In an alternate timeline where the Cybermen used Time Lord resources to conquer all of history, Cyber-Silurian was the name given by the Eleventh Doctor, among the alternatives Cyberlurian, Cybersilon, and Cyber-Reptilia, to a variant of Cybermen that were created through the cyber-conversion of Silurians on prehistoric Earth. Their purpose was to reengineer Silurian Arks into Cyber-Arks that would seed the universe with Cyber-Technology before humanity could begin to evolve. (COMIC: Supremacy of the Cybermen)
The Cyber-Silurians were converted from Silurians that resembled the warrior caste, but with a pair of black eyes on their faces with no pupils, (COMIC: Supremacy of the Cybermen) unlike the warrior caste Silurians, who had humanoid faces. (TV: The Hungry Earth / Cold Blood) The Silurians' converted states varied greatly between individuals; while some Cyber-Silurians merely possessed a cybernetic implant on their faces and a small amount of cybernetic body parts, others had a large proportion of their bodies converted, and some even had near-complete Cyber-suits, with a minimal amount of the original Silurian visible. The Cyber-suits of these Cyber-Silurians featured unique Cyber-helmets that resembled a Silurian's head; the rest of their Cyber-bodies somewhat resembled those of the Cybermen that invaded Gallifrey in this timeline, although they lacked much of the fine detailing that these Cybermen possessed on their bodies, and the circular light on the chests of some Cyber-Silurians were coloured white instead of blue. Additionally, the lower chests of some Cyber-Silurians resembled those of the Cybermen of Cybus Industries. (COMIC: Supremacy of the Cybermen)
The Cyber-Silurians wielded guns (COMIC: Supremacy of the Cybermen) similar to those used by the warrior caste Silurians underneath Wales in 2020 of the original timeline, (TV: The Hungry Earth / Cold Blood) although their barrels were blue instead of green, and may have been capable of cyber-conversion. The tongues of Cyber-Silurians were capable of rendering even a Time Lord unconscious, (COMIC: Supremacy of the Cybermen) rather than merely poisoning a human. (TV: The Hungry Earth / Cold Blood)
Beyond themselves, the Cyber-Silurians also made use of partially-converted dinosaurs; while some Cyber-Silurians rode on converted dinosaurs as part of a patrol, such as Triceratops, others served as attackers, such as at least one Tyrannosaurus rex. The cybernetic implants of these dinosaurs could be briefly scrambled by the Eleventh Doctor's sonic screwdriver.
The ultimate development of the Cyber-Silurians, and their entire reason for existing, was the Cyber-Arks, Silurian Arks designed to seed whole planets with Cyber-Technology. Pterosaurs served as airborne security drones to prevent intruders from accessing the Cyber-Arks, which could be entered by activating a Silurian teleportal, through means such as the Doctor's sonic screwdriver.
At least one Cyber-Ark contained a mass conversion chamber, originally a workshop, filled with pods that could slowly "grow" cyber-components onto a Silurian inside the pod to convert them into a Cyber-Silurian. These pods were capable of converting the Doctor, a Time Lord, unlike most cyber-conversion methods. In addition the Cyber-Silurians within the pods could be awakened by an alarm to attack any intruders. The Cyber-Silurians could initiate retinal-mapping on those inside a pod to hijack their vision to see what individual Cyber-Silurians saw.
As a failsafe security protocol, the Cyberiad was capable of terminating the Cyber-Silurians if their emotional inhibitors were disabled, as the Doctor did when he was nearly fully converted. Furthermore, the Cyberiad was able to launch the Cyber-Arks manually even after terminating all the Cyber-Silurians. (COMIC: Supremacy of the Cybermen)
In an alternate timeline, Rassilon, following his exile from Gallifrey by the Twelfth Doctor, allied with an asteroid colony of Cybermen at the end of the universe to conquer all of time and space. One of the events of this timeline was the Cybermen's conquest of prehistoric Earth, where they converted the entire Silurian race into Cyber-Silurians.
These converted Silurians were encountered by the Eleventh Doctor and Alice Obiefune, who had visited prehistoric Earth to collect a fruit as a gift for their Silurian friend, Vastra. The duo escaped when the Doctor used his sonic screwdriver to briefly startle one of the Cyber-Silurians' Cyber-dinosaurs, and the Doctor and Alice eventually broke into a Cyber-Ark via a Silurian teleportal, where they found dozens of Silurians trapped in organic pods, slowly being converted into Cyber-Silurians. After triggering an alarm, numerous Cyber-Silurians at various different stages of conversion awoke and attempted to convert the Doctor and Alice; although the Doctor teleported Alice back to his TARDIS via the teleportal, the Time Lord was attacked by the Cyber-Silurians and wired to a pod to undergo cyber-conversion. However, the Doctor was able to use his new cyber-connection to disable the emotional inhibitors of the Cyber-Silurians, causing them all to suffer extreme mental breakdowns and saving Alice from a patrol of Cyber-Silurians outside the TARDIS. In retaliation, the Cyberiad terminated all of the Cyber-Silurians and proceeded to launch the Cyber-Arks, to the distress of the Doctor.
However, on Gallifrey at the end of the universe, Rassilon, having been betrayed by the Cybermen, allied with the Twelfth Doctor to use the regenerative energy stored in the Eye of Harmony to regenerate the universe back to its form prior to Rassilon's initial encounter with the Cybermen. The Cyber-Silurians had their original forms restored, shortly before this alternate timeline was erased from existence. (COMIC: Supremacy of the Cybermen)