Unlocking Gondwana’s 120-million-year archive: Comprehensive synthesis explains palaeo-climate dynamics, extinction events, and evolution in South Africa’s Karoo Basin

A 25-year synthesis refines Gondwana's 120-million-year geological archive

Integrating 25 years of sedimentological, geochronological, and palaeontological research, a systematic review refines the stratigraphic framework of Gondwana’s deep-time record

A new review led by Professor Emese Bordy at the University of Cape Town (UCT) Department of Geological Sciences, brings together more than two decades of research on the Karoo Supergroup, revealing how scientific understanding of this iconic geological archive has changed since 2000.

Published as an open-access article in the South African Journal of Geology, the review is freely available to researchers, educators, students and members of the public. It synthesises advances in sedimentology, stratigraphy, palaeontology and basin analysis, highlighting both major discoveries and key unanswered questions.

“The deeper we dig into the Karoo, the more complex and fascinating its story becomes,” said Professor Bordy. “The Karoo is far more than vast vistas above a stack of layered rocks; it is a global outdoor laboratory for understanding how ancient sea- and landscapes, climate systems, and living communities responded to extreme stress. By integrating sedimentology, stratigraphy, ichnology, palaeobotany, vertebrate palaeontology, and geochronology, this review is not the final word on the Karoo, but a progress report on an extraordinary geological archive that still has so much to teach us.”

A record of Gondwana’s past

The Karoo Supergroup records about 120 million years of Earth history, from the Late Carboniferous to the Early Jurassic. It preserves evidence of climatic change, volcanic and tectonic activity, ecosystem turnover and several major extinction events.

The Karoo has long been recognised as one of the most important archives of past events in Gondwana, the supercontinent that once united Africa, South America, Antarctica, India, Madagascar and Australia. Its rocks and fossils helped shape early ideas about continental drift and continue to provide insights into Earth’s past.

Reflecting the breadth of the Karoo record, the review is richly illustrated with original figures, alongside reproductions of earlier milestone publications and large panorama paintings by South African palaeo-artist Maggie Lambert-Newman. Together, they help visualise the ancient ecosystems discussed throughout the paper.

A more complex climate story

One of the review’s key findings is that the Karoo’s climatic history was more complex than previously thought. Earlier interpretations suggested a gradual shift towards increasingly dry conditions through Karoo times. However, research conducted over the past 25 years points to non-linear climatic changes and environmental fluctuations, particularly in younger parts of the Karoo succession.

According to the authors, multiple lines of evidence now show that climate, tectonics and sedimentation interacted in ways that produced a far more complex geological record than earlier models suggested.

New insights into life and extinction

The Karoo remains one of the world’s most important fossil archives. Advances in research methods, including high-resolution imaging and improved evolutionary analyses, have led to new fossil discoveries and refined fossil-based correlations across Gondwana.

The review highlights how these discoveries are improving understanding of ecosystem change during major biological crises, including the end-Capitanian, end-Permian, end-Triassic and end-Pliensbachian extinction events.

New evidence also points to ecosystem resilience during periods of profound environmental change, helping scientists better understand patterns of extinction and recovery in Earth’s history.

Refining the geological timeline

Researchers have also made significant progress in improving the Karoo’s chronological framework. Techniques such as radioisotopic dating via detrital zircon geochronology and magnetostratigraphy are helping scientists determine the ages of rock layers more accurately and strengthen correlations with equivalent rock records across former Gondwanan continents.

These advances are providing a more precise framework for understanding the timing of climatic, tectonic and biological events recorded in the Karoo Basin.

The next frontier

Despite major progress, important questions remain including exactly when and how key formation boundaries formed, how much of the basin's rock record reflects climate versus tectonic forces, and how different parts of the basin responded to the same global events. Addressing these will mean combining more precise dating techniques with expanded fossil surveys and, increasingly, remote sensing and machine-learning tools to analyse the huge datasets involved.

The stakes go beyond palaeontology. The same rock layers that record Gondwana's past are also being assessed for groundwater resources, potential for critical minerals and carbon storage, making the Karoo a live resource question as much as a historical one.

Twenty-five years on, the Karoo remains one of the world's most important places to study how climate, tectonics and life interact over long geological periods.