Otus Pennant

Rando, Juan Carlos, Pieper, Harald, Alcover, Josep Antoni & Olson, Storrs L., 2012, A new species of extinct fossil scops owl (Aves: Strigiformes: Strigidae: Otus) from the Archipelago of Madeira (North Atlantic Ocean), Zootaxa 3182, pp. 29-42 : 31

Genus Otus Pennant

Twenty seven nearly complete bones and fragments of a small strigiform species were collected. These bones are referred to the genus Otus on the basis of the following combination of characters: The coracoid is similar in size and shape to Otus , and it differs from the coracoid of the remaining small European strigiforms in that (1) the processus procoracoideus is characteristically narrow, with sides more or less parallel (not wide and triangular as in other species), and (2) the processus acrocoracoideus is elongated (cranio-caudally) and has a caudal lamellar process directed towards the processus procoracoideus. In Athene , Asio , Strix , Bubo , Surnia , Aegolius and Glaucidium this processus is absent. The scapula of Otus displays a characteristically very wide cranial region, with the scapular body narrow, and having a distinct extension in the cranial part of the margo dorsalis scapularis; this extension is also present in Asio and Strix , although it is less developed, and is absent in Athene . The cranial part of the scapula lacks a foramen pneumaticum, which is present in Athene , Asio , Strix , Bubo , Surnia and Aegolius . The humerus of Otus is highly characteristic. In addition to its small size, it has (1) a pointed epicondylus dorsalis more distant from the shaft of the bone (as in Strix and Asio , whereas it is closer to the shaft in Athene ), and (2) the fossa musculi brachialis longer and narrower than in Athene . The ulna has a pointed, narrow and markedly proximally elongated olecranon (in Athene , Asio , Strix , Bubo and Aegolius it is less prominent, with the general shape being more triangular); in relation to the length of the ulna, the exterior margin of the labrum condyli spreads more towards the shaft of the bone, and it slopes gradually to the cranial surface (in the other European genera there is a small indentation). The radius is relatively short in comparison to other strigids. The fragment from Porto Santo fits well in general shape and size with Otus . The carpometacarpus has the proximal end ventrally rotated in relation to the plane of the metacarpals II and III (as in Strix , Asio and Bubo , whereas in Athene and Glaucidium it is not rotated); the metacarpals are parallel, and less separated than in other genera (excepting Glaucidium ). The femur has the crista trochantericus decidedly less developed proximally than in Athene , Asio , Strix , Surnia , or Aegolius . The tibiotarsus has the sulcus extensorius markedly shallower than in Athene ; the condylus medialis is nearly continuous with the axis of the bone, whereas in Athene , Asio , Strix , Bubo , Surnia and Aegolius it is more medially inclined; Surnia and Glaucidium have the tibiotarsus distinctly flattened in the craniocaudal plane. The tarsometatarsus has the proximal articular surface well excavated; as in Strix and Asio the lateral margin of the shaft does not slope gradually towards the distal part but starts parallel with the medial side and ends more abruptly than in Athene ; the shape and orientation of the three trochleae are the most diagnostic trait of the tarsometatarsus of Otus . The central trochlea (trochlea metatarsi III) has two articular surfaces separated by a groove. In Otus the medial articular surface of the central trochlea is more rounded, whereas in all the remaining European strigiform genera this articular surface is pointed and more projecting towards the posterior part of the bone.