In this case, the skull in the photo is *Ekaltadeta ima* (Macropodoidea,
Hypsiprymnodontidae, Propleopinae) which is roughly a giant late Oligocene
to Miocene version of the smallest extant kangaroo species, *Hypsiprymnodon
moschatus*. The latter has relatively primitive hind feet, does not hop
bipedally, and is largely insectivorous/carnivorous.
As for the dinosaurs in the picture (i.e. the dromornithid birds), the idea
that they were carnivorous is not taken very seriously by many folks; Steve
Wroe, who came up with it (and blames Walter Boles for coining 'Demon Duck
of Doom'), says he's not at all committed to the idea. Certainly no-one
else is.