Centauroid

The subject has a quadrupedal lower body and a humanoid torso.
Type: Major positive.
Effect: This mutation can be applied to any bipedal creature, including moreaus. When applied to moreaus, the centauroid has a lower body akin to that of the quadrupedal it descended from and an upper body of a moreau of the appropriate type (thus, a centaur-lion has a lion’s body, and a lion-moreau’s torso). When applied to all other bipeds, the lower body can be that of any land-dwelling vertebrate, suitably scaled to the size of the individual—anything from zebra-centaurs to elephant-centaurs has been spotted somewhere. This mutation grants several advantages.
The mutant is considered to be a quadruped for carrying capacity and burden purposes.
Due to redundant hearts and lungs, the mutant is granted a +2 species bonus on all Fortitude saves, and a +3 species bonus to his massive damage threshold. The mutant gains 2 slam attacks (each inflicts 1d4 points of damage) from his front legs, if he did not already have such an attack. As a quadruped, the mutant gains a +4 bonus to CMD versus trip attempts.
The mutant may become Large, if his lower body is appropriately sized; this has both advantages and drawbacks. A Large mutant gains +2 to Strength and -2 to Dexterity, as well as a +1 size bonus to CMB and CMD. He takes a -1 penalty to attack rolls and to Defence, and -4 to Stealth checks. Damage from the mutant's slam attacks increases 1d6. The Large mutant does not gain reach and, as the upper body is still essentially Medium-sized, the character continues to use Medium weapons. Large weapons remain oversized for the character.
During the Shadow Years, this was considered an extreme form of personal body modification, something only the most determined “body hackers” would indulge in. Mutations to the retroviral tools used to induce the change enabled it to infect the germ-line, and thus it can show up randomly among almost any population.
Biotech: Graft.