Gallinula disneyi, Boles, 2005

Boles, Walter E., 2005, A New Flightless Gallinule (Aves: Rallidae: Gallinula) from the Oligo-Miocene of Riversleigh, Northwestern Queensland, Australia, Records of the Australian Museum 57 (2), pp. 179-190 : 182-185

Gallinula disneyi n.sp.

Fig. 2

Holotype. Queensland Museum , QM F20906, right proximal humeral fragment, broken through the shaft, with minor damage to the tuberculum ventrale.

Type locality. White Hunter Site, Hal’s Hill Sequence, Riversleigh, northwestern Queensland.

Age and local fauna. Late Oligocene/Early Miocene (System A); White Hunter Local Fauna.

Paratypes. Coracoid. QM F30692 (Dirks Towers), right shoulder fragment broken through the processus procoracoideus on the sternal side of the cotyla scapularis ; QM F31469 (White Hunter), left shoulder fragment, broken on the sternal side of the foramen n. supracoracoidei ; QM F31470 (White Hunter), right shoulder fragment, broken on the sternal side of the foramen n. supracoracoidei ; QM F31477 (Camel Sputum), left element, missing shoulder end beyond the sulcus m. supracoracoidei, with some damage to the medial margin. Humerus . QM F31471 (White Hunter), right proximal fragment, broken through the shaft, with damage to the caput humeri and the tuberculum ventrale, and abrasion to the crista deltopectoralis ; QM F31472 (White Hunter), left distal fragment, broken through the shaft. Tibiotarsus . QM F31473 (White Hunter), right proximal fragment, broken through the shaft distal to the proximal end of the crista fibularis, with abrasion to the proximal edge of the crista cnemialis medialis ; QM F31474 (White Hunter), right distal fragment, broken through the shaft, with abrasion to the rims of the condyli ; QM F31475 (White Hunter), right distal fragment, broken through the shaft . QM F24130 (Camel Sputum), left proximal fragment, broken through the shaft proximal to the distal end of the crista fibularis, with damage to the crista cnemialis medialis and edges of the facies articularis medialis ; QM F31480 (Dirks Towers), right distal fragment, broken through the shaft proximal to the crista fibularis, missing the crista cnemialis cranialis and much of the facies articularis medialis. Tarsometatarsus . QM F23723 (White Hunter), proximal right fragment, broken through shaft ; QM F20799 (Ringtail), proximal left fragment, broken through shaft ; QM F30720 (Creaser’s Ramparts), proximal right fragment, broken through shaft .

Referred specimens. Carpometacarpus. QM F30908 (Dirks Towers), left element lacking the distal end and the distal half of the os metacarpale minus; QM F31478 (Camel Sputum), complete left element. Ulna. QM F30693 (Dirks Towers), proximal left fragment with some abrasion to the rims of the articular surfaces. The olecranon is low and the processus cotylaris dorsalis is hooked ( Olsen, 1979). Its proximal width is 6.3 mm. Although this specimen agrees in configuration with ulnae of the Rallidae and of G. ventralis in particular, it is only tentatively assigned to this taxon. It is not considered further. Femur. QM F36542 ( LSO), proximal left fragment, broken through the shaft about ¾ of way to the distal end; complete except for slight damage to the proximal border of the crista trochanteris; QM F 31479 (Ringtail), left distal fragment, broken through the shaft, with damage to the medial side of the condylus medialis. Tarsometatarsus. QM F31476 (White Hunter), distal right fragment, comprising the trochleae metatarsi III and IV.

Etymology. Named for Henry John de Suffren Disney, formerly Curator of Birds at the Australian Museum, in honour of his contributions to the study of Australian birds, particularly another flightless rail, the Lord Howe Island Woodhen Gallirallus sylvestris .

Diagnosis. Gallinula disneyi is distinguished from other species of the genus by the following suite of humeral characters. It agrees with G. mortierii , and differs from other species, by having the proximal end round rather than elongate proximodistally (in posterior view); it is broader than in G. hodgenorum . The tuberculum ventrale is situated distal to the tuberculum dorsale, and is more pronounced than in G. mortierii . The crista deltopectoralis is short distally; it is more produced anteriorly compared to G. hodgenorum . The crista bicipitalis is short distally, joining the shaft more abruptly; ventrally it is rounder than in G. mortierii and more produced anteriorly than in G. hodgenorum . The condylus lateralis is thinner, not bulbous distally, and does not extend to the lateral margin of the bone (in anterior view). The tuberculum supracondylare is narrow, not round. Compared to that of G. hodgenorum the condylus dorsalis does not extend as far either distally or dorsally, relative to the shaft, and the fossa olecrani is shallower with less sharply defined edges.

Measurements. See Table 1.

Description

Coracoid. The processus acrocoracoideus is flattened, more so than in the other species, and is rotated such the tip is directed ventrally, more so than in G. ventralis ; it is not directed anteriorly but is directed more laterally than in G. hodgenorum . The processus procoracoideus is broader distally and more rectangular than in the other species with a blunter tip (this is pointed in G. hodgenorum ). The facies articularis humeralis and facies articularis clavicularis are smaller. Compared with the other species, the anterior end is more gracile while the sternal end is larger and more robust, with the area encompassing impressio m. sternocoracoidei broader, particularly anteriorly, than it is in G. ventralis . The sulcus m. supracoracoidei is more rounded (in ventral view) than in G. ventralis .

Carpometacarpus. The element is rather stout; it is between those of G. mortierii and G. hodgenorum in size and robustness. The os metacarpale minus is curved posteriorly; in this it resembles G. mortierii and G. hodgenorum and differs from G. ventralis , in which it is straight. The symphysis metacarpalis proximalis is shortened, agreeing with G. mortierii . The dorsal surface is flattened, more so than in G. hodgenorum . Compared to G. ventralis , the symphysis metacarpalis distalis is broader and shorter and the spatium intermetacarpale shorter. The distal end is narrower than in G. mortierii .

Femur. The collum trochanteris is rather short and deep (in anterior view). The distal end of the medial branch of the linea muscularis caudalis is prominent, more so than in G. ventralis and G. hodgenorum . The trochlea fibularis is broad and robust (in posterior view), with the distolateral corner square (in posterior view) and only moderately produced laterally compared to G. hodgenorum . The condylus medialis is well produced posteriorly. The ridge extending proximolaterally from the condylus lateralis is slightly pronounced, less so than in G. hodgenorum .

Tibiotarsus. Both cristae cnemialis are proportionally deeper than in G. hodgenorum . The foramen interosseum

proximale is moderately long, extending proximally and cutting into the distal side of the facies articularis lateralis, which is consequently shortened. The impressio lig. collateralis mediale is situated more proximally than in the other species. The mediodistal portion of the shaft is not as curved medially as in the other species, while being more robust distally than in G. ventralis . The distal end of the sulcus extensorius is narrower and both it and the pons supratendineus are situated more medially than in the other species. The condylus lateralis is moderately flattened on the distal and anterodistal borders, and there is a greater difference between its anterior extension and that of the condylus medialis than in G. hodgenorum .

Tarsometatarsus. The proximal end is broader than in G. ventralis . The proximal end is broader relative to the shaft compared to G. mortierii . The hypotarsus is placed more medially than in the other species and the plantar apex is rounded. Both canales hypotarsi are enclosed. The shaft is more robust than that of G. ventralis . Compared to that of G. hodgenorum , the ridge extending distally from the hypotarsus is higher, longer and more centrally situated, thus making the plantar surface of the shaft more angular and less flattened.

Figures

Fig. 2. Specimens of the fossil gallinule Gallinula disneyi. (A) coracoid, shoulder end (QM F31470; White Hunter Site); (B) coracoid, sternal end (QM F31477; Camel Sputum Site); (C) humerus, proximal end (QM F20906: holotype; White Hunter Site); (D) humerus, proximal end (QM F31471; White Hunter Site); (E) humerus, distal end (QM F31472; White Hunter Site); (F) carpometacarpus (QM F31478; Camel Sputum Site); (G) femur, proximal end (QM F36452; LSO Site); (H) femur, distal end (QM F31479; Ringtail Site); (I) tibiotarsus, proximal end (QM F31473; White Hunter Site); (J) tibiotarsus, distal end (QM F31475; White Hunter Site); (K) tibiotarsus, distal end (QM F31474; White Hunter Site); (L) tarsometatarsus, proximal end (QM F20799; Ringtail Site); (M) tarsometatarsus, distal end (QM F31476; White Hunter Site). Scale equals 10 mm.