It's not a full reset
The (not so) new antarctic brumbles

Like hoofpoles and stottmice, brumbles also had a great, yet not so remarkable, evolutionary radiation with the start of the Incertocene. Size and shape has remained relatively similar to the bodyplan of snow brumbles, with a sketched trend toward two routes, one more cursorial and another more graviportal.
The reason of their low diversification must be found in their ecology, which is very generalized and suitable for many types of environments without much significant changes. But generalism has consequences: in more stable and complex environments, specialists benefit more while generalists become less frequent. It is not a case that brumbles are more diverse and abundant in the isolated mountain system of Lorentia, where the group radiated after the end of the Biancocene, rather than the productive plains of the Great Depresseaon like most vertebrate species.

All species of brumbles do not exceed 60 kg, with the largest being also the more graviportal species, the underbrumble (Junipluma humilis), which dwells in the dense underwood of the Amery Plateau. Its scientific name, "feather of Jupiter", refers to its plumage pattern that resembles the coloration of planet Jupiter.
No higher than a full-grown man, this brumble has few weapons to counter its predators. The species has then developed an acute hearing for a bird, which help at hearing every sound in the forest, approaching predators included. Their rumble is so low that it can be heard by other underbrumbles through their feet, like an elephant.
In case of a possible danger, underbrumbles are capable of a medium-slow endurance run of up to 30 km/h, but if it is not enough they can also fend off small enemies with their beak tusks like a shovel.
Underbrumbles tend to live in breeding pairs in order to raise as many eggs as possible. Each individual possesses two wingpouches, which means that with the help of a partner a female can raise up to four chicks in a row. Underbrumbles keep their eggs incubated in their wings for about one month, after which small chicks hatch, already able to move properly without the help of the mother. Chicks can often return to the wingpouch in the next three months, where they are safe from predators and are sometimes fed by their parents.

The robust body of the underbrumble is opposed by the gracile and agile body of the prairie brumble (Velocidon longicollis), which has switched to a cursorial body to live in the semi-open environments of the Great Depresseaon, being the only brumble actually present in that bioregion. While being cursorial, its body is not as adapted for running as a stottmouse or hoofpole, which makes this bird one of the easiest prey for a middle-sized carnivore. Because of this, prairie brumbles have developed a longer neck to better spot predators over the large grassy plains of the Great Depreasseon. Beak tusks have greatly reduce, being a nuisance for an animal that has started to adapt for fast running. 

While this cursorial form does not work properly like other cursorial vertebrates, it works enough to survive. Evolution does not find perfect solutions, just sub-optimal ones that are good enough. Maybe, in the future, this brumble species will disappear because of increased competition from other herbivores and hunting pressure, but until now, it works. Not better, just enough.