Njalila
Njalila is an extinct genus of gorgonopsian that lived during the Late Permian of East Africa, known from fossils found in what is now Tanzania. The type and only species, Njalila nasuta, was originally named as a species of the gorgonopsian genus Dixeya in 1950. The taxon was subsequently recognised as distinct from Dixeya and other gorgonopsians following repeated revisions of gorgonopsian taxonomy during the rest of the 20th century, but it did not receive its own genus name until 2007. However, because this name was first proposed in a PhD thesis, it remained a nomen nudum until its formal validation through an official publication in 2026. With a skull reaching up to in length, Njalila is a medium-sized gorgonopsian characterised by a distinctive straight snout profile with an upturned and "pinched" nose. The fossil record of the Usili Formation where it was discovered shows that Njalila was contemporaneous with many other gorgonopsians, including much larger representatives such as Inostrancevia and rubidgeines.
Research history
Njalila was originally described in 1950 by the German palaeontologist Friedrich von Huene on the basis of two skulls collected from the Usili Formation, located in the Ruhuhu Basin of southern Tanzania. The two specimens in question are now catalogued as GPIT/RE/7118 and GPIT/RE/7119 in the palaeontological collection of the University of Tübingen. Von Huene regarded these specimens as representatives of a second species of the genus Dixeya, a taxon previously erected in 1927 by the South African palaeontologist Sidney H. Haughton to include its type species D. quadrata. In 1970, French paleontologist Denise Sigogneau-Russell re-assigned the type species of Dixeya to the genus Aelurognathus in her systematic revision of gorgonopsian taxonomy, thus synonymising the two genera. However, she did not consider D. nasuta to belong to Aelurognathus, instead tentatively referring the species to Arctognathus as Arctognathus? nasuta. Furthermore, Sigogneau only considered the holotype of D. quadrata from Malawi to belong to Aelurognathus, and she did not consider two additional specimens referred to D. quadrata by von Huene in 1950 from Tanzania to belong to the same species. Instead, she suggested that they may also be referable to Ar.? nasuta—in addition to three other Tanzanian specimens referred to D. quadrata by British palaeontologist Francis Rex Parrington in 1955. Nonetheless, Sigogneau was cautious in the referral of "D." nasuta to Arctognathus, and had previously acknowledged that it was not a resolved matter, especially as—in her opinion— that the roof of the skull of this species was not well preserved enough for comparison.The genus name Njalila was first proposed for "D." nasuta in 2007 by the German palaeontologist Eva Gebauer in her unpublished PhD thesis, in which it was named after the Njalila River, a tributary of the Ruhuhu River in Tanzania. However, because the International Code of Zoological Nomenclature does not recognize theses as valid published works, Njalila was therefore regarded as a nomen nudum. In 2015, the American paleontologist Christian F. Kammerer likewise acknowledged that "D." nasuta probably represents a single taxon that does not belong to Arctognathus, while remaining cautious about its taxonomic placement. He considered that further study of the material and more rigorous phylogenetic analyses were required, and recommended provisionally leaving its taxonomy open under the designation "Dixeya" nasuta until the issue could be resolved. In an article published in early 2026, Gebauer and her German colleague Michael W. Maisch formally redescribed the fossils of this taxon. In doing so, they officially established and diagnosed the genus Njalila as the valid and available name for "D." nasuta, in the new combination N. nasuta.
Also in her 2007 thesis, Gebauer proposed the existence of a second species of the genus Njalila, "N. insigna", based on another Tanzanian skull that had previously been referred to the South African gorgonopsian Scylacops capensis. She distinguished "N. insigna" from N. nasuta by the presence of thicker arches between its skull openings, a posteriorly wider skull, and a slightly more rounded snout profile. The specific epithet of this proposed taxon is a Latin term meaning "remarkable" or "conspicuous", in reference to the differences noted between it and N. nasuta. However, in their 2026 publication, Gebauer and Maisch did not follow this interpretation, instead cautiously referring the specimen to N. cf. nasuta.
Description
Njalila is only known by its skull and jaws, which measured roughly in length and had a relatively short and compact snout. Compared with similarly short-snouted gorgonopsians the skull is not as wide at the rear, with only weakly flaring zygomatic arches and little constriction of the snout behind the canines. As such, its skull appears much more straight-sided when viewed from above, and is also generally wider than it is tall. Similarly, the profile of the skull along the top of the snout is also largely straight, although the tip is characteristically turned up in a sharp point above the nostrils, which were positioned far-forwards on the snout. The snout is also distinctive for its unusual 'pinched' appearance. The nasal bones along the top of the snout are broad, but are constricted along the middle. Furthermore, the septomaxilla bulges strongly outwards under and behind the nostrils but then rapidly hollows out just behind them on either side, giving the bridge of the nose the pinched appearance.Behind the snout, the roof of the skull is distinctly concave with the rims of the orbits above the eyes noticeably raised above it. The orbits themselves are proportionately large and rounded, and face laterally out to the sides. The temporal fenestra, a hole in the skull behind the eye socket for jaw muscle attachment, is also very large. Subsequently, the bony arches surrounding and separating these openings are proportionately slender and thin. The parietal foramen on top of the skull is large and surrounded by a raised boss of bone, and is positioned at the very back of the skull right above the occiput. The occiput itself is tall and roughly rectangular in shape, slightly concave and only gently sloping.
As in other gorgonopsians, Njalila has large blade-like caniniform teeth. The incisor teeth, however, are smaller than those of related gorgonopsians, and it only had four to five small postcanine teeth. The jawline of the maxilla in the upper jaw is notably convex, with a much more exaggerated curve of the toothrow than in other gorgonopsians except for Arctognathus. This exaggerated curvature is due to the post-canine teeth being housed in a raised bony flange of the maxilla behind the canines. The maxilla also has an unusual groove over the postcanine teeth, starting shallowly above the first postcanine and running down to the edge of the bone behind the 5th postcanine, deepening along its length. Like other gorgonopsians Njalila also possessed palatal teeth, three on each palatine and two on each pterygoid bones, with only weakly developed bosses supporting them. The vomer on the roof of the mouth is very broad at the front, but narrows rapidly to a constricted splint halfway down its length. This more resembles the vomer of the derived rubidgeines than the narrower vomer of earlier gorgonopsians. The vomer sports three ridges, one down its middle and two running along each edge.
The dentary bone of the lower jaw is comparatively slender, with a sloping mandibular symphysis that nonetheless bears the characteristic 'chin' of gorgonopsians. The reflected lamina of the angular bone towards the back of the jaw is only moderately ridged, in comparison to other gorgonopsians.
Classification
The phylogenetic relationships of Njalila were first analysed by Gebauer in her unpublished 2007 PhD thesis in the first computerised phylogenetic analysis of gorgonopsians ever conducted. Gebauer found Njalila as a member of the family Gorgonopsidae, which in her classification excluded the most basal genera of gorgonopsians in her tree that she regarded as plesiomorphic for the group. Within Gorgonopsidae, Njalila was a relatively derived member but outside of the clade including the giant Rubidgeinae and Inostrancevia, occupying part of an evolutionary grade between them and more ancestral gorgonopsids. The results of Gebauer are depicted in the cladogram below.The analysis of Gebauer was the first major attempt to perform a phylogenetic analysis of gorgonopsians; however, its results have not been borne out by subsequent independent analyses. Namely, Kammerer regarded Gebauer's analysis as "unsatisfactory", citing that many of the characters used by her analysis were based upon skull proportions that are variable within taxa, both individually and ontogenetically. As an example of a potential problem created by this, he highlighted the basal position of Aloposaurus compared to the stratigraphically older and morphologically basal Eoarctops being found in a relatively more derived position.
Since a 2018 study authored by Kammerer and his Russian colleague Vladimir Masyutin, gorgonopsians have been divided into two subgroups of African and Russian origin, with the exception of the basal genera Nochnitsa and Viatkogorgon. In their 2026 publication, Gebauer and Maisch recovered Njalila within the African clade, where it is identified as a potential sister taxon to Arctognathus, although this result is only weakly supported in their analysis.
Paleoecology
All known fossil specimens of Njalila have come from the Usili Formation, Ruhuhu Basin, southern Tanzania. This formation, dating from the Upper Permian, is known to provide a fairly considerable number of fossils of various tetrapods. During this period, this formation would have been an alluvial plain which would have had numerous small meandering streams passing through well-vegetated floodplains. The basement of this formation would also have housed a generally high phreatic zone.Njalila was contemporary with many other gorgonopsians. These include Cyonosaurus, Gorgonops, Inostrancevia, Lycaenops, "Sauroctonus" parringtoni, Scylacops and the rubidgeines Aelurognathus, Dinogorgon, Rubidgea, Ruhuhucerberus and Sycosaurus The other theriodonts present are represented by the therocephalians Silphictidoides and Theriognathus as well as by the cynodont Procynosuchus.
The most numerous tetrapods in the formation are the dicynodonts, among which are Compsodon, Daptocephalus, Dicynodon, Dicynodontoides, Endothiodon, Euptychognathus, Geikia, Katumbia, Kawingasaurus, Oudenodon, Pristerodon, Rhachiocephalus and an indeterminate cryptodont. An undetermined biarmosuchian similar to Burnetia is also known. Therapsids are not the only tetrapods present in the Usili Formation. Indeed, sauropsids such as the archosauromorph Aenigmastropheus and the pareiasaurs Anthodon and Pareiasaurus are known. The only temnospondyl recorded is Peltobatrachus.