Back to the future: A fossil found in the Sixties has been reanalysed by a student at Wits. Photos: Supplied
History is “written in rocks”, said Fonda Matlhaga, a master’s student at the Evolutionary Studies Institute at the University of the Witwatersrand.
“If we neglect what happened in the past, then it will be difficult for us to predict the future,” he said.
“It’s important to go back in time and see how we ended up where we are because you can only connect the dots by looking back.”
Matlhaga is the lead author of research that has unveiled a new species of biarmosuchian therapsid, Impumlophantsi boonstrai. The discovery marks a significant development in palaeontology from the South African Karoo Basin.
This middle Permian species, dating back about 260 million years, adds a new piece to the evolutionary puzzle of therapsids, the long extinct group of vertebrates that eventually gave rise to modern mammals and were “mammal-like reptiles”.
The new description of the 100mm-long skull was published in the journal Palaeontologia africana by Matlhaga; his supervisor and co-author Julien Benoit and Bruce Rubidge, a distinguished professor at the Evolutionary Studies Institute at Wits University.
The authors said that their findings filled a gap in the understanding of the early evolutionary history of biarmosuchians, “one of the most basal branches of the therapsid lineage”.
“This research is important because biarmosuchians are the most basal therapsids and are represented by relatively few specimens,” said Matlhaga.
“Impumlophantsi boonstrai is of importance as very few biarmosuchian fossils are known from the middle Permian Tapinocephalus Assemblage Zone deposits of the Karoo Basin.”
The newly described species helps illuminate a lesser-understood chapter in this group’s evolution.
This zone is part of the fossil-rich Beaufort Group and is crucial for understanding a period of evolutionary change among early therapsids.
The researchers said that burnetiamorphs, the sub-group of biarmosuchians to which Impumlophantsi belongs, are notable for their distinctive and “often bizarre” cranial ornamentation.
Many species sported ridges, knobs and other bony structures that probably played a role in species recognition or social signalling. But Impumlophantsi stands apart with a more subdued nasal crest, which earned it its name — “impumlophantsi” means “low nose” in isiXhosa.
The species was named in honour of Lieuwe D Boonstra, a pioneering South African palaeontologist who initially discovered the specimen but “did not appreciate its significance”.
What makes Impumlophantsi particularly important is its place in time. The fossil skull comes from the middle Permian, a period in which burnetiamorph fossils are relatively scarce. Before this discovery, most known burnetiamorph fossils came from the late Permian, leaving a gap in the record.
Impumlophantsi helps fill that gap: “This specimen indicates that mid-Permian biarmosuchian diversity has been underestimated and helps to fill in a major ghost lineage in the evolution of this group,” Matlhaga noted.
“The presence of such a basal species in the middle Permian suggests that the diversification of biarmosuchians began earlier than previously documented, reshaping our understanding of their evolutionary timeline.”
While burnetiamorphs are primarily known to be from the Karoo, their evolutionary history extends across much of what was once the supercontinent Pangaea.
The researchers said this finding raised the possibility that there are undiscovered fossils in other regions of Pangaea, particularly in places where middle Permian rocks remain under-explored.
It also underscores the importance of revisiting historical fossil collections, because Impumlophantsi was found decades ago but was only recently identified as a new species through Matlhaga’s modern preparation and analytical techniques, which the 25-year-old ascribed to his curiosity and dedication.
The specimen of Impumlophantsi was described in the Sixties but misclassified as a gorgonopsian. Only through Matlhaga’s re-examination with updated methodologies and technology was its true nature as a burnetiamorph revealed.
“These animals were rare and they are still even rare in the fossil record,” he said. “Even when you go into the field, you hardly find them — around the world, they are not that abundant.”
There is still much to unravel, Matlhaga added. “Expanding our knowledge of biarmosuchians during the middle Permian opens new avenues of research into how these creatures responded to the environmental pressures of the time, including climate fluctuations and competition with other emerging species.
“We would like to discover more biarmosuchians and basal therapsids in future fieldwork as that will give us an insight about the diversity of these distant ancestors of mammals,” he said.