Journal of Threatened
Taxa | www.threatenedtaxa.org | 26 September 2026 | 18(9): 29772–29775
ISSN 0974-7907 (Online) | ISSN 0974-7893 (Print)
https://doi.org/10.11609/jott.10287.18.9.29772-29775
#10287 | Received 26 January 2026 | Final received 02 August 2026 | Finally
accepted 21 August 2026
Observations on the dental
morphology of the North African Sandfish Scincus
scincus (Squamata: Scincidae)
Shreya Bhattacharya 1 & Indraneil Das 2
1,2 Institute of Biodiversity and
Environmental Conservation Universiti Malaysia
Sarawak 94300 Kota Samarahan, Sarawak, Malaysia.
1 bshreya93@gmail.com, 2
idas@unimas.my (corresponding author)
Editor: Aditya Srinivasulu,
Zoo Outreach Organisation, Hyderabad, India. Date of publication: 26
September 2026 (online & print)
Citation:
Bhattacharya, S. & I. Das (2026). Observations on the dental morphology of
the North African Sandfish Scincus scincus (Squamata: Scincidae). Journal of Threatened Taxa 18(9): 29772–29775. https://doi.org/10.11609/jott.10287.18.9.29772-29775
Copyright: © Bhattacharya & Das 2026. Creative Commons Attribution 4.0 International License.
JoTT allows unrestricted use, reproduction, and
distribution of this article in any medium by providing adequate credit to the
author(s) and the source of publication.
Funding: Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak.
Competing interests: The authors declare no competing interests.
Acknowledgements: Jayasilan Mohd Azlan is thanked for access to the IBEC Ecology Lab; Faisal Ali Anwarali Khan for use of the SEM Lab. Rahah binti Mohamad Yakup, Heira Vanessa anak Nelson, and Mohamad Hasri Al-Hafiz bin Haba provided support with laboratory and field equipment. We thank Shafri bin Semawi for help with Analytical Scanning Electron Microscopy. Protocol was approved by the Animal Ethics Committee, UNIMAS (UNIMAS/AEC/2025/19). For publication support, we thank Awang Ahmad Sallehin bin Awang Husaini of the Centre for Research, Development, Innovation, Commercialisation and Economy, Universiti Malaysia Sarawak.
Abstract: The dental morphology of the
North African Sandfish Lizard Scincus scincus (Linnaeus, 1858) was studied using field
emission scanning electron microscopy. The primary aim of the study was to
observe structural features of teeth in the species and generalize functional
adaptations with respect to its feeding ecology. Specimens were euthanized,
decapitated, the cranial removed and tissues macerated, using standard
protocols. Cranial elements, including maxillary and mandibular elements were
prepared separately using an ethanol series, critically point-dried, and
examined under an electron microscope. S. scincus
exhibits monostichous, bicuspid, sub-equal,
sub-conical, posteriorly-oriented mandibular, and maxillary teeth rows
comprising of faint ridges. The dentition appeared to mirror a predator of
arthropods, as in a majority of members of the lineage, in addition to
adaptations for larger prey, such as small vertebrates.
Keywords: Cranial elements, dentition,
feeding ecology, generalize functional, sandfish skink, scanning electron
microscopy, structural features of teeth.
The Scincidae
is one of the largest families within the Squamata (Uetz
et al. 2026) and exhibits a wide array of ecologically diverse species (Greer
2007). While the greatest diversity is associated with tropical forests,
significant numbers are to be encountered in more arid regions, such as steppes
and deserts (Greer 2007; Melville & Swain 2000). Their diets are also
diverse, including herbivory, carnivory, and omnivory
(Greer 2007). Skinks exhibit polyphyodontic
dentition, where teeth are replaced multiple times in their life time (Ramzade et al. 2024). Based on dietary adaptations, dental
morphology can be characterized as narrow and cylindrical tooth, these being
bluntly pointed or with sharp edges and may either show multiple ridges, a
feature that is sometimes absent (Townsend et al. 1999; Greer 2007;
Bhattacharya & Das 2026). However, little is known about the adaptations of
dental morphology, especially macro or micro dentition structures, their
specific functions and correlation with feeding ecology.
The genus Scincus
comprises five species from the Saharo-Arabian
region (Šmíd et al. 2021). The Sandfish Lizard, Scincus scincus
(Linnaeus, 1758), arguably the most familiar amongst these, is a diurnal, deserticole species and known from across northern Africa
and south-western Asia (Schleich et al. 1996; Stadler
et al. 2016). Due to extreme environmental conditions of such areas, including
high temperatures and low humidity, morphological, and physiological
adaptations are necessary for survival of species inhabiting such extreme
environments (Stadler et al. 2016). S. scincus
maintains its body temperature by burying itself in sand layers, only surfacing
for foraging, mating, and defecating (Hetherington 1992; Stadler et al. 2016).
Its movement in sand is characterized as ‘fish-like’, hence its name in
English, as well as in numerous vernacular names (Stadler et al. 2016).
Scincus scincus
is reportedly
a dietary generalist (Attum et al. 2004, 2006; Kosma 2004; Salem et al. 2017), its diet including members
of the orders Coleoptera, Araneae,
Diptera, Orthroptera, and
Lepidoptera (Attum et al. 2004). Additionally, seeds
and vegetation have also been found in stomachs of the species, assumed to be
intentionally consumed due to their high frequency of occurrence. The
occurrence of Acanthodactylus longipes, a diurnal species of Lacertidae in a stomach sample of S. scincus,
suggests opportunistic feeding of small vertebrates. Wind-blown detritus
materials, such as seeds and dry leaves, have also been recorded in its diet (Attum et al. 2004).
In the present study, we observed
structural features of dentition and attempted to correlate with the known
feeding ecology of S. scincus. Two individuals
of the lizard from the pet trade were examined, and were of unknown origin,
although the nominotypical subspecies is the most commonly encountered in the
pet trade, and reportedly originates from Egypt (Al-Johany
et al. 2021).
Material and Methods
Two specimens of adult S.
scincus (UNIMAS 9812, 9813) were used for
studying gross dental morphology. The specimens obtained from a commercial
importer and euthanized using tricaine injection. Subsequently, they were
decapitated, the cranium macerated and manually cleaned with commercial
detergents for removal of skull muscles and tissues in the laboratory.
Mandibles and maxillae were dehydrated using ethanol series and critically
point dried (Das & Coe 1994) with QuotumTM
K 850 Dryer (12 V dc), riveted to 4 mm aluminum stubs, platinum-coated using a JeolTM JEC-3000FC autofine
coater, set to auto function at 300 secs / 20 mA. The prepared samples were
observed using field-emission scanning electron microscope (FE-SEM) (JeolTM JSM-IT500) (Delgado et al. 2003).
Screen captures of key areas were
saved as tiff files and edited using Photoshop 2024 (version 26.1). Voucher
specimens were retained in the systematic collection of the Museum of the
Institute of Biodiversity and Environmental Conservation, UNIMAS (UNIMAS 9812,
9813).
For nomenclatural conformity, we
use cusps to refer to obtuse, rounded structures on occlusal surfaces of teeth
of both jaws, ridges for striations on body of tooth (‘crests’ of Caputo 2004;
‘apicobasal striations’ of Cernanský et al. 2019);
and occlusal grooves (‘sulcus’ of Caputo 2004). Tooth counts were made on the
left/right (L/R) sides of maxilla (including premaxillary and maxillary bones)
and the mandible.
Results
Teeth were observed to be monostichous, bicuspid, sub-equal, sub-conical, and
posteriorly-oriented, both mandibular and maxillary teeth showing weak ridges
(Image 1). The occlusal surfaces were flat and rounded. maxillary tooth counts
were 17/18, while mandibular counts were 16/17.
The maxillary teeth were oriented
obliquely towards the oral cavity. Dental cusps were well defined, each tooth
basally with weak longitudinal ridges (Image 1D). Anterior mandibular teeth
exhibited recurved, pointed tips, as well as faint ridges (Image 1F), followed
by sub-equal and sub-conical teeth in mesial and posterior mandible. Lingual
aspect of both maxillary and mandibular teeth was characterized by flattened
surfaces with indistinct ridges; whereas the labial aspect was smooth with
absence of ridges or cusps. No diastema was observed in either maxillary or
mandibular teeth rows. Apical tooth crown of maxillary and mandibular teeth
comprised of flattened surfaces (characterized by a distinctly smooth appearance,
rendered shiny due to platinum coating in the FE-SEM images). The resorption
pits were primarily circular in shape.
Discussion
Our findings match the brief
morphological description of S. scincus
dentition by Kosma (2004), with teeth crowns being bicuspid,
conical, consisting of constricted faint ridges on the lingual side. The
bicuspid squamate tooth is considered an adaptation for grasping and
manipulating prey, primarily insects (Townsend et al. 1999; Caputo 2004). The
anterior teeth of mandible exhibited recurved tooth crowns, whereas mesial and
posterior teeth were observed to be flattened and rounded, similar to Scincella lateralis (Townsend et al. 1999;
see Image 1). Recurved teeth have been considered adaptative
for rupturing slippery prey items such as earthworms in Coeranoscincus
reticulatus (Greer 2007) which can be compared to
the presence of larvae and pupae of Coleoptera in the
diet of S. scincus (Attum
et al. 2004; Kosma 2004). Unlike S. lateralis
which exhibits both labial and lingual cusps, the latter was not observed in S.
scincus (Townsend et al. 1999).
Blunt and flattened tooth crowns
have been considered as an adaptation for either durophagy or omnivory (Townsend et al. 1999; Caputo 2004), and are
comparable to maxillary, mesial, and posterior mandibular teeth in S. scincus. The current species is known to feed on
scorpions, coleopterans of genus Phyllognathus,
Pentodon, and Pimelia,
among others that possess strong exoskeleton (Attum
et al. 2004; Kosma 2004). Vegetation, including flowers
(Genista saharae)
and seeds (Aristidia pungens,
Retama raetam,
Cyperus conglomeratus)
has also been recorded in its diet (Attum et al.
2004; Kosma 2004). It can be concluded that the
dental morphology is adaptive for both durphagy and omnivory. S. scincus is
opportunistically known to feed on Acanthodactylus
longipes, a syntopic
desert lizard (Attum et al. 2004). The anterior
recurved, mandibular teeth, along with flattened, blunt maxillary teeth are
suspected to serve as adaptations for capturing, holding, and processing large
prey types. A similar dental pattern has been observed in the omnivorous Varanus olivaceus,
which exhibits recurved conical mesial teeth, followed by blunted posterior
teeth, possessing faint ridges (Melstrom 2017),
features reminiscent of the non-familial species being reported.
Squamates can be considered as
ideal study subjects for exploring relationships between dentition morphology
and dietary patterns, as they exhibit diverse feeding preferences and variation
in dentitional complexities (Christensen & Melstrom
2021). Research on squamate dentition is rare, compared to mammals and hence,
there exists a considerable knowledge gap in understanding of dentitional
morphology and function (Razmadze et al. 2024). The
outcomes of the present study contribute to our understanding of dental
adaptations and its potential functions.
For
image - - click here for full PDF
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