A new species of extinct fossil scops owl (Aves: Strigiformes: Strigidae: Otus) from the Archipelago of Madeira (North Atlantic Ocean)
Author
Rando, Juan Carlos
Author
Pieper, Harald
Author
Alcover, Josep Antoni
Author
Olson, Storrs L.
text
Zootaxa
2012
3182
29
42
journal article
45508
10.5281/zenodo.209430
a052a993-3606-4cbf-b881-f58de263940c
1175-5326
209430
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.