Strigidae

James, Helen F., 2020, The Irvingtonian Avifauna of Cumberland Bone Cave, Maryland, Zootaxa 4772 (1), pp. 111-131 : 122

Strigidae sp.

Material. USNM PAL 641986 , r femur : distal end only, collected May 14, 1999 .

Description. Smaller than, and with the fibular trochlea wider than in, Tyto alba . Among extant North American owls, closest to Asio otus and males of Surnia ulula in size. Differs from S. ulula and agrees with A. otus in having the medial condyle less bulbous and projecting less far mediad, the popliteal fossa and the intercondylar sulcus shallower, and the juncture of the tibiofibular crest with the shaft forming a tight curve as opposed to a shallow slope.

Measurements. The maximum distal breadth in the fossil (8.4 mm) falls just below the range reported by Emslie (1982) for A. otus (8.5-10.2 mm, n=10).

Remarks. The fossil compares favorably with Asio , however, the possibility that it represents a large female of Megascops guildayi cannot be ruled out. I consider the bone to be undiagnostic at the level of the genus.