Metal Gear Sahelanthropus

Metal Gear Sahelanthropus, often known as simply Sahelanthropus, was a nuclear-armed bipedal tank developed in the 1980s. Utilized by XOF, its production was mostly done by scientist Huey Emmerich and the Soviet Union. Its main feature was the ability to stand and walk upright, and its name was derived from an extinct homine species, sahelanthropus.

Development
After Mother Base's destruction, Huey Emmerich went underground. He was eventually absorbed into XOF's ranks, being made chief engineer for a new Metal Gear that was being developed in Afghanistan. The Soviet Union financed and supplied resources for the project, leading Huey to believe he was working for the Soviets rather than Cipher. It was stored in a previously Soviet-controlled hangar behind the Serak Power Plant for most of its development, but was occasionally moved to OKB Zero as well. Due to its rushed development, the design of Sahelanthropus could not allow anyone other than a child to man the vehicle, as the cockpit was meant to house an AI pod instead. This resulted in a falling out between Huey and Strangelove, as he decided to use his toddler son, Hal, as a guinea pig to test the machine, something the latter vehemently disagreed with. This ultimately resulted in her death via suffocation by being trapped inside The Boss AI's casing by Huey.

Skull Face planned to use Sahelanthropus as a marketing tool in his grand scheme of arming the entire world with nuclear weaponry. The threat of Sahelanthropus' destructive capabilities would be made known to the world, sending them into a panic and forcing them to get their hands on nuclear weapons to defend against the powerful new technology. Skull Face would be the one supplying them, and using metallic archaea he would run a complete monopoly over the entire planet's nuclear armaments.

Deployment
Sahelanthropus' first recorded deployment was in 1984 to Da Smasei Laman, Afghanistan, where it grabbed mercenary Venom Snake with its giant hand from within a concealing mist created by the Parasite Unit. Catching a glimpse of Tretij Rebenok beforehand, Snake momentarily blacks out, awakening upside-down in the grasp of the Metal Gear's fist. Skull Face appears and taunts him momentarily before the hand drops Snake onto the ground, opening its palm to act as a platform for Skull Face to stand on. Skull Face, Tretij Rebenok, and Sahelanthropus then depart into the fog, leaving Snake to battle against the Parasite Unit.

Sahelanthropus is first seen in full by Venom Snake on his mission to make contact with Huey Emmerich and extract him from Soviet-controlled Serak Power Plant in a Side Mission. Behind the power plant was a large cave that had been modeled into a makeshift hangar for the continuous construction of Sahelanthropus. Skull Face, having grown impatient, was seen arguing with Huey over Sahelanthropus' current status. Huey insisted they wait until the AI was fully operational, but Skull Face claimed that giving the Metal Gear weapons AI would be the same mistake Hot Coldman made, instead planning for Tretij Rebenok to pilot it using his psychic powers. Skull Face deduced Huey's plan to defect and has him moved to the Afghanistan Central Base Camp as Sahelanthropus retreated into the depths of the hangar.

At the Central Base Camp, Venom Snake finally managed to rescue Huey, but their exit was interrupted by Sahelanthropus, Skull Face, and Tretij Rebenok inexplicably landing out of the sky in front of them. Skull Face retreated to an XOF chopper and ordered Sahelanthropus to attack the two. Huey was likewise left befuddled at Sahelanthropus being active, having been led to believe that it wasn't fully operational. Snake and Huey managed to evade Sahelanthropus and board a Diamond Dogs chopper. When Sahelanthropus attempted to jump into the air and strike the chopper Venom Snake opened fire on it using the chopper's minigun and managed to destroy its left arm and leg, sending the Metal Gear crashing back into the ground. It was then recovered and delivered back to the Serak Power Plant for repairs.

During the final confrontation between Venom Snake and Skull Face's forces, Tretij Rebenok decidedly activated Sahelanthropus prematurely. Unbeknownst to either Snake and Skull Face, Eli hijacked the Metal Gear by using Tretij Rebenok as a conduit; as means of enacting vengeance against Snake. As its loading platform rolled forwards, the Man on Fire lumbered towards the wheels and was crushed. The fact that someone wanted to enact revenge upon Snake more than even the Man on Fire left Skull Face so shocked he couldn't even bring himself to evacuate, necessitating two of his soldiers to physically drag him out to safety.

The Eli-controlled Metal Gear chased down Venom Snake, but was stopped by a narrow gap in the canyon it was running in, forcing Eli to switch the Metal Gear into the humanoid configuration, in which he caused further mayhem with a metallic archaea nano-fiber sword, destroying the various military hardware that Skull Face dispatched to take it out with little effort and wreaking havoc upon XOF. Sahelanthropus confronted and attacked Skull Face, resulting in him being trapped under a downed communications tower and mortally wounded. Eli would then focus his efforts on attempting to kill Venom Snake by using the Metal Gear, pursuing him as he attempted to escape in a leftover XOF vehicle.

Miller also inferred that the mere existence of Sahelanthropus, should it be revealed to the world would terrify the world so much that Skull Face wouldn't even need to use nukes as leverage against the world. Sahelanthropus destroyed the vehicle using its nano-fiber sword, then finally confronted Snake. After a prolonged battle, Venom Snake was able to incapacitate the Metal Gear, thus removing Eli's control over it. Diamond Dogs then retrieved the Metal Gear and placed it at Mother Base at Huey's request, much to the chagrin of Snake and Kazuhira Miller.

Its relocation to the R&D platform also posed some problems to the various staff, as transporting the mech had knocked over some APVs, and its mass also posed some initial problems to the two choppers airlifting it, having them stop and slightly descend before eventually gaining altitude with two additional choppers. However, Snake eventually warmed up to the idea of keeping Sahelanthropus around, believing it was a mark that the Diamond Dogs had successfully stopped a crisis and were not to be forgotten by history.

Relocation
For a long time Sahelanthropus remained at Mother Base, slowly and discreetly undergoing Huey's clandestine repairs. After being fully repaired, Sahelanthropus would be hijacked again by Tretij Rebenok and Eli, who had helped Huey with the repairs. The two would take several child soldiers via helicopter back to Africa along with Sahelanthropus, establishing a new stronghold that is likened to the Lord of the Flies. In an effort to neutralize Eli and his forces, Snake and a detachment of Diamond Dogs traveled to the island to put an end to Eli's chaos. Unbeknownst to them, however, XOF also discovered Eli's location in Africa and had sent a small platoon of soldiers to kill him and retrieve the Metal Gear so it could be brought back under their control. XOF's surprise attack on Eli and the children was thwarted by Tretij Rebenok, prompting Eli to activate the Metal Gear and strike back.

After killing the XOF soldiers Eli discovered Snake's hiding spot, sparking a rematch between Sahelanthropus and Snake. The subsequent battle devastated the entire island, a much more destructive battle that involved a large portion of Diamond Dogs' Combat Unit as well. Eli, Rebenok, and Sahelanthropus ultimately lost the battle when Sahelanthropus' torso was split in half at the waist and its remains rendered inoperable. In a final attempt to retrieve the ST-84, a crew of XOF soldiers surrounded Eli and prepared to execute him, but were all gunned down by Snake. Sahelanthropus's many fragments were then retrieved by Diamond Dogs, being airlifted by several heavy lift helicopters off the island.

Derived name
Sahelanthropus is an extinct hominine species possibly very close to the time of the chimpanzee-human divergence. This name is symbolic of all Metal Gear being the missing link between infantry and artillery, and this plays alongside its humanoid shape; the sahelanthropus is thought to be a likely candidate for the missing link between human and ape. It is also symbolic of Metal Gear Sahelanthropus closing the gap between the quadrupedal Peace Walker in 1974 and the bipedal TX-55 Metal Gear in 1995 as the missing link of the "evolution" of Metal Gear. Sahelanthropus was also the first Metal Gear to stand upright and walk like a human, furthering the theme of evolution. It is also widely believed that the reason the sahelanthropus went extinct was because they happened to live in an area filled with the most venomous snakes of the time period, likening them to its destruction at the hands of Venom Snake.

Armament
While not technically equipped with a nuke as standard like most Metal Gear, Sahelanthropus still had incredibly destructive nuclear potential in a very different way. Sahelanthropus' armor was composed of depleted uranium, a biproduct of the creation of uranium-235, carrying about 23 tons of it on its body. Being a heavy metal, it allowed for greater storage of kinetic energy and a fairly potent density. Although not quite the best choice for armor in Miller's opinion, Huey claimed that he wanted to reduce the bulk of certain areas on its upright body, not to mention he was unable to source ceramics technology from any manufacturers.

However, the main reason depleted uranium was used was so that Sahelanthropus would be able to create a nuclear bomb all on its own using the material. By using built-in uranium enrichment archaea, the Metal Gear would have been able to quickly melt parts of its own armor and extract the uranium-235 from it at a high concentration, the end result being highly-enriched weapons-grade uranium - Sahelanthropus itself would become a walking nuclear bomb. Huey claimed that if it were to self-destruct the nuclear yield would have been in the region of 15 kilotons, but it was fortunately recovered before it could be finished by Skull Face, and its uranium enrichment archaea were never activated.

Unlike many of its other Metal Gear brethren, Sahelanthropus was intended to function primarily as a battlefield control and front-line tactical armored platform, and thus had a larger arsenal. This is evidenced by its unique use of metallic archaea-based weaponry and specialized frontline artillery, with nuclear capability only in the case of a self-destruction. However, modifications were made by Diamond Dogs to allow Sahelanthropus to carry a conventional nuclear missile as well.
 * Archaea grenades - Sahelanthropus was capable of deploying clouds of metallic archaea, immediately disabling most technologies in an area. Small arms and archaea-manipulation platforms are left unaffected, but all forms of vehicles - land-based or airborne - are rendered inoperable by the cloud.
 * Archaea blades - A pair of flexible nano-fiber blades lined with archaea manipulators, these weapons are capable of either directly damaging metals that they come in contact with, or stimulating the metals in the soil to create metallic pylons that effectively function as remote mines.
 * Obsolete: Pylon arm - While still in development, a hydraulic pylon was used as a close-range armament in place of the archaea blades. This was no longer incorporated in the Metal Gear's weapon protocols once the blades were completed.
 * Surveillance mines - Hunter-killer probes that are capable of searching independently for targets, and relaying the results to Sahelanthropus. Once a target is identified, these probes function as self-guided anti-tank rockets.
 * Guided missile launchers - Conventional multi-wavelength guided anti-tank rockets. Sahelanthropus was capable of launching barrages of up to six at a time.
 * Twin gatling guns - Mounted on the head unit, twin gatling guns (caliber unspecified) are used as a multi-purpose primary weapon.
 * Frontline flamethrower - Equipped near the "groin" area, aimed at an angle to douse the area directly underneath Sahelanthropus in flame, eliminating the blind spot created by the Metal Gear's height.
 * Railgun - A high-powered prototype railgun capable of penetrating mountainsides to strike targets on the far side. This weapon requires a spotter to find targets, as the targeting solution is lost if the target is able to break line of sight. Sahelanthropus possesses enough power to fire this weapon continuously while re-acquiring the target, but has to go into its hunched-over "REX mode" in order to utilize it without knocking itself over.
 * High-mobility feet - While not technically weapons, Sahelanthropus is capable of using its bulk and mobility to devastating effect by intentionally trampling nearby enemies, even kicking Soviet tanks over with ease.

Although technically not armament, Sahelanthropus also possessed sensors in his head that indicated the threat level when trying to locate an enemy. When blue, it is not investigating the enemy actively, but nonetheless cautious. When yellow, it detects a nearby threat and is trying to investigate its presence. When red, it has confirmed the presence of an enemy and is in active hunting mode for the enemy.

Behind the scenes
Sahelanthropus was first revealed in the E3 2014 trailer of Metal Gear Solid V: The Phantom Pain. More details of it were given in the E3 2015 trailer and the Japanese special edition artbook of The Phantom Pain. In the latter, it is referred to as the ST-84 Metal Gear. However, this name isn't mentioned in the game itself. In its first appearance, Sahelanthropus was seen in its hunched-over form similar to Metal Gear REX, but was later seen to walk upright.

A leaked page from an Italian game guide first revealed Sahelanthropus' standing anthropoid form. Additionally, the color scheme and the general shape of humanoid form of the Sahelanthropus bears a resemblance to the orbital frame Naked Jehuty from Zone of the Enders: The 2nd Runner (another Hideo Kojima game), albeit a more bulky form and less advanced version.

Its inspiration was explained by Kojima on a series of Twitter posts: specifically, he decided to base Sahelanthropus on the ancient hominid Sahelanthropus tchadensis, citing that it was connected to the Pangaea concept from MSF as well as the theory that humans were able to among other things develop language upon becoming upright, with Sahelanthropus paralleling this theory by him stating that for evolution to proceed forward to the new world, one needs to "stand up." He also denied that it was an homage to the Tokusatsu anime that Sahelanthropus was able to walk upright, though he did admit that Guillermo del Toro liked the idea when he showed the cutscene to him in 2013 and noticed a Jason and the Argonauts homage in the scene. The Piggyback Collector's Edition Guide's Art Gallery annotations by Kojima reiterate these elements, and also elaborates that the vocal cord parasite theme goes hand in hand with the sahelanthropus element.

Sahelanthropus' capabilities and purpose were unknown at the time of its development, at first only being seen as a simple Metal Gear with no extra gimmicks.

In the "Making of a PV" video, Hideo Kojima described Sahelanthropus in the hangar as Metal Gear REX, presumably to avoid revealing plot details prior to the game's release.

The name "Sahelanthropus" and reason given for the name within the game represents an anachronism. The Phantom Pain takes place in the '80s. However, in real life, the first Sahelanthropus skull was not found until the early 2000s. This discrepancy is explained by Huey in a cassette tape. In it, he reveals that it had been discovered in the 1980s, but this information was suppressed by Cipher as a means of monopolizing information on human genetics.

In Mission 50: [Extreme] Sahelanthropus, Sahelanthropus can be fought again in a significantly more difficult version of the battle in Mission 31: Sahelanthropus. In this mission the Metal Gear takes on a slightly different color scheme, being painted charcoal black where the original was painted a gray-ish blue.

Appearances

 * Metal Gear Solid V: The Phantom Pain