Micromammals, referred to here as all mammals weighing up to 500g, are taxonomically diverse and thrive in a variety of environments. They do not generally migrate like larger mammals and are sensitive to fluctuations in climate and vegetation, making them excellent local indicators of environmental changes. In addition, their fossil remains are often found in large quantities in cave deposits. With the development of more meticulous excavations, involving fine sieving of sediments allowing for the recovery of smallest remains, interest in micromammal studies has been steadily increasing with main focus directed towards understanding the site formation processes and reconstructing past climate and environments that prevailed in the Quaternary. Unfortunately, that has not been the case for Botswana where faunal studies are scarce. This presentation will focus on the taphonomy and taxonomy of a new fossil micromammal assemblage from the Gcwihaba caves located in the Ngamiland District in the north-west of Botswana. These caves have yielded rich micromammal assemblages and most of these remain unstudied.
The Hominins in Botswana-Karst Research Project since its inception in 2021 has been identifying new areas of high archaeological and paleontological potential in karst zones (covering the Aha Hills, Koanaka Hills and Gcwihaba Hills). Initial fieldwork from this project resulted in uncovering a unique paleontological assemblage within the cave, comprising four distinct units —three stratified levels, likely of Holocene age, from the Deep Chamber and one unit of probable Plio- Pleistocene age from the Corridor area. Pending further absolute dating, they provide an opportunity for a diachronic comparison of the faunal composition and taphonomic signature of the bones. Additionally, we also collected a neotaphonomic owl pellet sample from the entrance of the cave to compare and contrast with fossil data.
The preliminary results of the taxonomic analysis mostly comprises of rodents with a few representations from some soricids, macroscelids, bats, herpetofauna and birds, which suggest a relatively consistent faunal composition over time. The taphonomic analysis (skeletal representation patterns, fragmentation, and surface bone modifications) provided insights into the processes responsible for the accumulation of these remains. The preliminary values obtained from the taphonomic analysis allowed for comparisons with the neotaphonomic values which indicated some similarities in terms of the accumulating agent.
In a subsequent phase, a range of paleoenvironmental reconstruction methods will be applied to investigate the evolution of the environments surrounding the cave from the Plio-Pleistocene to the present.