The Subfossil Occurrence and Paleoecological Significance of Small Mammals at Ankilitelo Cave, Southwestern Madagascar

Small mammals are rarely reported from subfossil sites in Madagascar despite their importance for paleoenvironmental reconstruction, especially as it relates to recent ecological changes on the island. We describe the uniquely rich subfossil small mammal fauna from Ankilitelo Cave, southwestern Madagascar. The Ankilitelo fauna is dated to the late Holocene (∼500 years ago), documenting the youngest appearances of the extinct giant lemur taxa Palaeopropithecus, Megaladapis, and Archaeolemur, in association with abundant remains of small vertebrates, including bats, tenrecs, carnivorans, rodents, and primates. The Ankilitelo fauna is composed of 34 mammalian species, making it one of the most diverse Holocene assemblages in Madagascar. The fauna comprises the 1st report of the short-tailed shrew tenrec (Microgale brevicaudata) and the ring-tailed mongoose (Galidia elegans) in southwestern Madagascar. Further, Ankilitelo documents the presence of southwestern species that are rare or that have greatly restricted ranges today, such as Nasolo\u27s shrew tenrec (M. nasoloi), Grandidier\u27s mongoose (Galidictis grandidieri), the narrow-striped mongoose (Mungotictis decemlineata), and the giant jumping rat (Hypogeomys antimena). A simple cause for the unusual small mammal occurrences at Ankilitelo is not obvious. Synergistic interactions between climate change, recent fragmentation and human-initiated degradation of forested habitats, and community-level processes, such as predation, most likely explain the disjunct distributions of the small mammals documented at Ankilitelo

A hyracoid from the Late Oligocene Red Sandstone Group of Tanzania, Rukwalorax jinokitana (gen. and sp. nov.)

[Extract] A striking array of fossil hyracoids has been described from northern Africa and the Arabian Peninsula, with several taxa recognized from Paleogene strata not only in the Fayum Depression of Egypt, but also in Morocco, Algeria, Tunisia, Libya and Oman (e.g., Sudre, 1979; Rasmussen, 1989 and references therein; Thomas et al., 1989; Gheerbrant et al., 2005). Hyracoids were abundant in these faunas, comprising up to 90% of the mammalian fauna recovered from the L-41 locality in the Jebel Qatrani Formation of Egypt (Rasmussen and Simons, 1991).\ud \ud Hyracoids appear to have achieved their apex in diversity during the Paleogene, at which time the group dominated the small-medium sized herbivorous niches in known faunas (Schwartz et al., 1995). During this time, they spanned a rabbit to rhinoceros range in body size, exhibiting a diversity of locomotor and dietary morphologies (Rasmussen et al., 1996). From the bunodont Geniohyus, to the common lophoselenodont Thyrohyrax, hyracoids flourished, assuming a vast array of niches that would later be occupied by immigrant artiodactyls and perissodactyls (Schwartz et al., 1995). Indeed, specializations for limb stabilization attributed to cursoriality in Antilohyrax pectidens suggest that in some ways it converged upon modern springboks in aspects of its locomotor habits (Rasmussen and Simons, 2000), whereas at the other extreme, postcranial specializations of the hind limb later emerged in some procaviids to permit extreme rotation for rock and tree climbing (Fischer, 1986)