A new species of ancient lungfish from the Triassic period has been identified from fossilized tooth plate material found in the Mid-Zambezi Basin, Zimbabwe.
Life reconstruction of a Devonian lungfish (smaller creature in the center) and other non-marine species of the Waterloo Farm biota. Image credit: Maggie Newman / R.W. Gess.
Ferganoceratodus edwardsi lived during the Norian age of the Late Triassic epoch, between 227 and 208 million years ago.
The species was a type of lungfish, a group of freshwater vertebrates belonging to the class Dipnoi.
“The distribution of lungfish is now restricted to the former landmasses of Gondwana, i.e., Australia with Neoceratodus, Africa with Protopterus, and South America with Lepidosiren,” said University of Edinburgh paleontologist Tom Challands and his colleagues from Switzerland, South Africa and Zimbabwe.
“The latter two are sister genera and result from a vicariant event associated with the opening of the South Atlantic.”
“The Neoceratodus lineage split is more obscure, and the inclusion of living species in the evolutionary framework is still unable to provide a clear picture of the phylogenetic relationships of post-Paleozoic lungfishes, including living lineages.”
“The Triassic period was a time of both change and stasis with respect to lungfish evolution,” they added.
“Although no substantial changes in gross tooth plate morphology and phylogenetic diversity were observed in Triassic lungfishes, this is the time when we first see changes in lungfish behavior, with abundant evidence for burrowing and aestivation as exemplified by the preservation of numerous burrows in the Chinle Formation of the southwestern United States.”
Petrological micrographs of Ferganoceratodus edwardsi tooth plate. Image credit: Challands et al., doi: 10.1080/02724634.2024.2365391.
A sample of isolated tooth plates from several Ferganoceratodus edwardsi individuals was found in the Pebbly Arkose Formation of the Mid-Zambezi Basin, Zimbabwe.
“The material was discovered at a field site nicknamed ‘The Dentist’ that is situated on the southern shoreline of Lake Kariba, within the boundaries of Matusadona National Park, approximately 50 km west of Kariba,” the paleontologists explained.
“It provides only the second record of a fossil lungfish from Zimbabwe and one of a handful of such occurrences from the Triassic of southern and eastern Africa (from Angola, South Africa, Tanzania, and Zambia).”
According to the study, Ferganoceratodus edwardsi is reminiscent of Ferganoceratodus acutus, which is probably from the Late Triassic of Morafenobe, Madagascar.
“Ferganoceratodus and closely related species arose in the Early Triassic in southern Gondwana and diversified worldwide in the Late Triassic,” the researchers said.
“The genus then became more common in Laurasia during the Jurassic and Early Cretaceous and declined thereafter with relict Late Cretaceous occurrences in Madagascar and South America.”
The team’s paper was published in the Journal of Vertebrate Paleontology.
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Tom J. Challands et al. A new lungfish from the Upper Triassic of the Mid-Zambezi Basin, Zimbabwe. Journal of Vertebrate Paleontology, published online July 31, 2024; doi: 10.1080/02724634.2024.2365391
