Accipitridae Vigors, 1824

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 : 6-7

Accipitridae Vigors, 1824

The lectotype of ‘Taphaetus’ lacertosus de Vis, 1905 , a distal right humerus, QM F5507 , is identified as an accipitrid based on the presence of the following characters: The distal margin of the fossa brachialis extends distal to the tuberculum supracondylare dorsale; a distinct sulcus scapulotricipitalis; the proximal margin of the condylus dorsalis is roughly level with the ventral tip of the epicondylus ventralis; a distinct circular dorsal insertion for the m. extensor metacarpi radialis on the dorsal projection of the tuberculum supracondylare dorsale; a distinct pit for the insertion of the m. pronator superficialis ventrally adjacent to and slightly proximal to the tuberculum supracondylare ventrale; and the epicondylus ventralis is markedly ventrally prominent .

This fossil is readily distinguished from the following similar-sized birds likely to be encountered in Pleistocene Australian fossil sites.

- From Ciconiidae ( Ephippiorhynchus asiaticus ) by the following characters (ciconiid state in brackets): The tuberculum supracondylare dorsale is strongly projecting (little to no projection); the dorsal sulcus of the m. humerotricipitalis is narrow, just under a third of the shaft width (broad, roughly half the shaft width); the ventral sulcus of the m. humerotricipitalis is broad, twice the width of the dorsal sulcus (narrow, half the width); the epicondylus ventralis and the tuberculum supracondylare ventrale are distinctly separated from each other (continuous/overlapping); the dorsal insertion of the m. extensor metacarpi radialis is oval restricted to the dorsal facies (circular with a ventrally projecting line leading onto the cranial facies).

- From Pelecanidae ( Pelecanus conspicillatus ) by the following characters (pelecanid state in brackets): The tuberculum supracondylare dorsale is strongly projecting (little to no projection); the origin of m. extensor digitorum communi is a small, circular pit on the dorsal facies between the tuberculum supracondylare dorsale and the epicondylus dorsalis (large, oval-shaped attachment scar); the tuberculum supracondylare ventrale is weakly projecting cranially (cranially flattened); there is no pneumatism of the distal end (pneumatic region present on cranial facies adjacent to tuberculum supracondylare ventrale); the epicondylus ventralis strongly projects ventrally (weak projection); the distal margin of the fossa brachialis is positioned distal to the tuberculum supracondylare dorsale (positioned proximal to the processus).

- From Phoenicopteriformes ( Phoenicopterus ruber ) by the following characters (phoenicopterid state in brackets): the epicondylus ventralis projects prominently ventrally (little to no projection), the dorsal sulcus for the m. humerotricipitalis is under a third of the shaft width (half of shaft width), the ventral sulcus for the m. humerotricipitalis is twice the width of the dorsal sulcus (half the width of the dorsal sulcus), the tuberculum supracondylare ventrale is weakly projecting cranially (cranially flattened), the condylus dorsalis and condylus ventralis are separated by a distinct, deep incisura (narrow, shallow incisura).

- From Ardeidae by the following characters (ardeid state in brackets): A deep fossa m. brachialis (shallow); a broad fossa m. brachialis, approximately two thirds of shaft width or more (narrow, one third of shaft width); a narrow sulcus for the dorsal belly of the m. humerotricipitalis (broad).

Several features of the bone, notably its large size, are only matched by Aquila audax and Haliaeetus leucogaster in the Australian fauna. However, the combination of a narrow dorsal part of sulcus humerotricipitalis, a markedly prominent epicondylus ventralis, the dorsally inflated facies between the tuberculum supracondylare dorsale and the epicondylus dorsalis, and a distally short processus flexorius, distinguish it from all other accipitrids. As this humerus is unambiguously identifiable as that of an accipitrid and is distinguished from all known genera and species, ‘Taphaetus’ lacertosus is confirmed as a distinct taxon. However, it requires a new genus, as Taphaetus de Vis, 1905 is a junior homonym of Taphaetus de Vis, 1891 , and the latter is a junior synonym of Uroaetus Kaup, 1844 and so of Aquila Brisson, 1760 .

As the quadrate QM F5508 was inaccessible at the time of this study, we instead used the descriptions and illustrations in de Vis (1905) to assess if the original identification was valid. QM F5508 differs distinctly from quadrates of accipitrids, instead being similar to those of Ardeidae , particularly species in the genera Ardea and Egretta , by the following characters (accipitrid state in brackets): A large foramen pneumaticum caudomediale is positioned ventral to the capitulum oticum articular surface (no foramen pneumaticum, though a depressio caudomediale is present in some species); the capitulum oticum is positioned further dorsally relative to the capitulum squamosum (capitulum squamosum further dorsal); the width of the capitula and the width of the shaft are very similar, with little narrowing between the dorsal and ventral ends (shaft distinctly narrower than dorsal end); in caudal view, the condylus mandibularis medialis is positioned level with the condylus mandibularis lateralis, with both being equally visible (condylus mandibularis medialis set back rostrally, less visible than the condylus lateralis); the condylus mandibularis caudalis is prominently projecting caudally (projecting medially); the condylus mandibularis lateralis barely extends laterally from the shaft (extends prominently caudally); the condylus mandibularis medialis extends prominently medially from the shaft (little to no extension); a prominent secondary facet is present on the condylus mandibularis medialis (no secondary facet); in ventral view, the condyles project rostrally past the rostral margin of the articular surface (roughly in line with margin). The reported dorsal height of 22 mm is distinctly larger than that observed in the Australasian Bittern Botaurus poiciloptilus (~ 15–16 mm). While the morphology of QM F5508 is a better match for a heron, it is much larger than compared specimens of White-faced Heron Egretta novaehollandiae and Grey Heron Ardea cinerea but could potentially be a match in size to that of the Great-billed Heron ( Ardea sumatrana ). As QM F5508 is not of an accipitrid, it is not considered further here.