Late Pleistocene songbirds of Liang Bua (Flores, Indonesia); the first fossil passerine fauna described from Wallacea

Abstract

BackgroundPasserines (Aves: Passeriformes) dominate modern terrestrial bird communities yet their fossil record is limited. Liang Bua is a large cave on the Indonesian island of Flores that preserves Late Pleistocene–Holocene deposits (∼190 ka to present day). Birds are the most diverse faunal group at Liang Bua and are present throughout the stratigraphic sequence.MethodsWe examined avian remains from the Late Pleistocene deposits of Sector XII, a 2 × 2 m area excavated to about 8.5 m depth. Although postcranial passerine remains are typically challenging to identify, we found several humeral characters particularly useful in discriminating between groups, and identified 89 skeletal elements of passerines.ResultsAt least eight species from eight families are represented, including the Large-billed Crow (Corvus cf. macrorhynchos), the Australasian Bushlark (Mirafra javanica), a friarbird (Philemon sp.), and the Pechora Pipit (Anthus cf. gustavi).DiscussionThese remains constitute the first sample of fossil passerines described in Wallacea. Two of the taxa no longer occur on Flores today; a large sturnid (cf. Acridotheres) and a grassbird (Megalurus sp.). Palaeoecologically, the songbird assemblage suggests open grassland and tall forests, which is consistent with conditions inferred from the non-passerine fauna at the site. Corvus cf. macrorhynchos, found in the Homo floresiensis-bearing layers, was likely part of a scavenging guild that fed on carcasses of Stegodon florensis insularis alongside vultures (Trigonoceps sp.), giant storks (Leptoptilos robustus), komodo dragons (Varanus komodoensis), and probably H. floresiensis as well.

Impact of the Mid-Pleistocene Revolution and Anthropogenic Factors on the Dispersion of Asian Black-Spined Toads (Duttaphrynus melanostictus)

“…This result is in agreement with the hypothesis that the most recent common ancestor of D. melanostictus diverged in the Western Ghats, current South Asia, before expanding to the Southeast Asia (Miocene; [ 102 , 103 ]). Several paleogeographic evidence on major avian and terrestrial fossils from Wallacea dated to the Mid to Upper Pleistocene highlight a population displacement pattern similar to the one described above for D. melanostictus [ 104 ].…”

Why did the chicken cross the Wallace Line? Archeological evidence suggests human‐mediated dispersal of Gallus to Flores first occurred at least ~2.25 ka cal. BP

“…Liang Bua preserves a rich faunal sequence with over 400,000 vertebrate elements recovered to date. Among this large assemblage, over 4,000 elements have been identified as avian representing more than 40 taxa, and birds are present throughout the entire stratigraphic sequence (Meijer & Due, 2010; Meijer et al, 2010, 2013, 2017, 2022; Sutikna et al, 2018). Despite this richness in avian taxa, no bones of Gallus have been recorded from the ~190‐ka sequence except those described in this study.…”

“…For large portions of the late Middle Pleistocene until $3 ka ago, the area surrounding Liang Bua would likely have been suitable habitat for wild junglefowl (Sutikna et al, 2018;Veatch et al, 2019;Westaway et al, 2009). The variety of avian taxa recorded at Liang Bua ranges from very small (e.g., swiftlets) to very large (e.g., giant marabou storks) birds, and includes forest, grassland, and aquatic adapted species (Meijer et al, 2013(Meijer et al, , 2017. The absence of Gallus is thus not reasonably explained by either taphonomic biases or habitat preferences.…”