Asio sp.

Pavia, Marco, Manegold, Albrecht & Haarhoff, Pippa, 2015, New early Pliocene owls from Langebaanweg, South Africa, with first evidence of Athene south of the Sahara and a new species of Tyto, Acta Palaeontologica Polonica 60 (4), pp. 815-828 : 824

Asio sp.

Fig. 3A .

Material. —Left tibiotarsus (SAM-PQ-L20691L3, shaft) from Langeberg Quartz Sand Member; right tibiotarsus (SAM-PQ-L33521I, distal part) from Muishond Fontein Pelletal Phosphorite Member; the Upper Varswater Formation at Langebaanweg, early Pliocene of South Africa.

Measurements. —Distal right tibiotarsus SAM-PQ-L33521I: distal width 8.4 mm; distal depth 7.2 mm; minimal width of shaft 3.5 mm (see Table 10).

Description. —The two tibiotarsi from Langebaanweg are more similar to the corresponding bones of Asio than to that of other Strigidae in having: (i) distal attachment of the fibula very close to the distal end of the bone; (ii) proximal part of the trochlea cartilaginis tibialis terminates in a ridge in caudal view; (iii) tuberculum retinaculi musculi fibularis prominent. The fossils are distinguished from As. otus , but are similar to As. flammeus and As. capensis , because of the less medially tilted condylus medialis and of the general shape of the epicondylus ventralis and medialis. It is further distinguishable from As. flammeus and As. capensis by its narrower incisura intercotylaris. The fossil specimens could not be compared with corresponding bones of the extant As. abyssinicus , a species endemic to the East African rift and often considered a subspecies of As. otus , and their preservation does not allow their assignment to any particular taxon of Asio . The ungueal phalanx of Asio sp. reported from Laetoli is comparable in size with As. capensis , As. abyssinicus and As. flammeus , shows no diagnostic feature that would allow an assignment to a particular species of long-eared owl ( Louchart 2011).

Figures

Fig. 3. Strigid owls from the early Pliocene, Upper Varswater Formation at Langebaanweg, South Africa. A. Asio sp. (SAM-PQ-L33521 I), right tibiotarsus, in cranial (A 1), lateral (A 2), caudal (A 3), medial (A 4), and distal (A 5) views. B. Strigidae gen. et sp. indet. (SAM-PQ-L28479 C), left tibiotarsus in cranial view. C. Bubo sp. (SAM-PQ-L28439 C), left tibiotarsus in cranial view.