Onchopristis numidus, (HAUG, 1905)

Villalobos-Segura, Eduardo, Kriwet, Jürgen, Vullo, Romain, Stumpf, Sebastian, Ward, David J & Underwood, Charlie J, 2021, The skeletal remains of the euryhaline sclerorhynchoid † Onchopristis (Elasmobranchii) from the ‘ Mid’ - Cretaceous and their palaeontological implications, Zoological Journal of the Linnean Society 193 (2), pp. 746-746 : 746-

† ONCHOPRISTIS NUMIDUS ( HAUG, 1905)

( FIGS 2–15 )

Diagnosis: Sclerorhynchoids of relatively large size (TL ~ 4 m). Rostrum massive and with reinforcements having a triangular shapes. Rostrum consists of tessellated cartilage formed by a layer of small of prismatic (tessellate or mosaic-like) calcified cartilage blocks covered by a layer of fibrous cartilage similar to wood cortex with several vertical, parallel and wellmineralized ridges (i.e. ‘wood-like’ cartilage layer), along the central part of the rostrum and covering the grooves of the ophthalmic nerves. The periphery of the rostrum presents a thick layer of porous cartilage, where an enlarged lateral series of rostral denticles attach. Rostral denticles on the lateral series of the rostrum are slender, their caps are larger than the peduncle with hook-like projections (barbs) on the apical posterior region of the cap. The number of barbs varies from one to three (one being the most common). The posterior surface of the enlarged rostral denticles presents several well-marked ridges (~11) extending from the base and converging at the base of the barb. The denticles’ anterior face is ornamented with smaller ridges that reach the lower third of the cap. The basal bulge is well marked. The peduncle is small with flat and strongly grooved lateral faces. The denticles on the lateral cephalic series do not present barbs and are smaller and wider than the rostrum series and do not present a pulp cavity. Lateral rostral denticles with a large pulp cavity at their base that becomes extremely narrow, almost undetectable at the cap. Tooth crown with a large medial cusp and laterally expanded by the lateral shoulders (cusplets). The acute cusp is triangular-shaped and bent lingually. On lateral view, the labial profile is convex and the long apron projects anteriorly, surpassing the root.The lingual profile is concave with an almost incipient uvula. The root is more prominent than the crown and protrudes laterally, and its vascularization is holaulacorhized. Large denticles with an enameloid crest on the anterior surface are associated with the body.

Differential diagnosis: Rostral denticles of † Onchopristis numidus have an orthodentine-filled cap, with a smaller pulp cavity that extends into the denticle cap, whereas the rostral denticles of † O.dunklei possess a larger pulp cavity that extends well into the denticle cap with a thin orthodentine layer.

Te m p o r a l a n d s p a t i a l d i s t r i b u t i o n: A l b i a n – Cenomanian of Africa ( Egypt by Werner, 1989: pls 19–20, 23, 35–38) and Morocco by Cappetta (1980) and the present study).

Etymology: The genus name is derived from Greek ὄγκος (oncos), a wart, referring to the protuberance of the lateral rostral teeth (barb) and Π ρίστης (pristis), a saw. The species epithet is named for Numidia, the old Berber kingdom that included Algeria and part of Tunisia.

Rostrum: The hypertrophied rostrum is robust and triangular-shaped, reaching its widest point at the base and narrowing towards the tip (length:width at base ratio = 0.0186) ( Figs 2 , 3 ). The base of the rostrum progresses smoothly into the neurocranium. After removal of the sediment, the specimens revealed the presence of a ‘wood-like’ cartilage layer, covering the inner tessellate (mosaic-like) cartilage along the central part of the rostrum. This layer was first observed in † Onchopristis by Stromer (1917) and was characterized as possible fossilized skin. Later it was described by Cappetta (1980) as the cartilage covering the canals for the ophthalmic nerves in the rostrum. Sternes & Shimada (2019; fig. 2c) describe a similar cartilage type located at the sides of the rostrum of † Ischyrhiza Leidy, 1856 next to slightly thinner cartilage on the periphery of the rostrum where the lateral rostral denticles are attached.

From the description of the specimens presented here, the presence of this wood-like layer seems not to be restricted to only the superficial ophthalmic nerve canals, but is more widely extended in the rostrum, similar to that observed in † Schizorhiza Weiler, 1930 (see: Kirkland & Aguillón-Martínez, 2002; fig 8). All three genera present a thick layer of heavily porous cartilage on the sides of the rostrum supporting the lateral series of enlarged of denticles. However, in † Schizorhiza , this layer is much less porous on the rostrum margins.

Based on the presence of fully functional (erect) enlarged denticles of different sizes on the sides of the rostrum of † Onchopristis , we hypothesize a constant addition of rostral denticles. While † Schizorhiza , a peculiar sclerorhynchoid, presents a similar rostral morphology that comprises a thin layer of ‘wood-like’ cartilage and a thick lateral layer of cartilage. The differences in the addition-replacement of lateral rostral denticles and rostral anatomy of † Onchopristis and † Schizorhiza suggest differences with other sclerorhynchoids in the use of them (i.e. possibly as a hunting tool or a defence mechanism in † Onchopristis and † Schizorhiza ).

Towards the centrum of the rostral cartilages, and next to the highly porous lateral layer of cartilage, on both the dorsal and ventral surfaces, are two canals, one on each side ( Fig. 4A–C ). The superficial ophthalmic nerve canal runs on the dorsal surface covered by a layer of cartilage and seems to terminate in a cavity next to the supraorbital crest. On the ventral side, the buccopharyngeal nerve canal terminates at the base of the nasal capsules. Both canals become narrower towards the tip of the rostrum and, in several places, are covered by the ‘wood-like’ cartilage, suggesting that this cartilage entirely covered the canals.

Lateral enlarged rostral denticles: All lateral rostral denticles in specimens NHMUK PV P 75502, IPUW

353500 and IGR 2818, as well as disarticulated denticles recovered from various sites in the ‘Kem Kem Beds’, display a small, flat base composed mostly of osteodentine and a large cap composed entirely of orthodentine, with an external layer of enamel, and a characteristic barb on the apical posterior margin of the denticle. Strongly marked cutting edges, accompanied by rectilinear crests, are developed on both anterior and posterior faces of the denticles ( Fig. 5 ). The presence of these cutting edges, and the lack of abrasion patterns on the denticles’ cap, suggest that these denticles were not used to probe in the sediment.

Denticles with multiple numbers of barbs were sporadically collected in Morocco ( Fig. 6 ). These denticles have similar dimensions to single-barbed denticles, indicating that there is no correlation between denticle size and barb numbers, and that the number of barbs is not a function of ontogenetic stages ( Fig. 6A ). The presence of multiple-barbed denticles in the Egyptian and Moroccan localities suggests the sporadic development of double- and even triple-barbed denticles within † Onchopristis numidus ( Stromer, 1917; pl. 1, figs 9, 11; Werner, 1989; pl. 20, figs 1a, b, 3, 6, 7), including a three barbed specimen (Wegner, 1989; pl. 20, fig. 5).

Isolated denticles present various barb sizes, despite the similar size of the denticles ( Fig. 7C ). The difference in barb size associated with the rostral denticles could be related to their position along the rostrum. Therefore, the barb grows with the denticle during its development. Sections and micro-CT scans of denticles have revealed a pulp cavity projecting beyond the base and narrowing significantly to a thin, almost absent canal when it reaches the barb region, suggesting that the barb could reach a fixed size faster than the remaining portions of the denticle cap ( Fig 7A, B ).

Enlarged denticle series: Different morphologies of enlarged denticles, possibly attributed to † Onchopristis numidus , have been reported in Egypt (e.g. Stromer, 1927: pl. 1, figs 30b–32b; Werner, 1989: pl. 20, figs 8, 9) and were collected in Morocco ( Fig. 8A–C ). The presence of a barbless and curved denticle between the jaws of specimen IPUW 353500 ( Fig. 8A ), and its morphological similarities with the lateral rostral denticles (i.e. a narrow base composed of osteodentine with several ridges on the sides, well-differentiated from the orthodentine-filled cap), confirm the presence of a multiple series of enlarged denticles in † Onchopristis numidus . Its placement in the mouth indicates displacement of the denticle during the taphonomic process (i.e. not preserved in situ). However, from its position and the comparison with those of † Sclerorhynchus atavus NHMUK PV P 4776 and Pristiophorus lanae Ebert & Wilms, 2013 (see: Welten et al., 2015: figs 6c, 8e), we hypothesize that this denticle corresponds to the lateral cephalic series.

The presence of different enlarged series of denticles in † Onchopristis numidus that vary according to their position in the rostral and cephalic regions, is similar to that of other sclerorhynchoids (e.g. † Sclerorhynchus Woodward, 1889 ; Welten et al., 2015; Underwood et al., 2016). Furthermore, the subsequent lateral section of differently shaped free denticles found in the localities showed no evidence of any projection on their posterior margins ( Fig. 8B, C ), which suggests that the development of the barb is restricted only to the lateral series of the rostrum.

Replacement of enlarged rostral denticles: We identified three different size-classes plus a replacement one in the lateral series of enlarged denticles of the rostrum of † Onchopristis numidus , with large denticles intercalated with smaller ones and vice versa (i.e. large denticles intercalated with smaller ones) in a single line. This type of arrangement is new in batoids, including Pristidae , in which the single lateral rostral series is composed of a single line of continuously growing rostral denticles. Miller (1974) observed that the size arrangement and number of rostral teeth are established during the embryological stages in Anoxypristis cuspidata (Latham, 1794) and Pristis pristis (Linnaeus, 1758) . Welten et al. (2015) described a similar observation, regarding the arrangement and number of rostral denticles, in pristioids. However, this last work suggests that if denticles are added, it would be caudally near the base of the rostrum or closer to the tip, but only more pristioid embryonic material will confirm this.

Based on the presence of highly porous cartilages along the sides of the rostrum, and the presence of fully functional denticles of different size-classes in † Onchopristis numidus , we hypothesize that in this species, the denticles are periodically added across the rostrum as it grows and develops over time ( Fig. 9 ). The presence of fully erect, small denticles followed by larger ones, as observed in specimens IPUW 353500 and IGR 2818, suggests a seriated appearance of the rostral denticles beginning with smaller denticles and subsequently followed by larger ones ( Fig. 9A, B ). The three-size cluster of rostral denticles with a mirrored arrangement (i.e. similar-sized denticles placed on opposite sides in dorsal view) recognized in IGR 2818, is interpreted to be the result of synchronized development on both sides of the rostral denticles. This mirroring pattern is unnoticeable, or less conspicuous, at the tip of the rostrum, probably because it is a more fragile region and denticles in this area could be more susceptible to fracture due to taphonomic processes. The presence in both specimens (IPUW 353500 and IGR 2818) of small denticles (G1) and larger denticles (G2 and G3) with fully enamelled caps suggests that the mineralization pattern between older (larger) and younger (smaller) denticles ( Welten et al., 2015). In addition, the triplet arrangement observed in the rostral denticles of Pliotrema warreni is not always present in † Onchopristis numidus , in which denticles of the same size as those of the functional generation replace or occupy the available space.This arrangement is a similar organization to that reported for other sclerorhynchoid species (e.g. † Sclerorhynchus, Welten et al., 2015 ), in which some replacement denticles are so closely associated with the existing functional ones that they seem to appear in pairs ( Fig. 2 , denticles marked with an arrow)’.

denticles do not gradually grow but, instead, that larger denticles are periodically added as the animal grows ( Fig. 9C ). Both the arrangement and addition sequence are different from other sclerorhynchoids (e.g. Smith et al., 2015; Welten et al., 2015; Underwood et al., 2016; Sternes & Shimada, 2019).

Overall, this arrangement is somewhat similar to that observed in Pristiophorus J. P. Müller & Henle, 1837 ( Welten et al., 2015; Underwood et al., 2016). With some notable differences: in † Onchopristis numidus , both small and large rostral denticles seem to lack a differentiated degree of mineralization and present a cap densely filled with orthodentine, whereas rostral denticles in Pliotrema warreni Regan, 1906 differ in Neurocranium: Only the post-nasal region and part of the posterior edge of the nasal capsules can be addressed here, as the most anterior part of the nasal capsules is missing. The neurocranium is box-like and rectangularshaped, with an oval-shaped precerebral fenestra located near the base of the rostrum at the centre of the anterior part of the neurocranium ( Fig. 10 ). The dorsal surface of the left nasal capsule is not discernible, because it is heavily crushed. In ventral view, the posterior region of the right nasal capsule is preserved and presents a deep nasal fenestra that smoothly progresses into the rostrum. The buccopharyngeal nerve cavities are located on the ventral surface anterior to the nasal capsules ( Fig. 11A, B ).

The profile of the antorbital cartilage is triangular, with its narrow distal edge pointing posteriorly and its wide proximal edge articulating with the nasal capsule ( Fig. 11A, B ). Even though the neurocranium presents some crushing dorsoventrally, the supraorbital crest stands above the dorsal surface of the chondrocranium and does not cover the eye cavity. The orbital cavity is large and houses a well-mineralized optic peduncle; additional nerve foramina were not observed ( Fig. 11C, D ). Next to the supraorbital crest is the cavity for the superficial ophthalmic nerve ( Fig. 10B ). The postorbital region is rectangular and narrow with a small, triangular, postorbital process. In the otic region, the orbital fissure is above the lateral commissure and below the postorbital crest. The lateral commissure covers part of the hyomandibular branch of the facial nerve foramen ( Fig. 11C, D ). The lymphatic foramina are present in the posterior part of the neurocranium. The jugal arches follow the otic region and are located anteriorly to the occipital condyles, which are well developed and expanded laterally, forming a broad and deep articulation facet for the anterior lateral process of the synarcual ( Fig. 10 ).

Hyomandibula: The hyomandibula is triangularshaped (length:width ratio at base = 0.51, length:width ratio at tip = 0.018), with its proximal end articulating with the neurocranium, and its narrow, distal end connected between the palatoquadrate and Meckel’s cartilages. A section of the dorsal surface of the hyomandibula is missing; however, the remaining parts are slightly elevated, which could indicate the presence of a process for muscle articulation. ( Fig 10 ). Jaw cartilages: Only part of the Meckel’s and palatoquadrate cartilages are observable in ventral view ( Fig. 11A, B ). The palatoquadrate is thin and narrows progressively towards the symphysis ( Fig. 11A, B ). In ventral view, there is no clear articulation with the neurocranium, the Meckel’s cartilage and palatoquadrate are present, and both jaw elements seem to be supported by the hyomandibula. The palatoquadrate and Meckel’s cartilage antimeres are separated, and they were connected by connective tissue at the symphysis. The Meckel’s cartilage is wider than the palatoquadrate but also becomes narrower towards the symphysis ( Fig. 11A, B ).

Oral teeth: Teeth of † Onchopristis numidus have been figured multiple times [e.g. by Stromer (1927: pl. I, figs 1–4), under the name † Squatina aegyptiaca ; by Werner (1989: pls 35–37), under the name † Sechmetia aegyptiaca . The teeth figured on plates 21 and 22 by Werner (1989) and were described as † Onchopristis , probably belong to a different sclerorhynchoid, such as † Renpetia Werner, 1989 ), and are similar to those of † O. dunklei ( Welton & Farish, 1993; Kriwet & Kussius, 2001: fig. 4; Cappetta, 2012: fig. 370M–R; Vullo et al. (2003: pl. 2, fig. 6)].

Both species have teeth with a sharp and acute cusp that bends lingually ( Figs 12C, G, K , 13J, L ). The labial apron is narrow, with a blunt distal edge that projects anteriorly and surpasses the root and present a pair of incipient lateral cusplets ( Figs 12A, E , 13O, K, S ). Several teeth collected in Morocco present a doublelobed labial apron ( Fig. 12A, E, D, H ). Some teeth also have a cutting edge on the labial and lingula crown faces ( Fig. 13A–E ). All teeth display well-developed cutting edges, which are continuous between the cusp and lateral cusplets ( Figs 12 , 13J, L ). The lingual uvula is absent ( Fig. 12C, G ), and the root is bilobed and laterally projected ( Figs 12B, F , 13P ).

Cross-sections of the oral teeth have revealed the presence of a large pulp cavity in the root that extends apically into the crow where it becomes narrower as it progresses towards the apex ( Fig. 13G, K, R .).

Synarcual: Only the anterior part of the synarcual is preserved, which presents a well-developed odontoid process (synarcual lip) that forms part of the articulation surface for the synarcual with the neurocranium, along with the extensive anterior lateral process that mirrors the odontoid processes in the neurocranium. This process and the depth of the odontoid process suggest a close and not mobile articulation with the neurocranium ( Fig. 14 ). The central portion of the synarcual is well developed and displays some spino-occipital foramina (the actual number remains unknown as only a portion of the synarcual is preserved). The anterior part of the medial crest is missing, but remaining portions are thin and well developed, and seem to have been folded during taphonomic processes. Only the right lateral stay is visible, and it becomes progressively narrower backwards. Its distal end is well developed and flattened, and it probably was dorsally directed during life ( Fig.14A, B ). In ventral view, no vertebral centra are observable, which suggests that the vertebrae centra did not pass the midpoint of the synarcual ( Fig. 14C, D ), as in other sclerorhynchoids ( Villalobos-Segura et al., 2019)

Vertebrae: The vertebral centra of † Onchopristis consist of the corpus calcareum and the intermedialia, as in other chondrichthyans. The corpus calcareum is well mineralized and shows clear and opaque bands, suggesting a cyclical deposition of mineral. Whether this pattern was seasonal, as in other chondrichthyans, remains ambiguous for the moment ( Fig. 15 ).

Dermal denticles: The rostrum also presents a small series of denticles at the base of the enlarged rostral denticles and on the ventral surface ( Fig. 16G ). Two morphologies are present, both with a rounded, wellenamelled cap and a stellated base with fringes that project just out below the cap and can be distinguished by the presence of a central cusp ( Fig. 16A–F ).

As in other fossil assemblages ( Werner, 1989), the occurrence of † Onchopristis in the ‘Kem Kem Beds’ coincides with that of ‘ Peyeria- like’ denticles ( Fig. 17 ). Cappetta (2012) noted that these two batoids are commonly found together, proposing that † Peyeria Werner, 1989 was, a synonym of † Onchopristis and the † Peyeria remains were, in fact, dermal denticles of † Onchopristis . Recently, similar enlarged dermal denticles were reported for † Ischyrhiza mira Leidy, 1856 by Sternes & Shimada (2019) in the Campanian‒ Lower Maastrichtian of Tennessee and Alabama, USA, suggesting that this feature might be even more common among sclerorhynchoids. The presence of these types of enlarged body denticles in Morocco agrees with the interpretations of Cappetta (2012) and Sternes & Shimada (2019).

† Onchopristis numidus dermal denticles found in Morocco are unique among sclerorhynchoids ( Werner, 1989: pl. 41, figs 1–4; Sternes & Shimada, 2019: fig. 4e, f). They present a thick enameloid layer on the anterior edge of the denticles. Additional cross-sections revealed a small pulp cavity followed by a thin, nonporous laminar layer, on which a thick layer of highly vascularized osteodentine, which reaches the tip of the denticle, is deposited ( Fig. 17C ).

PHYLOGENETIC ANALYSIS

The character matrix for the phylogenetic analysis used here is a modified version from that used by Villalobos-Segura et al., 2020. The main changes include recoding of the polymorphic characters 5, 6 and 9, which were changed for Amblyraja Malm, 1877 and Raja (see Supporting Information; Files S2 and S5–S10). These features refer to the absence/ presence of malar thorns, which are developed only in male rays ( Aschliman et al., 2012). Three different coding schemes were considered for these characters that included deactivating those characters, leaving them as a polymorphic character and coding them as present, small topological changes resulted from these different codifications (Supporting Information, Files S5–S10). However, we consider that, regardless of the sexual dimorphism link of these characters, the malar thorns are features that correspond to the genera and should be coded as present.

Character 20 (absence/presence of a differentiated lateral uvula on the teeth), was changed for Anoxypristis to present, as its teeth show a variably developed lateral uvula (e.g. Underwood et al., 2011; Cappetta, 2012).

Character 24 (absence/presence of a lingual uvula in the teeth) was changed for † Ptychotrygon Jaekel, 1894 , following the observations made on † Ptychotrygon rostrispatula by Villalobos-Segura et al. (2020) and four characters were included (Chars 25–29) to increase the morphological variance observed within sclerorhynchoids (see Supporting Information, File S2).

The TNT analysis recovered 13 most-parsimonious trees of 41 steps with a consistency index of 0.78 and a retention index of 0.85, whereas the TreeSearch analysis recovered a 41-step tree. Both strict consensus trees (Treesearch and TNT) place all sclerorhynchoids taxa, including † Schizorhiza , into a polytomy [ Fig. 18A, B , clade support Cs (strict) = 74%, Cs (majority) = 40%]. In both strict consensus and majority rule trees, this clade is supported by one shared feature: the lack of a rostral appendix [ Fig. 18A , Char. = 25, 0, consistency index (Ci) = 1], which refers to the absence of thin cartilage attached to the rostrum (Supporting Information, File S2). Although the lack of a rostral appendix is a feature shared by several batoid groups, the absence of this structure seems to be the result of different processes occurring in these groups. In Myliobatiformes , the rostral appendix is polymorphic, some groups present it (e.g. Potamotrygon Garman, 1877 and Urotrygon T. N. Gill, 1863 ) and others not (e.g. Rhinoptera van Hasselt, 1824 and Zanobatus Garman, 1913 ). The development of this structure in Myliobatiformes corresponds to the anteromedial growth of the trabecula (i.e. the rostral shaft or rostral cartilage) ( Miyake et al., 1992). In platyrhinoids, the trabecula does not present mid-growth, as a result the appendix is absent; also, these taxa develop a similar structure that is referred as a rostral process by McEachran & Aschliman (2004) and Aschliman et al. (2012). Within torpedinids, the development of the rostrum varies with different embryonic cartilages participating in its formation (e.g. in Torpedo Houttuyn, 1764 , the rostral cartilages develop from the lamina orbitonasalis, whereas in Narcine Henle, 1834 , the rostral cartilages derive from the trabecula, which also presents different chondrification periods) ( Miyake et al., 1992). In comparison, the development of rostral cartilages in sclerorhynchoids appears simpler, as they present a good anteromedial growth with no apparent rostral appendix (similar to that of sawsharks), suggesting a convergence between sclerorhynchoids and sawsharks, considering the anatomical differences between these shark and batoid groups (i.e. presence of synarcual and antorbital cartilages). The sclerorhynchoid clade is placed in a sister-relation to the Rajidae ( Amblyraja and Raja ; Fig. 18A, B , Cs = 80%). The monophyletic group Rajidae + Sclerorhynchoids [ Fig. 18A, B : Cs (strict) = 90%, Cs (majority) = 44%], is supported by four shared features in the majority rule tree and one in the strict consensus tree ( Fig. 18A ). Both TNT trees place the lack of differentiated lateral uvula in teeth ( Fig. 18A : Char. = 20, 0, Ci = 1) as a shared synapomorphy (see character discussion in Supporting Information, File 2). It is worth mentioning that sclerorhynchoids are not the only batoids lacking these projections. All sclerorhynchoid dentitions reviewed here lack these structures, suggesting more than just a dietary adaptation.

Within the sclerorhynchoids clade, two monophyletic groups are recovered by the strict consensus tree estimated with TreeSearch and one with TNT analyses ( Fig. 18A ). Both analyses coincide in the grouping of † Onchopristis and † Ischyrhiza as a monophyletic group [ Fig. 18A, B : Cs (strict) = 81%, Cs (majority) = 91%]. This relation is supported by one common synapomorphy in both strict consensus and majority rule trees, that is the presence of smaller denticles with a round cap associated with the base of the enlarged rostral denticles ( Fig. 18A : Char. = 28, 1, Ci = 1). The majority tree rule recovered two more shared features for the † Onchopristis and † Ischyrhiza clade, the reason why these characters are not considered a synapomorphy and do not appear in the strict consensus tree ( Fig. 18A ) is the presence of ambiguity; for Char. 18 (Ci = 1), the coding of † Schizorhiza (?) creates ambiguity. While, for Char. 6 (Ci = 1) the uncertainty comes from the collapse of the † Libanopristis , † Micropristis Capetta, 1980 , † Sclerorhynchus , † Ptychotrygon and † Asflapristis Villalobos-Segura et al., 2020 clade [ Fig. 18A, B , Cs (majority) = 74%]. Of these features, the presence of large denticles associated with the body (Char. 18, 1) is of relevance as † Onchopristis and † Ischyrhiza are currently the only sclerorhynchoids presenting them, suggesting a close relationship between these taxa.

The strict consensus tree estimated with the TreeSearch analysis is better resolved than that of the TNT analysis, recovering another monophyletic group that includes † Asflapristis + † Ptychotrygon [ Fig. 18B , Cs (strict) = 91%, Cs (majority) = 81%]. Three features support the relation (see MRT, Fig. 18A ): (1) lack of enlarged denticle series associated to the rostral cartilages (Char. 7, 0, Ci = 1), (2) presence of a transversal crest on teeth (Char. 17, 1, Ci = 1) and (3) lack of calcified suprascapula (Char. 22, 0, Ci = 0.5) (see, character discussion in Supporting Information, File S2).

Figures

Figure 2. A, cranial and rostral remains of †Onchopristis numidus (IPUW 353500). B, interpretative line drawing of the specimen remains. Denticles in pair arrangement marked with an arrow. Scale bar: 5cm.

Figure 3. A, cranial and rostral remains of †Onchopristis numidus (IGR 2818). B, line drawing of the specimen remains (darken areas represent rock matrix). Denticles in pair arrangement marked with an arrow. Scale bar: 10 cm.

Figure 4. A–C, rostrum of †Onchopristis numidus. A, ventral surface of IPUW 353500. B, dorsal surface of IPUW 353500. C, NHMUK PV P 75502. Scale bar: 1cm.

Figure 5. Enlarged rostral denticles of †Onchopristis. A–C, micro-CT-based volume rendering of denticle collected along with the specimen IPUW 353500 from Morocco: A, dorsoventral; B, anterior; C, posterior views. D–G, denticles collected in Egypt (Werner, 1989; pl. 19, fig. 2a–d): D, posterior view; E, dorsoventral; F, anterior; G, base. Scale bar: 1 mm.

Figure 6. A, C, rostral denticles with multiple barbs bought in Morocco. A, denticle composed of two different denticles brought from a fossil dealer in Morocco NHMUK PV P74053. B, sagittal section of denticle, the section where the denticles were glued marked with an arrow (single barb base attached to a double barbed tip denticle). C, Double barb denticle brought from a fossil dealer in Morocco NHMUK PV P74053. D, sagittal section of that denticle revealing no modifications. Scale bar: 1 cm.

Figure 7. Rostral denticles of †Onchopristis numidus found in the ‘Kem Kem Beds’ NHMUK PV P74045. A, CT scan of denticles (scale bar: 1mm). B, transverse section of denticle (scale bar: 2 mm). C, lateral section of the tip of rostral denticles. D, E, smaller denticles with different barb sizes (scale bar: 1 cm).

Figure 8. A, mouth of †Onchopristis numidus (IPUW 353500). B, close-up view of enlarged denticle in the mouth. C, disarticulated denticles with similar morphology found in the ‘Kem Kem Beds’ collection sites: KK1 (easting: 382819; northing: 3501936 UTM) and KK3 (easting: 416828; northing: 3418567 UTM). Scale bar: 1 cm.

Figure 9. Fragment of the rostrum of †Onchopristis numidus. A, IPUW 353500 (scale bar: 1 cm). B, NHMUK PV P 75503 (scale bar: 5 cm). C, hypothetical scheme of the growth and addition of rostral denticles in †Onchopristis. Denticles in grey in (C) are larger denticles replacing smaller ones that fell.

Figure 10. A, B, neurocranium of †Onchopristis numidus. A, picture of IPUW 353500. B, line drawing. C, picture of IGR 2818. D, line drawing. Scale bar 4 cm. Note: darken areas on drawing represent sediments.

Figure 11. Neurocranium of †Onchopristis numidus (IPUW 353500). A, ventral view. B, line drawing. C, lateral view. D, line drawing. (A, B, scale bar: 2 cm). (C, D, scale bar: 5 cm).

Figure 12. A–L, oral teeth of †Onchopristis numidus found in the ‘Kem Kem Beds’, collection site Boulalou (KK5: easting: 418413; northing: 3479178 UTM; zone: 30) NHMUK PV P 74050. M, N, teeth extracted from the preparation of specimen IPUW 353500. A, E, I, D, H, L, M, N, labial face. B, F, J, root. C, G, K, profile view. Scale bar: 2mm.

Figure 13. Micro-CT-based volume renderings and virtual sections of oral teeth of † found associated with IPUW 353500. A–E, broken main cusp in: A, labial; B, occlusal; C, lingual; D, medial; D, E, profile views. F–L, incomplete tooth lacking part of the labial apron and root in: F, labial; H, lingual; I, apical; J, L, profile views; tooth sections in (G) axial and (K) sagittal aspects; M–S, tooth with a broken main cusp in: M, labial; N, lingual; O, occlusal; P, basal; Q, S, profile views tooth section in (R).

Figure 14. Synarcual of †Onchopristis numidus (IPUW 353500). A, dorsal view. B, line drawing. C, ventral view. D, line drawing. Scale bar: 5 cm.

Figure 15. A, B, vertebral centra of †Onchopristis numidus from the ‘Kem Kem Beds’ collection sites Boulalou (KK5: easting: 418413; northing: 3479178 UTM) NHMUK PV P 74052. A, B, sagittal section of vertebra. C, articulation surface of the vertebra. Scale bars: 1 cm.

Figure 16. A–F, ventral rostral denticles from the section of the rostrum of †Onchopristis numidus (NHMUK PV P 75502). A–C, Morpho 1. D–F, Morpho 2 (scale bar: 2 mm) NHMUK PV P 74051. G, anterior part of the ventral surface of IPUW 353500 rostrum (scale bar: 1 cm).

Figure 17. Enlarged dermal denticles of †Onchopristis numidus from the ‘Kem Kem Beds’. A–C. B–C, Charles Underwood personal collection, lateral view, longitudinal section and close up of the enameloid layer. D–F, IGR 2819, lateral, anterior and basal views. G, IGR 2820, lateral view. H, IGR 2821, antero-apical view. Scale bars: 1 cm.

Figure 18. Phylogenetic trees recovered by the different analysis used in the present study.A, strict consensus and majority rule trees produced by the TNT analysis. B, strict consensus and majority rule trees produced by the TreeSearch analysis: clade support values from the Jackknife analysis displayed inside the parenthesis. Character supporting nodes of TNT’s majority rule tree (MRT): black circles, characters recovered by both consensus methods; white circles, characters recovered only by MRT.