(B)rumbling and trampling

One of the key factors contributing to the trample steppe ecosystem's high productivity is the minimal snow cover during winter, facilitating a swift transition to spring despite the region's high latitude. This contrasts with areas experiencing more frequent and abundant snowfall, such as the coldvanna, where the estimated net biomass is only half that of the trample steppe. Nevertheless, the coldvanna ecosystem is far from desolate, with its summers being generally hotter than those of the trample steppe, and its residents evolving various strategies to cope with the snow. While numerous rodent species have found niches in this habitat, very few have managed to attain large sizes. Instead, the coldvanna's megafauna is mainly dominated by a unique group of vertebrates—the brumbles—among the most successful rostrid species now present in Antarctica.

In the coldvanna, brumbles exhibit their highest diversity, with a total of three species widely distributed. However, the most remarkable inhabitant of this ecosystem is not a rodent or an otter, but a colossal brumble known as the brumblestilt (Ornithotitan dominator). Reaching heights of nearly 3 meters at the hip, the brumblestilt stands as the first true gigantic rostrid, comparable in size to some of the largest ducktails, reaching a remarkable weight of 800 kg. Its imposing stature is accentuated by its long, robust legs, each measuring up to 2 meters in length. These legs serve multiple purposes, facilitating both running and self-defense, while also offering a perfect adaptation to the region's heavy snowfall. Even in snow depths exceeding a meter, this spectacular bird can navigate effortlessly, thanks to its colossal stride. Locomotion is also optimized by partial webbed feet, which reduce snow sinking.