Driefontein 11_Synchrotron

The Karoo Supergroup, formed in the Main Karoo Basin of South Africa is an extremely rich and distinctive paleontological region. It records the largest mass extinction in history, the end-Permian extinction (±250 ma). The recovery of terrestrial ecosystems from this mass extinction is an active area of research and one of South Africa’s most important contributions to global palaeontological research. The farm Driefontein 11, in South Africa’s Free State Province, preserves a fossil lagerstattë in the Burgersdorp Formation of the Karoo’s Beaufort Group. Among its most important palaeontological resources are the ecologically, morphologically, and taxonomically diverse set of vertebrate fossils, ranging in size from insects to the largest animals from the earliest Triassic. These document the earliest radiation the most iconic vertebrate groups; including dinosaurs, crocodilians, mammals, squamates, frogs and turtles and so it is considered the ‘dawn of modern ecosystems’. Despite the importance of these fossils, the fauna of Driefontein remains incompletely known – reflecting the sheer numbers of specimens (±30,000 coprolites alone) as well as the fragile nature and microscopic size of many of its remains. Moreover, while taxonomic revisions are underway, the contributions of these fossils make to understanding palaeoecology through other analysis methods are completely untapped. Here, we are applying for permission to scan a wide diversity of fossil material from the Driefontein site at the European Synchrotron and Radiation Facility on BM18. These scans will be aimed at capturing multiple aspects of organismal biology, including growth history (through histology), functional morphology (through quantitative analyses of shape), and comparative anatomy.
The transformation of the European Synchrotron Radiation Facility (ESRF) into an Extremely Bright Source (EBS-ESRF) and the introduction of a new large-field imaging beamline, BM18, offers a new opportunity to push the limits of non-destructive fossil imaging. By imaging a diverse range of fossils at multiple resolutions, this project will create a large database of high-resolution scans that can be used for a wide variety of research and student projects. The multidisciplinary approach engendered by our multi-resolutions scans across the broadest possible sample of vertebrates will allow for the study of diversity, growth and development patterns, organismal biology, evolutionary history, and ecosystem function (e.g., food webs) of all trophic levels in a paleoenvironment.
We aim to scan a representative set of specimens from the vertebrate groups present at Driefontein 11 (See Table attached as separate addendum). These samples can be placed into one of three classes of vertebrate fossil remains namely, limb bones, teeth/jaws with teeth and coprolites. Synchrotron scanning of the limb bone midshafts offers a non-destructive alternative to osteohistological sections, enabling visualisation of the osteocyte lacunae (bone cells), vascular canals and annual growth marks. From this we can estimate minimum age at time of death, investigate the growth strategies present and taxonomic diversity. Multiresolution scanning of the teeth/jaws with teeth allows for the study of gross morphology and dental histology. Finally, multiresolution imaging of the coprolites allows for 3D visualisation of the inclusions which can then be identified to more precise taxonomic levels, and to use material cross-sections and three-dimensional properties to study the fabric of the coprolites to determine their origins.
Our recent imaging of the fossil macrofauna has shown that it is possible to scan a number of large fossils down to the histological level (microstructure of biological tissues), and that this approach can yield a tremendous amount of important scientific information. For example, we were able to image individual inclusions in coprolites (including hexapod mouthparts) and the osteohistology of type specimens.
The most publicized paleontological discoveries often focus on large animals, whereas we know from modern ecosystems that the majority of biomass and biodiversity is centered on the lower range of organismal body sizes. The microfauna present in coprolites is extremely difficult to study, being difficult to locate within the coprolite and almost impossible to study in its entirety. Synchrotron X-rays have already shown their ability to image inclusions, such as insects in amber, but with the multiresolution and hierachical approach, we are able to identify diagnostic micro-level structures for taxonomic families that were previously unknown in the early Triassic.
Altogether, this research will contribute to our knowledge of the recovery of terrestrial ecosystems after the largest mass extinction in history, the end-Permian extinction, and highlights the importance of Driefontein 11 as a site for future research in the field of palaeontology