methane (CH) in the atmosphere. Methane is a strong greenhouse gas, but with oxygen it reacts to form CO, a less effective greenhouse gas. When free oxygen became available in the atmosphere, the concentration of methane could have decreased dramatically, enough to counter the effect of the increasing heat flow from the Sun.


title: History of Earth

text: However, the term Snowball Earth is more commonly used to describe later extreme ice ages during the Cryogenian period. There were four periods, each lasting about 10 million years, between 750 and 580 million years ago, when the earth is thought to have been covered with ice apart from the highest mountains, and average temperatures were about . The snowball may have been partly due to the location of the supercontinent Rodinia straddling the Equator. Carbon dioxide combines with rain to weather rocks to form carbonic acid, which is then washed out to sea, thus extracting the greenhouse gas from the atmosphere. When the continents are near the poles, the advance of ice covers the rocks, slowing the reduction in carbon dioxide, but in the Cryogenian the weathering of Rodinia was able to continue unchecked until the ice advanced to the tropics. The process may have finally been reversed by the emission of carbon dioxide from volcanoes or the destabilization of methane gas hydrates. According to the alternative Slushball Earth theory, even at the height of the ice ages there was still open water at the Equator.


title: History of Earth

text: Modern taxonomy classifies life into three domains. The time of their origin is uncertain. The Bacteria domain probably first split off from the other forms of life (sometimes called Neomura), but this supposition is controversial. Soon after this, by 2 Ga, the Neomura split into the Archaea and the Eukarya. Eukaryotic cells (Eukarya) are larger and more complex than prokaryotic cells (Bacteria and Archaea), and the origin of that complexity is only now becoming known. The earliest fossils possessing features typical of fungi date to the Paleoproterozoic era, some 2.4 Ga ago; these multicellular benthic organisms had filamentous structures capable of anastomosis.


title: History of Earth

text: Around this time, the first proto-mitochondrion was formed. A bacterial cell related to today's "Rickettsia", which had evolved to metabolize oxygen, entered a larger prokaryotic cell, which lacked that capability. Perhaps the large cell attempted to digest the smaller one but failed (possibly due to the evolution of prey defenses). The smaller cell may have tried to parasitize the larger one. In any case, the smaller cell survived inside the larger cell. Using oxygen, it metabolized the larger cell's waste products and derived more energy. Part of this excess energy was returned to the host. The smaller cell replicated inside the larger one. Soon, a stable symbiosis developed between the large cell and the smaller cells inside it. Over time, the host cell acquired some genes from the smaller cells, and the two kinds became dependent on each other: the larger cell could not survive without the energy produced by the smaller ones, and these, in turn, could not survive without the raw materials provided by the larger cell. The whole cell is now considered a single organism, and the smaller cells are classified as organelles called mitochondria.


title: History of Earth

text: A similar event occurred with photosynthetic cyanobacteria entering large heterotrophic cells and becoming chloroplasts. Probably as a result of these changes, a line of cells capable of photosynthesis split off from the other eukaryotes more than 1 billion years ago. There were probably several such inclusion events. Besides the well-established endosymbiotic theory of the cellular origin of mitochondria and chloroplasts, there are theories that cells led to peroxisomes, spirochetes led to cilia and flagella, and that perhaps a DNA virus led to the cell nucleus, though none of them are widely accepted.


title: History of Earth

text: Archaeans, bacteria, and eukaryotes continued to diversify and to become more complex and better adapted to their environments. Each domain repeatedly split into multiple lineages, although little is known about the history of the archaea and bacteria. Around 1.1 Ga, the supercontinent Rodinia was assembling. The plant, animal, and fungi lines had split, though they still existed as solitary cells. Some of these lived in colonies, and gradually a division of labor began to take place; for instance, cells on the periphery might have started to assume different roles from those in the interior. Although the division between a colony with specialized cells and a multicellular organism is not always clear, around 1 billion years ago, the first multicellular plants emerged, probably green algae. Possibly by around 900 Ma true multicellularity had also evolved in animals.


title: History of Earth

text: At first, it probably resembled today's sponges, which have totipotent cells that allow a disrupted organism to reassemble itself. As the division of labor was completed in all lines of multicellular organisms, cells became more specialized and more dependent on each other; isolated cells would die.


title: History of Earth

text: Reconstructions of tectonic plate movement in the past 250 million years (the Cenozoic and Mesozoic eras) can be made reliably using fitting of continental margins, ocean floor magnetic anomalies and paleomagnetic poles. No ocean crust dates back further than that, so earlier reconstructions are more difficult. Paleomagnetic poles are supplemented by geologic evidence such as orogenic belts, which mark the edges of ancient plates, and past distributions of flora and fauna. The further back in time, the scarcer and harder to interpret the data get and the more uncertain the reconstructions.


title: History of Earth

text: Throughout the history of the Earth, there have been times when continents collided and formed a supercontinent, which later broke up into new continents. About 1000 to 830 Ma, most continental mass was united in the supercontinent Rodinia. Rodinia may have been preceded by Early-Middle Proterozoic continents called Nuna and Columbia.


title: History of Earth

text: After the break-up of Rodinia about 800 Ma, the continents may have formed another short-lived supercontinent around 550 Ma. The hypothetical supercontinent is sometimes referred to as Pannotia or Vendia. The evidence for it is a phase of continental collision known as the Pan-African orogeny, which joined the continental masses of current-day Africa, South America, Antarctica and Australia. The existence of Pannotia depends on the timing of the rifting between Gondwana (which included most of the landmass now in the Southern Hemisphere, as well as the Arabian Peninsula and the Indian subcontinent) and Laurentia (roughly equivalent to current-day North America). It is at least certain that by the end of the Proterozoic eon, most of the continental mass lay united in a position around the south pole.


title: History of Earth

text: The end of the Proterozoic saw at least two Snowball Earths, so severe that the surface of the oceans may have been completely frozen. This happened about 716.5 and 635 Ma, in the Cryogenian period. The intensity and mechanism of both glaciations are still under investigation and harder to explain than the early Proterozoic Snowball Earth.


title: History of Earth

text: Most paleoclimatologists think the cold episodes were linked to the formation of the supercontinent Rodinia. Because Rodinia was centered on the equator, rates of chemical weathering increased and carbon dioxide (CO) was taken from the atmosphere. Because CO is an important greenhouse gas, climates cooled globally.


title: History of Earth

text: In the same way, during the Snowball Earths most of the continental surface was covered with permafrost, which decreased chemical weathering again, leading to the end of the glaciations. An alternative hypothesis is that enough carbon dioxide escaped through volcanic outgassing that the resulting greenhouse effect raised global temperatures. Increased volcanic activity resulted from the break-up of Rodinia at about the same time.


title: History of Earth

text: The Cryogenian period was followed by the Ediacaran period, which was characterized by a rapid development of new multicellular lifeforms. Whether there is a connection between the end of the severe ice ages and the increase in diversity of life is not clear, but it does not seem coincidental. The new forms of life, called Ediacara biota, were larger and more diverse than ever. Though the taxonomy of most Ediacaran life forms is unclear, some were ancestors of groups of modern life. Important developments were the origin of muscular and neural cells. None of the Ediacaran fossils had hard body parts like skeletons. These first appear after the boundary between the Proterozoic and Phanerozoic eons or Ediacaran and Cambrian periods.


title: History of Earth

text: The Phanerozoic is the current eon on Earth, which started approximately 538.8 million years ago. It consists of three eras: The Paleozoic, Mesozoic, and Cenozoic, and is the time when multi-cellular life greatly diversified into almost all the organisms known today.


title: History of Earth

text: The Paleozoic ("old life") era was the first and longest era of the Phanerozoic eon, lasting from 538.8 to 251.902 Ma. During the Paleozoic, many modern groups of life came into existence. Life colonized the land, first plants, then animals. Two major extinctions occurred. The continents formed at the break-up of Pannotia and Rodinia at the end of the Proterozoic slowly moved together again, forming the supercontinent Pangaea in the late Paleozoic.


title: History of Earth

text: The Mesozoic ("middle life") era lasted from 251.902 Ma to 66 Ma. It is subdivided into the Triassic, Jurassic, and Cretaceous periods. The era began with the Permian–Triassic extinction event, the most severe extinction event in the fossil record; 95% of the species on Earth died out. It ended with the Cretaceous–Paleogene extinction event that wiped out the dinosaurs.


title: History of Earth

text: The Cenozoic ("new life") era began at  Ma, and is subdivided into the Paleogene, Neogene, and Quaternary periods. These three periods are further split into seven subdivisions, with the Paleogene composed of The Paleocene, Eocene, and Oligocene, the Neogene divided into the Miocene, Pliocene, and the Quaternary composed of the Pleistocene, and Holocene. Mammals, birds, amphibians, crocodilians, turtles, and lepidosaurs survived the Cretaceous–Paleogene extinction event that killed off the non-avian dinosaurs and many other forms of life, and this is the era during which they diversified into their modern forms.


title: History of Earth

text: At the end of the Proterozoic, the supercontinent Pannotia had broken apart into the smaller continents Laurentia, Baltica, Siberia and Gondwana. During periods when continents move apart, more oceanic crust is formed by volcanic activity. Because young volcanic crust is relatively hotter and less dense than old oceanic crust, the ocean floors rise during such periods. This causes the sea level to rise. Therefore, in the first half of the Paleozoic, large areas of the continents were below sea level.


title: History of Earth

text: Early Paleozoic climates were warmer than today, but the end of the Ordovician saw a short ice age during which glaciers covered the south pole, where the huge continent Gondwana was situated. Traces of glaciation from this period are only found on former Gondwana. During the Late Ordovician ice age, a few mass extinctions took place, in which many brachiopods, trilobites, Bryozoa and corals disappeared. These marine species could probably not contend with the decreasing temperature of the sea water.


title: History of Earth

text: The continents Laurentia and Baltica collided between 450 and 400 Ma, during the Caledonian Orogeny, to form Laurussia (also known as Euramerica). Traces of the mountain belt this collision caused can be found in Scandinavia, Scotland, and the northern Appalachians. In the Devonian period (416–359 Ma) Gondwana and Siberia began to move towards Laurussia. The collision of Siberia with Laurussia caused the Uralian Orogeny, the collision of Gondwana with Laurussia is called the Variscan or Hercynian Orogeny in Europe or the Alleghenian Orogeny in North America. The latter phase took place during the Carboniferous period (359–299 Ma) and resulted in the formation of the last supercontinent, Pangaea.


title: History of Earth

text: The rate of the evolution of life as recorded by fossils accelerated in the Cambrian period (542–488 Ma). The sudden emergence of many new species, phyla, and forms in this period is called the Cambrian Explosion. The biological fomenting in the Cambrian Explosion was unprecedented before and since that time. Whereas the Ediacaran life forms appear yet primitive and not easy to put in any modern group, at the end of the Cambrian most modern phyla were already present. The development of hard body parts such as shells, skeletons or exoskeletons in animals like molluscs, echinoderms, crinoids and arthropods (a well-known group of arthropods from the lower Paleozoic are the trilobites) made the preservation and fossilization of such life forms easier than those of their Proterozoic ancestors. For this reason, much more is known about life in and after the Cambrian than about that of older periods. Some of these Cambrian groups appear complex but are seemingly quite different from modern life; examples are "Anomalocaris" and "Haikouichthys". More recently, however, these seem to have found a place in modern classification.


title: History of Earth

text: During the Cambrian, the first vertebrate animals, among them the first fishes, had appeared. A creature that could have been the ancestor of the fishes, or was probably closely related to it, was "Pikaia". It had a primitive notochord, a structure that could have developed into a vertebral column later. The first fishes with jaws (Gnathostomata) appeared during the next geological period, the Ordovician. The colonisation of new niches resulted in massive body sizes. In this way, fishes with increasing sizes evolved during the early Paleozoic, such as the titanic placoderm "Dunkleosteus", which could grow long.


title: History of Earth

text: The diversity of life forms did not increase greatly because of a series of mass extinctions that define widespread biostratigraphic units called "biomeres". After each extinction pulse, the continental shelf regions were repopulated by similar life forms that may have been evolving slowly elsewhere. By the late Cambrian, the trilobites had reached their greatest diversity and dominated nearly all fossil assemblages.