Megascops guildayi ( Brodkorb and Mourer-Chauviré 1984 )

James, Helen F., 2020, The Irvingtonian Avifauna of Cumberland Bone Cave, Maryland, Zootaxa 4772 (1), pp. 111-131 : 121-122

Megascops guildayi ( Brodkorb and Mourer-Chauviré 1984)

Material. USNM PAL 641984, r ulna : shaft and proximal end, collected in 1991 ( Fig. 1O ).

USNM PAL 641985 , r ulna : distal articular end only, collected October 2, 1996 .

USNM PAL 769089 , l femur: proximal 2/3, collected Sept. 22, 1994 ( Fig. 1M ) .

CM 8040 holotype, l tarsometatarsus lacking proximal end. Not reexamined for this study .

USNM PAL 769088 , pedal phalanx: entire, collected Sept. 22, 1994 .

USNM PAL 641981 , ungual phalanx: entire, collected Sept. 22, 1994 .

Description. The bones of a strigid owl listed above are referred to M. guildayi based primarily on the criteria of size (smaller than Asio otus , larger than Megascops asio and M. kennicottii ) and agreement in morphological details with modern Megascops . The proximal half of the ulna agrees with those of Megascops , Athene , and Aegolius in being more curved than in Asio , Strix , or Surnia . The proximal articular surfaces of the femur are broader in relationship to depth than in Athene or Aegolius , agreeing in this trait with Megascops and larger owls. No complete long bones of the species are known, and the larger size of the fossil species compared with other Megascops is evident mainly from the thicker shafts of the ulna and femur. The tarsometatarsus, described and figured by Brodkorb & Mourer-Chauviré (1984: Figure 1 ), is referable to Megascops based on size and narrow, slender form, though proportionately stouter and shorter than in Athene cunicularia . The tarsometatarsus is not as stout as in Asio brevipes Ford & Murray 1967 from the Upper Pliocene of Idaho nor as slender as in Athene megalospeza ( Ford 1966) from the Upper Pliocene of Kansas and Idaho.

Measurements. USNM PAL 641984 (ulna), greatest width distal to cotylae, 5.2 mm. USNM PAL 769089 (femur), proximal lateromedial width from head through trochanter, 7.0 mm; width of head, 3.3 mm.

Remarks. The only previously known material of this species is the type specimen. The new material bolsters the evidence for a large extinct species of Megascops in the Irvingtonian of Maryland. It is odd that the species has no other fossil record, but perhaps some of the Pliocene fossils referred to Otus (= Megascops ) are relevant to it (i.e., two bones from the Hagerman local fauna of Idaho ( Ford & Murray 1967) and one from the Rexroad Formation of Kansas ( Ford 1966)).

Figures

FIGURE 1. Fossils from Cumberland Bone Cave compared with modern taxa.A) fossil left humerus of Meleagris sp., USNM PAL 641969, caudal aspect; B) left humerus of Meleagris gallopavo, USNM BIRDS 556334 f, caudal aspect; C) fossil left humerus of Meleagris sp., USNM PAL 641067, caudal aspect; D) fossil right femur of Coragyps atratus, USNM PAL 641790, cranial aspect; E) right femur of C. atratus, USNM BIRDS 647499 m, cranial aspect; F) fossil proximal right carpometacarpus of fossil Branta dickeyi, USNM PAL 641972, ventral aspect; G) proximal right carpometacarpus of B. canadensis, USNM BIRDS 488182 m, ventral aspect; H) left tarsometatarsus of Falcipennis canadensis, USNM BIRDS 557527 f, plantar aspect; I) fossil left tarsometatarsus of Bonasa umbellus, USNM PAL 641979, plantar aspect; J) left tarsometatarsus of B. umbellus, USNM BIRDS 600360 f imm., plantar aspect; K) fossil left tarsometatarsus of Ectopistes migratorius, USNM PAL 769090, plantar aspect; L) tarsometatarsus of E. migratorius, USNM BIRDS 292904 (captive), plantar aspect; M) fossil left femur of Megascops guildayi, USNM PAL 769089, caudal aspect; N) left femur of Megascops asio, USNM 623630 f, caudal aspect; O) fossil right ulna of M. guildayi, USNM PAL 641984, ventral aspect; P) right ulna of M. asio, USNM BIRDS 623630 f, ventral aspect; Q) right tarsometatarsus of Perisoreus canadensis, USNM BIRDS 639077 f, dorsal aspect; R) fossil right tarsometatarsus of a species of jay (Corvidae, aff. Perisoreus/Cyanocitta), CM 24274, dorsal aspect; S) fossil right tarsometatarsus of a species of jay (Corvidae, aff. Cyanocitta/Perisoreus), USNM PAL 641989, dorsal aspect; T) right tarsometatarsus of Cyanocitta cyanea, USNM BIRDS 499504 f, dorsal aspect. Scale bar 1, for images A–G, = 2 cm. Scale bar 2, for images H–N, = 1 cm.