If valid, this would mean that there are three groups of giant basal anseriformes, in chronological order of divergence first the gastornids (relatives of Gastornis) then Brontornis and finally the mihirungs of Australia.
The genus Gastornis itself contains three European species, as well as the North American species G. giganteus, a well-known prehistoric bird formerly classified as the distinct genus Diatryma.
Propalaeotherium was featured in Walking With Beasts, where it is shown as a skittish foraging creature that is a prey item of Gastornis and Ambulocetus