''Kembawacela'' ("iron digger") is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of cistecephalid

dicynodont Dicynodontia is an extinct clade of anomodonts, an extinct type of non-mammalian therapsid. Dicynodonts were herbivorous animals with a pair of tusks, hence their name, which means 'two dog tooth'. Members of the group possessed a horny, typic ...

from the

Late Permian Late may refer to: * LATE, an acronym which could stand for: ** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia ** Local-authority trading enterprise, a New Zealand business law ** Local average treatment effect, ...

of East Africa. The genus contains two known

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

, the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...

''Kembawacela kitchingi'' from the Madumabisa Mudstone Formation of

Zambia Zambia (), officially the Republic of Zambia, is a landlocked country at the crossroads of Central, Southern and East Africa, although it is typically referred to as being in Southern Africa at its most central point. Its neighbours are t ...

described in 2019, and a second species, ''K. yajuwayeyi'', from the Chiweta Beds of

Malawi Malawi (; or aláwi Tumbuka: ''Malaŵi''), officially the Republic of Malawi, is a landlocked country in Southeastern Africa that was formerly known as Nyasaland. It is bordered by Zambia to the west, Tanzania to the north and northeas ...

described in 2022. Like other cistecephalids, ''Kembawacela'' was specialised for a fossorial, burrowing lifestyle similar to modern day moles. It is unique amongst cistecephalids for the presence of a pair of tusks in the upper jaw, characteristic of many other dicynodonts but lost in other cistecephalids. It is likely that ''Kembawacela'' was a locally

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

species of cistecephalid in the

Luangwa Basin Luangwa may refer to: *Luangwa River, the major river of eastern Zambia * Luangwa Bridge, which crosses the Luangwa River * Luangwa River (Mporokoso), a tributary of the Kalungwishi River in Mporokoso District, Zambia; * Luangwa, Zambia, a town in Z ...

of Zambia.

Description

''Kembawacela'' broadly resembled other cistecephalids in size and shape. It was a small dicynodont (skull length roughly long along the base) and had a highly specialised body plan for digging. ''Kembawacela'' is known from skulls, lower jaws and various pieces of postcrania, including parts of the pelvis,

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...

ulna The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...

and various vertebrae. Although broadly similar in superficial appearance, the two species ''K. kitchingi'' and ''K. yajuwayeyi'' can be distinguished by details of the skull architecture. Its skull is typical for cistecephalids, with a broad head and large

temporal fenestra An infratemporal fenestra, also called the lateral temporal fenestra or simply temporal fenestra, is an opening in the skull behind the orbit in some animals. It is ventrally bordered by a zygomatic arch. An opening in front of the eye sockets ...

with a very short, tapered snout. It had large, strongly forward facing eyes like some other cistecephalids (including ''

Cistecephalus ''Cistecephalus'' is an extinct genus of dicynodont therapsid from the Late Permian of southern Africa (South Africa and Zambia). It was a small, specialised, burrowing dicynodont, possibly with habits similar to a modern mole. The head was flat ...

''), but unlike the smaller, sideways facing eyes of ''

Cistecephaloides ''Cistecephaloides'' is an extinct genus of dicynodont therapsids of the Cistecephalus Assemblage Zone, ''Cistecephalus'' Assemblage Zone, Beaufort Group of South Africa.Kawingasaurus''. Similarly, the

zygomatic arch In anatomy, the zygomatic arch, or cheek bone, is a part of the skull formed by the zygomatic process of the temporal bone (a bone extending forward from the side of the skull, over the opening of the ear) and the temporal process of the zygo ...

es project out almost laterally behind the eyes and curve back almost 90 degrees to the back of the skull. The

pineal foramen A parietal eye, also known as a third eye or pineal eye, is a part of the epithalamus present in some vertebrates. The eye is located at the top of the head, is photoreceptive and is associated with the pineal gland, regulating circadian rhyth ...

("third eye") is positioned very far back on the roof of the skull, overhanging the very back of the skull (similar to '' Sauroscaptor''). ''Kembawacela'' is most obviously distinguished by the prominent tusks in its upper jaw. The majority of ''Kembawacela'' specimens have these tusks, and it is possible that they were

sexually dimorphic Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

in this species. These tusks face slightly out to the sides, but do not sit out on a prominent caniniform process projecting from the jaw margin like in some other dicynodonts. Aside from the tusks, ''Kembawacela'' was otherwise toothless, and possessed a

keratin Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin (α-keratin) is a type of keratin found in vertebrates. It is the key structural material making up scales, hair, nails, feathers, ho ...

ous beak at the tips of its jaws, as is typical of dicynodonts. The beak was relatively broad and blunt, and the tip of the upper jaw was arched upwards. Between ''K. kitchingi'' and ''K. yajuwayeyi'', they can be distinguished by details of the individual bones and anatomy of the skull, including the shape of the

jugal bone The jugal is a skull bone found in most reptiles, amphibians and birds. In mammals, the jugal is often called the malar or zygomatic. It is connected to the quadratojugal and maxilla, as well as other bones, which may vary by species. Anato ...

of the cheek. In ''K. kitchingi'', the ascending process that joins to the

postorbital bone The ''postorbital'' is one of the bones in vertebrate skulls which forms a portion of the dermal skull roof and, sometimes, a ring about the orbit. Generally, it is located behind the postfrontal and posteriorly to the orbital fenestra. In some v ...

to form the

postorbital bar The postorbital bar (or postorbital bone) is a bony arched structure that connects the frontal bone of the skull to the zygomatic arch, which runs laterally around the eye socket. It is a trait that only occurs in mammalian taxa, such as most strep ...

rimming the eye socket is exposed on the back of the bar, while in ''K. yajuwayeyi'' it is hidden on the internal side. Further, the anterior process of the jugal beneath the eye is notably taller in ''K. yajuwayeyi'' than in ''K. kitchingi'', despite the only known skull of the former being slightly compressed. Another difference is in the position of the maxillary canal, a channel for the sensitive

trigeminal nerve In neuroanatomy, the trigeminal nerve ( lit. ''triplet'' nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for sensation in the face and motor functions such as biting and chew ...

and its blood vessels in the snout. In ''K. kitchingi'' it emerges and runs laterally from the

maxillary sinus The pyramid-shaped maxillary sinus (or antrum of Highmore) is the largest of the paranasal sinuses, and drains into the middle meatus of the nose through the osteomeatal complex.Human Anatomy, Jacobs, Elsevier, 2008, page 209-210 Structure It i ...

, whereas the canal sits just anteriorly in front of the sinus in ''K. yajuwayeyi''. The angle between the anterior rami of the

pterygoid bone The pterygoid is a paired bone forming part of the palate of many vertebrates Vertebrates () comprise all animal taxa within the subphylum Vertebrata () (chordates with backbones), including all mammals, birds, reptiles, amphibians, and fis ...

s (sheets of bone connecting to the palatine bones in front) on the roof of the mouth also differs between them, with ''K. yajuwayeyi'' having a much narrower ~46° angle between them compared to the ~61° of ''K. kitchingi''. The body of ''Kembawacela'' is poorly known, but the preserved skeleton of ''K. kitchingi'' resembles that of other cistecephalids like ''Cistecephalus''. It had three

sacral vertebra The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part ...

e and an ilium with well developed forward and backward pointing processes, and a large, robust ulna in the arm. Unlike ''Cistecephalus'', however, the head of the femur is roughly triangular shaped.

History of discovery

Specimens of ''Kembawacela'' were first discovered and collected in the 1960s by Alan Drysdall and

James Kitching James William Kitching (6 February 1922 – 24 December 2003) was a South African vertebrate palaeontologist and regarded as one of the world’s greatest fossil finders. Career His work in the southern hemisphere, including Antarctica, led ...

in the Luangwa Basin of Zambia. They reported discovering at least 13 specimens that they preliminarily assigned to ''Cistecephalus microrhinus'' and the now synonymous ''C. planiceps''. Four of these specimens were identified in the collections of the Evolutionary Studies Institute at the

University of the Witwatersrand The University of the Witwatersrand, Johannesburg (), is a multi-campus South African public research university situated in the northern areas of central Johannesburg. It is more commonly known as Wits University or Wits ( or ). The university ...

Johannesburg Johannesburg ( , , ; Zulu and xh, eGoli ), colloquially known as Jozi, Joburg, or "The City of Gold", is the largest city in South Africa, classified as a megacity, and is one of the 100 largest urban areas in the world. According to Dem ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. It is bounded to the south by of coastline that stretch along the Atlantic Ocean, South Atlantic and Indian Oceans; to the ...

, although a possible fifth specimen originally noted by Kitching has since been lost. The specimens were later suggested to belong to a new species of ''Cistcephalus'' in an unpublished BSc honours

thesis A thesis ( : theses), or dissertation (abbreviated diss.), is a document submitted in support of candidature for an academic degree or professional qualification presenting the author's research and findings.International Standard ISO 7144: ...

by Freeman in 1993. Further examinations and the discovery of an additional four specimens proposed that the Luangwa cistecephalid was an entirely new genus. In 2019, the taxon was formally described in detail and named ''Kembawacela kitchingi'' by Kenneth Angielczyk, Julien Benoit and Bruce Rubidge. The genus name is from the phrase "kemba wacela", translated to "iron digger" in the locally spoken

Bemba language The Bemba language, ''ChiBemba'' (also ''Cibemba, Ichibemba, Icibemba'' and ''Chiwemba''), is a Bantu language spoken primarily in north-eastern Zambia by the Bemba people and as a lingua franca by about 18 related ethnic groups. History Bem ...

. It was named for the iron-rich hematite nodules various specimens from the Luangwa Basin—including the

type specimen In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes th ...

of ''Kembawacela'' (NHCC LB18)—have been found in, as well referring to the proposed digging lifestyle of cistecephalids. The species was named to honour James Kitching, who collected the first specimens of ''Kembawacela''. The specimens were collected from various different localities in the Luangwa Basin, but were all from the upper Madumabisa Mudstone Formation. This formation is believed to overlap in time with the ''Cistecephalus'' Assemblage Zone (AZ) and ''Daptocephalus'' AZ of the Karoo Basin in

, which have been dated to the

Wuchiapingian In the geologic timescale, the Wuchiapingian or Wujiapingian (from in the Liangshan area of Hanzhong, Shaanxi Province) is an age or stage of the Permian. It is also the lower or earlier of two subdivisions of the Lopingian Epoch or Series. Th ...

to early

Changhsingian In the geologic time scale, the Changhsingian or Changxingian is the latest age or uppermost stage of the Permian. It is also the upper or latest of two subdivisions of the Lopingian Epoch or Series. The Changhsingian lasted from to 251.902 ...

in the

. The specimens are housed at both the Evolutionary Studies Institute in South Africa and at the National Heritage Conservation Commission in Lusaka, Zambia. In 2016, a cistecephalid skull (DMMM-PK-16-1) was found encased in a rock nodule during exploration of the Chiweta Beds in the Mount Waller Area of Northern Malawi. Due its small size and delicate nature, the examination of the specimen was performed using

x-ray microtomography X-ray microtomography, like tomography and X-ray computed tomography, uses X-rays to create cross-sections of a physical object that can be used to recreate a virtual model (3D model) without destroying the original object. The prefix ''micro-'' ...

to image the bones inside the rock matrix. This skull was formally described and named as a new species of ''Kembawacela'', ''K. yajuwayeyi'', by Araújo and colleagues in 2022. The authors named the species in honour of their friend Dr. Yusuf Juwayeyi, an accomplished archaeologist, professor, and international representative of Malawian research. The

species name In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

combines the surname Juwayeyi with ''Ya-'', the

possessive prefix In linguistics, a possessive affix (from la, affixum possessivum) is an affix (usually suffix or prefix) attached to a noun to indicate its possessor, much in the manner of possessive adjectives. Possessive affixes are found in many language ...

in the

Chichewa language Chewa (also known as Nyanja, ) is a Bantu language spoken in much of Southern, Southeast and East Africa, namely the countries of Malawi , where it is an official language, and Mozambique and Zambia. The noun class prefix ''chi-'' is used for ...

. The skull is mostly complete, missing only the tip of the snout, its left zygomatic arch and postorbital bar behind the eye, and parts of the

occiput The occipital bone () is a cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone overlies the occipital lobes of the cereb ...

Classification

''Kembawacela'' is well supported as a member of the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Cistecephalidae in the phylogenetic analysis of Angielczyk ''et al.'' (2019), where it was found as a relatively basal member of the clade: ''Kembawacela'' is primarily distinguished from other cistecephalids by its tusks, but can also be uniquely diagnosed by a trough on the underside of the

vomer The vomer (; lat, vomer, lit=ploughshare) is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right max ...

and an

interparietal bone An interparietal bone (os interparietale or Inca bone or ''os inca var.'') is a dermal bone situated between the parietal and supraoccipital. It is homologous to the postparietal bones of other animals. In humans, it corresponds to the upper p ...

with paired extensions that reach up from the back of the skull to flank the pineal foramen. There are also various other slight differences of the skull and skeleton between it and other cistecephalids.

Palaeobiology

It is possible that ''Kembawacela'' was sexually dimorphic, as two of the seven known specimens appear to have lacked tusks. Notably, one of these specimens is the largest known individual, implying that the lack of tusks was not due to it not being fully grown yet. Sexual dimorphism is known from other cistecephalids, such as the prominent ridges over the eyes in ''Cistecephalus'', and although ''Kembawacela'' lacks those traits the presence or absence of tusks is suggested to be an indicator of sexual dimorphism more broadly in dicynodonts. Unfortunately, the relatively small sample size means this possibility cannot be statistically analysed. The tusks of ''Kembawacela'' are also notable as one specimen preserves unerupted tusks within the jaw bones. There is no evidence that these tusks are replacements of a previous pair (as has been suggested to occur in ''

Diictodon ''Diictodon'' is an extinct genus of pylaecephalid dicynodont. These mammal-like synapsids lived during the Late Permian period, approximately 255 million years ago. Fossils have been found in the ''Cistecephalus'' Assemblage Zone of the Mad ...

''), and another specimen with the inside of the jaw exposed preserves no such replacements either. The size of the specimen is comparable to the others, which would suggest that the tusks of ''Kembawacela'' may not have erupted until quite late in the animal's life, close to their mature body size. It's possible that this relatively late eruption of the tusks in ''Kembawacela'' was taken even further in other cistecephalids, where their development was suppressed and prevented entirely from erupting in the tuskless species.

Burrowing

''Kembawacela'' shares various features with other cistecephalids associated with a fossorial (burrowing) lifestyle. The ulna, the only known bone from the forelimb, has the typically large

olecranon process The olecranon (, ), is a large, thick, curved bony eminence of the ulna, a long bone in the forearm that projects behind the elbow. It forms the most pointed portion of the elbow and is opposite to the cubital fossa or elbow pit. The olecranon ...

associated with scratch-digging found in other cistecephalids. The skull has various features associated with burrowing, being broad and wedge-shaped. The large, forward facing eyes may be related to seeing in low-light environments, with binocular vision providing greater light sensitivity, although this is not typical of modern fossorial mammals which have small eyes (as in ''Cistecephaloides'' and ''Kawingasaurus''). Interestingly, ''Kembawacela'' is the only known cistecephalid known to preserve pieces of the bony

sclerotic ring Sclerotic rings are rings of bone found in the eyes of many animals in several groups of vertebrates, except for mammals and crocodilians. They can be made up of single bones or multiple segments and take their name from the sclera. They are bel ...

surrounding the eye, and they are remarkably smaller than is suggested by the size of the

orbits In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a p ...

. However, they were too incompletely preserved to estimate the light sensitivity of the eyes. The footplates of the bony stapes are large, associated with hearing low-frequency sounds underground, although its inner-ear is not as specialised as ''Kawingasaurus''.

Palaeoecology

''Kembawacela'' coexisted with a wide variety and abundance of other dicynodonts in the upper Madumabisa Mudstone Formation, including ''

Endothiodon ''Endothiodon'' (/ɛndoʊθiːoʊdɔːn/ "inner tooth" from Greek endothi (ἔνδοθῐ), "within", and odon (ὀδών), "tooth", most likely named for the characteristic of the teeth being placed internally to the maxillaBoos A. S., Schultz C ...

'', ''

Compsodon ''Compsodon'' is an extinct genus of dicynodont belonging to the superfamily Emydopoidea. Fossils have been found in the Balfour Formation of South Africa and the Madumabisa Mudstone of Zambia. Description ''Compsodon helmoedi'' was original ...

'', ''

Pristerodon ''Pristerodon'' is an extinct genus of dicynodont therapsid from the Late Permian of South Africa, Zambia and India. Paleobiology Brain and senses ''Pristerodon'' were among the earliest land animals able to hear airborne sound as opposed to ...

'', the burrowing '' Diictodon feliceps'', ''

Emydops ''Emydops'' is an extinct genus of dicynodont therapsid from the Permian of South Africa. ''Emydops'' was first named by South African paleontologist Robert Broom in 1912 when he described ''Emydops minor''. In the following years, the genus gre ...

'', ''

Dicynodontoides ''Dicynodontoides'' is a genus of small to medium-bodied, herbivorous, emydopoid dicynodonts from the Late Permian. The name ''Dicynodontoides'' references its “dicynodont-like” appearance (dicynodont = two-dog-tooth) due to the caniniform t ...

'', a species similar to ''

Katumbia ''Katumbia'' is a genus of dicynodont from Late Permian (Changhsingian) of Tanzania Tanzania (; ), officially the United Republic of Tanzania ( sw, Jamhuri ya Muungano wa Tanzania), is a country in East Africa within the African Great ...

'', ''

Odontocyclops whaitsi ''Odontocyclops'' : Greek: “tooth” Greek: “round eye”, a kind of Greek mythological giant with one eye in the midline =toothy cyclops. The ''Odontocyclops'' is an extinct genus of Dicynodonts that lived in the Late Permian. Dicynodonts ...

'', ''

Oudenodon bainii ''Oudenodon'' is an extinct genus of dicynodont. It was common throughout southern Africa during the Late Permian. Several species of ''Oudenodon'' are known. Both ''O. bainii'', the type species, and ''O. grandis'' are known from South Africa ...

'', ''

Kitchinganomodon ''Kitchinganomodon'' is a genus of dicynodont from Late Permian (Wuchiapingian) of South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. It is bounded to the sout ...

'', '' Daptocephalus'', '' Syops'', '' Digalodon'' cf. ''rubidgei'' and a species of

lystrosaurid Lystrosauridae is a family of dicynodont therapsids from the Permian and Triassic time periods. It includes two genera, ''Lystrosaurus'' and '' Kwazulusaurus''. ''Kwazulusaurus'' includes a single species, ''K. shakai'', from the Late Permian of ...

. Other therapsids included the locally endemic predatory

therocephalia Therocephalia is an extinct suborder of eutheriodont therapsids (mammals and their close relatives) from the Permian and Triassic. The therocephalians ("beast-heads") are named after their large skulls, which, along with the structure of their ...

ns ''

Ichibengops ''Ichibengops'' is an extinct genus of therocephalian therapsids known from the type species ''Ichibengops munyamadziensis'', which lived in what is now Zambia during the Late Permian. ''Ichibengops'' was named in 2015 on the basis of fossils f ...

'' and '' Mupashi'', as well as the more widespread '' Theriognathus microps'' and '' Ictidosuchoides longiceps'', along with the semi-aquatic cynodont ''

Procynosuchus ''Procynosuchus'' (Greek: "Before dog crocodile") is an extinct genus of cynodonts from the Late Permian. It is considered to be one of the earliest and most basal cynodonts. It was 60 cm (2 ft) long. Remains of ''Procynosuchus'' have ...

'' and an indeterminate biarmosuchian. Reptiles are represented by the pareiasaur '' Pareiasuchus'', a herbivorous

parareptile Parareptilia ("at the side of reptiles") is a subclass or clade of basal sauropsids (reptiles), typically considered the sister taxon to Eureptilia (the group that likely contains all living reptiles and birds). Parareptiles first arose near th ...

. Much of the fauna of the Madumabisa Mudstone Formation is shared with that of the ''Cistecephalus'' AZ in the Karoo, South Africa, suggesting the two regions shared similar biomes and were broadly connected. However, the presence of endemic species like ''Kembawacela'' are indicative of fine scale variations between the two localities, such as environmental differences. The fossorial lifestyle of ''Kembawacela'' and other cistecephalids is a likely factor in its endemism, as its unique ecology would have limited its ability to disperse and so restricted its range to within the Luangwa Basin. The environment of the upper Madumabisa Mudstone Formation was a wet, vegetated floodplain within a wide

rift valley A rift valley is a linear shaped lowland between several highlands or mountain ranges created by the action of a geologic rift. Rifts are formed as a result of the pulling apart of the lithosphere due to extensional tectonics. The linear d ...

with plentiful sinuous

meandering river A meander is one of a series of regular sinuous curves in the channel of a river or other watercourse. It is produced as a watercourse erodes the sediments of an outer, concave bank (cut bank) and deposits sediments on an inner, convex bank ...

s, ponds and lakes prone to episodic flooding.

References

{{Taxonbar, from=Q71708346 Dicynodonts Anomodont genera Wuchiapingian genus first appearances Changhsingian genus extinctions Permian synapsids of Africa Fossils of Zambia Fossils of Malawi Fossil taxa described in 2019