Apex predators of a dying continent

Being no larger than 800,000 km², the Sanctuary Peninsula is relatively big but not large enough to host the once large carnivores present on the continent, which rapidly died out even before the Continental Crisis. Aside from two mesocarnivores, the carnivore guild is enriched by two vertebrates that have actually benefitted from the decline of the previous apex predator guild.

One of these is a mammal, the running carniere (Altigulo relictus), which is derived from relatively small (a few kilos in weight) ancestors that lived about 10 million years ago in the Trample steppe. After the extinction of beasters and the large barkdowners, the ancestor of this carniere gradually started to grow in size, reaching a weight of 20-30 kg today. Despite their larger size compared to their ancestors, running carnieri are far from capable of easily hunting the large land animals on the Sanctuary Peninsula because of their proportionally smaller head. While faster then its ancestors, they tend to relent in pursuit of their prey, preferring to feed on easy meals like carcasses, with its dietary intake of carrion ranging from 40% to 100%. Aside from dead animals, the second most consumed prey consists of small animals, lighter than 10 kg (22 lbs), which are caught by digging up their dens or by ambushing. Large rodents and birds are rarely preyed upon when alive, making up no more than 10% of their diet. While capable of taking down a snow brumble or a triple stottmice, running carnieri have no match against tramplerats, which, due to their size (more than 15 times larger), are completely unassailable. 

Because of the robust body of poop trenchcrawlers, even these 80 kg birds are not easy catches. These birds are more often taken down by the only truly active large predator of the continent, the plague pinpiercer (Gigaramphorhyncus fasciatus), which is one of the last two remaining pinpiercers in Antarctica. The plague pinpiercer is the largest, reaching the size of a golden eagle. Like its relatives, it possesses a large serrated beak that works like a knife to pierce the skin of its prey, similar to a saber-toothed cat. The second and last pinpiercer species is the wandering pinpiercer (Gigaramphorynchus minutus), which is relatively small compared to other species of the group, not exceeding one kg.

Thanks to its size (though not as big as some of its extinct relatives), the plague pinpiercer is capable of feeding on prey as large as a full-grown trenchcrawler. They are resistant hunters that can stalk their prey for up to an hour in flight before annihilating them with their strong beak. Despite reaching higher densities in the Sanctuary Peninsula, this bird can also be found in the sea ice of the Land-no-Land (in contrast to the running carniere, which is endemic to the continental part of the Sanctuary Peninsula), where it feeds on resting reefsurfers and the only two terrestrial vertebrates present: the ottofox and the banchisaraptor. These two mesopredators are found at lower densities where plague pinpiercers and running carnieri are more abundant, suppressing their numbers, which would be much higher in the Sanctuary Plateau. Mesopredator suppression by these two "large" predators is ecologically beneficial for microvertebrates, which tend to be more abundant where carnieri and pinpiercers are common.
Despite their size, plague pinpiercer chicks are often threatened by these mesocarnivores during the brooding period. To reduce this risk, these ground-nesting birds prefer to raise their chicks on small rocky islands in the Sanctuary Plateau or even on small icebergs in the Land-no-Land. Wandering pinpiercers, because of their smaller size, are even more threatened and have maintained a high-nesting behaviour, preferring large ravines. Where rocks are not present, wandering pinpiercers often make use of their hooked beak to dig up nest inside icebergs.

Thanks to the lack of large predators, these species were able to rule all terrestrial environments of Antarctica, but luck will not be forever. Eventually, when the last piece of land will be completely frozen, their small small reign will vanish, like the one of their past competitors.