Buteogallus, Lesson, 1830

Suárez, William, 2020, The fossil avifauna of the tar seeps Las Breas de San Felipe, Matanzas, Cuba, Zootaxa 4780 (1), pp. 1-53 : 17

Buteogallus cf. † B. fragilis (L. Miller, 1911)

Fragile Eagle; Águila Fragil

( Figure 8 : I–J)

Geranoaetus fragilis L. Miller, 1911 , Univ. Calif. Publ. Bull. Dept. Geol., Vol. 6, no.12, p 315.

Referred material. San Felipe II: Distal end of right tibiotarsus, MNHNCu 75.4735; distal segment of shaft of left tarsometatarsus, MNHNCu 75.4736.

Description. Smaller when compared with Buteogallus borrasi or “ Amplibuteo ” woodwardi. Specimen MNHN- Cu 75.4735 differs from the tibiotarsus of Geranoaetus melanoleucus , and agrees with those of B. fragilis (L. Miller, 1911) , in its slightly smaller size, flattened supratendinal bridge (not inflated or domed) with more horizontal orientation, less deep and wider tendinal groove, and medial condyle much more projected mediad. This specimen is identical in small details and size to tibiotarsus RLB E4091, within the series of this bone examined (N = 33). The distal fragment of tarsometatarsus MNHNCu 75.4736, differs from the equivalent element in G. melanoleucus , by having the metatarsal facet in a lower (or distad) position and being slightly smaller, also as in B. fragilis . This specimen is very similar in size and characters to RLB D3604, within the series of tarsometatarsi examined (N = 70) of the latter species. For comparisons between B. fragilis and B. borrasi , see Suárez & Olson (2007: 293).

Measurements. (RLB specimens in parenthesis). Tibiotarsus.—distal width: 15.3+ (15.3–17.8 [16.7] 27). Tarsometatarsus.—least width of shaft: 7.9 (6.4–8.4 [7.3] 33).

Comments. Comparisons with other accipitrids (see Appendix 1) and with extensive series of B. fragilis from Rancho La Brea, California, show that the two Cuban specimens are referable to this taxon. This record is the first for Cuba and the Antilles, as well as the first occurrence of the species outside the continental mainland. This raptor is probably another member of the Cuban avifauna derived from populations established in Florida, as the taxon is considered to have been present in that peninsula since the late Pliocene ( Emslie 1998).

Another extinct hawk, close in general character to those present in B. fragilis —see Howard (1932) for descriptions, comparisons, and discussion of characters that place “ Geranoaetus ” fragilis under Urubitinga (= Buteogallus )—but much smaller and not referable to the species B. gundlachii ( Cabanis, 1855) , B. anthracinus ( Deppe, 1830) , or any of the other member of the genus, is described below.

Figures

FIGURE 8. Buteogallus borrasi: Left tarsometatarsus (MNHNCu 75.4686) in anterior (A), posterior (B) and proximal (C) views; left tarsometatarsus (MNHNCu 75.4687) in posterior (D) view; left tibiotarsus (MNHNCu 75.4665) in anterior (E) and distal (F) views; phalanx I, digit I (MNHNCu 75.4696) in plantar (G) view; ungual phalanx, digit II (MNHNCu 75.4679) in lateral (H) view. Buteogallus cf. B. fragilis: Right tibiotarsus (MNHNCu 75.4735) in anterior (I) view; left tarsometatarsus (MNHNCu 75.4736) in posterior (J) view. Scale = 2 cm.