The Cuban giant owl or giant cursorial owl (Ornimegalonyx) is an extinct genus of giant owl that measured 1.1 metres (3 ft 7 in) in height. It is closely related to the many species of living owls of the genus Strix.[1] It was a flightless or nearly flightless bird and it is believed to be the largest owl that ever existed. It lived on the island of Cuba.
The first fossil specimen was mistakenly described as a bird in the family Phorusrhacidae, in part because the bones were so large. In 1961, Pierce Brodkorb reviewed the findings and placed them properly, with the owls. Remains have been abundant throughout the island, in cave deposits from the Late Pleistocene period (126,000 to 11,700 years ago) and at least three nearly complete skeletons have been found. These owls were primarily found in Cuba, their fossils were only ever found in the Cuban islands.
In the past, three additional species of Ornimegalonyx besides O. oteroi were regarded as valid. All were described in 1982 and include:
A 2020 study concluded that those species are all synonyms of O. oteroi, and describe a new valid species, Ornimegalonyx ewingi, from material formerly assigned to the prehistoric horned owl Bubo osvaldoi.[3]
"Ornimegalonyx arredondoi" is a nomen nudum; the name was proposed for this species before it was described but oteroi was eventually adopted by Oscar Arredondo (according to the rules of the ICZN, naming a species after oneself is not prohibited, but it is frowned upon as vain by the scientific community[citation needed]).
Arredondo estimated the height of Ornimegalonyx to have been 1.1 m (3 ft 7 in) tall.[4][5] It had very long legs for its size, but was bulky overall and probably short-tailed. Its body mass in life is estimated to have been approximately 13.5 kg (30 lb).[6][7][8] The modern owl that most resembles the Cuban giant owl in proportions is probably the dainty and quite small burrowing owl, the only surviving owl closely tied to the ground. This implies similar adaptations to the terrestrial lifestyle, but not a close phylogenetic relationship.[5]