key: cord-1052002-1e8vf5oz
authors: Cooper, Samuel L.A.; Martill, David M.
title: Pycnodont fishes (Actinopterygii, Pycnodontiformes) from the Upper Cretaceous (lower Turonian) Akrabou Formation of Asfla, Morocco
date: 2020-08-22
journal: Cretac Res
DOI: 10.1016/j.cretres.2020.104607
sha: db23a215251dd40c70c4c0dd11020ed2449af17d
doc_id: 1052002
cord_uid: 1e8vf5oz

The Upper Cretaceous (upper Cenomanian–middle Turonian) Akrabou Formation of Asfla, southeast Morocco is renowned for exceptionally preserved, often three-dimensional bony and cartilaginous fish fossils. Teleosts, rare holosteans and chondrichthyans are well known from the so-called ‘Goulmima ichthyological assemblage’, however pycnodonts (Actinopterygii, Pycnodontiformes) have received scant attention and remain undescribed until now. Five nominal species are recognised in the assemblage, including two new forms: Neomesturus asflaensis gen. et sp. nov. and Paranursallia cavini sp. nov. The Italian genus Polazzodus is reported in Morocco for the first time. Specimen taphonomy is examined in the context of substrate consistency and oxygenation of an outer shelf carbonate platform setting. Diversity and ecological disparity of the Goulmima assemblage is revised in regard to trophic partitioning with durophagy seemingly more diverse than previously recognised. Comparisons with other pycnodont-bearing horizons of similar age demonstrate strong faunal affinities between the Asfla pycnodonts and those in the western Tethys and South Atlantic.

The order Pycnodontiformes represents a successful, monophyletic clade of extinct neopterygian fishes in part characterised by a highly specialised feeding apparatus of robust, domed teeth. They have a temporal range of Late Triassic (Norian) to late Eocene (Ypresian) and were highly speciose throughout the Mesozoic but their diversity declined in the Paleogene. They are typically recognised by their deep, laterally compressed bodies, inequilateral fins and a reduced opercular series (Nursall, 1996a; Kriwet 2001) . Their most salient feature was their dentition (Capasso, 2019) . Prehensile teeth, situated on the reduced dentaries and premaxillae are typically spatulate or incisoriform, while those on the vomer and paired prearticulars (splenials in older literature) are typically blunt, rounded and arranged in several tooth rows on the dental pavement. Typically, the paired prearticulars of the lower jaw are strongly united along a broad symphysis, forming a "mortar" shaped occlusal surface with which the "pestle"-like unpaired vomer of the upper jaw occludes during feeding (Kriwet, 2001) . This specialised adaptation of the jaws is unique in pycnodonts and is well suited for processing hard-shelled invertebrates like molluscs, crustaceans and echinoderms (Nursall, 1996a; Kriwet 2001; Poyato-Ariza and Wenz, 2002; Capasso, 2019; Cooper and Martill, 2020) . However, a few pycnodont genera show evidence of a piscivorous diet (e.g. Serrasalmimus, Eoserrasalmimus Vullo et al., 2017; Piranhamesodon Kölbl-Ebert et al., 2018) as indicated by their specialised blade-like dentition with sharp cutting edges suited for piercing and tearing flesh from other fishes. Acrorhinichthys poyatoi Taverne and Capasso (2015) from the Cretaceous of Lebanon, preserves small actinopterygian remains in the gastric tract of some specimens (Capasso, 2019), presenting direct evidence for carnivory in some pycnodonts. The maxillae, pterygoids and parasphenoid are always edentulous.

Pycnodonts are predominantly marine fishes with an ecology typically compared to that of some extant reef fishes (Nursall, 1996a; Poyato-Ariza, 2013) . However, a few fresh water and prearticular morphotypes are tentatively matched based on similar morphologies of the medial teeth seen in both elements. Usually vomer and prearticular elements are described separately in the absence of associated material (e.g. Longbottom, 1984) . However, as only two morphologies of each element are present from a sample consisting of multiple individuals of each form, with distinct ontogenetic sizes present, it is parsimonious to assume that only two species of Anomoeodus are present in the Akrabou Formation.

Material. AK-PYC 6, large complete vomer (Fig. 3) . AK-PYC 8 and 12 (Fig. 4) , left prearticulars. 9, 10, 11, right prearticulars. locality. Asfla fossil mines on the escarpment called Assemer N'Tadirhoust, 4km south-east of the oasis village Asfla, Errachidia province, south-east Morocco, 31˚52'01"N 4˚52'30"W.

Horizon. Mammites ammonite biozone, Chalky-Marl facies, Asfla Member, Akrabou Formation.

Description. Anomoeodus sp. A is described from a single well-preserved vomer and a composite of six prearticular elements. Both elements show medial teeth which are thin and laterally elongate (as opposed to short and wide in Anomoeodus sp. B, below) and hence are tentatively described as single species here.

Vomer. Specimen AK-PYC 6 consists of a near complete vomer lacking only the ascending process on matrix exposed in occlusal view. The vomer is narrow and elongate with a minimum of fifteen lozenge-shaped teeth on the medial row (Fig. 3A) . AK-PYC 6 measures 90 mm, 30 mm and 1.8 mm in anteroposterior length, width and palatal thickness, respectively. In cross-section, the vomer is thin (1.8 mm) and flat, with medial teeth not elevated above the height of the lateral rows (unlike in Anomoeodus sp. B). Posteriorly it is damaged and has been poorly repaired by the original collector with some teeth absent and others incorrectly glued in place. Consequently, the tooth count for each row is estimated based on the teeth that are present and the number of damaged or unoccupied sockets on the vomer.

Teeth on the medial row are short and laterally expanded with a width more than twice as great as the anteroposterior crown length (Fig. 5A ). The teeth are convex and unornamented with lateral tooth faces curved slightly anteriorly; a condition typical of Anomoeodus (Forir, 1887; Kriwet, 2002) . Teeth on the medial row are separated longitudinally by a wide diastema while teeth of the lateral rows are tightly interspaced both laterally and longitudinally. Tooth size on the medial row decreases slightly towards the anterior, with tooth dimensions ranging between 15 mm x 5 mm posteriorly and 13 mm x 4 mm anteriorly in width and anteroposterior length. At the most anterior end of the medial row, a small sub-rectangular tooth is situated in succession to the anterior most medial tooth (Fig. 5A ). This strange tooth is distinguished from the medial teeth by the presence of an oval contour and a central occlusal facet; similar to that of the lateral teeth. This tooth is unlike a typical second generational replacement tooth observed in other taxa, which are always spherical and unornamented (Longbottom, 1984; Cooper and Martill, 2020, fig. 5, A) . Its function is unclear; however, it is possibly a consequence of a morphological change associated with ontogeny.

The paired primary lateral tooth rows are composed of at least fifteen pisiform to sublachrymiform convex teeth, ranging in size from 7 mm x 6 mm posteriorly and 4 mm x 4 mm anteriorly in width and anteroposterior length. Each lateral tooth is steeply convex with a single, unornamented occlusal wear facet, present on the dorsolateral face of the dental crown.

The secondary (outer) lateral row is composed of no less than fourteen sub-pisiform to reniform convex teeth, ranging in size from 5 mm x 5 mm posteriorly to 4 mm x 5 mm in width and anteroposterior length. Similar to the primary lateral row, these teeth are strongly convex with a small occlusal facet present on the dorsolateral face of the tooth crown. However, unlike the primary lateral row, the secondary lateral teeth are slightly smaller and show a greater anteroposterior elongation in occlusal view (Fig. 3) .

Prearticular. Six prearticular specimens: AK-PYC 6-11 are assigned to Anomoeodus sp. A based on characteristic dentitions (Fig. 4) . All specimens are partial or somewhat damaged except for AK-PYC 7 which consists of a complete pallet with coronoid process intact. AK-PYC 7 measures 62 mm, 37 mm and 17 mm in anteroposterior length, width and prearticular thickness respectively (anteroposterior length of the dental pavement in 2.2 x greater than the width of the occlusal pavement posteriorly). Three continuous tooth rows are present on the prearticular, consisting of one medial (main) and two laterals. The presence of any labial dentition along the medioventral lamina is unknown because this element is poorly preserved in all 6 specimens. The prearticular is concavely elliptical in cross section and relatively thicker compared to the dentition (approximately 5.2 x greater in AK-PYC 10).

The medial (main) row is positioned medio-labially on the dental pavement and composed of at least ten lozenge-shaped medial teeth. Medial teeth are laterally elongate, convex, unornamented and slightly sigmoidal with the labial face of each tooth curved antero-labially. Some specimens do not show curved faces 12) and thus this feature is regarded as natural variation of no taxonomic significance. Tooth dimensions on the medial row decrease slightly towards the anterior, ranging from 5 mm x 16 mm (posterior) to 4 mm x 9 mm (anterior) in AK-PYC 7. Each medial tooth is separated longitudinally by a prominent diastema, whilst the lateral rows lack J o u r n a l P r e -p r o o f this diastema -a condition also encountered in the vomer. Specimen AK-PYC 7 displays two partially unerupted teeth at the posterior extremity of the prearticular, just preceding the first erupted medial tooth (Fig. 4A) . These unerupted teeth are positioned deeper into the bone than the active teeth on the occlusal pavement and show poorly developed enamel crowns with a distinctive variation in enamel colour as a result. The presence of new, partially developed teeth preserved in the act of eruption is rarely seen in pycnodonts and suggests a sub-mature individual (Sally Collins, pers. com. 2020).

The primary lateral row is composed of up to thirteen (AK-PYC 9), laterally elongated oval to reniform teeth which measure between 4 mm x 11 mm (posterior) and 3 mm x 5 mm (anterior) in AK-PYC 7. Crown topography is slightly concave, as opposed to convex in the adjacent medial teeth.

Each tooth on the row is ornamented with a shallow, slit-like occlusal fossa encompassed by marginal micro-crenulations, positioned medially along the crown apex (Fig. 4) . The primary lateral teeth are less wide than the medial teeth and never show curvature of lateral or labial tooth faces.

The secondary (outer) lateral row is composed of at least twelve rhombic to sub-pisiform teeth, measuring between 5 mm x 7 mm posteriorly to 4 mm x 3 mm in anteroposterior length and width in 5) . Dental topography of this row is gently convex with a short and narrow occlusal fossa on the crown apex with ornamentation similar to that on the primary lateral teeth.

Lateral faces of these teeth are relatively flat, creating a straight lateral profile of the dental pavement in occlusal view, as opposed to antero-labially curving in Anomoeodus sp. B (see below).

The coronoid process protrudes 90˚adjacent to the dental pavement and is only complete on AK-PYC 7 and poorly preserved in AK-PYC 9 and 10. The shaft of the coronoid is short and thick with a rectangular cross section. The head of the coronoid has an axe head-like, narrow and anteroventrally elongate outline in occlusal view, with the posterior lobe of the process more elongate than the anterior lobe.

Remarks. Specimens are assigned to Anomoeodus Forir (1887) due to similar characters shared with the type species A. subclavatus (Agassiz, 1833) from the Late Cretaceous of Maastricht, Belgium.

These are: medial teeth on the prearticular are more than twice as wide as the laterals; lateral faces of the medial teeth are curved anteriorly; primary and secondary lateral tooth rows on the vomer are of near equal size and are closely interspaced whilst the medial teeth are not. Anomoeodus sp. A differs from A. subclavatus by: primary lateral teeth on the prearticular more elongate than the secondary lateral, opposed to equally proportioned in the type species; only the labial faces of the medial teeth are curved anteriorly. A. subclavatus possesses a discontinuous labial tooth row J o u r n a l P r e -p r o o f situated along the anterior region of the medioventral lamina (Friedman, 2012) . This feature is absent in Anomoeodus sp. A, possibly due to damage of the symphyseal region in all specimens.

A similar medial tooth morphology with only the labial face curved anteriorly is also present in Anomoeodus cretaceous (Agassiz, 1833 ), A. barberi Hussakof, 1947 and A. pauciseriale Kriwet, 2002 . Anomoeodus cretaceous from the Cretaceous of Bohemia possesses laterally elongate medial teeth with anteriorly curved labial tooth faces and two lateral tooth rows similar to the Asfla form.

Unlike Anomoeodus sp. A, the lateral tooth rows of A. cretaceous are of equal size respectively.

Fritsch (1878, table 2, figs 3 and 4) first figured the prearticular of A. cretaceous and labels five tooth rows, consisting of the medial row, two lateral rows and an irregular cluster of smaller teeth anteriorly. Capasso (2019, fig. 1a ) illustrates a specimen of Anomoeodus sp. from the Turonian of Gabon with a similar dental configuration to that figured by Fritsch (1878, table 2, figs 3, 4), which also shows unorganised replacement teeth situated within cavities of broken first-generation teeth.

This taxon is reappraised here as only possessing four tooth rows (one labial, one medial and two lateral) and we consider that the "fifth tooth row" are second generational teeth which should not be regarded as taxonomic in diagnosing pycnodont tooth rows.

Anomoeodus barberi Hussakof, 1947 from the Late Cretaceous Marlbrook Marl of Arkansas (USA), varies drastically from the Asfla forms by the presence of two labial rows, one medial, two organised laterals and several other lateral rows which are poorly organised, representing at least four additional lateral tooth rows. Cooper and Martill (2020) regard Anomoeodus as a taxonomic waste bin genus and erected a new genus, Agassizilia to accommodate specimens of 'Anomoeodus' with more than four true tooth rows. We disagree with the assignment of A. barberi to Anomoeodus due to the striking difference in tooth row number and reassign it as Agassizilia barberi (Hussakof, 1947) . Shimada and Everhart (2009) figured an incomplete paratype specimen of A. barberi which is broken between the secondary and third lateral tooth row. The authors suggest that the absence of these additional tooth rows is due to "considerable amount in variation… in A. barberi". This opinion is tentative and disregarded here. The paratype the authors figure is incomplete and the additional tooth rows present in the holotype have likely just broken off.

The paired primary lateral row is composed of at least ten (AK-PYC 14) reniform to subpisiform convex teeth, each possessing an anteroposteriorly orientated, elliptical to circular dental fossa with ornamentation similar to the medial teeth. Teeth which are reniform, especially in the more mature specimen (AK-PYC 13) are mildly elongated towards the anteroposterior plane of the pallet (Fig. 4D ). Teeth in AK-PYC 14 are more pisiform than reniform, suggesting the tooth morphology in this row changes gradually with ontogeny. Tooth size remains similar along the primary lateral row, only varying by 1 mm in both length and width between the first (posterior) and last (anterior-most) tooth in both AK-PYC 13 and 14.

At least nine reniform to triangularly lachrymiform teeth are present on the paired secondary (outer) lateral row. Secondary lateral teeth are convex and tightly interspaced both longitudinally along the row but also laterally with the adjacent primary lateral tooth row. Teeth on this row each possess a single, anteroposterior orientated fossa which is narrowly oval, shallow and mildly ornamented with micro-granules. As with adjacent primary lateral teeth, tooth size on the secondary lateral row remains near enough uniform anteriorly, with dimensions variating less than 1 mm between the anterior most and posterior most tooth in both specimens. Both lateral tooth rows are tightly interspaced with tooth crowns orientated approximately 45 ⁰ postero-laterally to the dorsal occlusal surface of the medial teeth in cross section -this is a consequence of the steep convex curvature of the vomer which has elevated the medial teeth dorsal of the lateral teeth on the occlusal pavement (Fig. 5B ). The medial tooth row is composed of no more than seven (average six) convex, rhombic to reniform teeth with well-rounded tooth faces. In more mature specimens, teeth narrow towards the labial, with the labial tooth face slightly curved antero-labially, as per the condition seen in the type J o u r n a l P r e -p r o o f species A. subclavatus. Some juvenile and sub-adult specimens 20, 21, 24) show a poorly developed, weakly ornamented and short furrow-like fossa positioned along the dorsal anterior margin of the dental crown. Most specimens only preserve this feature on the posterior most (first) tooth of the medial row. Successive anterior teeth are older and therefore are more worn due to durophagy; thus, any ornamentation was destroyed and replaced by largely undiagnostic wear facets. Adult individuals do not show any dental ornamentation on the medial rows, even on the youngest teeth (posterior-most) which are unaffected by wear faceting. Medial teeth show a gradual tooth size reduction anteriorly. Teeth in juvenile specimens (AK-PYC 21) range from 3 mm x 6 mm (posterior) to 2 mm x 4 mm (anterior), whilst adult medal teeth (AK-PYC 23) range from 6 mm x 17 mm (posterior) to 5 mm x 16 mm in anteroposterior length and width respectively. Successive medial teeth are closely interspaced down row in juvenile specimens and some sub-mature specimens, while more mature specimens (AK-PYC 22 and 23) show a prominent diastema separating these teeth longitudinally.

Between seven and ten (average nine) reniform to oval teeth are present on the primary lateral tooth row. These teeth are slightly laterally elongate with shallowly concave crowns, each possessing a weakly ornamented fossa along the occlusal apex. Teeth on this row are approximately one third smaller than the medial teeth in all dimensions. Anteroposterior length and width of these teeth range from 1 mm x 4 mm posteriorly to 0.5 mm x 1.5 mm anteriorly in juvenile specimen AK-PYC 21; 3 mm x 7 mm posteriorly to 2 mm x 3.5 mm anteriorly in sub-mature specimen AK-PYC24 and 6 mm x 12 mm posteriorly to 5 mm x 12 mm anteriorly in AK-PYC 23.

The secondary (outer) lateral tooth row is composed of nine to eleven teeth which are sublachrymiform to reniform or triangular depending on ontogeny. Teeth are slightly wider than they are long and are closely spaced longitudinally, with some teeth preserving a minorly ornamented, oval fossa on the dental apex -similar to those on the other tooth rows. Anteroposterior length and width of these teeth ranges from 1.5 mm x 2 mm (post.) to 0.5 mm x 0.5 mm (ant.) in AK-PYC 21 (juvenile), 3 mm x 4 mm (post.) to 2 mm x 2 mm (ant.) in AK-PYC 24 (sub-adult) and 6 mm x 7.5 mm (post.) to 5.5 mm x 5 mm (ant.) in AK-PYC 23 (mature adult). In Juvenile and sub-adult individuals, tooth morphology is sub-lachrymiform to oval or reniform posteriorly, gradually becoming subrectangular to pisiform anteriorly. Mature adult specimens (AK-PYC 22 and 23) show a more triangular tooth morphology posteriorly, becoming more sub-lachrymiform to oval anteriorly. The overlap of dental morphologies between different sized individual is evident that the sample represents a complete prearticular ontogenetic series of Anomoeodus sp. B (Fig. 4 ). Due to a combination of a reducing tooth size and morphology change of teeth along this row, the lateral profile of the occlusal pavement forms a distinctive curvature towards the anterior labial margin J o u r n a l P r e -p r o o f anteriorly (Fig. 5D ). This lateral curvature is not present in species A, which instead has a straight lateral profile of the dental pavement, likely due to less variation in tooth morphology along the row.

A single sub-adult individual, AK-PYC 18, shows an unusual cluster of three small, perfectly spherical teeth at the anterior most margin of the occlusal pavement (Fig. 4G ). These teeth are distinct and do not show organised alignment with either the lateral tooth rows, inferring they are second generational teeth which have grown to replace those lost to damage or shedding (Longbottom, 1984; Sally Collins, pers. comm. 2020) . A similar dental anomaly was recently reported for the vomer of Neoproscinetes africanus from the Moroccan Kem Kem Group at Tarda (Cooper and . The presence of these teeth on a sub-mature specimen and their absence in the mature specimens, suggests that this phenomenon is not dictated by ontogeny as suggested by Longbottom (1984) , but rather is a consequence of individual variation.

The coronoid process is well preserved in AK-PYC 23 and AK-PYC 24, and is remarkably similar to Anomoeodus sp. A, by possessing a short shaft, but with a large anteroposterior elongate condyle with is recurved posteriorly with an oval dorsal profile.

The mandibular symphysis is flat and straight, originating laterally adjacent of the diastema separating the first and second medial tooth and extends longitudinally, anterior of the last medial tooth. The mandibular symphysis and the labial faces of the medial teeth are separated by a wide medioventral lamina which is edentulous, concave and constitutes roughly one third the total lateral width of the prearticular in occlusal view.

Remarks. Specimens AK-PYC 6, 8 ,7, 9, 10, 11 and 12 are assigned to Anomoeodus for the same justification as specimens of Anomoeodus sp. A discussed above. Although not yet found associated, vomer and prearticular elements are tentatively matched on the basis of medial (main) tooth morphologies which are near identical across all specimens and sufficiently characteristic to differentiate them from Anomoeodus sp. A. The medial teeth in Type B are significantly less laterally elongate and relatively thicker anteroposterior than Anomoeodus sp. A. Prearticular medial teeth of Anomoeodus is also known from the coeval Turonian "Series of Azilé" of Gabon, which like the Moroccan Akrabou Formation, is composed of outer shelf limestones, marls and dolomites (Capasso, 2019). Similar to Asfla, pycnodont remains are rare in the Turonian of Gabon according to Capasso (2019) who records a single form of Anomoeodus sp. based on a composite of isolated vomer, prearticular and prehensile remains. The Gabon Anomoeodus sp. appears to share strong affinities with Anomoeodus sp. B from Asfla. Both posses sub-reniform medial teeth which lack diastemas on the prearticular but are prevalent on the vomer; the secondary lateral row on the prearticular both show anterior-labial curved lateral profiles. However, Asfla Anomoeodus sp. B and the Gabon Anomoeodus sp. specimens cannot be confidently synonymised due to the following: vomer teeth in Gabon Anomoeodus sp. are strongly triangular, whereas in Anomoeodus B they are oval to sub-reniform. Furthermore, the secondary lateral teeth on the prearticular of the Gabon Anomoeodus sp. shows strong anterior curvature of both the lateral and labial tooth faces. By contrast, these teeth in the Asfla Anomoeodus sp. B lack any anterior curvature. Therefore, it is concluded that the pycnodont material from Gabon represents a species distinct from Anomoeodus sp. A and sp. B from the Turonian of Asfla.

Family PYCNODONTIDAE, Agassiz, 1833 (sensu Nursall, 1996b Subfamily NURSALLIINAE, Poyato-Ariza and Wenz, 2002. Genus Paranursallia, Type species: Paranursallia spinosa Paranursallia cavini sp. nov.

Holotype. AK-PYC 4, isolated left particular with complete dental pavement (Fig. 4 , J-K).

Referred specimen. AK-PYC 1, complete vomer with ascending process preserved (Fig. 3E) . Etymology. Named in honour of Lionel Cavin for his pioneering work on the Goulmima ichthyological assemblage and who first recorded pycnodonts in the Akrabou Formation.

Diagnosis. Paranursallia cavini is distinguished from the type species P. spinosa and P. gutturosa (Arambourg, 1954) by the following autapomorphies: A nursalline-like prearticular dental pavement composed of six distinctive tooth rows, as opposed to four in P. gutturosa and two in the closely related genus Nursallia Blot (1987) . Vomer elliptically contoured in occlusal view. Description. Paranursallia cavini sp. nov. is described from an isolated vomer and left prearticular.

Although not yet found associated, we combine these elements in a single taxon due to close similarities with the dentition of an articulated individual of the closely related form Paranursallia gutturosa (Arambourg, 1954) figured by Amalfitano et al., (2020) 

Level of north-eastern Italy. Furthermore, only a single morphotype of each element is known from extensive collecting, suggesting that only a single nursalline pycnodont species was present in the Akrabou Formation.

Vomer. AK-PYC 1 consists of a single vomer, measuring 35 mm long anteroposteriorly and 11 mm wide wide. The vomer is longitudinally elongate and narrow with curved lateral tooth faces creating an elliptical profile in occlusal view (Fig. 6A) . Five tooth rows are present although teeth in the paired primary lateral rows are discontinuous, small and randomly intercalated between the J o u r n a l P r e -p r o o f medial and secondary lateral rows. The medial row is composed of six, sub-spherical to subrectangular molars that lack ornamentation or pitting. Posterior medial teeth are sub-rounded posteriorly but become more laterally compressed towards the anterior until becoming subtriangular to elliptical when seen in occlusal view. Teeth in the paired primary lateral rows are small (2-3 mm), spherical or oviform and tightly intercalated between the medial and secondary lateral teeth.

Teeth on the secondary lateral rows are sub-rectangular to 'D' shaped with straight and flattened lateral tooth faces. Longitudinal alignment of the lateral tooth faces creates a pair of curved profiles on each side of the vomer when combined, appears strongly elliptical in occlusal view ( Fig. 6, C) . Eight pairs of teeth were present on the secondary lateral rows of P. cavini., their morphology changing progressively along the row. The first five posterior teeth are almost identically sub-rectangular to 'D' shaped with the occlusal faces steeply inclined towards the labial margin. This morphology is reminiscent of that seen in the serrasalmimid pycnodonts (see Vullo et al., 2017) . The three anterior teeth of the secondary lateral row are slightly more sub-spherical with similar angles of inclination of the lateral and labial tooth faces creating a medially placed tooth ridge longitudinally in occlusal view.

The ascending process is obtusely convex with a medially set apex and extends from the posterior-most to the anterior-most tooth margins of the pallet in lateral view. The process measures 36 mm, 24 mm and 0.4 mm in anteroposterior length, height and lateral width, respectively. The height of the process is approximately five times greater than the height of the secondary lateral teeth.

Prearticular. AK-PYC 4 (holotype) is a well-preserved left prearticular which is complete with some minor damage to the head of the coronoid process. It is 44 mm long anteroposteriorly and 20 mm wide. Six distinct tooth rows are present on the prearticular comprised of one medial row, two lateral rows and three labial rows. The medial row is positioned just lateral of the medial margin of the element when seen in occlusal view. Eight obtusely elliptical teeth are present on the medial row (6 mm x 4 mm av.), with lateral faces of each tooth longitudinally orientated almost fully anteroventrally. The primary lateral row consists of eleven spherical teeth which are less than half the diameter of the associated medial and secondary lateral teeth (3 mm x 2 mm av.). This condition is similar to that observed in the vomer (AK-PYC 1) where the primary lateral teeth are intercalated between the medial and secondary laterals. However, the primary lateral teeth on the prearticular form a regular, better defined tooth row compared to those on the vomer.

Ten teeth of approximately equal proportion to those on the medial row are present on the secondary lateral row (5 mm x 4 mm av.). Secondary lateral teeth are distinctively monocuspid with J o u r n a l P r e -p r o o f a shallow cingulum and longitudinal occlusal ridge forming a 'cutting' edge, vaguely comparable to the Serrasalmimidae (see Vullo et al., 2017) . The apparent 'cutting edge' is smooth and blunt, inferring a very different feeding strategy for P. cavini than the supposed "flesh eating" serrasalmimid pycnodonts described by Vullo et al., (2017) .

Three labial tooth rows are present between the medial row and the mandibular symphysis.

Labial rows are set more anteriorly than the laterals, with the first tooth of the primary labial row positioned approximately halfway towards the anterior of the occlusal pavement, with the second and third labial rows beginning approximately two-thirds towards the anterior in occlusal view (Fig.   6C ). Most prominent is the primary labial row situated just labially of the medial margin. Teeth here are sub-rounded posteriorly, becoming more oval anteriorly, and are only slightly smaller than the adjacent medial teeth (4 mm x 3 mm av.). Eight sub-spherical teeth are present on the secondary labial row and all of near equal size measuring 3 mm x 3 mm (av.). The third labial row is discontinuously situated tightly between the secondary labial teeth and the narrow articulatory surface of the mandibular symphysis. Teeth on this row are of equal size and proportionate to those in the primary lateral row, which both have average longitudinal and lateral tooth dimensions of 3 mm x 2 mm. The reduction of these tooth rows may be the result of dental overcrowding on the prearticular due to extrapolation of larger teeth in the medial and secondary lateral rows which likely played a more prominent role during occlusion.

All teeth on both the prearticular and vomer of P. cavini are smooth and lack any ornamentation on the occlusal faces. A few teeth on the prearticular display a pitted surface on occlusal faces. However, examination of these surfaces under light microscopy reveals they are actually associated with dental wear and are absent on unworn surfaces.

The prearticular is laterally compressed and anteroventrally elongated in dorsal view (Figs.

3J-K, 6C). This morphology is likely associated with a specialised feeding strategy, as the secondary lateral 'cutting' teeth have become dorsally elevated, well above other rows on the occlusal surface.

The mandibular symphysis is placed anteriorly, is broad and flat due to a reduction of the medioventral lamina. This is unlike other pycnodontiforms which have a thinner, longitudinally elongated symphysis supported by a wide, often tooth-bearing medioventral lamina (e.g.

Anomoeodus, [Forir, 1887; this paper]), Macromesodon (Woodward, 1890; Blake, 1905) and

Pycnodus (Longbottom, 1984 , Poyato-Ariza, 2013 . A similar modification of the mandibular symphysis also occurs in the prearticular of Phacodus (Dixon, 1850; Arambourg, 1952) and other species of Paranursallia (Arambourg, 1954; . tethysensis (Cenomanian, Capasso et al., 2009) and N. veronae (Eocene, Blot, 1987) . The sister genus, Paranursallia is restricted to the Late Cretaceous (Cenomanian-Turonian). Paranursallia gutturosa (formerly 'Paleobalistum' gutturosa, Arambourg, 1954) differs greatly from that of both P. gutturosa and P. cavini sp. nov. The prearticular of the type species is "triangular" and "as deep as it is long" , with only five teeth of unequal size along the outer lateral row, compared to P. gutturosa and P. cavini sp. nov. which both have ten teeth on the lateral-most row and a prearticular which is almost twice as long as it is deep.

The exact number of tooth rows is unknown in P. spinosa because the specimens consist of articulated individuals with the majority of the dental surfaces of the oral cavity obscured by the lateral profile of the prearticular.

The vomer of Paranursallia spinosa is poorly preserved, consisting of "three teeth" from "the lateral row" , and thus is regarded here as taxonomically undiagnostic.

However, the vomer of P. gutturosa from Morocco and north-eastern Italy is known from several well-preserved individuals, often partially disarticulated with the vomer visible in occlusal view (Amalfitano et al., 2020, figs. 7, 8) . The vomerine and prearticular dental pavements of P. gutturosa and the Asfla nursalline are remarkably similar and therefore we assign the new form, with confidence, to the genus Paranursallia. Paranursallia cavini sp. nov. represents the third recorded species of Paranursallia and extends the genera's stratigraphic range from the Cenomanian into the Turonian (P. spinosa = Cenomanian; P. gutturosa = Cenomanian; P. cavini sp. nov. = middle Turonian).

Both P. cavini sp. nov. and the closest comparable species, P. gutturosa share the following characters: circular to subcircular medial teeth that decrease in size anteriorly on the vomer; Prearticular has a "high and straight dorsal boarder" and is longer than it is deep; Prearticular medial teeth show an "oval contour" and are "weakly ornamented" with nine teeth present on the medial row of both species; lateral-most teeth on the vomer and prearticulars are slightly concave due to the presence of a specialised cingulum forming a weak 'cutting edge'-like occlusal ridge. However, the new form is distinguished from P. gutturosa due to the following: three to four prearticular tooth rows in P. gutturosa as opposed to six in P. cavini; the vomer of P. cavini is elliptical in occlusal view, as opposed to triangular in P. gutturosa. Both Arambourg (1954) and Amalfitano et al., (2020) record "coarsely serrated cutting edges" on both the prearticular and vomerine lateral teeth of P.

gutturosa. These teeth in P. cavini are blunt and lack serrations, even along the so called 'cutting edges'. Furthermore, Amalfitano et al., (2020) Neoproscinetes possess three vomerine tooth rows, however the morphology varies considerably from Paranursallia, most notably by a reoccurring series of "one large tooth followed by two smaller paired teeth" along the medial row (Figueiredo and Silva Santos, 1987; Wenz, 1991; Cooper and Martill, 2020) . Furthermore, the presence of small additional teeth intercalated between the medial and lateral rows of P. cavini is unseen in these other genera.

The small pycnodont vomer tentatively reported as 'cf. Palaeobalistum sp.' by Cavin (1996) from "Goulmima", shows greater affinity to Paranursallia cavini. Both specimen AK-PY 1 and Cavin's specimen comprise three tooth rows, longitudinally elongated anterior medial teeth, and slightly concave lateral teeth which possess a cutting edge and cingulum. Due to the fragmentary nature of Cavin's specimen, it is unclear whether it belongs in Nursallia or Paranursallia, as both have the same number of tooth rows. The Goulmima specimen does differ from P. cavini by the presence of bicuspid occlusal surfaces on lateral teeth. Lateral teeth of P. cavini are monocuspid with a single occlusal ridge and therefore the Goulmima specimen cannot be synonymised with the new species.

The distinctive morphology of the lateral teeth in the Goulmima specimen is absent in Palaeobalistum and is reassigned as 'cf. Paranursallia sp.' It is possible that the Goulmima pycnodont J o u r n a l P r e -p r o o f may represent a different species of Paranursallia or even a junior synonym of P. cavini; but more material is needed to investigate this.

Family ?PYCNODONTIDAE, Agassiz, 1833 (sensu Nursall, 1996b Subfamily ?NURSALLINAE, Poyato-Ariza and Wenz, 2002. NEOMESTURUS gen. nov.

Etymology. Named for the apparent convergent dental configuration with the Late Jurassic pycnodont Mesturus (Wagner, 1862) , with Neos (G) for new.

Holotype. AK-PYC 3 (Fig. 3H ), Isolated vomer with complete dental series and ascending process.

Referred specimen, AK-PYC 2, isolated vomer with an incomplete dental series (Fig. 3G) .

Type locality. Asfla fossil mines, Asseme N'Tadirhoust, 4km south-east of Asfla, Errachidia province, south-east Morocco. 31˚52'01"N 4˚52'30"W.

Horizon. (?)Mammites ammonite biozone, Chalky-Marl facies, Asfla Member, Akrabou Formation.

Etymology. Named after the small oasis village of Asfla (Errachidia Province) where the holotype was obtained.

Diagnosis. Neomesturus is diagnosed on a single dental autapomorphy: paired primary lateral rows composed of small, rounded teeth which are unornamented and significantly smaller than teeth in the adjacent medial and secondary lateral rows. A combination of the following synapomorphies: five vomerine tooth rows; teeth on the primary lateral rows are reduced but are continuous J o u r n a l P r e -p r o o f opposed to being intercalated (e.g. Paranursallia). Unlike Mesturus which has well ornamented teeth, those on the new Turonian form are mostly unornamented and smooth on unworn occlusal surfaces. Secondary lateral teeth are slightly concave, possessing a cingulum and bevelled cutting edge on the occlusal surfaces.

Description. Neomesturus asflaensis is described from two complete isolated vomers, AK-PYC 2 and AK-PYC 3 (holotype). The holotype consists of a complete, medium sized vomer preserved on a piece of chalky limestone in occlusal view, measuring 23 mm long anterioposteriorly, 12 mm wide and 5 mm in pallet thickness (excluding the ascending process). Referred specimen AK-PYC 2 represents a slightly larger individual but shows damage to the posterior end of the right secondary lateral tooth row. Comparable to the Late Jurassic form Mesturus, the dental pavement of Neomesturus consists of approximately three regular rows and two discontinuous rows (Poyato-Ariza and Wenz, 2002) .

The vomer is triangular in occlusal view and is relatively thin (3.8 mm maximum) in cross section and lacks any convex elevation of the medial teeth above those on the adjacent lateral rows.

The medial teeth are convex, unornamented and slightly wider than they are long. Eight to nine teeth are present on the medial row, collectively showing a slight decrease in tooth size anteriorly (0.3 mm x 0.4 mm posterior; 1.0 mm x 1.5 mm anterior).These teeth are oval posteriorly to pisiform anteriorly and all possess well-rounded lateral and occlusal faces. Teeth are tightly interspaced longitudinally due to lack of diastemas between successive teeth on the row.

Teeth on the paired, primary lateral row are significantly smaller and poorly organised compared to teeth on the medial and secondary lateral rows. Teeth along this row show wide variation of size, dental shape and occlusal morphology. On the holotype (AK-PYC 3), primary lateral tooth diameter ranges from 0.3 mm to 2 mm apparently randomly. Both specimens show a random tooth size distribution along the rows, with larger teeth apparently intercalated between smaller ones, and vice versa (Fig. 7) . Teeth are all convex, but their morphology varies between circular and oval to almost sub-elliptical at random intervals longitudinally. Dental topography also varies with smooth, unornamented domes on larger teeth, whilst some smaller teeth possess a small, nipplelike protuberance on the crown apex. The number of teeth present on this row varies slightly between specimens (16 on AK-PYC3 and 22 on AK-PYC 2) and is therefore interpreted as interspecies variation; or possibly ontogeny as AK-PYC 2 represents a slightly larger individual than AK-PYC 3.

Teeth on the secondary (outer) lateral row are on average, twice as large in length and width as the primary lateral teeth but are less than half the width of the medial teeth respectively. Tooth size on this row decreases very subtly towards the anterior (2 mm x 1.8 mm at the posterior, and 1 mm x 1 mm at the anterior). Similar to the primary lateral row, teeth on the secondary lateral row J o u r n a l P r e -p r o o f show a slight heterodonty -on the holotype, the first four teeth are 'D' shaped, with a poorly developed cingulum and a shallow bevelled ridge along the posterior crown margin. These occlusal ridges (cutting edges) in Neomesturus are similar to those of Paranursallia (Figs. 6, 7) but are significantly less developed and have a convex occlusal surface, as opposed to the concave aspect seen in P. cavini. The six succeeding teeth are subspherical, convex with a poorly developed cingulum and a shallowly raised occlusal fossa with smooth, unornamented margins. The change between these two morphologies is abrupt in AK-PYC 3, but gradual in AK-PYC 2 with intermediate morphologies present.

The ascending process of the vomer is well preserved in AK-PYC 3 but absent in AK-PYC 2 (Figs. 3H, 6A) . The process is short and elongated longitudinally with an asymmetrical apex situated close to the posterior margin of the dental pallet in lateral view.

Remarks. Neomesturus is erected as a new genus on the premise of a vomerine dental pavement which is strongly convergent on that of Mesturus Wagner, 1862 but lacks the ornamented tooth crowns typical of that genus (Fig. 7) . Both Mesturus and Neomesturus gen. nov. possess five vomerine tooth rows composed of one medial and two paired lateral rows, the primary laterals of which are reduced and unorganised. Although distinct from adjacent other tooth rows, the primary lateral rows of both genera are regarded as true rows, as if removed would create a distinct diastema between teeth in adjacent rows (as opposed to teeth which are intercalated between other tooth rows -e.g. Paranursallia cavini, see above). Unlike Neomesturus, the vomerine and prearticular teeth of Mesturus are strongly ornamented (Fig. 6C) with "apical tubercle[s] and crimped margins" (Martill and Hudson, 1991) . By contrast the vomerine teeth of Neomesturus asflaensis are completely devoid of crown ornamentation and therefore differs from Mesturus.

Horizon. (?)Mammites ammonite biozone, Chalky-Marl facies, Asfla Member, Akrabou Formation.

Description. Polazzodus sp. is identified in the Akrabou Formation from a single, isolated vomer measuring 21 mm by 11 mm (max.) in anteroposterior length and maximum width posteriorly. The vomer is strongly triangular in occlusal view, with perfectly straight lateral profiles of the outermost teeth (Figs 3D, 8A) . Teeth on the vomer are organised into five distinct tooth rows. The element is relatively thin (4 mm), with minor elevation of the medial and primary lateral rows slightly above the secondary lateral rows in cross section.

The medial teeth are strongly triangular with rounded corners -similar to Coccodus Pictet, 1850 and Ichthyoceros Gayet, 1984 . Seven medial teeth are present in AK-PYC 5, although slight damage to the anterior margin suggest possibly eight or more teeth were originally present. The occlusal surface of each tooth in the row is moderately ornamented with numerous fine crenulations radiating outwards from a shallow central fossa. Medial teeth decrease in size anteriorly, ranging from 3 mm x 3.5 mm posteriorly to 2 mm x 2.3 mm anteriorly. Each medial tooth is separated longitudinally by a narrow diastema measuring on average half the length of the associated tooth.

The primary lateral and secondary lateral teeth are of near equal size relative to their position along the element. Seven lachrymiform to sub-pisiform teeth are present on the primary lateral rows. A short longitudinal ridge is present medially on each dental crown. These ridges are poorly developed and unornamented with occlusal wear facets only situated on the lateral slope of each ridge. Teeth on this row measure 4 mm x 3 mm posteriorly and 2 mm x 1 mm anteriorly in length and width respectively. Seven teeth are also present on the secondary lateral row, measuring between 4 mm x 3 mm posteriorly and 2 mm x 1 mm anteriorly in length and width respectively. Secondary lateral teeth are longitudinally elongate and reniform to sub-lachrymiform. The lateral faces of these teeth are flat, forming a perfectly straight lateral topography of the vomer (Fig. 8A ).

Due to the specimen being prepared in occlusal view, the ascending process of the vomer (if present) is concealed by matrix.

Remarks. Specimen AK-PYC 5 is assigned to the genus Polazzodus due to the dentition being near identical to vomer specimens of the type (and only) species, P. coronatus figured by Poyato-Ariza (2010, fig. 5D ) from the type locality. Both P. coronatus from the Late Cretaceous of Polazza (northeastern Italy) and the new Asfla specimen share a very similar dental pavement in regards to tooth shape, tooth count and number of tooth rows: both possess five tooth rows with no more J o u r n a l P r e -p r o o f than seven teeth on the medial row; medial teeth are strongly triangular with curved faces; lateral teeth are sub-triangular to lachrymiform; secondary lateral teeth are oval to reniform; all lateral teeth are elongated longitudinally. However, the triangular medial teeth of AK-PYC 5 are more equilateral than in the Italian specimens. Furthermore, Poyato-Ariza (2010) diagnoses Polazzodus coronatus with "eight to nine teeth on the lateral rows", whereas the Asfla specimen show no more than seven on the lateral rows (Fig 8) . Despite the minute variations observed between P. coronatus and AK-PYC 5, we do not deem it appropriate to erect a new species of Polazzodus for the Asfla specimen at this time. The slight variation in medial tooth shape and number of teeth on the lateral row may be a consequence of interspecies variation or ontogeny. More Asfla specimens are needed to investigate how these variations change with ontogeny, in order to determine if AK-PYC 5 is a distinct species of Polazzodus or a synonym of P. coronatus.

Polazzodus outside of Italy, suggesting a wider geographic distribution than previously considered.

The vicarious distribution of Polazzodus between northeast Italy and south-eastern Morocco is direct evidence of faunal dispersal within the western Neotethys. The type species Polazzodus coronatus is known from complete articulated specimens from the Late Cretaceous (early Santonian) of Polazza (Italy) and therefore assignment to Pycnodontidae is justified and agreed upon here. The presence of Polazzodus in the Akrabou Formation represents the oldest occurrence of the genus and extends its stratigraphic range from the middle Turonian to lower Santonian. Polazzodus is a small (97 mm maximum standard length, [Poyato-Ariza, 2010]), low-bodied pycnodont, rather than round-bodied like the closely related Oropycnodus Poyato-Ariza and Wenz, 2002 . The snout is elongate and gently downturned with a shallow caudal region creating an overall truncated lateral topography (Fig. 8C) .

A similar bauplan is seen in some extant coral reef fishes (e.g. Butterflyfishes and Leaffishes) which use their elongated rostrum to aid extraction of small prey items from narrow crevasses and burrows in hard ground substrates. It is likely that Polazzodus occupied a similar niche within the Goulmima assemblage (see discussion), feeding on smaller, perhaps more difficult to access prey items than the larger pycnodonts present in the assemblage.

Pycnodonts were initially considered rare and "indeterminate" in the Akrabou Formation (Cavin 1997; 1999; Cavin et al., 2010) with only a single, poorly preserved vomer of "cf. Palaeobalistum sp." figured (Cavin, 1997; reassigned here to cf. Paranursallia sp., see systematic palaeontology).

However, from new data presented here, pycnodonts in the Akrabou Formation are proven to be both diverse and well preserved in the Asfla area, with five nominal species now recorded and formally described: Anomoeodus sp. A, Anomoeodus sp. B, Paranursallia cavini sp. nov., Neomesturus asflaensis gen. et sp. nov. and Pollazodus sp. The apparent discrepancy for the lack of pycnodont material described before this study is unknown, although it is likely the result of a research bias due to their material being rather abundant and well preserved in the formation. This high diversity of pycnodont fishes is typically seen in many other Mesozoic marine (reef) assemblages (e.g. Nursall, 1996a; Kriwet, 2001; Poyato-Ariza, 2013 ), but we note that the Akrabou Formation generally lacks reef facies (Ettachfini and Andreu, 2004).

Two vomer and two prearticular morphotypes of Anomoeodus are identified, and are tentatively grouped under two preliminary taxa: Anomoeodus sp. A and Anomoeodus sp. B (see above). Despite both Anomoeodus species in the Akrabou possessing autapomorphic characters, they have not been erected as new species at this time. As previously discussed, Anomoeodus in its current state is a 'taxonomic waste bin' (Cooper and and adding further taxa to this genus would be inappropriate as the genus requires a thorough review. Collectively Anomoeodus sp.

A and Anomoeodus sp. B. comprise approximately 79 % of the pycnodont assemblage at Asfla (Anomoeodus sp. A = 29 %, Anomoeodus sp. B = 50 %. See Fig. 9 ). The reason for this high abundance is unknown. However, one plausible explanation could be interpreted from specimen size. Most vomer and prearticular specimens of Anomoeodus are much larger than those of other taxa in the assemblage, and likely represent large individuals (>1 m). The larger size of these elements in contrast to those of smaller pycnodont taxa (e.g. Pollazodus sp., this paper) better-favoured preservation due to their more robust nature and advanced ossification. It is also plausible that (post-decay) these elements were heavier and more easily sank into soupy substrates than the smaller examples. Juvenile Anomoeodus specimens are rare in the assemblage, only comprising 20 % of the Anomoeodus sample. Juveniles experience high mortality rates from predation by larger piscivorous fishes and reptiles (e.g. selachians, ichthyodectids, tethysaurs) while adults experience reduced predation rates (Stewart and Jones, 2001) which would infer juvenile pycnodonts had a much lower preservation potential than adult forms. Small fishes in general are scarce in the Asfla Member Lagerstätte, except within the stomach contents of larger individuals (Cavin 1997 , 1999 , Cavin et al., 2010 .

The Asfla pycnodonts show robust durophagous dental pallets with blunt teeth arranged into sophisticated rows as per the typical pycnodontiform condition (e.g. Poyato-Ariza and Wenz, 2002; Kriwet, 2005) . This specialised dental apparatus strongly suggests a bottom feeding ecology (benthic) as their jaws are well equipped to predate on sessile and recumbent benthos. The precise diet of the Asfla pycnodonts is unknown due to a current lack of articulated material with in-situ stomach contents. However, a rich diversity of benthos including bivalves (Astarte and Rynchostreon, Lebedel et al., 2015) , foraminifera, indeterminate gastropods, scleractinian corals , irregular echinoids (Ettachfini and Andreu, 2004) and possible crustaceans (indicated by Thalassinoides burrows) may hint at the varied diet of the Asfla pycnodonts. This variety of potential prey resources may explain the high diversity of pycnodonts at Asfla and the sustainability of an apparently over-crowded benthic durophagous niche in the assemblage (Fig. 10) . Firstly, examination of rare pycnodont stomach contents from other Konservat Lagerstätten by Kriwet (2001; 2005) and Capasso (2019) demonstrate them to be monospecific feeders, with each pycnodont species typically feeding exclusively on one prey item, sometimes specific to genus level (e.g. echinoderms, bivalves, crustaceans). This niche partitioning would have allowed for pycnodontiforms to diversify and reduce intraspecies competition within a single assemblage as each pycnodont species was adapted to feed on a unique prey resource. The considerable variation in dental size and morphology between pycnodonts described here strongly suggest a similar niche partitioning was present in the Asfla pycnodont assemblage. Theorising which prey resource specific pycnodonts preyed on would be completely speculative without associated stomach contents, however it is likely that larger forms like Anomoeodus spp. fed on larger invertebrates with tougher shells like oysters (Rynchostreon sp.) and echinoderms. Smaller forms on the other hand with smaller teeth (Polazzodus sp. and Neomesturus asflaensis gen et sp. nov.) were better suited to feed on smaller and softer shelled prey like small crustaceans and benthic foraminifera.

Paranursallia outside of the Akrabou Formation is known from complete individuals from the Jebel Tselfat (Morocco, Arambourg, 1954,) the Agua Nueva Formation of Mexico (e.g. Stinnesbeck et al., 2019) and the Cenomanian of Italy (Amalfitano et al., 2020) although no stomach contents have been recorded for this genus.

The apparent 'cutting edges' present on the lateral tooth rows of both Paranursallia cavini sp. nov. and Neomesturus asflaensis gen. et sp. nov. are rarely observed in Pycnodontiformes and hint at a specialised feeding niche perhaps unrelated to durophagy. The presence of a cingulum with longitudinal occlusal ridges on these teeth is comparable to that of the so-called 'Piranha jawed' Serrasalmimidae pycnodonts of the Late Cretaceous to Eocene (Vullo et al., 2017) which possess a cingulum and modified papilla forming incisor-like teeth with prominent cutting edges. These J o u r n a l P r e -p r o o f 'cutting teeth' in the Asfla Member forms are smoother, less concave and lack a modified papilla.

Despite the apparent convergency, the cutting edges in the new forms are less developed and somewhat blunt, suggesting a different feeding strategy to Serrasalmimidae.

Polazzodus sp. is only know in Morocco from a single isolated vomer, but the type species P.

coronatus Poyato-Ariza (2010) , from the Late Cretaceous of Polazzo (northeatern Italy) is known from complete articulated specimens. Unfortunately, stomach contents have not yet been recorded in these specimens. The bauplan of Polazzodus is strongly convergent on extant butterflyfishes (Chaetodontidae) that possess slightly elongate rostrums used to forage on small invertebrates (e.g. polyps and small crustaceans), hidden within hard ground crevasses of coral reefs (Hastings et al., 2014) . Hard grounds are mostly absent in the Akrabou Formation, however rare scleractinian coral fragments present in the fossiliferous packstone beds near Asfla (pers. obs. SC) hints at isolated patches of hard ground suitable to this proposed ecological niche.

Pycnodont fishes are surprisingly diverse across the Cretaceous of Morocco (see Table 1 Rare, complete pycnodont specimens attributed to Paranursallia gutturosa (syn.

Palaeobalistum gutturosa, Arambourg, 1954) are recorded from the Cenomanian Jebel Tselfat (Arambourg, 1954; Amalfitano et al., 2020) . This taxon is also recorded from the upper Cenomanian of Italy (Amalfitano et al., 2020) as well as the new species, P. cavini (this paper) from the lower Turonian of Asfla. The vicarious distribution of Paranursallia between southern J o u r n a l P r e -p r o o f Europe and Northern Africa suggest the pycnodont was well distributed across the western Tethys during the upper Cenomanian and lower Turonian.

At least two different pycnodont taxa are present in the upper Cenomanian so-called 'Agoult assemblage' (Cavin, 1997; 1999) of the Gara Sbaa Plattenkalk Konservat Lagerstätte (Gara Sbaa Member). Martill et al., (2011) figured a complete individual of cf. Pycnodus sp. from this horizon but did not formally describe it. The specimen shows closer affinities with that of Sylvienodus (Poyato-Ariza, 2013) from the Cenomanian of Portugal than it does to Pycnodus which is now considered restricted to the Eocene. Therefore, it is justified to reassign the specimen here as cf. Sylvienodus sp.

A second pycnodont specimen, distinctive from that of cf. Sylvienodus sp. was figured by Murray et al., (2013;  fig. 4 ) but again, no systematic description was provided. Determining a possible taxonomic assignment of the Murray et al. specimen is problematic based on the scarce data available. Therefore, the specimen is referred here as 'Gara Sbaa pycnodont A' (Table 1) Arambourg (1952) . Arambourg (1964) also records the occurrence of Stephanodus and Hadrodus from the formation, however the taxonomic validity of the latter as a pycnodont is disputed (Poyato-Ariza and Wenz, 2002) and is therefore disregarded here in the context of pycnodont diversity. Vullo et al., (2017) Akrabou Formation of the Errachidia province (exact horizon unspecified). Taxonomic assignment of the specimen is currently undetermined. However, the dentition is comparable to that of nursalline pycnodonts and is tentatively referred here as 'Nursallinae indet.'. Due to current logistical complications regarding the Covid-19 pandemic, the specimen is temporarily unavailable and will be formally described at a later date (SC). Scale bar is equal to 10 mm. Paranursallia gutturosa (Arambourg, 1954) vomer from the Cenomanian of Italy (Amalfitano et al., 2020, figs 7-8) . By contrast to P. cavini, the dental pavement of P. gutturosa is triangular and lateral teeth lack longitudinal cutting ridges. (C), AK-PYC 4 Holotype of P. cavini sp. nov., left prearticular showing six clearly defined tooth rows with the medial row (see key) positioned on the lateral side of the dental pavement. (D), prearticular of P. gutturosa figured in Amalfitano et al., (2020; fig 9) showing four tooth rows with the medial row positioned medially on the dental pavement. Formation of Peterborough, England. Drawn from Martill and Hudson, 1991 (plate 41, fig. 6 ). Notice the unorganised arrangement of the small teeth on the discontinuous primary lateral rows in both genera. Unlike Mesturus, the medial and primary lateral teeth in Neomesturus are unornamented.

All scale bars are equal to 10 mm. 

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The authors wish to thank the following individuals for their contribution to this paper: Emma Bernard (NHMUK) for her helpful hospitality during a visit to NHMUK; Alex Veysey and Alex Srdic (Portsmouth) for their field work assistance at Asfla in 2017; Kyle Marson (Portsmouth) for donating