Madumabisa is a genus of dicynodont, an extinct type of therapsid (the group which modern mammals also belong to), that lived in eastern Africa during the Late Permianperiod. Fossils of Madumabisa have been discovered in what is now Zambia from rocks of the Madumabisa Mudstone Formation, which it is named after. The type and only known species is M. opainion, and was named in 2025. Madumabisa is an early member of the familyLystrosauridae and a close relative of the near-cosmopolitan genus Lystrosaurus that would survive the mass extinction at the end of the Permian. It is less specialised than other lystrosaurids, lacking features such as the drawn-down snout of Lystrosaurus or the unusual proportions of the contemporary Euptychognathus, superficially resembling more typical dicynodonts like Dicynodon. Madumabisa is one of the most abundant species found in the upper Madumabisa Mudstone Formation, contrasting with the relative rarity of Lystrosaurus in the Permian of the Karoo Basin. It demonstrates that lystrosaurids were not uniformly rare in Permian ecosystems prior to the mass extinction event, and were important components of the fauna in some locations.
The first fossils of Madumabisa were collected by Thomas S. Kemp in 1974 on a joint expedition from the University of Oxford and the Geological Survey of Zambia to the Luangwa Basin of northeast Zambia. The fossils were assigned to the genus Dicynodon, which at the time acted as a wastebasket taxon for many Permian dicynodonts. The specimens were tentatively assigned to Dicynodoncf.huenei, a species which has since been reassigned to Daptocephalus. These specimens consist of a partial skull missing the back end, and a collection of eight skulls (six complete) and abundant postcranial remains of young juveniles. These specimens, formerly in T. S. Kemp's own collections in Oxford, are now housed in the Natural History Museum, London (NHMUK).[1][2]
Madumabisa would not be recognised until new fossils were collected during a series of expeditions returning to the Luangwa Basin from 2009 to 2019 by a multi-institutional research group.[2]As of 2025[update], these specimens are held in the National Heritage Conservation Commission (NHCC) in Lusaka, Zambia, but will be permanently housed in Zambia's Livingstone Museum.[1][2]Madumabisa was described and named in 2025 by Christian Kammerer, Kenneth Angielczyk and Jörg Fröbisch. The holotype specimen is a nearly complete skull with a femur and partial rib fragments, catalogued as NHCC LB37. Three other nearly complete skulls were collected, NHCC LB206, LB822 (both with lower jaws) and the smaller LB794, as well as the front half of a fourth skull, NHCC LB857. Combined with the specimens collected by Kemp, Madumabisa is known from a nearly complete growth series and is one of the most abundant dicynodonts in the upper Madumabisa Mudstone Formation.[1]
The genus is named after the Madumabisa Mudstone Formation its fossils hail from, which itself comes from "Ndumebiza", the name of a prominent hill in the Hwange District of Zimbabwe (where rocks of this formation are also exposed).[2] The specific nameopainion is derived from the Ancient Greek words ὀπαῖος (opaios), meaning "with a hole", and ἰνίον (inion), referring to the occipital bone or the back of the skull. The combination refers to the unique additional pair of holes in the back of the skull below the postemporal fenestra in Madumabisa.[1]
Skull of Madumabisa (NHMUK PV R 37363) in dorsal view (from above)
All fossils of Madumabisa come from the protected Munyamadzi Game Management Area of the Luangwa Valley of Zambia's Muchinga Province.[1] The fossils were found in the upper layers of the Madumabisa Mudstone Formation, which is exposed in the Luangwa Basin of northeastern Zambia and further south in the Mid-Zambezi Basin along the Zambia-Zimbabwe border.[2] The stratigraphy of the Madumabisa Mudstone Formation has not been formally subdivided, however its fossil fauna is recognised as falling into at least a distinct lower and upper faunal assemblage. These assemblages have been correlated with those of the well-studied framework in the Karoo Basin of South Africa, which correlates the upper Madumabisa Mudstone Formation with the Daptocephalus Assemblage Zone (AZ) of the Karoo.[3] The Daptocephalus AZ has been dated to between 255.2 and roughly 252 million years ago.[4] Within the upper assemblage, fossils of Madumabisa come from the stratigraphically highest (and so the youngest) rocks in the Madumabisa Mudstone Formation. Below them, the fauna is comparable to the Dicynodon-Theriognathus Subzone (Sz) of the Daptocephalus AZ. The abundance of Madumabisa stratigraphically higher may suggest the uppermost portion of the Madumabisa Mudstone Formation correlates to the Lystrosaurus maccaigi-Moschorhinus Sz of the Daptocephalus AZ, paralleling the increase of lystrosaurids in the Karoo.[3] The L. maccaigi-Moschorhinus Sz has been approximately dated to between 253 and 252 million years ago.[4]
Classification
Madumabisa is a member of the family Lystrosauridae under Linnaean taxonomy, which is defined phylogenetically as the clade of dicynodonts closer to Lystrosaurus than to Dicynodon or the Triassic kannemeyeriiforms.[5] A phylogenetic analysis by Kammerer and colleagues in 2025 found Madumabisa as the sister taxon to the two species of Euptychognathus at the base of the Lystrosauridae. However, the authors noted that some traits of Madumabisa are more like those of Lystrosaurus than Euptychognathus, which may indicate it is in fact more closely related to it than to Euptychognathus.[1]
The cladogram below depicts the simplified results of the phylogenetic analysis in Kammerer et al. (2025):[1]
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