A Morphological Analysis of the Humerus and Calcaneus of Endemic Rats from Liang Bua, Flores, Indonesia Open Access
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Liang Bua, an archaeological cave site on the Indonesian island of Flores, is best known as the type locality of the enigmatic hominin species, Homo floresiensis. Excavations at Liang Bua have recovered a very large number of vertebrate remains, including more than 230,000 bone fragments identified as murine rodents (order Rodentia, family Muridae, subfamily Murinae; i.e., rats). Previous research on the rats of Liang Bua indicates that at least five genera are represented (Papagomys, Spelaeomys, Komodomys, Paulamys, and Rattus), including species of small, medium, huge, and giant body size. The materials used in this study derive primarily from excavations at Liang Bua of Sector XXI, a 2 x 2 m area excavated in 2010. A suite of 22 measurements were used to analyze humeri (n = 1474) and calcanei (n = 372) from this assemblage in order to address questions about Liang Bua rat size, taxonomy, functional morphology, and taphonomy. Murine dental remains from Sector XXI show that rats of giant (Papagomys armandvillei), huge (Papagomys theodorverhoeveni and Spelaeomys florensis), large (Hooijeromys cf. nusatenggara), medium (Komodomys spp. and Paulamys naso) and small (Rattus hainaldi and Rattus exulans) body size are present. All of these taxa, except S. florensis and P. naso, were also plausibly identified through a series of multivariate analyses of the postcranial elements studied here. Functional analyses of the preserved humeri and calcanei suggest multiple terrestrial rats inhabiting densely forested habitats (P. armandvillei, P. theodorverhoeveni, Hooijeromys) as well as open grassland environments (Komodomys spp.). Taphonomic analyses of the humeri suggests that owls (Tyto sp.) were the primary accumulating agent of a majority of the murine assemblage based on characteristic digestive etching and breakage patterns observed on the bones. In total, these analyses of two postcranial elements indicate that considerable variation in size and morphology is present among the Liang Bua rats. This variation reflects a diverse array of murine taxa that differ dramatically from one another not only in body size, but also in shape and ecological adaptations.