Remains of a barn owl (Tyto alba) from the Dinaledi Chamber, Rising Star Cave, South Africa

Ashley Kruger,Shaw Badenhorst

doi:10.17159/sajs.2018/5152

Abstract

Excavations during November 2013 in the Rising Star Cave, South Africa uncovered over 1550 specimens of a new hominin, Homo naledi. A total of four modern bird bones were collected from the surface of the Dinaledi Chamber during the first phase of the initial excavations. While mentioned in the geological and taphonomic descriptions, the presumably modern or sub-modern bird remains have not been formally identified or described until now. Here we identify these remains as indistinguishable from those of a modern barn owl (Tyto alba). Tyto alba is today common to the region and known to contribute microfaunal remains at many Plio-Pleistocene sites in the Cradle of Humankind. Based on the greatest length measurement and breadth of the proximal articulation of the specimen, it is suggested that the owl from the Dinaledi Chamber is more similar to that of females of the species, despite the small sample sizes available for comparison. It is unclear how the remains of this female owl came to be in the remote Dinaledi Chamber. Significance:  Owl bones from the Dinaledi Chamber are the only other macro-vertebrate remains from this Chamber. The other remains discovered are that of more than 15 individuals of the enigmatic Homo naledi. The remains of the Dinaledi Chamber owl further our understanding of the contents of the important material contained within the Dinaledi system as they are the only more recent fossils to be recovered from this area of the Rising Star Cave system and are therefore important in and of themselves as an indicator that more proximal parts of the Rising Star Cave system have been suitable for use by barn owls at greater time depths than the present.

Highlights

The Rising Star siteThe Rising Star Cave system is located in the Cradle of Humankind UNESCO World Heritage Site, 50 km westnorthwest of Johannesburg, South Africa (Figure 1)
The remains of the Dinaledi Chamber owl further our understanding of the contents of the important material contained within the Dinaledi system as they are the only more recent fossils to be recovered from this area of the Rising Star Cave system and are important in and of themselves as an indicator that more proximal parts of the Rising Star Cave system have been suitable for use by barn owls at greater time depths than the present
This assemblage is the largest single collection of fossil hominin material found on the African continent to date, and the Rising Star Cave system is the only current location of remains of the hominin taxon, H. naledi.[1,2,4,5]

Summary

Introduction

The Rising Star Cave system is located in the Cradle of Humankind UNESCO World Heritage Site, 50 km westnorthwest of Johannesburg, South Africa (Figure 1). Sites such as Sterkfontein, Kromdraai, Swartkrans and Malapa are noted for yielding fossil remains typically contained in lithified breccias, or found in decalcified sedimentary units derived from clastic lithified breccia.[6,7,8,9,10,11] In the majority of Cradle of Humankind fossil-bearing caves, it is hypothesised that skeletal material was brought into the system through a variety of agents, before being lithified.[12] Such agents can be biotic or abiotic, and include processes such as the effects of gravity (for example a fatal fall into a natural death trap, or downslope movement on talus slopes), vertebrate accumulation (predation or scavenging by carnivores, or accumulation by rodents), mass movement of sediments, fluvial transportation, or animal movement into the systems, or a combination of such processes. We describe the four bird remains from the Dinaledi Chamber, using several possible explanations, expressed as hypotheses, to try explain how these bird bones were introduced into the Dinaledi Chamber

Methods and results

Findings

Discussion and conclusion