HARRISON, C. J. O., WALKER, C. A. 1975. The Bradycnemidae, a new family of owls from the upper Cretaceous of Romania. Palaeontology, 18, 3, 563–570.
The only bird hitherto known from the upper Cretaceous (supposed Maestrichtian) of Transylvania is the pelecaniform Elopteryx nopscai Andrews (1913), based on the proximal half of a femur; referred material includes the distal ends of three tibiotarsi from the same beds. Re-examination of these tibiotarsi, however, shows that they belong to the owls (Strigiformes); they represent the oldest owls known and are described and named as two species in new genera, Bradycneme and Heptasteornis. The posterior side of the condylar region in both genera differs so much from that of the tibiotarsi of Recent owls as to warrant the separation of these Cretaceous forms into the new family Bradycnemidae.