as only tentative inferences can be made about the habits of "eremopezus", it is not clear why it became extinct. still, nothing even remotely resembling a possible descendant is known or inferred, making it rather likely that its lineage did not progress very far. it is sometimes believed that flightless birds cannot compete with carnivorous mammals, but the phorusrhacidae prove that even carnivorous flightless birds can very well thrive in the presence of mammalian competitors. however, the rather comprehensive ecological data indicates that habitat in the faiyum region changed at the start of the oligocene: for some time, savanna dominated by true grasses (poaceae) and shrubland seem to have displaced the swamp forest to a considerable extent, creating a habitat similar to that found at the less humid regions along the lower sénégal river. when the forest expanded again, different mammals—an abundance of monkeys but far fewer of the huge pliohyracidae hyraxes—inhabited it. in general, the emerging picture is one of an economic upheaval that lasted for perhaps 10 million years, and during which the paleogene ecosystem at faiyum with its numerous now-extinct lineages gave way to a more modern one, inhabited by the ancestors of animals that live in tropical africa today. if "eremopezus" was indeed a swamp forest bird, it may well have succumbed to this change. in that respect, it is notable that the "african" fauna found in europe was replaced by animals originating in asia starting at about the same time.