caudal 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.