The Karoo igneous rocks represent one of the largest continental flood basalt events (by volume) on Earth, and are not normally associated with fossils remains. However, these Pliensbachian-Toarcian lava flows contain sandstone interbeds that are particularly common in the lower part of the volcanic succession and are occasionally fossiliferous. On a sandstone interbed in the northern main Karoo Basin, we discovered twenty-five tridactyl and tetradactyl vertebrate tracks comprising five trackways. The tracks are preserved among desiccation cracks and low-amplitude, asymmetrical ripple marks, implying deposition in low energy, shallow, ephemeral water currents. Based on footprint lengths of 2-14 cm and trackway patterns, the trackmakers were both bipedal and quadrupedal animals of assorted sizes with walking and running gaits. We describe the larger tridactyl tracks as "grallatorid" and attribute them to bipedal theropod dinosaurs, like Coelophysis, a genus common in the Early Jurassic of southern Africa. The smallest tracks are tentatively interpreted as Brasilichniumlike tracks, which are linked to synapsid trackmakers, a common attribution of similar tracks from the Lower to Middle Jurassic record of southern and southwestern Gondwana. The trackway of an intermediate-sized quadruped reveals strong similarities in morphometric parameters to a post-Karoo Zimbabwean trackway from Chewore. These trackways are classified here as a new ichnogenus attributable to small ornithischian dinosaurs as yet without a body fossil record in southern Africa. These tracks not only suggest that dinosaurs and therapsids survived the onset of the Drakensberg volcanism, but also that theropods, ornithischians and synapsids were among the last vertebrates that inhabited the main Karoo Basin some 183 Ma ago. Although these vertebrates survived the first Karoo volcanic eruptions, their rapidly dwindling habitat was turned into a land of fire as it was covered by the outpouring lavas during one of the most dramatic geological episodes in southern Africa.

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The rock record from the late Early Jurassic in southern Africa encompasses the history of voluminous continental flood basalt outpourings associated with the magmatic events in the Karoo–Ferrar Large Igneous Province (LIP) in southern and eastern Gondwana. This multiphase magmatism produced one of Earth’s largest continental flood basalt successions volumetrically and is assumed to have been a main driving mechanism in late Early Jurassic global environmental perturbations, including mass extinctions and changes in climate. In southern Africa, these Lower Jurassic flood basalts are interbedded with fossiliferous sedimentary rocks, which in turn host the last signs of ‘Karoo life’ in the form of fossil plants, invertebrates and vertebrates, including the trackways of hopping mammals and the ultimate Karoo dinosaurs. The sedimentology and palaeontology of the interbeds archived depositional and biotic processes in running water as well as in and around shallow, up to ∼10 m deep freshwater lakes and ponds in the late Early Jurassic. This study explains how a complex freshwater palaeo-habitat prevailed – albeit temporarily – in this extremely stressful environment, which was unlike any modern volcanic system. The evidence collectively points to seasonally wet, warm temperate climatic conditions during the early phases of Karoo volcanism. Moreover, the evidence in the rocks also suggests that the dynamic volcanic conditions resulted in shifting habitats that likely facilitated the migration of the ultimate Karoo biota towards the north and west, away from the main Karoo land of fire, just before Gondwana started to disassemble. This refinement of the environmental dynamics in southern Gondwana presented herein lays the groundwork for future high-resolution volcanological, geochronological and chemostratigraphical studies aimed at the nuanced understanding of the global environmental effect of the Karoo–Ferrar LIP.

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