Abstract

 
 
 Computed tomography (CT) imaging of fossils has revolutionised the field of palaeontology, allowing researchers to gain a better understanding of fossil anatomy, preservation and conservation. Micro focus X-ray computed tomography (μXCT) has been far more extensively used for these purposes than medical CT (XCT) – mostly because of the exquisite detail that the μXCT scanning modality, using slices of micron thicknesses, can produce. High energy X-rays can potentially penetrate breccia more effectively than lower energy beams. This study demonstrates that lower energy beams produce superior images for prioritising breccia for preparation. Additionally, XCT scanners are numerous, accessible, fast and relatively cost-effective when compared to μXCT scanners – the latter are not freely available, scanning times are much longer and there are significant limitations on the size and weight of scannable objects. Breccia blocks from Malapa were scanned at high and lower energy and images were analysed for image quality, artifact and certainty of diagnosis. Results show that lower energy images are deemed superior to higher energy images for this particular application. This finding, taken together with the limitations associated with the use of μXCT for the imaging of the large breccia from Malapa, shows that XCT is the better modality for this specific application. The ability to choose fossil-bearing breccia, ahead of manual mechanical preparation by laboratory technicians, would allow for the optimal use of limited resources, manual preparatory skills as well as the curtailment of costs.
 
 
 
 
 Significance: 
 
 
 
 ‘Blind’ manual preparation of fossil-bearing breccia is a costly and time-consuming exercise – and often results in a low yield.
 The ability to triage fossil-bearing breccia ahead of manual preparation would allow for the optimal use of limited resources.
 Medical CT is better than micro-CT to triage breccia to allow for prioritisation of rocks for manual preparation.
 
 
 
Highlights
The use of computed tomography (CT) in the analysis of fossils has become common place[1,2,3,4], most of the CT work to date has been performed on prepared or partially prepared specimens[3,5,6]
Results were assessed to determine which kVp choice scored higher per reader, per object and per criterion, and whether the reader assigned the same score per criterion per object – the latter indicating an indeterminate result of neither kilovoltage setting producing a superior image (Table 3)
Microcomputed tomography is well established as an imaging modality for the imaging of prepared fossils
Summary
The use of computed tomography (CT) in the analysis of fossils has become common place[1,2,3,4], most of the CT work to date has been performed on prepared or partially prepared specimens[3,5,6]. The site of Malapa has yielded hundreds of breccia blocks, which have the potential to contain fossils of the hominin Australopithecus sediba. Breccia has undergone manual preparation – with a single block taking months to adequately prepare, with no guarantee of obtaining any fossils. This process is costly – both in time and money – and is not a prudent use of scarce preparatory skills
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