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The pterosaur assemblage of the mid-Cretaceous Kem Kem Group of Morocco is reviewed. This analysis examines their taxonomy, palaeoecology and palaeobiology with comments on taphonomy. New material permits the rediagnosis of the azhdarchoids Alanqa saharica and Afrotapejara zouhrii. Several specimens are reported that do not ft within the paradigms of previously named taxa. They represent three distinct jaw morphotypes, but are not assigned to new taxa here. The assemblage is highly diverse, including four tooth-bearing taxa assigned to Ornithocheiridae and fve named taxa and three additional morphotypes assigned to Azhdarchoidea. The Kem Kem Group assemblage is the most diverse for any pterosaurbearing fuvial deposit and one of the most diverse of any pterosaur assemblage. The assemblage is heavily biased in terms of preservation with an as yet unexplained high abundance of jaw fragments. We highlight the importance of fragmentary material in pterosaur studies.
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https://doi.org/10.1007/s12542-022-00642-6
RESEARCH PAPER
The pterosaurs oftheCretaceous Kem Kem Group ofMorocco
RoyE.Smith1 · NizarIbrahim1· NicholasLongrich2· DavidM.Unwin3· MeganL.Jacobs1· CariadJ.Williams1,4·
SamirZouhri5· DavidM.Martill1
Received: 11 February 2022 / Accepted: 16 September 2022
© The Author(s) 2023
Abstract
The pterosaur assemblage of the mid-Cretaceous Kem Kem Group of Morocco is reviewed. This analysis examines their
taxonomy, palaeoecology and palaeobiology with comments on taphonomy. New material permits the rediagnosis of the
azhdarchoids Alanqa saharica and Afrotapejara zouhrii. Several specimens are reported that do not fit within the para-
digms of previously named taxa. They represent three distinct jaw morphotypes, but are not assigned to new taxa here. The
assemblage is highly diverse, including four tooth-bearing taxa assigned to Ornithocheiridae and five named taxa and three
additional morphotypes assigned to Azhdarchoidea. The Kem Kem Group assemblage is the most diverse for any pterosaur-
bearing fluvial deposit and one of the most diverse of any pterosaur assemblage. The assemblage is heavily biased in terms
of preservation with an as yet unexplained high abundance of jaw fragments. We highlight the importance of fragmentary
material in pterosaur studies.
Keywords Pterosauria· Taxonomy· Palaeoecology· Kem Kem Group· Morocco
Introduction
Pterosaurs were a diverse and important part of Meso-
zoic faunas, ranging from the Triassic to the end of the
Cretaceous and occurring worldwide. Theirfossil record,
however, is rather scant. Until recently, relatively little
was known about pterosaurs from Africa, or from the mid-
dle Cretaceous. In just over two decades however, a large
number of pterosaur fossils have been collected from the
Cretaceous Kem Kem Group in Morocco (Mader and Kell-
ner 1999; Ibrahim etal. 2010, 2020; Martill etal. 2018,
2020a; Jacobs etal. 2019, 2020; McPhee etal. 2020; Smith
etal. 2020a). This has transformed the Kem Kem Group
intoan important horizon for understanding the diversity
and evolution of pterosaurs in the Cretaceous, not only in
Africa but beyond. Here, we provide a detailed review of
the Kem Kem Group pterosaurs. We evaluate the pterosaurs
in terms of their taxonomy, palaeoecology, palaeobiology,
taphonomy and evolution, both in a spatial context that
includes Africa and elsewhere in the world and in a tempo-
ral context: the Cretaceous.
Historical narrative
The pterosaur material from Africa has previously been
reviewed by Kellner etal. (2007), Barrett etal. (2008),
and Ibrahim etal. (2020). The fossil record of pterosaurs
in Africa is sparse,comprising just 18 fossil localities/hori-
zons in 12 countries (see Fig.1, TableS1), compared to at
least 55 in North America, for example (Barrett etal. 2008).
This includes body and trace fossils, ranging from the Lower
Jurassic (Hettangian) to the Upper Cretaceous (end Maas-
trichtian) (see Fig.2, TableS1), an interval of over 100 mil-
lion years. This patchy distribution reflects both the overall
Handling Editor: Hans-Dieter Sues.
* Roy E. Smith
roy.smith@port.ac.uk
1 School oftheEnvironment, Geography andGeosciences,
University ofPortsmouth, PortsmouthPO13QL, UK
2 Department ofBiology andBiochemistry andMilner Centre
forEvolution, University ofBath, BathBA27AY, UK
3 Centre forPalaeobiology andBiosphere Evolution
andSchool ofMuseum Studies, University ofLeicester,
LeicesterLE17RF, UK
4 Center forPaleontology, Illinois Natural History
Survey, Prairie Research Institute, University ofIllinois
atUrbana-Champaign, Forbes Natural History Building 1816
S. Oak Street, Champaign, IL61820, USA
5 Laboratoire de Santé et Environnement, Faculté des Sciences
Aïn Chock, Université Hassan II, Casablanca, Morocco
R. E. Smith etal.
1 3
record of pterosaurs, and the fact that, historically,Africa has
seen less study thanmuch of the rest of the World.
The first pterosaur from Africa, reported by Reck
(1931),comes from the Upper Jurassic (Kimmeridgian-
Tithonian) Tendaguru Beds of Tanzania. The first possibly
Cretaceous Africanpterosaur was described by Swinton
(1948) from the Democratic Republic of Congo. It com-
prises a partial pterodactyloid metacarpal IV, probably from
an ornithocheirid (Fig. S1). Later, pterosaur material was
described from Algeria, Angola, Cameroon, Egypt, Mada-
gascar, Morocco, Niger, Senegal, South Africa and Tunisia
(see Figs.1, 2, TableS1for references). Morocco has the
most pterosaur-bearing deposits in Africa with six locali-
ties/horizons (three trace fossil and three body fossil) (see
Figs.1, 2, TableS1).
French explorer and palaeontologist René Lavocat was
the first to recover pterosaur remains, from beds now termed
the Kem Kem Group in the 1940s and 1950s. These early
discoveries consisted of isolated ornithocheirid teeth, now
in the collection of Muséum National d'Histoire Naturelle,
Paris (MNHN) (Fig.3) (Ibrahim etal. 2020). The first
pterosaur bone reported from the Kem Kem Group was an
Fig. 1 Map of continental Africa showing the locations of pterosaur bearing deposits. See SI TableS1 for detailed locality informationand refer-
ences
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
isolated azhdarchid cervical vertebra (LINHM 014) men-
tioned in an abstract by Kellner and Mader (1996) and later
figured by Rodrigues etal. (2011, fig.4). Also in an abstract,
Mader and Kellner (1997) described an ornithocheirid jaw
fragment (LINHM 016) which became the holotype of
Siroccopteryx moroccensis Mader and Kellner (1999, figs.2,
3). This represented the first pterosaur to be named from the
Kem Kem Group.
The first indication of edentulous pterosaurs in the Kem
Kem Group assemblage was published by Wellnhofer and
Buffetaut (1999) who described three toothless jaw frag-
ments (BSP 1993 IV 338; BSP 1997 I 67; BSP 1996 I 36)
identified as a pteranodontid, tapejarid and azhdarchid,
respectively. These would later be referred to the ?chaoy-
angopterid Apatorhamphus gyrostega McPhee etal. 2020;
tapejarid Afrotapejara zouhrii Martill etal., 2020a and the
azhdarchid Alanqa saharica Ibrahim etal. 2010. However,
the first edentulous pterosaur from the Kem Kem to be
named was Alanqa saharica (Ibrahim etal. 2010).
Subsequently, four more edentulous taxa, Xericeps
curvirostris Martill etal. 2018, Apatorhamphus gyrostega
McPhee etal. 2020, Afrotapejara zouhrii Martill etal.
2020a, and Leptostomia begaaensis Smith etal. 2020a were
described. In addition, a second toothed taxon, Coloborhyn-
chus fluviferox Jacobs etal. 2019 and material attributable to
the genera Anhanguera and Ornithocheirus were described
(Jacobs etal. 2019, 2020). For a detailed history of explora-
tion of the Kem Kem Group see Ibrahim etal. (2020). See
TableS2 for all pterosaur material described and figured
from the Kem Kem Group.
Locality
The Kem Kem Group is a widespread stratigraphic unit
exposed mainly in the northwestern Sahara Desert of
Morocco and along the southern flank of the Atlas Moun-
tain fold belt (Ibrahim etal. 2020; Fig.4). Lateral equiva-
lents occur extensively in neighbouring Algeria (Alloul etal.
2018; Ibrahim etal. 2020).
Most fossils from the Kem Kem Group made available by
local collectors come from outcrops in the Tafilalt region,
Fig. 2 Chronostratigraphic chart showing the temporal distribution
of pterosaur bearing deposits of continental Africa. See Fig. 1 for
localities corresponding to the numbers and SI TableS1 for detailed
locality informationand references. Red star indicates the Kem Kem
Group. Note that the Mibladen, Morocco and DR Congo pterosaur
localities are not included because their precise ages are not known
Fig. 3 Photograph of the first pterosaur material recovered from the
Kem Kem Group of Morocco by René Lavocat comprising orni-
thocheirid teeth. The specimens shown here were tentatively identi-
fied as fish teeth. The specimens are presently in the collections of
MNHN, Paris. Scale bar represents 10mm
R. E. Smith etal.
1 3
where a nearly continuous outcrop flanks the valleys of the
Oued Ziz and Oued Gheris and rims the immense plain of
the Tafilalt and the sand dunes of Erg Chebbi.
By far the most prolific source of fossils is found along
a stretch of the outcrop between Gara Sbaa and Taouz,
between Takmout and Douira, the area around Zrigat and
between Tarda and Goulmima (Fig.4). Some fossils are also
mined near Tadighoust from a folded outcrop at the foot of
the Atlas Mountains. Extensive areas of outcrop to the east
and west remain unexplored for fossils (e.g., in the Anoual
and Ouarzazate basins).
The most fossiliferous outcrops appear to be those along
a ~ 250km escarpment of the Guir and Kem Kem hama-
das along the Moroccan–Algerian border (Ibrahim etal.
2010, 2020). The northern extent of the escarpment is
located ~ 30km south of Errachidia, extending southeast
towards Taouz along the western edge of the Hamada du
Guir. It then extends southwest following the western edge
of the Hamada du Kem Kem (Ibrahim etal. 2020) (see
Fig.4). Pterosaur remains have been collected from most
of the extent of the Kem Kem Group from Takmout in the
north to Gara Tabroumit in the south.
Geological andstratigraphical context
The Kem Kem Group is represented by anapproximately
200m thick sequenceof mainly siliciclastic strata and is
divided into two distinct formations, a lower sandy unit,
the Ifezouane Formation, and an upper mudstone unit, the
Aoufous Formation following the nomenclature of Ettachfini
and Andreu (2004). A revised stratigraphic nomenclatural
scheme was proposed by Ibrahim etal. (2020) for geographi-
cally more restricted outcrops in the southern Tafilalt, but we
do not employ it here, finding that the scheme of Ettachfini
and Andreu (2004) can be extended easily into this region.
In the Tafilalt region, the Kem Kem Group lies with angu-
lar and gently topographic unconformity on folded marine
Palaeozoic strata (Ibrahim etal. 2010; Martill etal. 2018),
with the base of the Ifezouane Formation usuallybeing com-
posed of a thin breccia or conglomerate (Cavin etal. 2010).
Elsewhere, the Kem Kem Group appears to lie on Middle
to Upper Jurassic strata with only minor unconformity, as
at Tadighoust and in the Anoual Basin. Almost everywhere
the Kem Kem Group is overlain by a thick succession of
Cenomanian–Turonian carbonates of the Akrabou Forma-
tion (Ibrahim etal. 2010; Martill etal. 2018).
The Kem Kem Group’stwo formations, the Ifezouane
Formation and overlying Aoufous Formation, differ in their
lithology. The Ifezouane Formation is characterised by red-
dish fluvial detritic sandstones, with high angled, metre-
thick cross-bedding representing channel fills, with interca-
lations of pedogenic overbank mudstones (Belvedere etal.
2013), pinkish sand, and thinconglomerates with quartz
pebbles (Cavin etal. 2010). The overlyingAoufous Forma-
tion is characterised by variegated mudstones and marls,
with calcitic palaeosols, thin intercalations of evaporites,
detrital sandstone and micro-conglomerates, and carbonate
cemented layers (Cavin etal. 2010; Belvedere etal. 2013).
The vast majority of vertebrate material comes from intra-
formational, mud-flake conglomerates in the upper Ifez-
ouane Formation (Martill etal. 2018).
Age
The age of the Kem Kem Group is problematic due to the
rarity of biostratigraphically useful fossils. Correlations with
the Bahariya Formation of Egypt based on similar vertebrate
assemblages have been used to infer an early Cenomanian
age, particularly due to the shared presence of the dinosaur
Spinosaurus and the sawfish Onchopristis (Sereno etal.
1996). The overlying limestones of the Akrabou Formation
contain the ammonite Neolobites vibrayeanus (d'Orbigny
1840), of late Cenomanian age (Cavin etal. 2010). There-
fore, the Kem Kem Group may be late Albian to early
Cenomanian (Ibrahim etal. 2020)or older. Further work is
needed to refine the age of the beds.
Palaeoenvironment
The Kem Kem Group was deposited in a continental envi-
ronment dominated by a fluvial setting, with some lacustrine
Fig. 4 Map of south-east Morocco showing the Kem Kem Group
exposures. Kem Kem Group exposures outline adapted from Sereno
etal. (1996)
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
horizons. Rare, short-lived shallow marine environments are
recorded in some northern localities (Adardor etal. 2021;
Beevor etal. 2021). Overall, the lithologies record a trans-
gressive sequence terminating in a thick succession of fully
marine carbonates represented by the Cenomanian Akra-
bou Formation (Ettachfini and Andreu 2004; Ibrahim etal.
2010; Belvedere etal. 2013). The Ifezouane Formation has
been interpreted as a braided river system (Belvedere etal.
2013). These deposits are detritic in nature and are strictly
freshwater in origin as demonstrated by the presence of
lungfishes,sirenid urodeles and frogs (Cavin etal. 2010);
the high diversity of turtles (Ibrahim etal. 2020) is also
consistent with a freshwater environment. The Ifezouane
Formationfines upwards into the low-energy deltaic, estua-
rine and playa lake deposits of the Aoufous Formation (Bel-
vedere etal. 2013; Martill etal. 2018) where fossils include
freshwater gastropods and rare unionid bivalves (DMM, NI,
RES pers. obs.). Assuming extant vertebrates associated
with recent river systems can be used as analogues, then
it seems likely that the Kem Kem Group palaeo-river sys-
tem incorporated a wide range of possible niches. Environ-
ments likely included river channels, river banks, sandbars,
oxbows, marshes, estuaries, and tidal flats.
Materials andmethods
Kem Kem Group pterosaur material was examined in the fol-
lowing collections: BSPG, CMN, FSAC, MNHM, MSNM,
NHMUK and UCRC. A variety of techniques were used to
examine the material, including light microscopy, scanning
electron microscopy (SEM) and X-ray computed tomogra-
phy (XCT). Several specimens were thin-sectioned using
standard techniques. The specimens were imaged using a
Nikon D5600 DSLR camera and images processed using
Combine ZP and Corel Draw Graphics Suite X8. Specimens
were topographically scanned using an Einscan Pro + 3D
scanner and scans processed using Geomagic Design X.
Joint fieldwork by multiple universities (University of Ports-
mouth, University College Dublin, University of Detroit
Mercy, University of Casablanca, University of Bath) was
conducted in the Tafilalt region of Morocco over the past
12years to collect fossil material and record taphonomic
and sedimentological data. Our comparisons and criteria for
taxonomic assignment of postcranial material are limited
to the clades present within the Kem Kem Group: Azhdar-
choidea and Ornithocheiridae.
Definitions
The following terminology describing pterosaur jaw ele-
ments is used throughout: lateral angle—angle between the
dorsal/ventral margin and the occlusal surface as seen in
lateral view; dorsal/ventral angle—the angle between the
occlusal margins as seen in dorsal/ventral view; rostrum—
the fused left and right premaxillae and maxillae; mandi-
ble—the lower jaw.
Rationale andproblems
The isolated and fragmentary nature of Kem Kem Group
pterosaur remains renders taxonomic distinction and deter-
mination of pterosaur diversity challenging. The high
abundance, in the Kem Kem Group of pterosaur jaw frag-
ments(see taphonomy section), especially those attributable
to Azhdarchoidea has resulted in the erection ofseven ptero-
saur species foundedsolely on fragmentary jaw material. In
all cases the holotype is little more than a jaw tip, and all are
anterior of the nasoantorbital fenestra or the divergence of
the mandibular rami.
The similarity between upper and lower jaws, as seen in
more complete fossils elsewhere (e.g., Chaoyangopteridae of
the Yixian Formation of China) sometimes renders distinc-
tion ofrostra and mandibles difficult. It is possible that spe-
cies currentlyerected on upper jaws may become synonyms
of species erected on lower jaws and vice versa. However,
this similarity can also be useful; the similar profiles and
cross-sections of the rostrum and mandibles, for Alanqa and
Leptostomia, for example, make it possible to refer these fos-
sils to the same species even in the absence of association.
Niche partitioning, different feeding strategies and diets
canresult in dramaticmodifications to the skull and feeding
apparatus (i.e., the jaws and teeth), as seenin birds (e.g.,
Abzhanov etal. 2004). In pterosaurs, profound differences
are seen in jaw morphology across higher clades, presumably
reflecting diverse feeding strategies (Witton and Naish 2008;
Navarro etal. 2018; Pêgas etal. 2021a). Thus, subtle differ-
ences in jaw morphology seen in Kem Kem Group pterosaurs
may provide clues for evaluating species diversity. However,
small differences (or sometimes even large differences) may
also reflect ontogenetic variation, interspecific variation, and/
or sexual dimorphism (Bennett 1992; Manzig etal. 2014;
Wang etal. 2014; Pinheiro and Rodrigues 2017).
The impact of ontogenetic change on the morphology of
the pterosaur skeleton has been discussed in detail by several
authors for Jurassic pterosaurs (Bennett 1995, 2007; Hone
etal. 2021) and the Late Cretaceous Pteranodon (Bennett
1993). However, the consequences of ontogenetic variation
on overall jaw morphology for Kem Kem Group pterosaurs
is far from understood (Smith etal. 2021).
It does appear that immature individuals of some Kem
Kem Group edentulous pterosaurs (e.g., Alanqa saharica
and Apatorhamphus gyrostega) have a similar morphol-
ogy (cross-sectional outline, jaw profile, and foramina dis-
tribution) to their adult counterparts (Smith etal. 2021).
Therefore, although many of the morphological differences
R. E. Smith etal.
1 3
exhibited by Kem Kem Group jaws are likely not the result
of ontogenetic variation, a cautious approach to naming taxa
must still be taken.
Remarkably, and for reasons not as yet fully under-
stood, not a single Kem Kem Group pterosaur jaw frag-
ment exhibits either the mandibular symphysis divergence
or the anterior border of the nasoantorbital fenestra, which
are diagnostic characters for distinguishing lower and upper
jaws (respectively). This is especially surprising as some
200 pterosaur jaw fragments have now been collected from
the Kem Kem Group. In addition, no associated material
has been discovered where the association is convincingly
genuine.
Fig. 5 Diagram showing the cross-section change across the jaw in
edentulous pterosaurs from the Kem Kem Group. A Alanqa saha-
rica holotype mandibular symphysis (FSAC-KK 26); B Afrotapejara
zouhrii holotype rostrum (FSAC-KK 5004); C Xericeps curvirostris
holotype mandible (FSAC-KK 10700); D Apatorhamphus gyrostega
holotype rostrum (FSAC-KK 5010); E, Leptostomia begaaensis holo-
type rostrum (FSAC-KK 5075); F Leptostomia begaaensis paratype
mandibular symphysis (FSAC-KK 5076); G jaw ‘morphotype B’,
?mandibular symphysis (FSAC-KK 5085). Cross-sections and jaws
not to scale
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
Consequently, the approach of naming taxa based on
sometimes subtle morphological differences (i.e., jaw cross-
sectional outline) is likely less reliable than any analysis
involving more complete skulls, but these appear to be valu-
able diagnostic characters, which have been used in other
pterosaurs. Nonetheless, the Kem Kem Group pterosaur
material is frequently preserved in three-dimensions and
parameters such as rostral angle, bone-wall thickness and
cross-sectional shape (see Fig.5) can be reliably obtained
from the material, which often cannot be obtained from more
two-dimensionally preserved specimens such as those from
the Solnhofen Limestone Formation, Niobrara Chalk For-
mation, or Jehol Group. When combined with data derived
from techniques such as XCT scanning and thin-section pal-
aeohistology, internal structure can also be incorporated into
any analysis (e.g., Martill etal. 2020a), although we note this
is not a technique available to all.
The advantage of studying isolated remains is their abun-
dance; since most fossils are incomplete, focusing on skulls
and skeletons ignores the vast majority of the pterosaur fos-
sil record. The material here provides a remarkable insight
into pterosaur evolution for a time and place that is other-
wise unknown.
Distinguishing betweenrostrum andmandible
Distinguishing between fragmentary and isolated rostra and
mandibles in edentulous pterosaurs is challenging, especially
when specimens lack key landmarks (i.e., anterior margin
of the NAOF or the divergence of the mandibular rami). In
taxa where both the upper and lower jaws are preserved the
overall morphology (i.e., cross-sectional outline, profile) is
often very similar (Smith etal. 2020b), as for example in
Albadraco Solomon etal. 2020. Generally, mandibles have
a smaller lateral angle than rostra, but exceptions are known
where the lateral angle of the mandible is somewhat larger
than that of the upper jaws (e.g., Bakonydraco galaczi and
Pteranodon longiceps: see McPhee etal. 2020).
For Kem Kem Group edentulous pterosaurs, we use a
combination of similar overall morphology and lateral
angle to tentatively identify upper jaw and lower jaw pairs.
In particular we rely on the overall cross-sectional outline
and the degree of smoothness/sharpness of the dorsal/ventral
Table 1 Table of measurements of azhdarchoid jaws figured for the first time in this study
Species or
morphotype
Specimen Length (mm) Anterior
height
(mm)
Posterior
height
(mm)
Anterior
occlusal width
(mm)
Posterior
occlusal width
(mm)
Lateral angle
(°)
Dorsal angle (°)
A. saharica FSAC-KK 5204 281 ? ? 18.9 25.2 ? ~ 3
A. saharica FSAC-KK 5205 374 39.6 19.2 ~ 6 ~ 4
A. saharica FSAC-KK 5213 460 23.4 28.2 ~ 4 ~ 4
X. curvirostris FSAC-KK 5203 195 21.2 15.3 ~ 6 ~ 3
Morph. A FSAC-KK 5206 75 11.1 17.2 11.1 13.2 ~ 9 ~ 5
Morph. B FSAC-KK 5085 57.3 6.1 7.3 4.6 5.8 ~ 1.5 ~ 1.7
Morph. C FSAC-KK 5200 244 13.8 38.7 9.0 22.4 ~ 7 ~ 5
Morph. C FSAC-KK 5201 232 10.8 ? 7.5 20.6 ? ~ 4
Morph. C FSAC-KK 5202 232 28.2 15.1 ~ 6 ?
Table 2 Table of mid-series cervical vertebra morphotypes and their characters
Character Cervical morphotype
M1 M2 M3 M4 M5 M6 M7 M8 M9
Dorsoanterior foramen: present (A); absent (B) A A A A B A A A B
Dorsoposterior foramen: present (A); absent (B) B A B B B A A B B
Posterolateral foramina: present (A); absent (B) A A A A A A A B A
Subcotylar foramina: present (A); absent (B) A A B B B B B A B
Foramina on lateral sides of centrum: present (A); absent (B) B B B B B B A B A
Length: elongate, length ≥ two times width (A); short, width sub-
equal to length (B)
AAAAAAAAB
Neural spine: low/absent (A); moderate-high (B) A A A A A A B A A
Prezygapophysis angled: more dorsally (A); more anteriorly (B) A A A A A A B A A
R. E. Smith etal.
1 3
border, but other parameters are used too, including presence
or absence of median tuberosities on the occlusal surface,
topography of the occlusal surface and distribution of neural
foramina, and cortical bonethickness.
For toothed pterosaurs, upper jaws are distinguished from
lower jaws by the presence of a median ridge on the palatal
surface, opposed to a median groove present on the occlusal
surface of lower jaws. These features are widespread in
Table 3 Synopsis of pterosaur material from the Kem Kem Group
Azhdarchoidea
Tapejaridae
Afrotapejara
Afrotapejara zouhrii:
Rostra: (FSAC-KK 5004 [holotype], FSAC-KK 5006, FSAC-KK 5007, MN
(UFRJ) 7054 V).
?mandibular symphysis: (BSP 1997 I 67).
Indeterminate jaw fragments: (FSAC-KK 29, FSAC-KK 32, UCRC PV 161).
Azhdarchidae
Alanqa
Alanqa saharica:
Rostra: (FSAC-KK 5204, FSAC-KK 5205).
Mandibular symphyses: (FSAC-KK 26 [holotype], BSP 1996 I 36, FSAC-KK
4000, FSAC-KK 5213/UOP-PAL-KK 0006).
Indeterminate jaw fragments: (FSAC-KK 4002, FSAC-KK 5078, FSAC-KK
5079, FSAC-KK 5080).
Azhdarchidae indet.
Cervical vertebrae: CMN 50801, LINHN 014, FSAC-KK 34, FSAC-KK 3088, FSAC-KK 5077,
FSAC-KK 5083, FSAC-KK 5214, FSAC-KK 5215, FSAC-KK 5216, FSAC KK-5218, FSAC-KK 7251.
Notarium: FSAC-KK 5207.
Wing phalanx: FSAC-KK 5212.
?Azhdarchidae indet.
Femur: FSAC-KK 7141.
?Chaoyangopteridae
Apatorhamphus
Apatorhamphus gyrostega:
Rostrum: (FSAC-KK 5010 [holotype]).
?rostra: (FSAC-KK 27, FSAC-KK 5011, FSAC-KK 5012, FSAC-KK 5084, FSAC-
KK 5014, BSP 1993 IX 338).
?mandibular symphyses: (FSAC-KK 5013, CMN 50859).
Indeterminate jaw fragments: (FSAC-KK 5081, FSAC-KK 5082).
Azhdarchoidea indet.
Jaws: FSAC-KK 28, FSAC-KK 5206 (‘morphotype A’); FSAC-KK 5085 (‘morphotype B’); FSAC-KK 5200,
FSAC-KK 5201, FSAC-KK 5202 (‘morphotype C’); FSAC-KK 31 (indeterminate morphotype).
Cervical vertebrae: FSAC-KK 34, FSAC-KK 5217, FSAC-KK 5219, FSAC-KK 5220, FSAC-KK 7177.
Scapulocoracoid: FSAC-KK 5210.
Humeri: CMN 50814, FSAC-KK 5211.
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
ornithocheirans (Rodrigues and Kellner 2013) and are seen
in the rare Kem Kem Group examples where the relevant
element is preserved (Jacobs etal. 2019, 2020).
Other identifications of upper and lower jaws of isolated
jaw fragments in other deposits (e.g., Aerotitan and Mis-
tralazhdarcho) may also require revaluation.
Institutional abbreviations
FSAC Faculté de Sciences Aïn Chock, Laboratoire de Géo-
sciences, Université Hassan II, Casablanca, Morocco; BSPG
Bayerische Staatssammlung für Paläontologie und Geologie,
Munich, Germany (formerly BSP); CMN Canadian Museum
of Nature, Ottawa, Canada (formerly NMC); LINHM Long
Table 3 (continued)
Ulnae: FSAC-KK 5209, FSAC-KK 7142.
Metacarpal IV: FSAC-KK 4001.
Tibiotarsus: FSAC-KK 7140.
Family incertae sedis
Leptostomia
Leptostomia begaaensis:
Rostrum: (FSAC-KK 5075 [holotype]).
Mandibular symphysis: (FSAC-KK 5076 [paratype]).
Xericeps
Xericeps curvirostris:
Mandibular symphysis: (FSAC-KK 10700 [holotype], FSAC-KK 5203).
Ornithocheiroidea
Ornithocheiridae
Anhanguera
Anhanguera cf. piscator:
Mandibular symphysis: (FSAC-KK 5005).
Coloborhynchus
Coloborhynchus fluviferox:
Rostrum: (FSAC-KK 10701 [holotype]).
Coloborhynchus sp.:
Rostrum: (FSAC-KK 5024/SMNK PAL 45833).
Ornithocheirus
Ornithocheirus cf. simus:
Rostrum: (FSAC-KK 5025/SMNK PAL 45831).
Siroccopteryx
Siroccopteryx moroccensis
Rostrum: (LINHM 016 [holotype]).
Ornithocheiridae indet.
Mandibular ramus fragment: FSAC-KK 33.
Isolated teeth: BSP 1993 IX 4, 590-596, BSP 1993 IX 314, 597-607, BSP 1993 IX 332, 608-
617, BSP 1993 IX 618-621, FSAC-KK 44, FSAC-KK 197, FSAC-KK 885-887, FSAC-KK 941, FSAC-
KK 17001, LINHM 007, MNHN MRS 1108.
Notarium: FSAC-KK 5208.
R. E. Smith etal.
1 3
Island Natural History Museum, Long Island, USA (there is no
current record of this institution); MN Museu Nacional/Univer-
sidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil (collec-
tion likely destroyed by the catastrophic fire of 2018); MNHN
Muséum national d’Histoire naturelle, Paris, France; MSNM
Museo Civico di Storia Naturale, Milan, Italy; NHMUK Nat-
ural History Museum, London, United Kingdom (formerly
BMNH); RGP (RMCA) Royal Museum for Central Africa—
Registre Général Paléontologie, Tervuren, Belgium; SMNK
Staatliches Museum für Naturkunde Karlsruhe, Germany;
UCRC University of Chicago Research Collection, Chicago,
USA; UOP University of Portsmouth, School of the Environ-
ment, Geography and Geosciences collection, UK.
Results
The following account is based on material described in the
literature and newly collected material described herein.
Data on size, morphology, and identification of specimens
is provided in Tables1, 2 and 3, with additional details sup-
plied in the supplementary information (TableS2).
Taphonomy
The Kem Kem Group pterosaur material occurs as isolated
but three-dimensionally preserved elements, which are often
broken (Ibrahim etal. 2020). Although fragmentary the
internal structures at macroscopic and microscopic levels
are often extremely well preserved (Williams etal. 2021).
The deposit is unusual compared to other pterosaur-bearing
deposits, in being dominated by edentulous jaw fragments
(Martill etal. 2018). This bias towards the preservation of
jaw fragments, is as yet unexplained but could be a con-
sequence of robustness of triangular shaped bones, hydro-
dynamic sorting, pterosaur autecology, selective predation/
scavenging, collecting bias or any combination of these. The
Kem Kem Group has a high abundance of ornithocheirid
teeth but ornithocheirid skeletal material is comparatively
rare. Presently, there are no convincing explanations for this
disparity. Other significant anomalies include the complete
lack of syncarpals, elements that are both robust and com-
mon in other pterosaur bone concentrations, such as the
Cambridge Greensand Member of England (Unwin, 2001).
Systematic palaeontology
Pterosauria Kaup, 1834
Pterodactyloidea Plieninger, 1901
Azhdarchoidea Nesov, 1984 sensu Unwin, 2003
Tapejaridae Kellner, 1989
Afrotapejara Martill, Smith, Unwin, Kao, McPhee, Ibrahim,
2020
Type and only species. Afrotapejara zouhrii Martill, Smith,
Unwin, Kao, McPhee, Ibrahim, 2020
Diagnosis. As for type species A. zouhrii.
Genus Zoobank reference number. urn:lsid:zoobank.
org:act:4D288F04-8FEF-493E-8767-A3B448CCF2C2
Species Zoobank reference number. urn:lsid:zoobank.
org:act:4CFBB0A7-6865-4DE6-ABEE-E1698E7B2334
Afrotapejara zouhrii Martill, Smith, Unwin, Kao, McPhee,
Ibrahim, 2020
Synonymy. All mentions where the citation refers to speci-
mens here identified as A. zouhrii are included, as are all
mentions of A. zouhrii.
1999 ‘Tapejaridae… fragment of anterior mandibular sym-
physis’—Wellnhofer and Buffetaut, p. 137, fig.5
(specimen BSP 1997 I 67)
2007 ‘Pteranodontidae… mandibular symphysis’—Kellner
etal., p. 262, figs.1–2 (specimen MN [UFRJ] 7054-V)
2008 Azhdarchidae indet. ‘posterior fragment of premax-
illa’—Averianov etal., p. 641 (specimen BSP 1997 I
67 [spec. number not reported])
2010 ‘Tapejaridae… anterior portion of mandibular sym-
physis’—Ibrahim etal., p. 1, table1 (specimen BSP
1997 I 67)
2011 ‘Tapejaridae… partial lower jaw’—Rodrigues etal.,
p. 156 (specimen BSP 1997 I 67)
2014 Alanqa saharica IBRAHIM etal.—Averianov, p. 6,
fig.1 (specimens BSP 1997 I 67, MN [UFRJ] 7054-V)
*2020a Afrotapejara zouhrii MARTILL etal.—Martill
etal., p. 1, figs.4–15, tables1–3
2020 Afrotapejara zouhrii MARTILL etal.—Ibrahim etal.,
p. 69, figs.97, 100
2020 Apatorhamphus gyrostega MCPHEE etal.—Ibrahim
etal., p. 121–122, fig.100 (specimens FSAC-KK 29,
FSAC-KK 32, UCRC PV 161)
2020b Afrotapejara zouhrii MARTILL etal.—Martill etal.,
p. 10, tables2–3
2020b Afrotapejara zouhrii MARTILL etal.—Smith etal.,
p. 122, fig.14
2021 Afrotapejara zouhrii MARTILL etal.—Martill etal.,
p. 5
2021 Afrotapejara zouhrii MARTILL etal.— Smith etal.,
p. 2, tableS1
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
Holotype. FSAC-KK 5004 (Fig.6A–E), partial rostrum
anterior to the nasoantorbital fenestra, missing the anterior
terminus.
Type locality and horizon. Takmout, Oued Ziz valley, Erra-
chidia Province, south-east Morocco; ?Albian-Cenomanian,
Ifezouane Formation, Kem Kem Group.
Fig. 6 Holotype rostrum FSAC-KK 5004 (AE) and tentatively
referred mandibular symphysis BSP 1997 I 67 (FI) of Afrotapejara
zouhrii. A, F in right lateral view; B, G in occlusal view; C in dorsal
view; H in ventral view, D in anterior view, E in posterior view and I
cross-sectional outline. Scale bars represent 10mm. Cross-sectional
outline redrawn from Wellnhofer and Buffetaut (1999)
R. E. Smith etal.
1 3
Referred material. Seven jaw fragments. Rostral fragments:
FSAC-KK 5006, FSAC-KK 5007 (referred by Martill etal.
2020a) and MN (UFRJ) 7054V (referred by Ibrahim etal.
(2020); ?mandibular symphysis: BSP 1997 I 67 (Fig.6F–I,
referred by Martill etal. 2020a); indeterminate jaw frag-
ments FSAC-KK 29, FSAC-KK 32 and UCRC PV 161
(referred here).
Original diagnosis. (from Martill etal. 2020a). Tapejarid
pterosaur with the down-turned tip typical of the family. Dis-
tinguished from other tapejarids by the following characters:
presence of a row of small foramina on the lateral margins of
the rostrum located close to the occlusal margin of the jaw,
and a small, boss-like protuberance located posteriorly on
the occlusal surface.
Revised diagnosis. A reanalysis of the holotype requires
a slightly revised diagnosis. Tapejarid pterosaur with the
down-turned tip typical of the family. Distinguished from
other tapejarids by the following characters: presence of two
rows of small foramina on the lateral margins of the rostrum,
one located close to the occlusal margin of the jaw and the
other towards the dorsal margin, and a small, boss-like pro-
tuberance located posteriorly on the occlusal surface.
Remarks. An occlusal protuberance has been reported in
members of Azhdarchoidea (e.g., Alanqa saharica), and
occlusal surface modifications have been reported in some
tapejarids (e.g., Caupedactylus ybaka -a pair of grooves that
diverge posteriorly, and Caiuajara dobruskii—two elongate
boss-like ridges extending posteriorly). Occlusal modifica-
tions are widespread within Azhdarchoidea (see discussion)
and differ in morphology and location. However, atpresent
we have insufficient information to use the presence, mor-
phology and position of these modifications for taxonomic
assignment.
Distinguishing between rostrum and mandible. Both jaws of
Afrotapejara zouhrii were identified by Martill etal. (2020a).
The holotype upper jaw (FSAC-KK 5004, Fig.6A–E) of A.
zouhrii has a downturn as seen in all other tapejarids where
the upper jaw is preserved. The average lateral angle of the
holotype is approximately 20°. The upper jaw also has the
start of a posteriorly located median boss on the occlusal
surface, and the start of a sagittal crest. This combination
of features makes it easily identifiable as an upper jaw. A
lower jaw originally described by Wellnhofer and Buffetaut
(1999) (BSP 1997 I 67, Fig.6F–I) was tentatively referred
to A. zouhrii (Martill etal., 2020a) as it has a comparable
cross-section to the holotype and referred material of A.
zouhrii (see Figs.5, 6). It has a straight occlusal margin and
a concave ventral margin. Its overall morphology is compa-
rable to the lower jaws of other tapejarids (e.g., Tapejara).
Azhdarchidae Nesov, 1984
Alanqa Ibrahim, Unwin, Martill, Baidder, Zouhri, 2010
Type and only species. Alanqa saharica Ibrahim, Unwin,
Martill, Baidder, Zouhri, 2010
Diagnosis. As for type and only known species A. saharica.
Genus Zoobank reference number. urn:lsid:zoobank.
org:act:B6244462-2CDC-409A-91F7-5A5A1F1A99BC
Species Zoobank reference number. urn:lsid:zoobank.
org:act:19995B00-FFB3-4747-8A37-17EBFCA8B2B2
Alanqa saharica Ibrahim, Unwin, Martill, Baidder, Zouhri,
2010
Synonymy. All mentions where the citation refers to spec-
imens here identified as A. saharica are included, as are
all mentions of A. saharica. Annotations follow Matthews
(1973). Where multiple publications have the same year,
they are listed in author alphabetical order.
1999 ‘?Azhdarchidae… anterior fragment of premaxilla’—
Wellnhofer and Buffetaut, p. 136, Fig.4 (specimen
BSP 1996 I 36)
2008 ‘anterior end of the premaxilla of Azhdarchidae(?)’—
Averianov, etal., p. 641 (specimen BSP 1996 I 36)
*2010 Alanqa saharica IBRAHIM etal.—Ibrahim, etal., p.
1, Table 1–2, Figs.2–4
2010 (non) Alanqa saharica IBRAHIM etal.—Ibrahim
etal., p. 3, Fig.4, Tables 1, 2 (specimens BSP 1993
IX 338, FSAC-KK 27)
2010 Alanqa saharica IBRAHIM etal.—Vremir, p. 652
2011 Alanqa saharica IBRAHIM etal.—Rodrigues etal.,
p. 150
2012 Alanqa saharica IBRAHIM etal.—Averianov, p. 43
2012 Alanqa saharica IBRAHIM etal.—Novas etal., p.
1448
2013 Alanqa saharica IBRAHIM etal.—Witton, p. 248
2014 Alanqa saharica IBRAHIM etal.—Averianov, p. 1,
Fig.1
2014 (non) Alanqa saharica IBRAHIM etal.—Averianov,
p. 6, Fig.1 (specimens BSP 1993 IX 338, BSP 1997 I
67, CMN 50,859, MN [UFRJ] 7054-V)
2015 Alanqa saharica IBRAHIM etal.—Martill and Ibra-
him, p. 59, Table 1, Figs.3–5
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
2016 Alanqa saharica IBRAHIM etal.—Pêgas etal., p. 13
2017 Alanqa saharica IBRAHIM etal.—Masrour, etal., p.
774
2018 Alanqa saharica IBRAHIM etal.—Longrich, etal.,
p. 23
2018 Alanqa saharica IBRAHIM etal.—Martill etal., p.
1, Fig.6
2018 Alanqa saharica IBRAHIM etal.—Pêgas etal., p. 6
2018 Alanqa saharica IBRAHIM etal.—Vremir etal., p. 7
2019 Alanqa saharica IBRAHIM etal.—Jacobs etal., p. 77
2020 Alanqa saharica IBRAHIM etal.—Ibrahim etal., p.
10, Fig.98
2020 (non) Alanqa saharica IBRAHIM etal.—Ibrahim
etal., p. 123 (specimens CMN 50,859 and FSAC-KK
28)
2020 Alanqa saharica IBRAHIM etal.—Jacobs etal., p. 2
2020a Alanqa saharica IBRAHIM etal.—Martill etal., p. 1
2020 Alanqa saharica IBRAHIM etal.—McPhee etal., p. 1
2020 Alanqa saharica IBRAHIM etal.—Solomon etal., p. 6
2020a Alanqa saharica IBRAHIM etal.—Smith etal., p. 4
2020b Alanqa saharica IBRAHIM etal.—Smith etal., p.
123, Fig.14
2021 Alanqa saharica IBRAHIM etal.—Andres, p. 203,
Fig.1
2021 Alanqa saharica IBRAHIM et al.—Andres and
Langston, p. 96
2021 Alanqa saharica IBRAHIM etal.—Campos, p. 5
2021a Alanqa saharica IBRAHIM etal.—Pêgas etal., p.
630
2021b Alanqa saharica IBRAHIM etal.—Pêgas etal., p.
2, Figs.9–11
2021 Alanqa saharica IBRAHIM etal.—Martill etal., p.5,
Fig.5
2021 Alanqa saharica IBRAHIM etal.—Smith etal., p. 2,
Figs.2–3, 6, Tables 2, S1
2021 Alanqa saharica IBRAHIM etal.—Williams etal.,
supplemental information
2021 (non) Alanqa sp. IBRAHIM etal.—Williams etal.,
p.1, Figs.1–2 (specimen FSAC-KK 5077)
Holotype. FSAC-KK 26 (Fig.7A–E), mandibular symphy-
sis, anterior of the divergence of the mandibular rami.
Type locality and horizon Aferdou N’Chaft, near Hassi el
Begaa, Errachidia Province, south-east Morocco; ? Albian—
Cenomanian, Ifezouane Formation, Kem Kem Group.
Referred material. Nine jaw fragments. Rostra: FSAC-KK
5204 and FSAC-KK 5205 (referred here; Fig.8); man-
dibular symphyses: BSP 1996 I 36 (referred by Ibrahim
etal. 2010),FSAC-KK 4000 and a specimen in a private
collection (Fig.7F–H), 3D prints of which are numbers
UOP-PAL-KK 0006 and FSAC-KK 5213 (both specimens
referred by Martill and Ibrahim 2015); indeterminate jaw
fragments:FSAC-KK 4002 (referred by Martill etal. 2021);
FSAC-KK 5078, FSAC-KK 5079, FSAC-KK 5080 (imma-
ture individuals referred by Smith etal. 2021).
Fig. 7 Mandibular symphyses of Alanqa saharica. AE holotype
FSAC-KK 26 and FH referred specimen in private collection, 3D
prints UOP-PAL KK 0006 and FSAC-KK 5213 (digital images). A, F
In left lateral view; B, G in occlusal view; C, H in ventral view; D-E,
cross-section images (D anterior and E posterior). Scale bars repre-
sent 10mm, cross-sections not to scale
R. E. Smith etal.
1 3
The holotype FSAC-KK 26 was originally described as a
mandibular symphysis by Ibrahim etal. (2010) based on its
low lateral angle. The specimen was later reinterpreted as a
premaxilla by Ibrahim etal. (2020). Here we agree with the
original description as a mandibular symphysis (see discus-
sion below). Specimen BSP 1996 I 36, described originally
as an anterior premaxilla of an indeterminate azhdarchid
(Wellnhofer and Buffetaut 1999), was reinterpreted as a
mandible by Ibrahim etal. (2010) and referred to A. saha-
rica. Here we tentatively agree with the interpretation by
Ibrahim etal. (2010) of BSP 1996 I 36 as a partial mandibu-
lar symphysis of A. saharica. FSAC-KK 4000 is a fragment
of occlusal surface posteriorly located in the jaw and bearing
bony protuberances, identified as a fragment of rostrum by
Martill and Ibrahim (2015). Here we interpret it as a frag-
ment of mandibular symphysis because of the similarity of
its bony protuberances to those of the holotype.
Original diagnosis. (from Ibrahim etal. 2010). Elongate man-
dibular symphysis (length/maximum depth ratio 0.10) with
remarkably straight dorsal and ventral profile in lateral view
and a well-developed ‘‘V’’-shaped midline ridge that bounds
the posterior end of the occlusal surface of the mandibular
symphysis, bifurcates posteriorly and projects well above the
occlusal margin of the symphysis.
Revised diagnosis. Reanalysis of the holotype enables a revi-
sion of the diagnosis thus: elongate mandibular symphysis
with a straight dorsal and ventral profile in lateral view, a
cross-sectional outline which is triangular anteriorly and
becomes ‘Y’ shaped posteriorly with concave lateral margins
(Fig.7), and bifurcating bony protuberances on the posterior
occlusal surface, which project above the occlusal margin
but do not meet anteriorly (Fig.7).
Two specimens are considered premaxillae of A. saharica
(FSAC-KK 5204 and FSAC-KK 5205). We can supplement
the original diagnosis with the following characters: rostrum
with a similar overall morphology to the mandibular sym-
physis (cross-section and profile) but with a single median
boss located posteriorly on the occlusal surface (Fig.8).
Remarks. Several other fragmentary jaws have been referred
to A. saharica including BSP 1993 IX 338, FSAC-KK 27
(referred by Ibrahim etal. 2010), BSP 1997 I 67, CMN
50859, MN (UFRJ) 7074-V (referred by Averianov 2014)
and FSAC-KK 28 (referred by Ibrahim etal. 2020). All were
subsequently referred to other taxa. Specimens BSP 1993
IX 338 and CMN 50859 were re-evaluated and referred to
Apatorhamphus gyrostega by McPhee etal. (2020). Jaw
fragment FSAC-KK 27 was also reinterpreted and referred
to A. gyrostega by Ibrahim etal. (2020) on account of its
rounded dorsum. Specimens BSP 1997 I 67 and MN (UFRJ)
7074-V were also reinterpreted and referred to Afrotapejara
Fig. 8 Alanqa saharica referred rostra. AD FSAC-KK 5205 and EH FSAC-KK 5204. A, E in right lateral view; B, F in occlusal view; C, G
in dorsal view; D, in posterior view and H in anterior view. Scale bars represent 10mm
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
zouhrii by Martill etal. (2020a) and Ibrahim etal. (2020)
respectively. We identify FSAC-KK 28 as Azhdarchoidea
indet. jaw ‘morphotype A’ (see below).
In addition to jaw fragments, some authors referred post-
cranial elements to Alanqa saharica because at the time A.
saharica was the only namedtaxon of azhdarchoid ptero-
saur recorded from the Kem Kem Group. Cervical verte-
brae CMN 50801, LINHM 014 and FSAC-KK 5077 were
referred by Averianov, (2014) and Williams etal. (2021) to
this taxon. In the latter case Williams etal. (2021) identified
the vertebra as Alanqa sp. A right humerus, CMN 50814,
was also referred to A. saharica by Averianov (2014). We
consider postcranial azhdarchoid material from the Kem
Kem Group to be non-diagnostic at genus or species level,
and, until associated material is found, postcranial material
cannot be referred with certainty to any jaw-based taxon.
Therefore, we identify the vertebrae CMN 50801, FSAC-
KK 5077 and LINHM 014 as Azhdarchidae indet. and the
humerus CMN 50814 as Azhdarchoidea indet. (see below).
Distinguishing between rostrum and mandible. The holotype
of Alanqa saharica (FSAC-KK 26, Fig.7A–E) was origi-
nally described as a lower jaw (Ibrahim etal. 2010), and sub-
sequently several authors followed this interpretation (Rodri-
gues etal. 2011; Averianov 2014; Martill and Ibrahim 2015;
Martill etal. 2018; Vullo etal. 2018; McPhee etal. 2020)
whereas more recently, it has been suggested it is an upper
jaw (Ibrahim etal. 2020). Several specimens were referred
to A. saharica as upper jaws including BSP 1993 IX 338
(Ibrahim etal. 2010) and FSAC-KK 4000 (Martill and Ibra-
him 2015). Specimen BSP 1993 IX 338 was subsequently
referred to Apatorhamphus gyrostega (Ibrahim etal. 2020).
The occlusal modification on the holotype of A. saharica
described by Ibrahim etal. (2010) was misinterpreted and
is the same as that seen on FSAC-KK 4000. Two specimens
referred here to A. saharica, with a comparable morphol-
ogy (cross-sectional outline, foramina distribution) but with
a single median boss on the occlusal surface (FSAC-KK
5204 and FSAC-KK 5205, Fig.8), represent the rostrum of
this taxon. The holotype has a lateral angle of ~ 4°, as does
a similar specimen in a private collection figured by Mar-
till and Ibrahim (2015) (3D-print UOP-PAL KK 0006 and
FSAC-KK 5213, Fig.7F–H). Specimen FSAC-KK 5205 has
a lateral angle of ~ 6°. FSAC-KK 5204 is missing its dorsal
margin, and therefore a lateral angle cannot be measured.
The lateral angle is generally larger in the upper jaw com-
pared to the lower, therefore we tentatively interpret FSAC-
KK 26, UOP-PAL KK 0006/FSAC-KK 5213 and FSAC-KK
4000 as lower jaws and FSAC-KK 5204 and FSAC-KK 5205
as upper jaws.
Azhdarchidae indet.
Cervical vertebrae
Material. Mid-series cervical vertebrae: CMN 50801
and LINHM 014 (described by Rodrigues etal. 2011);
FSAC-KK 34 (described by Ibrahim etal. 2010); FSAC-
KK 3088 (described by Ibrahim etal. 2020); FSAC-KK
5077 (described by Williams etal. 2021); FSAC-KK 5083
(described by Smith etal. 2021); FSAC-KK 7251 (referred
here, Fig. S2); FSAC-KK 5214 (referred here, Fig. S3);
FSAC-KK 5215 (referred here, Fig. S4); FSAC-KK 5216
(referred here, Fig. S6). Posterior cervical vertebra: FSAC-
KK-5218 (referred here Fig. S10).
Taxonomic assignment. Elongate mid cervicals (C3-C7)
from the Kem Kem deposits that exhibit the following cervi-
cal morphotypes: 1–6, and 8 (see below) are assigned here to
Azhdarchidae. These vertebrae are clearly distinguished from
those of ornithocheiroids which are relatively short with a high
‘spine line’ neural spines and large foramina on the lateral sur-
faces of the centrum (Wellnhofer 1991; Kellner 1995). Among
azhdarchoids, azhdarchid mid-series cervical vertebrae are dis-
tinguished by their remarkable elongation, reduced, vestigial,
or even absent neural spine, absence of foramina on the lateral
surfaces of the centrum, a neural arch that is confluent with
the centrum forming a tubular vertebral body, a neural canal
that is subsumed into the centrum and large dorsoventrally
flattened zygapophyses (e.g., Howse 1986; Frey and Martill
1996; Averianov 2010). Several of these features are present on
these Kem Kem mid-cervicals, supporting their assignment to
Azhdarchidae.
The cervical vertebra FSAC-KK 5218 (cervical mor-
photype 9) has an almost quadrilateral outline in dorsal/
ventral view, with vertebral length subequal to its width.
This morphology compares closely to that of cervical
number 8 of Azhdarcho (Averianov 2010) and cervical
number 3 (Vremir, 2010) or cervical number 7 (Naish and
Witton 2017) of Hatzegopteryx sp. The C8 described by
Averianov (2010) bears foramina on the lateral surfaces
of the centrum, similar to those on FSAC-KK 5218 (Fig
S10), whereas lateral foramina do not appear to be present
on the cervical referred to Hatzegopteryx sp. A compara-
ble morphology is evident in mid-series cervicals of thal-
assodromeids which also have a squarish outline but differ
in exhibiting a well-developed hatchet-like neural spine
and multiple large foramina on the lateral surfaces (Vila
Nova etal. 2015). A neural spine appears to be absent
on the cervical referred to Hatzegopteryx sp. (Naish and
Witton 2017) but may have been present on the cervi-
cal assigned to Azhdarcho. Overall, the morphology of
FSAC-KK 5218 matches most closely that of the C8 of
azhdarchids, therefore it is identified here as a posterior
R. E. Smith etal.
1 3
cervical vertebra (?C8) of an indeterminate species of
Azhdarchidae.
Remarks. There is no current record of LINHM, therefore
the location of LINHM 014 described by Rodrigues etal.
(2011) is currently unknown.
Notarium
Material. FSAC-KK 5207, partial notarium fragment includ-
ing anterior-most dorsal vertebra (Fig.9A–E).
Taxonomic assignment. A well-preserved but incomplete
dorsal vertebra (FSAC-KK 5207; Fig.9A–E), lacking the
Fig. 9 Pterosaur notaria from the Kem Kem Group. AE azhdarchoid
anterior notarium fragment (FSAC-KK 5207): A, anterior view;
B posterior view; C right lateral view; D dorsal view and E ventral
view. FI ornithocheirid anterior notarium fragment (FSAC-KK
5208): F anterior view; G right lateral view; H dorsal view and I ven-
tral view. Scale bars represent 10mm
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
neural spine but retaining the proximal portion of a rib
which is fused to the right side of the vertebra, appears to be
the anteriormost element of a partially fused notarium and
thus from position 10 (= dorsal number 1) in the vertebral
column. This specimen compares closely to the first dorsal
in the notarium of several azhdarchoids including thalasso-
dromines (Aires etal. 2013: fig.4), Tupuxuara (Aires etal.
2020: fig.7) and Quetzalcoatlus (Andres and Langston
2021: fig.26). Typical azhdarchoid features include pneu-
matopores flanking the neural canal and short, robust, later-
ally directed parapophyses. Notably, in anterior view, the
ventral margin of the centrum bears a distinctive, rounded,
midline notch, a feature that, for those few species where
the notarium is well preserved (Aires etal. 2020) appears
to be restricted to Quetzalcoatlus. Furthermore, in terms
of its general shape and proportions FSAC-KK 5207 com-
pares closely to the first notarial vertebra of Quetzalcoatlus,
consequently this specimen can be confidently assigned to
Azhdarchidae.
Wing phalanx
Material. FSAC-KK 5212, right wing phalanx 1 missing
distal end (Fig.10, referred here).
Taxonomic assignment Wing phalanges are simple structures
and show relatively little morphological variation across
Pterodactyloidea, generally only differing in the extent to
which individual phalanges contribute to the length of the
wing-fingerand in cross-sectional outline. In azhdarchoids,
for example, the wing-phalanx one typically forms at least
40%, or more, of the wing-finger and as a consequence is
relatively elongate,with in Zhejiangopterus and Quetzal-
coatlus, length/width ratios of between 25 and 30. Azhdar-
choid wing phalanges two and three are also distinguished
by a ‘T-shaped’ cross-section resulting from the presence
of an elongate ridge that extends along the ventral margin
of the phalanx (Martill and Frey 1999). In other pterodacty-
loids wing phalanges are oval, sub-triangular, or D-shaped
in cross-section. A wing-phalanx one (FSAC-KK 5212)
from the Kem Kem deposits (Fig.10) lacking its distal ter-
mination is likely to have exceeded a length/width ratio of
25, when complete. Moreover, the proximal articulation is
unusual in that the profile of the dorsal articular facet, when
seen in dorsal aspect, is asymmetrical with the portion of the
arc that faces proximally of markedly greater length than the
portion that faces posteriorly. This asymmetry is also evi-
dent in the wing-phalanx one of the azhdarchids Azhdarcho,
Quetzalcoatlus and, seemingly, Zhejiangopterus, and is pos-
sibly restricted to azhdarchids because in other azhdarchoids
such as Tupuxuara the articular facet appears to be much
Fig. 10 Azhdarchid right wing phalanx 1 missing the distal
end(FSAC-KK 5212) from the Kem Kem Group: A, dorsal view and
B, ventral view. Scale bar represents 50mm
R. E. Smith etal.
1 3
more symmetrical. In ornithocheirids, the dorsal articular
facet is symmetrical, subtends a greater arc and occupies
only about 50% of the total width of the proximal articular
end of the phalanx, unlike FSAC-KK 5212, Quetzalcoat-
lus and Azhdarcho where the dorsal articular facet extends
across more than 66% of the antero-posterior width of the
proximal articulation. FSAC-KK 5212 can be confidently
referred to Azhdarchoidea and likely represents Alanqa or
one of the other putative Kem Kem azhdarchids.
Fig. 11 Hind-limb elements of
Kem Kem Group pterosaurs.
A-D ?azhdarchid complete right
femur (FSAC-KK 7141): A
posterior view; B anterior view;
C proximal view and D distal
view. EH azhdarchoid left
tibia with fused fibula missing
distal end (FSAC-KK 7140): E
medial view; F lateral view; G
magnified lateral view showing
partial fused fibula (arrows) and
H proximal view. Scale bars
represent 10mm
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
?Azhdarchidae indet.
Femur
Material. FSAC-KK 7141 (Fig.11A–D), complete right
femur (referred here).
Taxonomic assignment. A well-preserved near complete right
femur (FSAC-KK 7141) lacking only part of the proximal head
can be confidently assigned to Azhdarchoidea. It lacks typical
features of ornithocheiroids including a femoral head directed
at > 160°, a heavily reduced greater trochanter and a more or less
straight shaft of uniform diameter throughout much of its length
(e.g., Kellner and Tomida 2000: Fig.51). By contrast, FSAC-KK
7141 exhibits a slender femoral neck, a well-developed and proxi-
mally directed greater trochanter, a prominent pneumatopore in
the base of the posterior aspect of the femoral neck, a long slender
slightly medially curved shaft that is narrowest immediately dis-
tal to the proximal articulation and gently increases in diameter
posteriorly, and a relatively complex distal articulation in which
the central sulcus (which separates the lateral and medial con-
dyles) is flanked on either side by a shallow groove that extends
anteroposteriorly and gently bisect each articular condyle. These
accessory grooves are well developed, for example, in Azhdarcho
(Averianov 2010: fig.34J) but present in only an incipient state
here, though visible as slight arcuate excavations of the distal con-
dyles in posterior aspect (Fig.11A). These features, most notably
the pneumatopore and complex distal articulatory surfaces, are
apomorphies of Azhdarchoidea (e.g., Unwin 2003). Within this
clade, FSAC-KK 7141 shows closest similarity to the femora of
the thalassodromeid Tupuxuara (IMCF 1052) and the azhdarchid
Azhdarcho (Averianov 2010) but is less robustly constructed than
the femur of Quetzalcoatlus (Andres and Langston 2021). Simi-
larly, it is more elongate and slender than the femora of tapejarids
such as Sinopterus (e.g. IVPP V.12693, D2525) and Tupandacty-
lus (Beccari etal. 2021) and of chaoyangopterids such as Chaoy-
angopterus (IVPP 13,397) and Jidapterus (Wu etal. 2017). Pend-
ing the discovery of more complete remains, FSAC-KK 7141 is
identified as ?Azhdarchidae.
?Chaoyangopteridae Lü etal., 2008
Apatorhamphus McPhee, Ibrahim, Kao, Unwin, Smith,
Martill, 2020
Type and only species. Apatorhamphus gyrostega McPhee,
Ibrahim, Kao, Unwin, Smith, Martill, 2020
Diagnosis. As for type species A. gyrostega.
Genus Zoobank reference number urn:lsid:zoobank.
org:act:BB7F9696-23CC-4A54-BCB3-6D1D7A31826A
Species Zoobank reference number urn:lsid:zoobank.
org:act:86D6C1C7-9CD3-46AA-9CED-20E3B1BC2EF6
Apatorhamphus gyrostega McPhee, Ibrahim, Kao, Unwin,
Smith, Martill, 2020
Synonymy. All mentions where the citation refers to speci-
mens here identified as A. gyrostega are included, as are all
mentions of A. gyrostega.
1999 ‘?Pteranodontidae… anterior part of premaxilla’—
Wellnhofer and Buffetaut, p. 135, Figs.2–3 (specimen
BSP 1993 IX 338)
2006 Pteranodontidae or Azhdarchidae… edentulous ros-
tral tip’—Rodrigues etal., p. 116A (specimen CMN
50,859)
2008 Azhdarchid ‘mandibular beak’—Averianov etal., p.
641 (specimen BSP 1993 IX 338 [spec. no not stated])
2010 Alanqa saharica IBRAHIM etal.—Ibrahim etal., p.
3, Fig.4, Tables1, 2 (specimens BSP 1993 IX 338,
FSAC-KK 27)
2011 Pteranodontidae… lower jaw’—Rodrigues etal., p.
156 (specimen BSP 1993 IX 338)
2011 ‘Dsungaripteroidea indet… ?lower jaw’—Rodrigues
etal., p. 150, Fig.1 (specimen CMN 50,859)
2014 Alanqa saharica IBRAHIM etal.—Averianov, p. 6,
Fig.1 (specimens BSP 1993 IX 338, CMN 50,859)
*2020 Apatorhamphus gyrostega MCPHEE etal.—McPhee
etal., p. 1, Figs.3–10, Table 1
2020 Apatorhamphus gyrostega MCPHEE etal.—Ibrahim
etal., p. 70, Fig.96
2020 Alanqa saharica IBRAHIM etal.—Ibrahim etal., p.
123 (specimen CMN 50,859)
2020 (non) Apatorhamphus gyrostega MCPHEE etal.—
Ibrahim etal., p. 121–122, Fig.100 (specimens FSAC-
KK 29, FSAC-KK 32, UCRC PV 161)
2020 Apatorhamphus gyrostega MCPHEE etal.—Jacobs
etal., p. 2
2020a Apatorhamphus gyrostega MCPHEE etal.—Martill
etal., p. 1
2020b Apatorhamphus gyrostega MCPHEE etal.—Smith
etal., p. 123, Fig.14
2021 Apatorhamphus gyrostega MCPHEE etal.—Andres,
p. 205, Fig.1
2021 Apatorhamphus gyrostega MCPHEE etal.—Martill
etal., p. 5
2021 Apatorhamphus gyrostega MCPHEE etal.—Smith
etal., p. 2, Figs.2–3, Tables2, S1
Holotype. FSAC-KK 5010 (Fig.12), a portion of rostrum
anterior to the margin of the nasoantorbital fenestra, missing
the anterior end (3D print UOP-PAL-KK 0001).
R. E. Smith etal.
1 3
Type locality and horizon. Aferdou N’Chaft, near Hassi el
Begaa, Errachidia Province, south-east Morocco; ?Albian—
Cenomanian, Ifezouane Formation, Kem Kem Group.
Referred material. 11 jaw fragments. ?rostra: FSAC-KK 27
(referred by Ibrahim etal. 2020), FSAC-KK 5011, FSAC-
KK 5012, FSAC-KK 5014, BSP 1993 IX 338 (referred by
McPhee etal. 2020) and FSAC-KK 5084 (referred by Smith
etal. 2021); ?mandibular symphyses: FSAC-KK 5013, CMN
50859 (referred by McPhee etal. 2020) and two indetermi-
nate jaw fragments of immature individuals FSAC-KK 5081
and FSAC-KK 5082 (referred by Smith etal. 2021).
Diagnosis (from McPhee etal. 2020). Apatorhamphus gyro-
stega can be diagnosed by a unique combination of characters:
cross-sectional profile has an inverted U-shape anteriorly, pos-
teriorly developing a more teardrop-like outline as the lateral
margins become slightly convex (a possible autapomorphy) and
rostrum long and edentulous, with a straight occlusal border and
slightly concave anterior dorsal border in lateral view. The bone
wall is massively thickened at the rostrum tip (autapomorphy).
The occlusal surface is moderately concave with paired,slightly
off-set foramina; foramina of the occlusal surface are slit-like
anteriorly becoming circular posteriorly (possibly autapomor-
phic) and a single row of slit-like neurovascular foramina on the
lateral margins is aligned parallel to the dorsal margin.
Remarks. Specimens FSAC-KK 29, FSAC-KK 32 and
UCRC PV 161 referred by Ibrahim etal. (2020) to A.
gyrostega are reinterpreted here as Afrotapejara zouhrii,
based on the following characters: triangular cross-section
outline with convex lateral surfaces; presence of parallel ver-
tical septa and two rows of foramina on the lateral surfaces.
Specimen CMN 50859 incorrectly cited as ‘CMN 50895’
(pg. 123 Ibrahim etal. 2020).
Distinguishing between rostrum and mandible. The rostrum
and mandible of Apatorhamphus gyrostega were described
by McPhee etal. (2020). Both have a similar overall mor-
phology and were distinguished as upper and lower jaws
by their lateral angle (upper jaws had a higher lateral angle
compared to lower jaws). The holotype rostrum (FSAC-KK
5010, Fig.12) has a lateral angle of approximately 12° and
the referred possible mandible (FSAC-KK 5013) has a lat-
eral angle of approximately 8°.
Azhdarchoidea Nesov 1984 (sensu Unwin 2003)
Family incertae sedis
Leptostomia Smith, Martill, Kao, Zouhri, Longrich, 2020
Type and only species. Leptostomia begaaensis Smith, Mar-
till, Kao, Zouhri, Longrich, 2020
Diagnosis. As for type species L. begaaensis
Genus Zoobank reference number urn:lsid:zoobank.
org:act:1CAC21B5-E226-47EA-9432-C50E09650D0D.
Fig. 12 Holotype rostrum FSAC-KK 5010 of Apatorhamphus gyrostega. A in right lateral view; B in dorsal view; C in occlusal view; D anterior
view and E posterior view. Scale bars represent 10mm
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
Species Zoobank reference number urn:lsid:zoobank.
org:act:52,727,043-2A97-4FDA-B586-D97E27CC0595
Leptostomia begaaensis Smith, Martill, Kao, Zouhri, Lon-
grich, 2020
Synonymy. All mentions of L. begaaensis are included.
*2020a Leptostomia begaaensis SMITH etal.—Smith etal.,
p. 1, Figs.2–10, Tables 1
2020a Leptostomia begaansis SMITH etal.—Smith etal.,
p. 12. Lapsus calami
2021 Leptostomia begaaensis SMITH etal.—Andres, p.
212, Fig.1
2021 Leptostomia begaaensis SMITH etal.—Andres and
Langston, p. 89
2021 Leptostomia begaaensis SMITH etal.—Smith etal.,
tableS1
Holotype. FSAC-KK 5075 (Fig.13A–E), a fragment of
rostrum from anterior to the margin of the nasoantorbital
fenestra, missing the terminus.
Fig. 13 Holotype rostrum FSAC-KK 5075 (AE) and paratype man-
dibular symphysis FSAC-KK 5076 (FH) of Leptostomia begaaensis.
A in dorsal view; B, G in occlusal view; C, H in right lateral view; D
in anterior view; E in posterior view and F in ventral view. Scale bars
AD, FH represent 5mm; D-E 1mm
R. E. Smith etal.
1 3
Paratype. FSAC-KK 5076 (Fig.13F–H), a partial mandib-
ular symphysis lacking any divergence of the mandibular
rami, missing the anterior end.
Type locality and horizon. Aferdou N’Chaft, near Hassi el
Begaa, Errachidia Province, south-east Morocco; ?Albian—
Cenomanian, upper Ifezouane Formation, Kem Kem Group.
Diagnosis. (from Smith etal. 2020a). Edentulous pterosaur,
with a long and slender beak lacking dorsal or ventral crests.
The following features are autapomorphic: lateral and dorsal
rostral angles (sensu McPhee etal. 2020, tb. 1) less than or
equal to an arc of three degrees; cross-sectional outline of
anterior rostrum and mandibular symphysis semi-circular;
cross-section of rostrum and mandibular symphysis with
thick cortices and reduced central cavity.
Distinguishing between rostrum and mandible. The incom-
plete upper and lower jaws of Leptostomia begaaensis, a
possible probe-feeding pterosaur, were described by Smith
etal. (2020a). Both jaws have a similar shape with a semi-
circular cross-sectional outline, but minor differences sug-
gest one is a lower and the other is an upper jaw. There is no
reason to believe they represent remains from a single indi-
vidual. The holotype rostrum (FSAC-KK 5075, Fig.13A–E)
has a median ridge on the occlusal surface that extends for
the length of the specimen, whereas the paratype mandible
(FSAC-KK 5076, Fig.13F–H) has a complimentary median
occlusal groove that flattens anteriorly. They are identified as
upper and lower jaw based upon their lateral angles, where
the holotype has a slightly higher lateral angle compared
to the paratype (~ 2.5° vs 2.0°) (Smith etal. 2020a), and
the presence of a ridge on the rostrum and groove on the
mandible.
Xericeps Martill, Unwin, Ibrahim, Longrich, 2018
Type and only species. Xericeps curvirostris Martill, Unwin,
Ibrahim, Longrich, 2018.
Diagnosis. As for type species X. curvirostris.
Genus Zoobank reference number urn:lsid:zoobank.
org:act:0E0893BC-AF20-4CF0-AFB5-0BE3A1090EF3.
Species Zoobank reference number urn:lsid:zoobank.
org:act:46AEB1A1-D274-4D07-A1EA-B42315349A28.
Xericeps curvirostris Martill, Unwin, Ibrahim, Longrich,
2018
Synonymy. All mentions of X. curvirostris are included
*2018 Xericeps curvirostris MARTILL etal.—Martill etal.,
p. 1, Figs.3–6, Table 1
2018 ‘Xericeps (holotype FSAC-KK 10,700)’ MARTILL
etal.—Vullo etal., p. 4
2019 Xericeps curvirostris MARTILL etal.—Jacobs etal.,
p. 77
2020 Xericeps curvirostris MARTILL etal.—Ibrahim etal.,
p. 69, Fig.99
2020 Xericeps curvirostris MARTILL etal.—Jacobs etal.,
p. 2
2020 Xericeps curvirostris MARTILL etal.—McPhee etal.,
p. 1, Fig.9, Table 1
2020 Xericeps curvirostris MARTILL etal.—Solomon
etal., p. 6
2020b Xericeps curvirostris MARTILL etal.—Smith etal.,
p. 123, Fig.14
2021 Xericeps curvirostris MARTILL etal.—Andres, p.
212, Fig.1
2021 Xericeps curvirostris MARTILL etal.—Campos, p. 5
2021 Xericeps curvirostris MARTILL etal.—Martill etal.,
p. 5
2021b Xericeps curvirostris MARTILL etal.—Pêgas etal.,
p. 3, Figs.10, 12, 14
2021 Xericeps curvirostris MARTILL etal.—Smith etal.,
p. 2, Table S1
Holotype FSAC-KK 10700 (Fig.14A–E), partial mandibular
symphysis.
Type locality and horizon. Aferdou N’Chaft, near Hassi el
Begaa, Errachidia Province, south-east Morocco; ?Albian—
Cenomanian, Ifezouane Formation, Kem Kem Group.
Referred material. Partial mandible FSAC-KK 5203
(Fig.14F–H) (referred here).
Diagnosis (from Martill etal. 2018). Lower jaw upcurved
(dorsally recurved), with occluding surface exhibiting a con-
cave profile. Ventral margin lacking keel, but with continu-
ous longitudinal midline sulcus (autapomorphy); occlusal
surface with paired ridges, confined to the posterior portion
of the mandibular symphysis, that project slightly dorsal to
the dentary’s lateral margin, thereby defining a broad mid-
line groove. Deep sulcus on occluding surface of mandibular
symphysis shallows anteriorly into jaw tip. Thick cortices of
dentary anteriorly. Lateral surface of lower jaw tip distinctly
convex, cross-section U-shaped.
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
Remarks. Due to the lack of autapomorphic features of
Azhdarchidae on the holotype and referred material of X.
curvirostris, we consider X. curvirostris an indeterminate
non-tapejarid azhdarchoid, following Martill etal. (2018).
Distinguishing between rostrum and mandible Only the
lower jaw of Xericeps curvirostris has so far been described.
The holotype (FSAC-KK 10700, Fig.14A–E) is dorsally
curved with a deep sulcate occlusal surface that deepens
posteriorly. A further specimen (FSAC-KK 5203, Fig.14F–
H) has been discovered with a comparable morphology. It
appears that the jaws of X. curvirostris are less common than
other Kem Kem Group pterosaurs. The corresponding upper
jaw of Xericeps is unknown.
Azhdarchoidea indet.
Jaw morphotype A
Referred material Two edentulous fragments: FSAC-KK 28
(originally referred to A. saharica by Ibrahim etal. 2020)
and FSAC-KK 5206 (referred here; Fig.15).
Description. Both specimens have a triangular cross-sec-
tion with acute dorsal and occlusal apices, and flat lateral
surfaces. Specimens FSAC-KK 28 and FSAC-KK 5206 have
a gently sulcate occlusal surface with paired foramina on
the occlusal surface. The lateral surface has a single row of
foramina located medially (see Table1 for measurements).
Remarks. Of the edentulous pterosaur taxa from the Kem
Kem Group, two have a triangular cross-sectional outline:
Alanqa saharica and Afrotapejara zouhrii. The acute dor-
sal and occlusal apices of these jaws distinguish them from
Alanqa saharica and Afrotapejara zouhrii, both of which
have more rounded apices. Furthermore, the flat lateral
surfaces of these specimens distinguish them from Alanqa
saharica, which has a more concave lateral surface and Afro-
tapejara zouhrii, which has convex lateral surfaces anteri-
orly which become more concave posteriorly. Significantly,
these specimens differ from all described Kem Kem Group
edentulous pterosaurs, suggesting they represent an as yet
unidentified taxon. We await better material before attempt-
ing to establish a new taxon.
Jaw morphotype B, aff. Apatorhamphus
Referred material. FSAC-KK 5085, a partial ?mandible
missing the anterior tip and not extending posteriorly as far
as the divergence of the mandibular rami (Fig.16).
Fig. 14 Mandibular symphyses of Xericeps curvirostris. AE Holo-
type FSAC-KK 10700; FH referred specimen FSAC-KK 5203. A,
F In left lateral view; B, G in occlusal view; C, H in ventral view; D,
in posterior view and E, in anterior view. Scale bars represent 10mm.
A-C Ammonium chloride coated specimen
R. E. Smith etal.
1 3
Description. The specimen is a fragment of jaw, likely a
mandibular symphysis that lacks any trace of the diverging
rami and lacks the anterior tip. It is free from matrix and
has a maximum length of 57.3mm, a maximum height of
7.3mm, and a maximum width of 5.8mm (Table1). Much
of the surface is pitted where sand grains of the original
matrix have been pressed into the bone surface. Along its
entire length the cross-sectional outline presents a U-shaped
profile. The occlusal surface is gently sulcate, becoming
slightly deeper posteriorly. The lateral angle is ~ 1.5° and
the dorsal angle is ~ 1.7°. All surfaces have elongated neural
foramina, those of the lateral margins being highly elongate
and aligned in two medial rows parallel to the long axis of
the jaw (Fig.16A, B). On the occlusal surface neurovascu-
lar foramina are arranged in alternating pairs (Fig.16D). In
cross-section, the bone wall appears thickened, especially
in the vertices where it has a maximum breadth of 2.1mm
(Fig.16E–F). The bone wall is thinnest at the posterior ter-
mination where it is approximately 1.0mm thick(Fig.16F).
Fig. 15 Jaw fragments of jaw ‘morphotype A. AD FSAC-KK 28 and EG FSAC-KK 5206. A, E in lateral view; B, F in dorsal/ventral view;
C, G in occlusal view and D, G in posterior view. Scale bars represent 10mm
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
Remarks. This specimen exhibits a unique combination of
characters. The cross-sectional outline is U-shaped, similar
to that of Apatorhamphus gyrostega and its lateral and dor-
sal angles are low, suggesting an extremely elongate, slen-
der, needle-shaped jaw comparable to that of Leptostomia
(see below). The morphology hints at a distinct taxon and
perhaps a different feeding ecology. More material of this
pterosaur is needed to determine its validity as a new taxon
and its potential phylogenetic affinities.
Jaw morphotype C
Referred material Partial jaw fragments FSAC-KK 5200,
FSAC-KK 5201 and FSAC-KK 5202 (Fig.17, referred
here).
Descriptions. All three specimens show some signs of com-
paction and damage. This is most extensive on FSAC-KK
5201, which has most of its dorsal section and large frag-
ments of the lateral surface missing. Compaction has caused
the posterior lateral margins on specimen FSAC-KK 5200
to fold in medially. FSAC-KK 5202 (Fig.17J–N) has a dor-
sally curved profile, which is likely the result of distortion
(Fig.17M). This is evident when looking at the occlusal
surface, which appears ‘twisted’ (Fig.17L).
All three specimens have a similar morphology with a
U-shaped cross-sectional outline and a sulcate occlusal sur-
face that deepens posteriorly. The lateral surfaces have a
single row of small foramina, which are positioned slightly
more towards the dorsal margin. The occlusal surface bears
paired foramina. Specimens FSAC-KK 5200 and FSAC-KK
5201 are missing the anterior portion of the jaw, whereas
FSAC-KK 5202 extends almost to the jaw tip. Specimen
FSAC-KK 5200 has a lateral angle of approximately 7°
whereas that of FSAC-KK 5202 is approximately 6°. As
specimen FSAC-KK 5201 lacks the majority of the dorsal
margin a lateral angle cannot be accurately measured.
All three specimens have a median boss-like eminence on
the occlusal surface. FSAC-KK 5202 has only the anterior-
most portion of the boss preserved. The boss is more exten-
sively preserved in specimens FSAC-KK 5200 and FSAC-
KK 5201, which shows that the boss widens and heightens
posteriorly. Specimen FSAC-KK 5200 has the boss broken
off at a point level with the occlusal margin, whereas in
specimen FSAC-KK 5201 the boss projects approximately
19mm above the occlusal margin. All three specimens have
a slight downward curve to the occlusal margin posteriorly
(see Fig.17) (see Table1 for measurements).
Remarks. The U-shaped cross-sectional outline of all three
specimens suggests possible affinities with either Apator-
hamphus or Xericeps. However, due to the fragmentary
nature of the material, it is not possible to determine the
affinities of the taxon they represent. We posit three possi-
bilities: 1, they are the lower jaw of Apatorhamphus which
may have borne a median boss; 2, they are the upper jaw of
Xericeps, which may have been straight, unlike the curved
lower jaw typical of this species; 3, they represent a new
taxon.
Fig. 16 Jaw fragment of jaw ‘morphotype B’, FSAC-KK 5085. A in ?right lateral view; B in ?left lateral view; C dorsal/ventral view; D in
occlusal view; E in anterior view and F in posterior view. Scale bar represents 10mm
R. E. Smith etal.
1 3
Indeterminate jaw fragment
Material. FSAC-KK 31, a jaw fragment missing the dor-
sal surface, originally referred to A. saharica by Ibrahim
etal. (2010), but not figured.
Remarks. Due to the specimen only comprising the occlusal
surface, a complete cross-sectional outline cannot be confi-
dently determined. Therefore, assignment of this specimen
to a particular taxon is not currently possible because mul-
tiple azhdarchoids occur in the Kem Kem Group.
Fig. 17 Jaw fragments of jaw ‘morphotype C’. AD FSAC-KK 5201;
EI, FSAC-KK 5200; JN FSAC-KK 5202. A, E, J in lateral view;
B, F, K in dorsal/ventral view; C, G, L in occlusal view; D, H, N
in posterior view; I in anterior view and M in lateral view but with
some of the distortions caused by breakage and compaction digitally
removed. Scale bars represent 10mm
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
Cervical vertebrae
Material. Mid-series cervical vertebrae: FSAC-KK 5217,
FSAC-KK 7177 (referred here, Fig. S8); cervical vertebra
fragments FSAC-KK 34 (described by Ibrahim etal. 2010).
Posterior cervical vertebrae (cervical IX/dorsal vertebra I
[cervicalised dorsal vertebrae]): FSAC-KK 5219 and FSAC-
KK 5220 (referred here, Fig.18).
Taxonomic assignment. FSAC-KK 34 (indeterminate cer-
vical morphotype), FSAC-KK 5217 and FSAC-KK 7177
(cervical morphotype 7), exhibit several features, includ-
ing elongation, partial coalescence of the neural arch and
Fig. 18 Azhdarchoid cervical vertebrae ?IX FSAC-KK 5219 (AF) and FSAC-KK 5220 (GJ) from the Kem Kem Group. A, I in anterior view;
B in left lateral view; C, in right lateral view; D, J in posterior view; E, H in ventral view and F, G in dorsal view. Scale bars represent 10mm
R. E. Smith etal.
1 3
centrum and the presence of pneumatic openings dorsal to
and either side of the neural canal that support their identi-
fication as cervicals of one or more species of azhdarchoid
pterosaurs. Their relative shortness and the presence of a
well-developed, tall, blade-like neural spine are not consist-
ent with the morphology of azhdarchid mid-series cervicals.
These vertebrae are comparable to those of tapejarids and
chaoyangopterids but our knowledge of vertebral anatomy
in these pterosaurs is not sufficient to determine to which of
these families they may belong.
A superbly preserved, almost complete single poste-
rior cervical vertebrae (FSAC-KK 5219), likely the ninth,
Fig. 19 Reconstructed Kem
Kem Group azhdarchoid mid-
series cervical vertebra (C3-C8)
morphotypes. M1 based on
FSAC-KK 7251 (Fig. S2); M2
based on FSAC-KK 5214 (Fig.
S3); M3 based on FSAC-KK
5215 (Fig. S4); M4 based on
CMN 50801 (Fig. S5); M5
based on FSAC-KK 5216 (Fig.
S6); M6 based on FSAC-KK
3088 (Fig. S7); M7 based on
FSAC-KK 5217 and FSAC-KK
7177 (Fig. S8); M8 based on
FSAC-KK 5083 (Fig. S9); M9
based on FSAC-KK 5218 (Fig.
S10). Not drawn to scale
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
compares closely to the ninth cervical of azhdarchoids
including Azhdarcho (Averianov 2010: fig.16) and inde-
terminate thalassodromines (Aires etal. 2013; fig.3; Vila
Nova etal., 2015; fig.7). Unlike the ninth cervical of orni-
thocheirids (e.g., Anhanguera; Wellnhofer, 1991: fig.11)
where the neural spine and the cotyle are relatively narrow
and the lateral surfaces of the centrum are pierced by multi-
ple pneumatopores, in azhdarchoids the neural spine is rela-
tively broad, as is the cotyle, and pneumatopores are absent
from the lateral surfaces of the centrum. Notably, the promi-
nent pneumatopores flanking the neural canal of FSAC-KK
5218 are absent in Quetzalcoatlus, though deep blind pits
are reported at this location (Andres and Langston 2021).
Morphology of cervical vertebrae. Nine azhdarchoid mid-
series cervical vertebra (C3-C8) morphotypes were identi-
fied from the Kem Kem Group (Figs.19, S2–S10, Table2).
The morphotypes vary in the presence/absence of anterior
lateral and dorsal foramina; posterior lateral and dorsal
foramina; foramina on the lateral surfaces of the centrum
and foramina on the anterior end of the ventral surface
beneath the cotyle, here referred to as sub-cotylar foramina
(see Table2). Most of the specimens had a relatively simi-
lar length to width ratio of ~ 2, apart from morphotype 9
(M9) which had a width subequal to its length. Morpho-
type 7 (M7) (Fig. S8) has a taller neural spine than all other
Kem Kem Group cervical vertebrae, a character widespread
within Azhdarchoidea, and is therefore referred to Azhdar-
choidea indet. rather than Azhdarchidae indet. These cervi-
cal morphotypes likely represent a combination of different
cervical positions within the neck of an individual, interspe-
cific variation, and ontogenetic variation.
Scapulocoracoid
Material. FSAC-KK 5210 (Fig.20A–C), right scapulocora-
coid missing articular facets on the coracoid and scapula
(referred here).
Taxonomic assignment. A near complete scapulocoracoid
(FSAC-KK 5210) lacking only its distal terminations can
be confidently identified as azhdarchoid. This specimen
lacks any of the many diagnostic features of the scapuloc-
oracoid of ornithocheiroids (e.g., Wellnhofer 1991; Veldmei-
jer 2003) including a relatively short scapula with a highly
constricted shaft and strongly expanded proximal and distal
terminations, a prominent procoracid tubercle, and small or
no coracoid flange. By contrast, the general proportions of
FSAC-KK 5210, the presence of a well-developed coracoid
flange and a supraglenoid tubercle that is separated from
the glenoid by a distinct gap are typical features of the azh-
darchoid scapulocoracoid. Among azhdarchoids, FSAC-
KK 5210 compares most closely to the scapulocoracoid
of Tupuxuara (IMCF1052) although the gap between the
glenoid buttress and the supraglenoid tubercle is relatively
much greater in the Kem Kem specimen. The latter feature
is observed in Quetzalcoatlus (Andres and Langston 2021)
but the scapulocoracoid of this azhdarchid differs in other
respects, most notably the presence of a massive coracoid
flange that rounds into the glenoid buttress and marked flex-
ure medially of the scapula at approximately mid-length.
Humeri
Material. Humeri: CMN 50814, right humerus with proxi-
mal and distal ends but lacking a small section of the
shaft (referred by Rodrigues etal. 2011); FSAC-KK 5211
(Fig.20D–G), right humerus with damage to proximal and
distal ends (referred here).
Taxonomic assignment Fragmentary remains of two ptero-
saur humeri, CMN 50814 (Rodrigues etal. 2011: figs.7, 8)
and FSAC-KK 5211, have been recovered from the Kem
Kem deposits. Both are easily distinguished from the humeri
of ornithocheiroids, which exhibit a suite of unique char-
acters: a distinctive deltopectoral crest that has a long base
and bears a terminal expansion that is twisted (warped)
obliquely to the humeral shaft (Bennett, 1989); a prominent
pneumatic opening on the anconal surface of the proximal
end of the humerus; and the distal end of the humerus has a
sub-triangular outline); neither of these features is present
in FSAC-KK 5211 or CMN 50814. As noted by Rodrigues
etal. (2011), CMN 50814 compares closely to azhdarchoid
humeri. Where comparable, FSAC-KK 5211 is identical to
CMN 50814, and the former also exhibits two additional
features, a flange-like deltopectoral crest that extends per-
pendicular to the humeral long axis (Witton etal., 2009) and
a highly constricted shaft, with markedly expanded proxi-
mal and distal terminations that, among pterosaurs, compare
most closely to the humeri of azhdarchoids. The identity of
the Kem Kem humeri can be further resolved because the
distal termination of CMN 50814, when viewed in distal
aspect, presents a complex structure that is almost identi-
cal to that of the humeri of Azhdarcho and Quetzalcoat-
lus. Notably, the profile appears thicker and more rounded
than in other azhdarchoids such as Tupuxuara, where it has
a more rectangular outline. In addition, there is a distinct
rounded notch toward the anterior of the entepicondyle
unlike that of Tupuxuara which lacks this feature.
Ulnae
Material. FSAC-KK 5209, left ulna missing the proximal
end; FSAC-KK 7142, proximal end of ?right ulna (Fig.21,
referred here).
R. E. Smith etal.
1 3
Fig. 20 Azhdarchoid right scapulocoracoid (FSAC-KK 5210) and
humerus (FSAC-KK 5211) from the Kem Kem Group. AC right
scapulocoracoid missing distal articulations on both scapula and
coracoid: A posterior view; B lateral view, oriented to better show the
glenoid; C anterior view. DG right humerus with damaged proximal
end, distal end and deltopectoral crest: D, dorsal view; E ventral; F
lateral view and G medial view. Scale bars represent 10mm
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
Taxonomic assignment. Seen in distal view, the ulnae of
ornithocheiroids are principally distinguished from those
of other pterodactyloids by the relatively narrow transverse
width of the dorsal condyle (e.g., Wellnhofer 1985: fig.37c).
By contrast, in non-ornithocheiroids, the transverse width
of the dorsal condyle is greater than that of the transverse
width of the ventral half of the distal end of the ulna. This is
especially pronounced in azhdarchoids such as Azhdarcho
Fig. 21 Ulnae fragments from the Kem Kem Group. AC azhdar-
choid proximal fragment of ?right ulna (FSAC-KK 7142): A anterior
view; B posterior view and C, proximal view. DG azhdarchoid distal
left ulna (FSAC-KK 5209), shaft left unprepped to show mud-flake
conglomerate: D anterior view; E posterior view; F distal view and G
ventral view. Scale bars represent 10mm
R. E. Smith etal.
1 3
(Averianov 2010), Quetzalcoatlus (Andres and Langston
2021), and Tupuxuara (DMU pers. obs.). The presence of
a strongly expanded dorsal condyle in FSAC-KK 5209 an
incomplete left ulna, and its similarity in all respects to the
ulnae of other azhdarchoids (Azhdarcho, Quetzalcoatlus
and Tupuxuara) support the assignment of this specimen
to Azhdarchoidea. Within this clade ulna morphology is
not sufficiently well known as to permit the assignment of
isolated ulnae to a particular group though we note here
Fig. 22 Left azhdarchoid metacarpal IV missing proximal end (FSAC-KK 4001) from the Kem Kem Group: A posterior view; B anterior view;
C ventral view; D dorsal view and E distal view. Scale bar represents 10mm
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
that FSAC-KK 5209 is remarkably similar to the ulnae of
theneoazhdarchoids (Tupuxuara and Quetzalcoatlus).
The proximal articular portion of a right ulna (FSAC-KK
7142) is beautifully preserved and exhibits fine anatomical
detail including a well-developed, partially fused olecranon
on the posterior aspect and a prominent pneumatic opening
on the anterior aspect. The ‘C-shaped’ profile, evident in
proximal view, with a deeply excavated anterior margin, is
typical of azhdarchoids (e.g., Andres and Langston 2021:
fig.31I, J) and quite unlike the more triangular profile, in
proximal view, of the ulna of ornithocheiroids, the anterior
margin of which is irregular with slightly convex projections
(e.g., ‘Santanadactylus’; Wellnhofer 1991: fig.27). FSAC-
KK 7142 differs in minor respects from the corresponding
elements ofQuetzalcoatlusandTupuxuara(IMCF 1052),
notably in that the ventral articular facet is relatively large.
In the absence of more complete specimens, and details of
ulnar morphology in other azhdarchoids, FSAC-KK 7142 is
assigned to Azhdarchoidea indet.
Metacarpal IV
Material. FSAC-KK 4001 (Fig.22), left metacarpal IV miss-
ing proximal end (referred here).
Taxonomic assignment. The well-preserved distal portion
of a wing-metacarpal (MC IV), FSAC-KK 4001, exhibits
several features typical of azhdarchoids. The shaft is rela-
tively elongate and slender. In azhdarchoids such as Tape-
jara (Martill etal. 2013) and Quetzalcoatlus (Andres and
Langston 2021) the length: minimum width ratio of this
element is approximately 1:20, whereas ornithocheiroids
(e.g., Anhanguera piscator, Barbosania gracilirostris and
Santanadactylus araripensis) have a relatively short, more
robust wing-metacarpal with a slenderness ratio of 1:10.
The shape of the distal condyle, when seen in anterior or
posterior view, is asymmetrical whereas it is symmetrical
in ornithocheiroids and also bears a median ridge (Kellner
and Tomida 2000: fig.42), which is absent in azhdarchoids
and other pterosaurs. In addition, the dorsal profile of the
wing-metacarpal is somewhat excavated immediately proxi-
mal to the distal condyle (e.g., Averianov 2010; Martill etal.
2013) to accommodate the wing-phalanx 1 when it is fully
flexed, whereas this margin remains more or less level in
ornithocheiroids (e.g., Kellner and Tomida 2000: fig.42).
The wing-metacarpal of azhdarchids exhibits a distinctive
anterior flexure of the distal portion of the shaft + distal con-
dyle in Quetzalcoatlus (Andres and Langston, 2021: fig.38);
Zhejiangopterus (DMU pers. obs.) and an azhdarchid from
Dinosaur Park (Godfrey and Currie 2005: fig.16.9). This is
seemingly absent in FSAC-KK 4001, suggesting that it is
azhdarchoid but not azhdarchid.
Tibiotarsus
Material. FSAC-KK 7140, left tibia missing distal end
(Fig.11E–H, referred here).
Taxonomic assignment. A single incomplete tibiotarsus
(FSAC-KK 7140), lacks its distal end, but is otherwise well
preserved (Fig.11E–H). It consists of a slender, elongate,
composite tubular structure dominated by the tibia, but bear-
ing a small splint-like fibula which is fused proximally to the
proximal end of the tibia and extends distally along its lateral
margin to a point at approximately the mid-length of the
tibia where it merges into the tibia shaft. The development
of the fibula suggests that FSAC-KK 7140 does not repre-
sent an ornithocheiroid in that the fibula is reduced to a tiny
splint (in Pteranodon) or entirely absent (ornithocheirids)
in that clade (Unwin 2003). By contrast, FSAC-KK 7140
compares closely to tibiotarsi of Tupuxuara (IMCF 1052)
and Quetzalcoatlus (Andres and Langston, 2021: fig.46),
most notably in terms of the morphology of the proximal
articulation, which is inclined posteriorly and laterally, and
bears a distinctive notch in the anterolateral margin. Fur-
ther comparisons are severely constrained by the lack of
uncompressed examples of the tibiotarsus in other azhdar-
choids, and pterodactyloids, more generally. Consequently,
until more complete, better-preserved remains are found we
assign FSAC-KK 7140 to an indeterminate species within
Azhdarchoidea.
Ornithocheiroidea Seeley, 1891
Ornithocheiridae sensu Unwin, 2003
Anhanguera Campos and Kellner, 1985
Anhanguera cf. A. piscator Kellner and Tomida, 2000
Referred specimen. FSAC-KK 5005 (Fig.23), a partial man-
dibular symphysis.
Locality and horizon. Aferdou N’Chaft, near Hassi el Begaa,
Errachidia Province, south-east Morocco; ?Albian—Cenom-
anian, upper Ifezouane Formation, Kem Kem Group.
Remarks. This specimen is comparable to A. piscator on
account of the shape of the mandibular crest in lateral view
and the position of the teeth.
Coloborhynchus Owen, 1874
Genus Zoobank reference number urn:lsid:zoobank.
org:act:26335C50-25FD-4BA1-8183-FFE40A0F51C0.
R. E. Smith etal.
1 3
Type species. Coloborhynchus clavirostris Owen, 1874
Coloborhynchus fluviferox Jacobs, Martill, Ibrahim, Lon-
grich, 2019.
Species Zoobank reference number urn:lsid:zoobank.
org:act:41DB8186-0F23-4C59-AF2E-38C5FF3752AE.
Synonymy. All mentions of C. fluviferox are included.
*2019 Coloborhynchus fluviferox JACOBS etal.—Jacobs
etal., p. 77, Figs.3–8, Tables1–2
2019 Coloborhynchus fluviferox JACOBS etal.—Pêgas
etal., p. 1278
2020 Nicorhynchus fluviferox (JACOBS etal.)—Holgado
and Pêgas, p. 743, Figs.3, 10–11
2020 Coloborhynchus fluviferox JACOBS etal.—Ibrahim,
etal., p. 69
2020 Coloborhynchus fluviferox JACOBS etal.—Jacobs
etal., p. 1, Fig.10
2020 Coloborhynchus fluviferox JACOBS etal.—McPhee,
etal., p. 1
2021 Coloborhynchus fluviferox JACOBS etal.—Smith
etal., Table S1
Holotype. FSAC-KK 10701 (Fig.24A–E), anterior rostrum
displaying the alveoli of the first, second, and partial third
tooth pairs.
Type locality and horizon. Southern Morocco, possibly
Aferdou N'Chaft, Hassi el Begaa, Errachidia Province in
south-eastern Morocco, ?Albian—Cenomanian, Ifezouane
Formation, Kem Kem Group.
Diagnosis. Based on Jacobs etal. (2019). Species of Colo-
borhynchus in which the upturned palate (90-degree upturn)
has a slightly depressed deltoid face. The deltoid face defines
a high isosceles triangle with concave dorsolateral margins
in anterior view. The deltoid face bears two shallow, sub-
circular depressions located dorsal to tooth pair one. Dor-
sally, this becomes a shallow groove defined by low ridges
that transition into a broad rugose anterodorsal margin of
the premaxilla. Central point of alveoli for first tooth pair
level with dorsal border of second tooth pair. Mediodorsal
crest rises steeply from dorsally turned palatal margin at an
angle of 60°.
Remarks. Coloborhynchus fluviferox was referred to a new
genus, Nicorhynchus by Holgado and Pêgas (2020) for which
Coloborhynchus capito Seeley, 1870 from the Cambridge
Fig. 23 Anhanguera cf. A. piscator anterior mandibular symphysis, FSAC-KK 5005 from the Kem Kem Group. A in dorsal view; B in right lat-
eral view; C in ventral view and D in posterior view. Scale bar represents 10mm
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
Greensand was made the type species (N. capito). The dis-
tinguishing features used to separate Nicorhynchus from
Coloborhynchus are subtle shape differences in the anterior
deltoid facet of the rostrum tip. Here we consider such subtle
differences to possibly be sufficient to diagnose species but
are of little or no importance at generic level. Such minor
differences may reflect ontogenetic changes, interspecific
variation, or sexual dimorphism. We have studied the rel-
evant material and note here that it is highly abraded and
fragmentary. Thus, such small morphological differences are
likely to be of little or no taxonomic significance. Accord-
ingly, we consider Nicorhynchus to be a subjective junior
synonym of Coloborhynchus. Holgado and Pêgas (2020)
also name a new species Nicorhynchus (Coloborhynchus)
smaugi, but this is not described or figured, with no speci-
men referral; thus, this taxon is a nomen nudum.
Coloborhynchus sp.
Referred material. An anterior fragment of rostrum in a pri-
vate collection (Fig.24F–J), casts specimen numbers FSAC-
KK 5024, SMNK PAL 45833.
Remarks. Jacobs etal. (2020) described and figured a
specimen of Coloborhynchus from a private collection that
differed somewhat from C. fluviferox, notably in anterior
cross-sectional shape (more closely resembling that of C.
clavirostris) and a central groove in the premaxillary crest.
Jacobs etal. (2020) suggested the specimen might be a new
species, but refrained from naming it, referring to it as ‘Colo-
borhynchus sp. A’. Holgado and Pêgas (2020) referred this
specimen to Nicorhynchus fluviferox. However, as discussed
above, we synonymise Nicorhynchus with Coloborhynchus.
Fig. 24 Coloborhynchus anterior rostrum fragments from the Kem
Kem Group. AE holotype of Coloborhynchus fluviferox, FSAC-KK
10701; FJ Coloborhynchus sp. in private collection, casts FSAC-KK
5024, SMNK-PAL 45833. A, F in anterior view; B, G in posterior
view; C, H in left lateral view; D, I in ventral view; E in dorsal view
and J in slightly oblique dorsal view. Scale bars represent 10mm
R. E. Smith etal.
1 3
It is possible that the differences between FSAC-KK 5024/
SMNK PAL 45833 and the holotype of C. fluviferox are
the result of ontogenetic changes and/or sexual dimorphism.
More fossils and a better understanding of ontogeny and
dimorphism in pterosaurs are needed to help resolve these
issues.
Ornithocheirus Seeley, 1870.
Ornithocheirus cf. O. simus Owen (1861)
Age and distribution (from Jacobs etal., 2020). The holo-
type of O. simus (CAMSM B54.428) is from the Cambridge
Greensand (Cenomanian, with derived fossils of Albian
age), of Cambridgeshire, England, UK (Unwin, 2001). O.
simus has not previously been recorded outside of southern
England.
Referred specimen. Anterior fragment of premaxilla in a pri-
vate collection (Fig.25), casts specimen numbers FSAC-KK
5025, SMNK PAL 45831.
Locality and horizon. Aferdou N’Chaft, near Hassi el Begaa,
Errachidia Province, south-east Morocco; ?Albian-Cenoma-
nian, upper Ifezouane Formation, Kem Kem Group.
Remarks. This specimen is comparable to the holotype of
O. simus on account of its tooth placement, tooth size, and
jaw outline (Jacobs etal. 2020). Given the geographic and
perhaps temporal separation between the two, they may rep-
resent distinct species. The Kem Kem material is too frag-
mentary for detailed comparisons and its relationships to O.
simus must await the discovery of more complete remains.
Siroccopteryx Mader and Kellner, 1999
Type and only species. Siroccopteryx moroccensis Mader
and Kellner, 1999
Diagnosis. As for type species S. moroccensis
Genus Zoobank reference number. urn:lsid:zoobank.
org:act:7E4CA95A-78CE-41F5-950F-533FCB092ACD
Species Zoobank reference number. urn:lsid:zoobank.
org:act:379D4E2F-140B-4759-ACE3-A8068D3FF857.
Siroccopteryx moroccensis Mader and Kellner, 1999
Synonymy. All mentions where the citation refers to
specimen LINHM 016, now known as S. moroccensis are
included, as are all mentions of S. moroccensis.
1997 Anhangueridae—Mader and Kellner, p. 62A
*1999 Siroccopteryx moroccensis MADER and KELL-
NER—Mader and Kellner, p. 2, Figs.2–3
2001 Siroccopteryx moroccensis MADER and KELLNER—
Dalla Vecchia etal., p. 223
2001 Coloborhynchus moroccensis (MADER and KELL-
NER)—Unwin, p. 206
2003 Coloborhynchus moroccensis (MADER and KELL-
NER)—Frey etal., p. 60
2003 Siroccopteryx moroccoensis MADER and KELL-
NER—Pereda Suberbiola etal., p. 79. Lapsus calami
2003 Coloborhynchus moroccensis (MADER and KELL-
NER)—Unwin, p. 145, Table1
2003 Siroccopteryx moroccensis MADER and KELLNER—
Veldmeijer, p. 98
Fig. 25 Anterior rostrum fragment of Ornithocheirus cf. O. simus from the Kem Kem Group in a private collection, casts FSAC-KK 5025,
SMNK-PAL 45831. A in anterior view; B in posterior view; C in left lateral view and D in ventral view. Scale bars represent 10mm
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
2006 Coloborhynchus moroccensis (MADER and KELL-
NER)—Unwin, p. 272
2006 Siroccopteryx moroccensis MADER and KELLNER—
Veldmeijer, p. 41
2007 Siroccopteryx moroccensis MADER and KELLNER—
Kellner etal., p. 259, Table2
2008 Coloborhynchus moroccensis (= Siroccopteryx moroc-
censis) MADER and KELLNER—Barrett etal., p. 85
2008 Siroccopteryx moroccensis MADER and KELLNER—
Rodrigues and Kellner, p. 222
2009 Coloborhynchus (= “Siroccopteryx”) moroccensis
MADER and KELLNER—Vullo and Neraudeau, p.
280
2010 Siroccopteryx moroccanus MADER and KELLNER—
Cavin etal., p. 399. Lapsus calami
2010 Coloborhynchus moroccensis (MADER and KELL-
NER)—Ibrahim etal., p. 1, Table1
2010 Siroccopteryx moroccensis MADER and KELLNER—
Rodrigues and Kellner, p. 163
2011 Siroccopteryx moroccensis MADER and KELLNER—
Rodrigues etal., p. 150
2012 Coloborhynchus moroccensis (MADER and KELL-
NER)—Martill and Unwin, p. 4, Fig.8
2013 Siroccopteryx moroccensis MADER and KELLNER—
Andres and Myers, p. 13
2013 Siroccopteryx moroccensis MADER and KELLNER—
Rodrigues and Kellner, p. 33
2014 Siroccopteryx moroccensis MADER and KELLNER—
Bantim etal., p. 206
2015 Coloborhynchus moroccensis (MADER and KELL-
NER)—Martill, p. 377
2015 Coloborhynchus (= Siroccopteryx) moroccensis
MADER and KELLNER—Myers, p. 7
2017 ‘Coloborhynchus moroccensis or Siroccopteryx moroc-
censis’ MADER and KELLNER—Masrour etal., p.
774
2018 Siroccopteryx sp.—Dridi, p. 275
2019 Siroccopteryx moroccensis MADER and KELLNER—
Jacobs etal., p. 77, Figs.6–8, Table2
2019 Siroccopteryx moroccoensis MADER and KELL-
NER—McCurry etal., p. 249. Lapsus calami
2019 Siroccopteryx moroccensis MADER and KELLNER—
Pêgas etal., p. 1278
2019 Siroccopteryx moroccensis MADER and KELLNER—
Pentland etal., p. 2
2020 Siroccopteryx moroccensis MADER and KELLNER—
Holgado and Pêgas, p. 744, Figs.8, 12
2020 Siroccopteryx moroccensis MADER and KELLNER—
Ibrahim etal., p. 69, Fig.95
2020 Siroccopteryx moroccensis MADER and KELLNER—
Jacobs etal., p. 1, Fig.10
2021 Siroccopteryx moroccensis MADER and KELLNER—
Andres, p. 212, Fig.1
2021 Siroccopteryx moroccensis MADER and KELLNER—
Fernandes etal., p. 14
2021 Siroccopteryx moroccensis MADER and KELLNER—
Richards etal., p. 2
2021 Siroccopteryx moroccensis MADER and KELLNER—
Smith etal., Table S1
Holotype. LINHM 016 (Fig.26), anterior section of rostrum.
Type locality and horizon.? Albian-Cenomanian Kem Kem
Group, Morocco.
Diagnosis. (from Mader and Kellner, 1999). Anhanguerid
pterosaur with the anterodorsal margin of the premaxillary
sagittal crest almost straight and a comparatively massive
and broad snout with the anterior tip straight and higher than
in Anhanguera but lower than Tropeognathus and less later-
ally expanded than in ‘Coloborhynchus’ wadleighi.
Remarks. There is no current record of LINHM, therefore
the location of LINHM 016 is not known.
Ornithocheiridae indet.
Jaw fragment
Material FSAC-KK 33, partial mandibular ramus referred
by Ibrahim etal. (2020).
Remarks. Assignment of this ramus fragment to a specific
taxon is not possible because multiple ornithocheirids are
present within the Kem Kem Group.
Isolated teeth
Material. BSP 1993 IX 4, 590–596 (morphotype 1) BSP
1993 IX 314, 597–607 (morphotype 2) BSP 1993 IX 332,
608–617 (morphotype 3) BSP 1993 IX 618–621 (mor-
photype 4) (described by Wellnhofer and Buffetaut 1999),
FSAC-KK 44, FSAC-KK 197, FSAC-KK 885–887, FSAC-
KK 941 (described by Ibrahim etal. 2020), FSAC-KK 17001
(described by Martill etal. 2018), LINHM 007 (described
by Mader and Kellner 1997), MNHN MRS 1108 (referred
here, Fig.3).
Remarks. Assignment of any of these teeth to a specific
taxon is not currently possible because multiple taxa of orni-
thocheirids are present in the Kem Kem Group, and have
R. E. Smith etal.
1 3
similar (and highly variable) tooth morphologies. There
is no current record of LINHM, therefore the location of
LINHM 007 described by Mader and Kellner (1997) is cur-
rently unknown.
Notarium
Material. FSAC-KK 5208, anterior notarium fragment com-
prising the anterior most three and partial fourth dorsal ver-
tebrae (Fig.9, referred here).
Taxonomic assignment A notarium consisting of three co-
ossified vertebral centra and possibly the anterior section of
a fourth (FSAC-KK 5208) is uncrushed but badly damaged
and lacks most surficial details. It differs in several impor-
tant respects from FSAC-KK 5207, identified as azhdarchid:
it bears massive ventrolaterally directed parapophyses that
extend well beyond the lateral margins of the centrum; the
cotyle is dorsoventrally pinched, resulting in a lemniscate
profile; and blind pits, rather than pneumatopores, flank-
ing the neural canal. All these features are present in orni-
thocheiroid notaria including, for example, Pteranodon
(Bennett, 2001: figs.45–47), ‘Santanadactylus’ (Wellnhofer
etal., 1983:fig.2), Ornithocheirus (Kellner etal., 2013),
and Coloborhynchus (Veldmeijer, 2003: fig.7). Thus, FSAC-
KK 5208 is assigned here to an indeterminate species of
Ornithocheiridae.
Discussion
Modification totheocclusal surface
Bony protuberances occur on the occlusal surfaces of the
jaws of at least three Kem Kem Group azhdarchoids; Afro-
tapejara zouhrii (FSAC-KK 5004; Fig.27J), Alanqa saha-
rica (FSAC-KK 26, FSAC-KK 4000, UOP-PAL KK 0006/
FSAC-KK 5213, FSAC-KK 5204–5205; Fig.27A–E) and
Xericeps curvirostris (FSAC-KK 10700; Fig.27I) (Ibrahim
etal. 2010; Martill and Ibrahim 2015; Martill etal. 2018,
2020a). They are also observed on three jaws referred to here
as ‘morphotype C’ (FSAC-KK 5200–5202; Fig.27F–H).
Alanqa saharica has complementary bony protuber-
ances on the upper and lower jaws. The holotype mandibular
Fig. 26 Holotype anterior rostrum of Siroccopteryx moroccensis, LINHM 016 from the Kem Kem Group. A in left lateral view; B in dorsal
view; C in anterior view. Scale bar represents 10mm. Image courtesy of Dr. Bryn Mader
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
Fig. 27 Photographs (left) and digital 3D model images generated
from topographic scans (right) of bony protuberances on the occlusal
surface of Kem Kem Group edentulous pterosaur jaw fragments in
occlusal view. A Alanqa saharica mandibular symphysis FSAC-KK
4000; B Alanqa saharica mandibular symphysis UOP-PAL KK 0006
and FSAC-KK 5213; C Alanqa saharica holotype mandibular sym-
physis FSAC-KK 26 (topographic scan unavailable); D Alanqa saha-
rica rostrum FSAC-KK 5205; E Alanqa saharica rostrum FSAC-KK
5204; F jaw ‘morphotype C’ FSAC-KK 5201; G jaw ‘morphotype
C’ FSAC-KK 5200; H jaw ‘morphotype C’ FSAC-KK 5202; I Xeri-
ceps curvirostris holotype mandibular symphysis FSAC-KK 10700;
J Afrotapejara zouhrii holotype rostrum FSAC-KK 5004. Arrow
indicates bony protuberance on occlusal surface. Scale bars represent
10mm
R. E. Smith etal.
1 3
symphysis (FSAC-KK 26) was originally described as hav-
ing a ‘V’ shaped caudally bifurcating midline ridge on the
occlusal surface (Ibrahim etal. 2010, Fig.27C). Subse-
quently Martill and Ibrahim (2015) described a specimen
(FSAC-KK 4000), which was attributed to a possible ros-
trum of cf. Alanqa saharica, with “paired, elongate tapered
protuberances extending from a position exterior to the
lateral margins of the jaw posteriorly and extend toward
the median line of the occlusal surface of the jaw.” The
structures did not meet in the middle but tapered to a point
anteriorly and posteriorly (Fig.27A). A second specimen
with similar structures (held in a private collection) was also
figured (Martill and Ibrahim, 2015 Fig.5; 3D print UOP-
PAL KK 0006/FSAC-KK 5213; Figs.7F–H and 25B here).
Martill and Ibrahim (2015) proposed that the structure seen
on the holotype mandible was complimentary to the struc-
tures on FSAC-KK 4000 and UOP-PAL KK 0006/FSAC-
KK 5213. Re-examination of the holotype has indicated
that these structures are identical (see Fig.27A–C) and that
all three specimens are most likely mandibular symphyses
of Alanqa saharica. Two specimens (FSAC-KK 5204 and
FSAC-KK 5205) have been discovered with a cross-section
and shape, that while similar to the mandibular symphyses
of A. saharica, differs in the presence of a single median
eminence (boss) on the occlusal surface (see Fig.27D–E).
This eminence extends medially for approximately 110mm
along the occlusal surface of FSAC-KK 5204, widening,
rising and becoming more prominent posteriorly, attaining
a maximum height of 8mm and maximum width of 5mm.
In the case of FSAC-KK 5205 the eminence extends for at
least 90mm along the occlusal surface, and reaches a maxi-
mum height of 9mm and width of 4mm. These bones are
interpreted as sections of rostra, composed of fused premax-
illae-maxillae, with the single eminence complementing the
paired structures seen on the occlusal surface of the lower
jaws. This construction consisting of a midline ridge, keel,
or boss of bone borne on the occlusal surface of the rostrum
that matches a groove-like structure on the occlusal surface
of the mandibular symphysis is a common but not universal
feature of pterosaurs (e.g., Martill and Ibrahim 2015).
Bony protuberances similar to those found on the holo-
type of Alanqa saharica are also present on the rostrum of
the holotype of Xericeps curvirostris (FSAC-KK 10700,
Fig.27I). However, these elongate, tapered protuberances
are much narrower in Xericeps, measuring 2mm in width
and projecting 1.5mm above the occlusal surface (see
Fig.27I). Posterior to these protuberances the occlusal sur-
face becomes deeply sulcate (see Fig.14 and cross-section
Fig.5), deepening posteriorly to a maximum depth of 9mm.
This deeply sulcate occlusal surface could accommodate a
large median protuberance similar to that seen in the upper
jaw of A. saharica. However, as rostra of X. curvirostris have
yet to be recovered this hypothesis remains untested.
Three jaw fragments (FSAC-KK 5200-5202) here
referred to as jaw ‘morphotype C’, exhibit a U-shaped cross-
section and bear a large median eminence on the occlusal
surface (see Fig.17, 27F–H). These fragments could rep-
resent mandibular symphyses of Apatorhamphus gyrostega
due to their similar cross-sectional outline and low lateral
angle. However, this is not consistent with the standard con-
figuration in pterosaurs where such structures are borne on
the rostrum. Moreover, not one of the specimens referred to
A. gyrostega by McPhee etal., (2020) displays a sulcus that
would accommodate a boss although this may be because
these specimens are not sufficiently complete as to preserve
these features. Alternatively, these specimens could repre-
sent the rostrum of X. curvirostris, which is straight, with
the large median boss fitting in the deeply sulcate occlusal
surface of the mandibular symphysis. Such an animal would
possess a gape perhaps comparable to the African Openbill
(Anastomus lamelligerus). A third possibility is that these
specimens represent an as yet unnamed species with affini-
ties to either A. gyrostega or X. curvirostris.
The rostrum of the holotype of Afrotapejara zouhrii
(FSAC-KK 5004) also bears a small posteriorly located
‘boss’ on its occlusal surface (Fig.27J). Such a feature
has not previously been reported for Tapejaridae. How-
ever, modifications of the occlusal surface are seen in the
tapejarids Caupedactylus ybaka and Caiuajara dobruskii.
Caupedactylus ybaka has a slightly raised area between two
grooves located on the posterior part of the rostrum (Kellner,
2013: fig.3c), referred to as ‘a low palatal boss’ by Pêgas
etal. (2021b), whereas Caiuajara dobruskii has two elongate
boss-like ridges, extending posteriorly and similar to those
observed in A. saharica (Manzig etal., 2014: fig.5a). In
addition to a low median eminence anteriorly, the mandibu-
lar symphysis of the putative tapejarid Bakonydraco galaczi
also exhibits a transverse eminence located at approximately
the mid-point of the mandibular symphysis (Ősi etal., 2005:
fig.2; Pêgas etal., 2021b).
Several other azhdarchoid pterosaurs also exhibit modifi-
cations to the occlusal surface of the jaws. The ?mandibular
symphysis of the azhdarchid Mistralazhdarcho maggii Vullo
etal., 2018 has a large single median eminence that pro-
trudes dorsally approximately 9mm above the lateral margin
of the occlusal surface (Vullo etal., 2018: fig.1). A low but
prominent median longitudinal eminence was also reported
on the occlusal surface of the ?premaxilla/maxilla (consid-
ered a lower jaw by Pêgas etal., 2021b) of the holotype of
the azhdarchid Aerotitan sudamericanus Novas etal., 2012
(Novas etal., 2012: fig.2D, H; Pêgas etal., 2021b: fig.4).
This feature is, however, not clearly evident in their figures.
Comparable structures are also present on the jaws of the
thalassodromeids Tupuxuara leonardii Kellner and Campos,
1994, which has a large median eminence on the rostrum
of the holotype (Kellner and Campos, 1994: figs.3–6), and
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
Thalassodromeus sethi which also has an occlusal median
eminence on the rostrum and an interlocking sulcus on
the mandibular symphysis (Pêgas etal. 2018, 2021a). The
mandibular symphysis of Tupuxuara lacks a complimentary
sulcus that could accommodate the large median eminence
on the rostrum (Pêgas etal. 2021b). A median ridge is also
present on the mandibular symphysis of the holotype of the
tapejaromorph Keresdrakon vilsoni (Kellner etal. 2019:
fig.4), but the rostrum lacks a complementary sulcus (Kell-
ner etal. 2019; Pêgas etal. 2021b). The mandibular symphy-
sis of the holotype of Argentinadraco barrealensis Kellner
and Calvo 2017 (MUCPv-1137) bears a groove bounded on
either side by lateral ridges that converge but do not meet
anteriorly (Kellner and Calvo 2017: figs.2–3), a structure
comparable to that present on mandibular symphyses of
Alanqa saharica and Xericeps curvirostris. To summarise,
modifications to the occlusal surfaces of the jaws are wide-
spread within Azhdarchoidea, present on both the rostra and
mandibular symphyses and often complement each other.
The function of the occlusal ridges and grooves in azh-
darchoid jaws is most likely related to feeding. The robust
nature of these structures, which have thickened bony cor-
tices and extensive modification to the trabeculae directly
beneath or abovethe structure (Martill and Ibrahim 2015),
suggests that they were used for crushing or shearing hard
prey items such as crustaceans, shelled molluscs or small
vertebrates (e.g., turtles) (Martill and Ibrahim 2015; Pêgas
etal. 2021a). But other functions cannot be ruled out. Martill
and Ibrahim (2015) speculate, for example, that the protuber-
ances could have acted as anchoring points for soft tissues
that formed ‘cheeks’ or elaborate display structures.
Phylogeny
Of the eight major pterosaur clades present in the late
Early Cretaceous—early Late Cretaceous (Ornithocheiri-
dae, Ctenochasmatinae, Gnathosaurinae, Lonchodectidae,
Tapejaridae, Chaoyangopteridae, Thalassodromidae and
Azhdarchidae) (Fig.28), at least three are present in the
Kem Kem Group (Azhdarchidae, Ornithocheiridae and
Tapejaridae) and possibly four if Apatorhamphus gyrostega
is a chaoyangopterid. A. gyrostega was tentatively referred
to ?Chaoyangopteridae by McPhee etal. (2020) based on
its similar jaw profile to other chaoyangopterids including
Jidapterus and Chaoyangopterus. In a recent phylogenetic
analysis by Andres (2021), A. gyrostega was recovered as a
chaoyangopterid. The presence of a chaoyangopterid in the
Kem Kem Group would also extend the range of the fam-
ily into the Albian and possibly the Cenomanian depending
on the age of the Kem Kem Group. Alanqa saharica was
originally referred to Azhdarchidae by Ibrahim etal. (2010),
based on several features including its straight, elongate,
slender and low angled jaw profile and its Y-shaped cross-
section (Ibrahim etal. 2010; Pêgas etal. 2021b). However,
Longrich etal. (2018) recovered Alanqa as a thalassodro-
mid, but this was not well supported and was coded based
on their interpretation of the holotype as an upper jaw (Lon-
grich etal. 2018; Pêgas etal. 2021b).
Pêgas etal. (2021b) recovered Alanqa saharica as a sister
taxon to the tapejaromorph Keresdrakon vilsoni outside of
Azhdarchidae in a clade they called Alanqidae. This was
based on the presence of a ‘posterior V-shaped median
ridge’ (apomorphy) on the occlusal surface. However, due
to our reinterpretation of this structure on the holotype of A.
saharica as a pair of ridges like that seen on FSAC-KK 4000
(see Fig.27), this phylogenetic placement is likely incorrect.
Xericeps curvirostris was recovered as a sister taxon to
Argentinadraco barrealensis by Pêgas etal. (2021b). This
was based on the presence of ‘paired ridges bordered by
paired sulci’ on the occlusal surface. In their study, Xericeps
curvirostris and Argentinadraco barrealensis formed a sister
group to a trichotomy within Chaoyangopteridae containing
Chaoyangopterus, Jidapterus and Lacusovagus based upon
an upturned lower jaw (Pêgas etal. 2021b). We disagree
that Chaoyangopterus and Jidapterus, have upturned lower
jaws like X. curvirostris; the jaws on these taxa may be ever
soslightly upcurved but this is likely an artifact of compac-
tion (see Martill etal. 2018). Regarding the features it shares
with Argentinadraco (the pair of ridges), this character state
is also seen on the holotype and referred specimens of A.
saharica (FSAC-KK 26, Fig.27A–C). Pêgas etal. (2021b)
also suggested that X. curvirostris has a similar foramina dis-
tribution to some chaoyangopterids. Foramina distribution is
highly variable within Azhdarchoidea and therefore should
not be used as a feature for taxonomic assignmentuntil bet-
ter evaluated. Therefore, we do agree that X. curvirostris
could be a chaoyangopterid, but we consider that, due to the
fragmentary nature of the material and limited number of
characters, it is not possible to regard X. curvirostris with
any confidence as a chaoyangopterid at the present time.
In addition, in a recent analysis by Andres (2021), Alanqa
saharica, Leptostomia begaaensis, and Xericeps curvirostris
were recovered as thalassodromids within Thalassodromi-
nae. We are sceptical of any assignment of these taxa with
any certainty to a pterosaur clade due to the highly fragmen-
tary nature of the material with limited characters. We there-
fore take a cautious approach and consider L. begaaensis and
X. curvirostris indeterminate non-tapejarid azhdarchoids.
However, we do agree with the original assignment of A.
saharica to Azhdarchidae based on its straight and elongate
jaw, which is very similar to that of Quetzalcoatlus. Any
phylogenetic analysis based on such fragmentary material
should alwaysbe treated cautiously.
R. E. Smith etal.
1 3
Diversity andpalaeoecology ofKem Kem Group
pterosaurs
The Kem Kem Group pterosaurs are represented by two of
the four main pterodactyloid clades, ornithocheiroids and
azhdarchoids. Ornithocheiridae is the only one of the three
principal ornithocheiroid clades to have been recorded in
the Kem Kem Group so far. The other groups, are known to
have existed at that time (Istiodactylidae) or, based on phylo-
genetic inference, are likely to have existed (Pteranodontia)
but remain unrecorded.
The toothed pterosaurs Anhanguera, Coloborhynchus
and Siroccopteryx have been interpreted as aerial piscivores
(e.g., Veldmeijer etal. 2007; Amiot etal. 2010; Tütken and
Hone 2010; Bestwick etal. 2020; Pêgas etal. 2021a). This
is based upon tooth morphology and arrangement, theo-
retical modelling of fishing behaviour (Veldmeijer etal.
2007), microwear analyses (Bestwick etal. 2020), tooth
carbon isotope ratios indicative of aquatic foraging (Amiot
etal. 2010; Tütken and Hone 2010), and bite force analy-
ses (Pêgas etal. 2021a). The similarities in jaw and dental
morphology between Anhanguera and Coloborhynchus and
the other Kem Kem Group ornithocheirids, Ornithocheirus
and Siroccopteryx, suggest that they were also piscivores.
However, the differing tooth arrangements (dental location,
spacing, size and number) and jaw morphologies of the four
Kem Kem Group ornithocheirids, might indicate that they
occupied subtly different niches, foraging in different ways
and/or specialising on different prey. It is also conceivable
that these pterosaurs could have exploited other prey, such a
small reptiles or dinosaurs or even other pterosaurs.
There is far less agreement regarding the palaeoecology
of the edentulous azhdarchid pterosaurs, and several alter-
native lifestyles have been proposed. These include: carrion
feeding (Lawson 1975); probe feeding (Langston 1981;
Lehman and Langston 1996; Smith etal. 2020a); terrestrial
foraging (Chatterjee and Templin 2004; Witton 2007; Wit-
ton and Naish 2008, 2013; Padian etal. 2021); a heron-like
lifestyle (Bennett 2001; Padian etal. 2021) and skim/dip
feeding (Nesov 1984; Kellner and Langston 1996; Martill
1997; Prieto 1998). These possible palaeoecological sce-
narios have been summarised and reviewed by Humphries
etal. (2007) and Witton and Naish (2008).
Due to the range of sedimentary environments in which
azhdarchid fossils occur ranging from shallow-marine (e.g.,
Frey and Martill, 1996; Pereda Suberbiola etal. 2003; Lon-
grich etal. 2018) to fluvial and lacustrine settings (e.g., Law-
son 1975; Averianov 2010; Ibrahim etal. 2020) it is unlikely
that all azhdarchids had the same lifestyle. Similarly, due
to the long temporal range (at least 47 my from the Aptian
to Maastrichtian) of Azhdarchidae and their morphologi-
cal disparity, it is unlikely that individual species occupied
the sameecological nichethrough time. Nevertheless, it is
unlikely that they were skim/dip feeders due to their skull
and jaw morphology (Humphries etal. 2007). A role as
terrestrial foragers argued for by Witton and Naish (2008,
2013) is plausible. In this case it is proposed that some azh-
darchids were generalists feeding on larger invertebrates,
small vertebrates, and perhaps carrion, with a lifestyle some-
what similar to that of storks. However, it is equally plausi-
ble that some azhdarchids were heron-like feeders patrolling
the banks of rivers, lakes, and shorelines, feeding on a range
of vertebrates and invertebrates, albeit without the heron’s
ability to dart its neck at speed.
It is therefore possible that the Kem Kem Group azh-
darchid Alanqa saharica had a lifestyle similar to that of a
stork or heron, either foraging and fishing along the Kem
Kem river system or foraging on its extensive flood plains.
The presence of bony protuberances and corresponding
groove in the jaws of A. saharica have been interpreted as a
structure for crushing hard foods, such as shelled molluscs
and smaller vertebrates such as (perhaps) turtles and juvenile
crocodilians (Martill and Ibrahim 2015; Pêgas etal. 2021a).
The edentulous Leptostomia begaaensis has been inter-
preted as a probe feeder based on its long, narrow, dors-
oventrally compressed beak with thickened bone walls.
Such adaptations would decrease the resistance caused by
inserting the beak into sediment, as well as strengthening
it against compressional and bending stresses (Smith etal.
2020a).
Like other chaoyangopterids, which have been interpreted
as piscivores and generalists (Beskwick etal., 2018), it is
likely that the Kem Kem Group ?chaoyangopterid Apator-
hamphus gyrostega was a piscivore/generalist, possibly with
a similar lifestyle to Alanqa saharica.
Many diets have been suggested for tapejarids, includ-
ing herbivory/frugivory/nucivory (Wellnhofer and Kell-
ner 1991; Wang and Zhou 2006; Meijer etal. 2007; Vullo
etal. 2012; Henderson 2017; Pêgas etal. 2021a), carnivory
(Vullo etal. 2012), piscivory (Wang and Zhou 2006; Unwin
and Martill 2007), insectivory (Wang etal. 2008); Vullo
etal. 2012), and a generalist feeding ecology (Pêgas etal.
2021a). These suggestions are based upon comparative
anatomy, functional morphology, and associations with
certain environments (Bestwick etal. 2018) and have rarely
been tested. Recently, reconstructions of the jaw muscula-
ture of the tapejarids Tapejara wellnhoferi and Caupedac-
tylus ybaka by Pêgas etal. (2021a) inferred that they were
a frugivore/nucivore and generalist, respectively. It is likely
due to the morphological disparity, geographical range (see
Martill etal. 2020b: fig.7), and range of sedimentary envi-
ronments that tapejarids are found in, from possible desert
(Manzig etal. 2014) to fluvial and lacustrine (e.g., Martill
etal. 2020a) to shallow-marine (Kellner 1989), that they
had a wide range of diets. Morphological comparisons with
extant birds can be problematic, not least because many
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
birds exhibit a superficially similar jaw morphology to tape-
jarids but exhibit a wide range of diets, as seen, for example,
in frugivorous parrots and the helmeted vanga (Euryceros
prevostii), which has a generalist diet consisting of insects
and small vertebrates such as lizards (Marca and Thorstrom
2000). It is therefore difficult to establish the diet of Afro-
tapejara zouhrii, and tapejarids in general, but this taxon
may have been a generalist similar to Caupedactylus ybaka
as proposed by Pêgas etal. (2021a).
Flaplings togiants
The pterosaur material of the Kem Kem Group is unusual
compared to most of the other pterosaur-bearing deposits
in that it contains remains from both immature individuals
(Smith etal. 2021) and giant individuals. Material of imma-
ture individuals comprises several jaw fragments referred
to Alanqa saharica and Apatorhamphus gyrostega and a
possible azhdarchid cervical vertebra (Smith etal. 2021).
This cervical vertebra (FSAC-KK 5083) hints at a pterosaur
with a wingspan of approximately 1m. The giant material
comprises several very large teeth, jaw fragments, cervical
vertebrae, ulnae, and femora of both ornithocheirid and azh-
darchoid pterosaurs. These specimens have estimatedwing-
spans of up to 6–7m. Large jaw fragments suggest that
Alanqa saharica and Apatorhamphus gyrostega likely
reached large sizes. These immature and giant forms pre-
sumably occupied different ecological niches (ontogenetic
niche partitioning), which would have expanded the eco-
logical diversity of the Kem Kem Group pterosaur assem-
blage without extending its taxonomic diversity (Smith etal.
2021).
Diversity andpalaeoecology ofmid‑Cretaceous
pterosaurs
Excluding teeth, pterosaurs from the Kem Kem Group are
now represented by more than 400 remains consisting pri-
marily, but not only fragments of rostra and mandibular sym-
physes, but also including a range of postcranial remains,
among them numerous vertebrae and incomplete limb bones
(Tables3, S2). Assuming these remains each represent a sin-
gle individual, then the assemblage, as currently understood,
is comparable in scale to that of other pterosaur concentra-
tion Lagerstätten (Dean etal. 2016). This, and the ongoing
intensive study of this assemblage in terms of its taxonomic
composition, summarised in this paper, permit comparisons
with other important mid-Cretaceous pterosaur assemblages
including the Crato and Santana formations of Brazil (e.g.,
Kellner and Tomida 2000; Unwin and Martill 2007), the
Cambridge Greensand Member (Unwin 2001; Smith etal.
2021) and Lower Chalk of England (Bowerbank 1851; Owen
1851), and the Sannine Limestone Formation of Lebanon
(Kellner etal. 2019).
At the most inclusive taxonomic levels, these assemblages
are broadly comparable in terms of taxonomic diversity,
with ornithocheirids, azhdarchoids and ctenochasmatoids
(represented by lonchodectids) occurring in most assem-
blages, the exceptions being the Crato Formation and the
Kem Kem Group where ctenochasmatoids are unrecorded
and the Lower Chalk of England where azhdarchoids are
absent (though it should be noted that this sequence has
yielded considerably fewer specimens). In addition, and as
noted previously by Dean etal. (2016), there is a strong
correlation between numbers of specimens recovered and
diversity at the species level. Relatively high levels of diver-
sity, approaching or exceeding 10 species, are to be found in
deposits such as the Crato and Santana formations, the Cam-
bridge GreensandMember, and now the Kem Kem Group
where the assemblages approach or exceed 100 specimens.
Consequently, the relatively low diversity recorded in the
Lower Chalk (two species) and Sannine Limestone (three
Fig. 28 Time-calibrated phylogeny of the main pterodactyloid ptero-
saur clades showing their temporal ranges. Solid bar indicates the
known ranges and coloured lines inferred ‘ghost’ ranges. Bars in red
show the clades present in the Kem Kem Group; pink horizontal bar
with* indicates potential age range of the Kem Kem Group. Chaoy-
angopteridae ‘broken’ bar indicates range of Chaoyangopteridae if
Apatorhamphus gyrostega is a chaoyangopterid. Adapted from Lü
etal., 2010
R. E. Smith etal.
1 3
Fig. 29 Simplified reconstruction of the pterosaur assemblage Kem
Kem Group river system. 1. Leptostomia begaaensis; 2. Apator-
hamphus gyrostega; 3. Alanqa saharica; 4. Xericeps curvirostris; 5.
Afrotapejara zouhrii; 6. Ornithocheirus simus; 7. Coloborhynchus
fluviferox; 8. Anhanguera piscator; 9. Siroccopteryx moroccensis; 10.
Spinosaurus aegyptiacus; 11. rebbachisaurid sauropods; 12 a tree-like
representation of Welwitschiophyllum. Artwork by Emily Pilavachi
The pterosaurs of the Cretaceous Kem Kem Group of Morocco
1 3
species) likely reflect the small number of specimens col-
lected to date.
The Kem Kem Group pterosaur assemblage is of par-
ticular interest in that this deposit has yielded the greatest
number of species, representing four distinct clades (Orni-
thocheiridae, Azhdarchidae, Tapejaridae and ?Chaoyangop-
teridae) yet to be recorded from a fluvial system. Higher
diversity has been reported for pterosaurs in Cretaceous
lacustrine Lagerstätten such as the Yixian and Jiufotang for-
mations of the Chinese Jehol Group (Unwin etal. 2000; Lü
etal. 2006) and some lagoonal and quasi-marine horizons
such as the Crato and Santana formations of Brazil (Unwin
and Martill 2007). However, these strata have been more
intensively sampled and studied compared to the Kem Kem
Group.
There is some evidence to suggest a correlation between
particular palaeoenvironments and the kinds of pterosaurs
to be found in those environments. Thus, azhdarchoids are
present and often common in ‘continental’ and ‘marginal
continental’ sequences such as the Kem Kem Group and
Crato and Santana formations, but rare or even absent from
fully marine deposits such as the Cambridge Greensand,
Lower Chalk, and the stratigraphically younger Niobrara
Formation of the United States. By contrast, ornithocheirids,
which seem to have been able to inhabit any environments
in which water bodies occur, are practically ubiquitous in
mid-Cretaceous deposits, including the Kem Kem Group.
Conclusions
The Kem Kem Group pterosaur assemblage is highly diverse
with nine named taxa and at least three distinct and as yet
unnamed jaw morphotypes, hinting at even higher diversity
(Fig.29). This suggests that the Kem Kem Group samples
a period of high pterosaur diversity and that it represents
a sedimentary environment with diverse habitats. Despite
the fragmentary nature of the fossils, the pterosaur-yielding
horizons in the upper part of the Ifezouane Formation can
be considered as a concentration Lagerstätte and, because
the preservation is excellent (fossils are 3-D and bone micro-
histology is preserved with sub-cellular level detail), also
as a conservation Lagerstätte too (albeit not in the usually
accepted sense of the term). Thus, the Kem Kem Group
pterosaurs provide valuable insights into pterosaur palaeo-
biology with excellent preservation of both micro and macro
internal structures.
The preservation of the pterosaur assemblage is heavily
biased taphonomically, with a presently unexplained high
abundance of jaw fragments anterior to the nasoantorbi-
tal fenestra or divergence of the mandibular rami. Skeletal
fragments are dominated by edentulous taxa whereas teeth
of ornithocheirids are extremely abundant, suggesting this
group was not scarce in the Kem Kem Group environment.
The deposit is also unusual in that some of the edentulous
forms compriseboth immature and giant individuals of the
same species, suggesting that they may have lived alongside
each other but occupied different ecologicalniches. The first
pterosaur remains from the Kem Kem Group were reported
a quarter of a century ago. There have been numerous pub-
lications on the pterosaur assemblage since then, and likely
many more discoveries remain to be made. Despite its frag-
mentary nature, the material has lent itself to taxonomic, pal-
aeoecological, biogeographic, and functional morphological
studies and, though perhaps less convincingly, phylogenetic
studies.
Presently, this pterosaur assemblage is the most diverse
known assemblage from a fluvial setting, containing exam-
ples of taxa that otherwise have been reported from lacus-
trine and marine palaeoenvironmentsand is the most diverse
assemblage in Africa.
Supplementary Information The online version contains supplemen-
tary material available at https:// doi. org/ 10. 1007/ s12542- 022- 00642-6.
Acknowledgements A great many people have helped us in our
researches on Kem Kem Group pterosaurs over nearly two decades.
We are especially grateful to Drs. Dino Frey and Anusuya Chinsamy-
Turan. For technical support we thank Richard Hing, Geoff Long,
Bob Loveridge, William Keeble, Ben Morrisonand Dr. Alex Kao, all
sometime based at the University of Portsmouth. For assistance with
field work we thank Simon Penn, Rab Smyth, Michael Oates, James
McPhee, and many undergraduate and MRes students of DMM and
NI. For assistance with artwork we thank Lucy Smith, Emily Pilavachi
and Julian Kiely. For assistance and access to specimens in collections
we thank Drs. Mike Day (NHMUK), Ronan Allain (MNHN), Oliver
Rauhut (BSPG), Florias Mees and Jonathan Brecko (RMCA) and Bryn
Mader for supplying images. We especially thank the many people in
Morocco who have assisted us in the field, collected significant fos-
sil remains, and offered us incredible hospitality, including Mustapha
Meharich and Mohammed Ben Sekkou. We also thank our veteran
team members Matteo Fabbri, Simone Maganuco and Cristiano Dal
Sasso for helping us collect large numbers of vertebrate fossils over the
last few years. Mr. Ian Eaves is warmly thanked for making specimens
in his collection available for study. We thank Dr. Alexander Averianov,
an anonymous reviewer and the editors of Paläontologische Zeitschrift,
Dr. Michael Rasser and Dr Hans-Dieter Suesfor their very helpful
comments, which greatly improved the manuscript.
Funding No funding was received for this research.
Declarations
Conflict of interest The authors declare no competing interests.
Open Access This article is licensed under a Creative Commons Attri-
bution 4.0 International License, which permits use, sharing, adapta-
tion, distribution and reproduction in any medium or format, as long
as you give appropriate credit to the original author(s) and the source,
provide a link to the Creative Commons licence, and indicate if changes
were made. The images or other third party material in this article are
included in the article's Creative Commons licence, unless indicated
otherwise in a credit line to the material. If material is not included in
the article's Creative Commons licence and your intended use is not
R. E. Smith etal.
1 3
permitted by statutory regulation or exceeds the permitted use, you will
need to obtain permission directly from the copyright holder. To view a
copy of this licence, visit http:// creat iveco mmons. org/ licen ses/ by/4. 0/.
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