the general limit for weight in flying birds is at about 25 kg, the exceptional "argentavis magnificens" with its size and weight of a good-sized adult human notwithstanding as it evolved under unusual ecological conditions. large males of the kori bustard ("ardeotis kori") and great bustard ("otis tarda") are perfectly capable of flight, while weighing in excess of 20 kg. a wing loading of c. 25 kg/m is the known limit for bird flight under normal circumstances; thus, a case could be made for "eremopezus" to have been capable of flight. paleontologists do not consider this likely however, due to the stoutness of the bones, which in such a degree is only known from birds that were certainly flightless. the secretarybird's tarsometatarsus, for example, is only some 20% shorter but more than 60% slimmer than that of "e. eocaenus". thus, its wings and arm bones were probably reduced, a process known to have taken as little as 10,000 years in some island rails.