Sahelanthropus still fits into the canon. It was a failed piece of tech that had to be dramatically scaled down to even work in deployment, after it's destruction at Kingdom of Flies. I feel it's implied it's remains became Metal Gear Rex, with Hal following in his father's footsteps, not realizing how much of a horrible person his dad was. With how much of a shitty scientist he's revealed to be in later games, it's interesting that all of Hal's accomplishments (Rex, Stealth Camo, and possibly Mark 2) were all based on his dad's ideas and research. I like that Sahelanthropus had to be scaled down more to be properly functional. I find it amusing that Big Boss and Venom ended up not able to reproduce Huey's inovations in metal gear technology. (Even though Granin created the concept in the first place)