 The birds looked like oversized Eurasian coots, being about 45 cm long, but as they were more likely derived from the red-knobbed coot, it is not clear whether the distinguishing red knobs (which are easily overlooked) on top of the white frontal shield were not present or simply not reported by Dubois, who described the species in some detail in 1674 as "Waterhens which are as large as fowls.They are always black, and have a large white crest on the head.