Aegypiinae, Peters, 1931

Mather, Ellen K., Lee, Michael S. Y. & Worthy, Trevor H., 2022, A new look at an old Australian raptor places “ Taphaetus ” lacertosus de Vis 1905 in the Old World vultures (Accipitridae: Aegypiinae), Zootaxa 5168 (1), pp. 1-23 : 14-15

Aegypiinae .

The fossil is very similar to aegypiine species (see Figure 4 ), and consistent with them in the following 13 characters: (2) a narrow sulcus hypotarsus; (3) the sulcus hypotarsus is set plantar to the sulcus flexorius, though in species of Gyps and in Aegypius monachus to a lesser degree than in the fossil; (5) the notch for the nervus peroneus is very shallow in proximal view in all species, except those in Gyps and in Sarcogyps calvus (shallow but distinct notch); (6) the fossa parahypotarsalis lateralis extends over a third of the shaft length in all species except Aegypius monachus , in which it is barely present; (8) the fossa infracotylaris dorsalis is deepened proximally in all species except those in Gyps and Necrosyrtes monachus , in which it is shallow; (13) the medial shaft margin is thin dorsal to the fossa parahypotarsalis medialis; (15) the impressiones retinaculi extensorii are extremely flattened or absent; (16) the tuberositas m. tibialis cranialis directly abuts the foramina in all species except Trigonoceps occipitalis and S. calvus (separated by one tuberositas length); (21) the sulcus for m. abductor digit IV is broad; (22) the distal extent of trochlea metatarsi II is slightly longer than or roughly equal to that of trochlea metatarsi III in all species, except those in Gyps , Aegypius monachus and Necrosyrtes monachus , in which trochlea metatarsi III has slightly greater extent than trochlea metatarsi II; (24) the plantar flange of trochlea metatarsi II is short; (25) the plantar flange of trochlea metatarsi IV is short; (27) and trochlea metatarsi II is relatively narrow.

While, as shown, the lectotype and other fossils attributed to Cryptogyps lacertosus are broadly similar to those of aegypiines, they can be distinguished from those of all aegypiine genera as follows (aegypiine state in brackets).

The humerus has a more prominently projecting tuberculum supracondylare dorsale (tuberculum supracondylare dorsale non-projecting), moderate cranial projection of the tuberculum supracondylare ventrale (flattened or reduced cranial projection), a shallow, large attachment scar for the proximal head of pronator superficialis (small scar), and the epicondylus ventralis is highly distinct from the tuberculum supracondylaris ventralis. The tarsometatarsus has a prominent eminentia intercotylaris (flattened or barely projecting), medial and lateral cotylae of roughly equal depth (medial shallower), a deepened notch for the nervus peroneus (shallow or no notch), a broad and deep fossa parahypotarsalis lateralis (shallow), a deep sulcus extensorius (shallow), a deep sulcus flexorius (shallow), a shallow fovea lig. collateralis (deep in all species except Gyps coprotheres ), and the length of trochlea metatarsi II being slightly greater relative to trochlea metatarsi IV (significantly longer than trochlea metatarsi IV). The fossil can further be distinguished from individual genera by the following characters:

From species of Torgos , Trigonoceps , Sarcogyps , and Necrosyrtes by a deeper fossa m. brachialis (shallow); from species of Torgos , Sarcogyps , Aegypius and Gyps by lacking a prominent, visible m. extensor metacarpi ulnaris origin (distinct); from Torgos , Trigonoceps , Sarcogyps , Aegypius and Gyps by the condylus ventralis being continuous with the entepicondyle (not continuous); from Torgos , Trigonoceps , Sarcogyps , Aegypius and Necrosyrtes by the trochlea metatarsi IV being relatively broad (narrow); from Trigonoceps , Sarcogyps , Aegypius and Gyps by the impressio ligamentum collateralis lateralis being prominent laterally (flattened); from Torgos , Trigonoceps , and Sarcogyps by the lateral crista hypotarsus being longer than wide (wider than long) and the tarsometatarsus being overall short and robust in length (comparatively long and elongate, narrows between proximal and distal ends); from Necrosyrtes , Gyps and Aegypius by a deep fossa infracotylaris (shallow fossa); from Torgos and Necrosyrtes by the convexity between the supracondylaris dorsalis and epicondylus dorsalis being relatively flattened (forms prominent peak); from Torgos and Aegypius by the flange of trochlea metatarsi II being extremely short (short but notably projecting medioplantarly from the trochlea); from Torgos and Trigonoceps by the crista medianoplantaris ending adjacent to the foramina vascularia proximalia (ending proximal to the foramina), and the foramen vasculare distale being set close to the incisura intertrochlearis lateralis (positioned well proximal to the incisura); from Trigonoceps and Sarcogyps by the position of the tuberositas m. tibialis cranialis being adjacent to the foramina proximalia (one tuberositas length distal) and the impressio ligamentum collateralis lateralis distinctly projecting dorsally (flat); from Necrosyrtes and Gyps by the length of trochlea metatarsi III being roughly equal with trochlea metatarsi II (trochlea metatarsi III longer than trochlea metatarsi II); from Aegypius by the broad and shallow notch distally between the condyles (deep and narrow).

Figures

FIGURE 4. Comparisons of the elements of Cryptogyps lacertosus to those of six species of Aegypiinae, tarsometatarsus in plantar view to show structure of the hypotarsus (top), tarsometatarsus in dorsal view (middle) and distal humerus in cranial view (bottom): Trigonoceps occipitalis (A); Torgos tracheliotos (B); Sarcogyps calvus (C); Aegypius monachus (D); Necrosyrtes monachus (E); Gyps coprotheres (F); and Cryptogyps lacertosus (G). Numbers reflect the characters given in the tarsometatarsus description. Images are scaled to similar size.