Euparaves (4)

Notice that in the study below, Pedopenna is included with Epidexipteryx and Oviraptors within basal Euparaves. Other flying primitive birds such as Eosinopteryx, Aurornis, Xiaotingia and Anchiornis etc should also be included (with Pedopenna, Epidexipteryx and Oviraptors) as basal Euparaves. However, in this cladogram they are shown as troodontids. (They have been classified differently in various studies).

Let's now consider whether the basalmost Euparaves were ground-dwelling or whether they were flying in the trees. Pedopenna, Epidexipteryx and the other flying  primitive birds such as Eosinopteryx, Aurornis, Xiaotingia and Anchiornis etc were all flying in the trees.
So if the basalmost Euparaves were ground-dwelling, then they must all have BECOME flying primitive birds AFTER splitting from the dinosaur line. Not only that, but they must all have developed like that convergently, to become like the other flying birds that came later. That is not parsimonious. 

The most parsimonious alternative is that the basalmost Euparaves were feathered, long-bony-tailed, flying primitive birds. And the ground-dwelling oviraptors and alvarezsaurids that came later, were secondarily flightless.


For reference:
https://en.wikipedia.org/wiki/Pedopenna

Pedopenna was originally classified as a paravian, the group of maniraptoran dinosaurs that includes both deinonychosaurs and avialans (the lineage including modern birds), but some scientists have classified it as a true avialan more closely related to modern birds than to deinonychosaurs.[3]