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 : 187

Distribution of Gallinula disneyi

Gallinula disneyi , like G. mortierii , is unusual because of its continental distribution. Gallinula mortierii , now restricted to Tasmania, once extended well into eastern mainland Australia, where it has been recorded from Pleistocene and possible Pliocene deposits ( Fig. 1 ), with the youngest record at 4670±90B.P. ( Baird, 1991a). It is extensively represented in deposits in southeastern Australia in the Murray-Darling River system, with a northernmost record from Wyandotte Creek, northeastern Queensland ( Olson, 1975b; Baird, 1984, 1986; McNamara & Baird, 1991). A new record from the Plio-Pleistocene Floraville Local Fauna (west of Leichhardt River, south of Floraville Homestead, northwestern Queensland; 18°17'S 139°52'E), represented by a tarsometatarsus (QM F24605), extends the western edge of the known distribution (unpublished data). During the Plio-Pleistocene, G. mortierii persisted despite the presence of native marsupial carnivores, even as it does today in Tasmania in the company of the Tasmanian Devil Sarcophilus harrisii and, previously, the Thylacine Thylacinus cynocephalus . Baird (1984, 1986, 1991a,b) hypothesized that its extinction on the mainland was probably due to a combination of changing environmental conditions and the introduction of the Dingo Canis familiaris dingo (earliest known occurrence 3450±95B.P.; Milham & Thomson, 1976). Ridpath (1972) noted that the native marsupial species were/are nocturnal, and the diurnally active G. mortierii has evolved several methods of avoiding ground predators. The Dingo, in contrast, forages extensively during the day when the native-hens would receive no benefit from darkness. Gallinula disneyi also co-existed with numerous native marsupial carnivores (large Dasyuridae , Thylacinidae , Thylacoleonidae ), and it is doubtful that any of these could have caused its eventual extinction (see Baird, 1991a). As discussed below, it is possible that rather than becoming extinct, G. disneyi may have evolved into the living G. mortierii .

Figures

Fig. 1. Distribution of Recent and fossil Australian species of Gallinula. Key:black shading, current distribution of G. mortierii; grey shading, current distribution of G. ventralis; - Riversleigh (G. disneyi); Z Quaternary mainland sites producing G. mortierii (taken from De Vis 1888, 1892; Baird 1984, 1985, 1986, 1991b, 1992; McNamara & Baird 1991; Olson 1975b; and this work).