Estrildidae Bonaparte, 1850

Nguyen, Jacqueline M. T., Hand, Suzanne J. & Archer, Michael, 2016, The Late Cenozoic Passerine Avifauna from Rackham’s Roost Site, Riversleigh, Australia, Records of the Australian Museum 68 (5), pp. 201-230 : 216-218

Family Estrildidae Bonaparte, 1850

Genus et species indet.

Fig. 14

Material. QM F57940 , distal right humerus; QM F30821 and QM F57903 (AR19825), left carpometacarpi; QM F57933 (AR11261), right carpometacarpus.

Measurements (mm). QM F30821: preserved length 8.9, proximal width 2.8, proximal length 2.0, length of os metacarpale alulare 1.4, distal width>1.8. QM F57903 : preserved length 10.1, proximal width 2.7, proximal length 2.2, length of os metacarpale alulare 1.4, distal width 2.4. QM F57933 : preserved length 9.8, proximal width 3.0, proximal length 2.5, length of os metacarpale alulare 1.6, distal width 2.4. QM F57940 : preserved length 4.3, distal width>3.7, depth of condylus dorsalis 2.1.

Description and comparisons. Humerus. QM F57940 ( Fig. 14A–B ) is a distal humerus with breakage to the proc. supracondylaris dorsalis and the ventral portion of the proc. flexorius. It is referred to Estrildidae because of the following combination of features. The sulcus humerotricipitalis is deep and directed proximally. It extends proximally beyond the level of the base of the proc. supracondylaris dorsalis. The sulcus scapulotricipitalis is also strongly marked. The distal profile of the condylus dorsalis is convex. The muscle attachment scar on the caudal surface of the epicondylaris ventralis is very deep. The fossa m. brachialis is elongate and very deep. The tub. supracondylare ventrale protrudes proximo-cranially. In dorsal view, the proc. supracondylaris dorsalis is proximally of the level of the condylus dorsalis.

The fossil humerus approaches the size of the corresponding bone of the Java Sparrow, Lonchura oryzivora ( Fig. 14C–D ). It is similar in overall morphology to the humeri of species of Lonchura examined. QM F57940 differs from extant species of estrildids studied in the following character states. It differs from all estrildids examined in having a larger fossa m. brachialis. The fossa m. brachialis is deeper in the fossil than in Lonchura , Stagonopleura , Neochmia , Poephila and Erythrura . The fossil further differs from Neochmia , Poephila , and Erythrura , and from Heteromunia in having a relatively shorter proc. flexorius. It differs from Taeniopygia in that, when viewed ventrally, the caudal edge of the proc. flexorius is angled disto-caudally and is not parallel to the long axis of the shaft.

Carpometacarpus. QM F30821, QM F57903 and QM F57933 ( Fig. 14E–G, I–K ) are assigned to Estrildidae because they exhibit the following suite of character states. The carpometacarpus is small and stout and has a circularshaped trochlea carpalis ventralis. The proximal end of the os metacarpale minus is narrow and becomes wider distally. The caudal edge of the proc. intermetacarpalis is level with that of the os metacarpale minus. The spatium intermetacarpale is visible proximally of the proc. intermetacarpalis. The proc. dentiformis is located at about the proximo-distal midpoint of the os metacarpale majus. The distal end of the os metacarpale minus is square and broad. The ventral fossa on the distal end of the os metacarpale minus is very shallow. The sulcus interosseus is moderately deep.

QM F30821 ( Fig. 14E,I ) is most similar in size to the to the Blue-faced Parrotfinch, Erythrura trichroa , whereas QM F57903 ( Fig. 14F,J ) and QM F57933 ( Fig. 14G,K ) correspond in size to the Masked Finch Poephila personata . The fossil carpometacarpi differ from those of extant species of estrildids studied in the following features. QM F30821 differs from Stagonopleura , Lonchura ( Fig. 14H,L ) and Taeniopygia because it is shorter with respect to its proximal width. The fossil carpometacarpus is stouter than those of Neochmia , Taeniopygia , Heteromunia , Poephila and Erythrura . It further differs from Neochmia , Taeniopygia and Heteromunia in having a more circular trochlea carpalis ventralis. The fossil differs from Stagonopleura , Lonchura , Poephila and Erythrura in having a smaller fovea carpalis caudalis. It differs from Heteromunia and Erythrura in having a larger proc. dentiformis.

QM F57903 differs from Neochmia , Taeniopygia , Heteromunia and Erythrura in having a more circular trochlea carpalis ventralis. The fossil further differs from Erythrura in having a larger proc. dentiformis. It differs from Heteromunia and Stagonopleura in having a deeper ventral fossa on the distal end of the os metacarpale minus, and further differs from Heteromunia in being stouter. The fossil differs from Lonchura in that the distal end of the spatium intermetacarpale and the sulcus interosseus are narrower.

QM F57933 can be distinguished from the carpometacarpi of all estrildids examined by its relatively longer proc. dentiformis. It differs from the carpometacarpi of Neochmia , Taeniopygia , Erythrura , Poephila and Heteromunia in being stouter. It further differs from Erythrura , Poephila and Heteromunia in that the proc. intermetacarpalis does not protrude beyond the caudal edge of the os metacarpale minus. The fossil differs from Erythrura in having a shallower ventral fossa on the distal end of the os metacarpale minus, and from Poephila in having a shallower sulcus interosseus. It differs from Heteromunia in having a more circular trochlea carpalis ventralis. The fossil carpometacarpus is relatively shorter than the corresponding bone of Stagonopleura . QM F57933 differs from Lonchura in that the distal end of the spatium intermetacarpale and the sulcus interosseus are narrower. The fovea carpalis caudalis is shallower than in Neochmia , Lonchura , Erythrura and Heteromunia .

QM F30821 differs from QM F57903 and QM F 57933 in being stouter. QM F57903 is distinguished from the other two fossil carpometacarpi by its shorter and more pointed proc. dentiformis. QM F57933 differs from the other two fossils in having a deeper fossa for the M. flexor digiti minoris. The fossil carpometacarpi indicate at least two taxa; one of which is represented by the stouter QM F30821, and the second taxon by QM F57903 and QM F57933 . Additional fossil material and comparisons with a wider range of extant taxa will help to clarify the relationships of these specimens.

Remarks. Grassfinches and waxbills ( Estrildidae ) are small, often brightly coloured songbirds and comprise about 134 species in 32 genera (Dickinson & Christidis, 2014). Their range encompasses Australasia, the Pacific islands, South and Southeast Asia, Eurasia and Africa ( Payne, 2010). Within Australia most estrildid finches are found in grassy areas, often close to water. Their habitats include open sclerophyll woodland with a grassy understorey, grassland, grassy shrubland and swamp vegetation ( Higgins et al., 2006). Estrildid finches are typically gregarious and primarily feed on grass seeds on the ground and from low grass heads, but can also seek nectar, fruit, foliage, insects and other invertebrates (Schodde & Mason, 1999; Higgins et al., 2006; Payne, 2010). Late Pleistocene remains of indeterminate estrildids have been recorded from cave deposits in Victoria and Western Australia ( Van Tets, 1974; Baird, 1991a). This family is currently represented in the Riversleigh region by 9 species.

Figures

Figure 14. Wing bones of (A–B,E–G,I–K) fossil Estrildidae gen. et sp. indet. compared with those of (C–D,H,L) Lonchura oryzivora AM O.66319.(A–B) QM F57940, distal right humerus.(E,I) QM F30821, left carpometacarpus.(F,J) QM F57903, left carpometacarpus.(G,K) QM F57933, right carpometacarpus. (A,C) caudal view, (B,D) cranial view, (E–H) ventral view, (I–L) dorsal view. Some distinguishing features of Estrildidae shown: 1, sulcus humerotricipitalis deep and extends proximally beyond base of proc. supracondylaris dorsalis; 2, sulcus scapulotricipitalis strongly marked; 3, distal profile of condylus dorsalis convex; 4, fossa m. brachialis elongate and very deep; 5, tub. supracondylare ventrale protrudes proximo-cranially; 6, trochlea carpalis ventralis circular; 7, ventral fossa on distal end of os metacarpale minus very shallow; 8, distal end of the os metacarpale minus square and broad; 9, proximal end of os metacarpale minus narrow and becomes wider distally; 10, sulcus interosseus moderately deep. Scale = 2 mm.