Metal Gear Sahelanthropus

Metal Gear Sahelanthropus was a nuclear-armed bipedal tank developed in the 1980s. It was utilized by XOF, originally of Soviet origin, and its design and production was aided by scientist Huey Emmerich. Its main feature is its back which allows it to stand upright, and its name is derived from an extinct homine species, Sahelanthropus.

Development
Huey Emmerich was commissioned by XOF and Cipher to create Sahelanthropus shortly after the destruction of Mother Base. Sahelanthropus' capabilities and purpose were unknown at the time of its development, at first only being seen as a war machine with no extra gimmicks. The design of Sahelanthropus could not allow anyone other than a child to man the vehicle due to the small cockpit meant for an AI pod. This resulted in a falling out between Huey Emmerich and his wife, 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.

Deployment
Sahelanthropus was deployed in 1984 to Da Smasei Laman, Afghanistan, grabbing 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, Rebenok, and Sahelanthropus then depart into the fog, leaving Snake to battle against a platoon of Skulls.

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 is a large cave that has been modeled into a makeshift hangar for the continuous construction of Sahelanthropus. Skull Face, having grown impatient, is seen arguing with Huey over Sahelanthropus' current status. Huey insists they wait until the AI is fully operational, but Skull Face claims that giving the Metal Gear weapons AI would be the same mistake Hot Coldman made, instead planning for Rebenok to pilot it using his psychic powers. Skull Face deduces Huey's plan to defect and has him moved to the Afghanistan Central Base Camp as Sahelanthropus retreats into the depths of the hangar, kicking off Mission 12: Hellbound. At the Central Base Camp Venom Snake finally manages to rescue Huey, but their exit is interrupted by Sahelanthropus, Skull Face, and Rebenok inexplicably landing out of the sky in front of them. Skull Face retreats to an XOF chopper and orders 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 manage to evade Sahelanthropus and board a Diamond Dogs chopper. When Sahelanthropus attempts to jump into the air and strike the chopper Venom Snake opens fire on it using the chopper's minigun and manages 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 had more of a lust for revenge against Snake 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. 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 Miller. Its relocation to the Quarantine Facility also posed some problems to the various staff, as transporting the mech had knocked over some APVs and also trapped at least one soldier. 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. The two would take the rest of Eli's 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. Unknown 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 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 and its remains rendered inoperable. Its many fragments were then retrieved by Diamond Dogs, where their fate was unknown.

Derived name
Sahelanthropus is an extinct hominine species possibly very close to the time of the chimpanzee-human divergence. This name is symbolic of Metal Gear being the missing link between infantry and artillery, and the Sahelanthropus being a likely candidate for the missing link between human and ape. Another theme is how Sahelanthropus was the first Metal Gear to stand upright and walk like a human, again connecting the theme of evolution.

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 not armed until after Diamond Dogs recovered it.

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 has 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 missle.
 * 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 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.

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.

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.

Appearances

 * Metal Gear Solid V: The Phantom Pain