Aquila bullockensis, Gaff & Boles, 2010

Gaff, Priscilla & Boles, Walter E., 2010, A New Eagle (Aves: Accipitridae) from the Mid Miocene Bullock Creek Fauna of Northern Australia, Records of the Australian Museum 62 (1), pp. 71-76 : 72-74

publication ID	https://doi.org/ 10.3853/j.0067-1975.62.2010.1557
persistent identifier	https://treatment.plazi.org/id/2F6C8781-CB30-7B42-FC00-FB3C4501B9FC
treatment provided by	Felipe
scientific name	Aquila bullockensis
status	sp. nov.

Treatment

Aquila bullockensis n.sp.

Fig. 4 View Figure 4

Holotype. distal end of right humerus, QVM:2000:GFV:154. Locality and stratigraphy. Bin 23, Bullock Creek ( Fig. View Figure 1

1); Camfield Beds. Age. Mid-Miocene, 11–5mya. Etymology. Bullock Creek is the type locality, and “ensis”

(Latin) means “belonging to”.

Diagnosis. The Bullock Creek humerus is distinguished from Aquila audax , A. chrysaetos and A. fasciata by the following features:

The tuberculum supracondylare ventrale is flat in the fossil, but sits along the side of a raised shelf in A. audax , A. chrysaetos and A. fasciata , making the latter taxa relatively craniocaudally deeper compared to the length of the processus flexorius.

The two attachments of M. extensor metacarpi radialis proximal of the epicondylus dorsalis lie adjacent to each other in a dorsoventral line nearly perpendicular to the long axis of the shaft. In A. audax and A. chrysaetos , both pits are prominent and separate. In the fossil and A. fasciata , there is a single pit dorsally and a rugose scar ventrally.

The sulcus scapulotricipitalis is deeper than in A. audax and A. chrysaetos because the dorsal bordering ridge is more strongly developed. The condition in A. fasciata is similar to that of the fossil, although this may be size related.

leucocephalus ; open, H. leucogaster .

The epicondylus dorsalis in the fossil does not project as far dorsally as in A. audax , A. chrysaetos and A. fasciata .

The fossil is smaller than specimens of A. audax and A. chrysaetos , but larger than that of A. fasciata examined here ( Table 1; Fig. 3 View Figure 3 ). Louchart et al. (2005) provided distal width measurements for several living species of Aquila . In this feature, A. bullockensis is larger than A. fasciata and A. rapax (Tawny Eagle) and smaller than A. chrysaetos and A. heliaca / adelberti (Spanish/European Imperial Eagles). It is in the range of A. nipalensis (Steppe Eagle) . The distal depth of the humerus of A. bullockensis (14.1 mm) is well outside the range of A. nipalensis , as given by Louchart et al. (2005) (14.9–16.5 mm; n = 5). As many species of the Accipitridae in general, and Aquila in particular, display sexual dimorphism, however, size is not useful in distinguishing between taxa, and the fossil is only somewhat smaller than the smallest individuals of A. audax .

Description

Measurements: distal width 27.7 mm; width of shaft proximal to epicondylus dorsalis 18.5 mm; greatest width of brachial depression 9.4 mm; distal depth through condylis dorsalis 14.1 mm. The specimen preserves the distal end of the humerus, with the shaft broken above the fossa m. brachialis. In lateral view, the shaft is anteroposteriorly curved. In addition to those cited above, the fossil has the following features. The fossa m. brachialis is round and deep distally, and pointed proximally. The incisura intercondylaris is deep, narrow, and distally excavated in cranial view. The scars for M. pronator profundus and M. flexor carpi ulnaris on the epicondylus ventralis lie side by side; the former is noticeably deeper. In caudal view, the sulcus humerotricipitalis is shallow and wide. The sulcus scapulotricipitalis is narrow, with both sides of the groove at equal height in distal view. The fossa olecrani is shallow. In caudal view, the processus flexorius is bulbous, extending laterally from the shaft ( Fig. 4 View Figure 4 ).