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Carcharhinus sp. MATERIAL A dozen isolated teeth, figured material includes FSAC Bouj-345, 346 and 347. DESCRIPTION AND REMARKS Some rare medium-sized sharks (Fig. 3 G-I) are provisionally attributed to Carcharhinus sp. The upper tooth (Fig. 4G) reminds those of Negaprion sp. (unserrated cutting edges, main cusp separated from heels by notches) associated with erect and gracile lower teeth (Fig. 4H, I) usually observed in Carcharhinus, and especially in Priabonian species C. frequens (Dames, 1883). Assignement of middle Eocene carcharhinid teeth to genera Carcharhinus or Negaprion Whitley, 1940 remains debatable and uncertain (see also Sweydan et al. 2019 for discussion) but its attribution to Carcharhinus seemly more appropriate in regard to the dignathic heterodonty. Underwood et al. (2011) only reported a “ Carcharhinidae nov.gen. ” (sic) with smooth cutting edges in the middle Eocene MI, which is easily distinguishable from our material. No other mediumsized carcharhinid was collected within the studied area, particularly no representative of the “bull-shark” group among the Requiem sharks (see Adnet et al. 2007) that displays upper teeth with a modern morphology (e.g., serrated cutting edges). However, such representative was possibly reported in MI by Underwood et al. (2011: Carcharhinus sp. 1) but the rare specimens are often poorly preserved and were provisionally referred to taxa only well-identified in Priabonian levels. Underwood & Gunter (2012) illustrated a large and unique upper tooth probably representing one of the oldest evidences of “Bullshark” from Jamaica (Underwood & Gunter 2012: fig. 2); postulated to have been from the Yellow Limestone Group exposed at Broomwell and dated as middle Eocene. However, the age of this unique evidence in still uncertain and no other middle Eocene record was verified. Uncertainty about the age of Carcharhinus underwoodi Samonds, Andrianavalona, Wallett, Zalmout & Ward, 2019, the other oldest representative of “Bull-shark” group, is quite similar; being currently reported from middle to late Eocene of Madagascar. The lack of large modern Carcharhinus species in Boujdour area seems to indicate an early Bartonian age of the deposits, at least their absence is paleoenvironmentally controlled., Published as part of Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, pp. 121-150 in Geodiversitas 43 (5) on page 129, DOI: 10.5252/geodiversitas2021v43a5, http://zenodo.org/record/4605963, {"references":["SWEYDAN S., MERZERAU G., ESSID E. M., MARZOUGUI W., TEMANI R., AMMAR H. K., MARIVAUX L., VINAEY- LIAUD M., TABUCE R. & ADNET S. 2019. - A reworked elasmobranch fauna from Tunisia providing a snapshot of Eocene-Oligocene Tethyan faunas. Journal of African Earth Sciences 149: 194 - 206. https: // doi. org / 10.1016 / j. jafrearsci. 2018.08.008","UNDERWOOD C. J., WARD D. J., KING C., ANTAR S. M., ZAL- MOUT I. S. & GINGERICH P. D. 2011. - Shark and ray faunas in the middle and late Eocene of the Fayum area, Egypt. Proceedings of the Geologists' Association 122: 47 - 66. https: // doi. org / 10.1016 / j. pgeola. 20","ADNET S., ANTOINE P. O., HASSAN BAQRIS. R., CROCHET J. Y., MARIVAUX L., WELCOMME J. L. & METAIS G. 2007. - On the first modern and tropical Selachian association (Chondrichthyes) from the late Eocene-early Oligocene of Baluchistan, Pakistan. Dating interests, paleoenvironment and paleobiogeography. Journal of Asian Earth Sciences 30: 303 - 323. https: // doi. org / 10.1017 / S 0016756810000348","UNDERWOOD C. J. & GUNTER G. C. 2012. - The shark Carcharhinus sp. from the middle Eocene of Jamaica and the Eocene record of Carcharhinus. Caribbean Journal of Earth Science 44: 25 - 30.","SAMONDS K. E., ANDRIANAVALONA T. H., WALLETT L. A., ZALMOUT I. S. & WARD D. J. 2019. - A middle-late Eocene neoselachian assemblage from nearshore marine deposits, Mahajanga Basin, northwestern Madagascar. PLoS ONE 14 (2): e 0211789. https: // doi. org / 10.1371 / journal. pone. 0211789"]}

Superfamily GAVIALOIDEA Hay, 1930 Gavialoidea indet. EXAMINED MATERIAL. — FSACBouj-401, 403 and 404, anterior and posterior portion of left maxilla; 407, posterior portion of a left maxilla; 402, mid-portion of a right maxilla. All these specimens are from the same individual. Also 405, portion of a left dentary. DESCRIPTION The reconstruction of the maxillae shows a slender snouted form with 16 preserved teeth but more teeth were probably present (Fig. 7 L-N). The snout is wider than high and the palate is lower than the tooth row, so that the tooth row is underlined. The diameter of the alveoli is nearly constant along the tooth row and the interalveolus distances are equal or slightly longer than the alveolus diameter. The lateral margin of the maxilla is marked with shallow grooves visible in dorsal view for the occlusion of dentary teeth. FSAC Bouj-405 consists of a left portion of dentary, (Fig. 7K).Its lateral margin is marked by deep natural notches that indicate occlusal grooves for the maxillary teeth. The mandible was more than twice wider than high, and the symphysis was probably very long. Its morphology suggests than it is probably from the same species as the maxillary fragments. FSAC Bouj-407 is a fragment of the posterior portion of the left maxilla and with two complete teeth. Teeth are preserved. They are moderately long, circular in cross section (posteriormost being slightly compressed lateromedially) and their surfaces are smooth and bear anterior and posterior carinae. COMPARISON AND DISCUSSION All recovered vertebrae are procoelous, suggesting eusuchian affinity. The material belongs to at least two species, and both are longirostrine forms. FSAC Bouj-355 has a different morphology from other mandibular and maxillary fragments (Fig. 7I). It has large alveoli and its symphysis is slightly wider than high. The second form, represented by maxillae and portions of left and right dentaries (Fig. 7 K-P), has its symphysis much wider than high with smaller alveoli than the first species.Two groups of longirostrine eusuchians have been described from the late Eocene: the gavialoids and the tomistomines (Brochu 2003). FSAC Bouj-355 is too fragmentary to be attributed with certainty to any group, but its symphysis slightly wider than high with a straight lateral margin, the short distance between the left and right alveoli and their offset margins clearly differ from what is found in gavialoids and tomistomines. Even if no amphycoelous vertebra has been found, it cannot be excluded that this mandible pertains to a dyrosaurid, a group of non-eusuchian crocodyliformes, in which previously cited characters are present (Jouve et al. 2019). These neosuchians survived to the Lutetian in Africa and Burma (Buffetaut 1978). Awaiting more diagnostic material, FSAC Bouj-355 is thus considered as Crocodyliformes indet. The second mandible has laterally opened alveoli and its alveolar margin is not leveled with the palate, characters that are found in gavialoids (Hua & Jouve 2004; Jouve et al. 2006, 2014). Gavialoids are particularly scarce in the Eocene and Oligocene of the Peri-Tethys deposits, and only three gavialoids are known: “ Gavialis ” dixoni Owen, 1849, from the early-middle Eocene of England and now considered as a nomen dubium (Brochu 2007), unidentified Bartonian gavialoid remains from Dur At-Talah (Southern Libya) (Llinas Agrasar 2004), and Eogavialis africanum (Andrews, 1901) from the Priabonian and Rupelian of Fayum Egypt, (Müller 1927). The remains from Gueran strongly resemble Eogavialis africanum, but they are too poorly preserved for an in-depth comparison. Therefore, the Gueran gavialoid is here considered as Gavialoidea indet. (Jouve et al. 2019)., Published as part of Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, pp. 121-150 in Geodiversitas 43 (5) on page 138, DOI: 10.5252/geodiversitas2021v43a5, http://zenodo.org/record/4605963, {"references":["BROCHU C. A. 2003. - Phylogenetic approaches toward crocodylian history. Annual Review of Earth and Planetary Sciences 31: 357 - 397. https: // doi. org / 10.1146 / annurev. earth. 31.100901.141308","JOUVE S., KHALLOUFI B. & ZOUHRI S. 2019. - New Longirostrine crocodyliforms from the Bartonian of Morocco and Paleogene climatic and sea-level oscillations in peri-Tethys area. Journal of Vertebrate Paleontology 39 (3): e 1617723 https: // doi. org / 10. 1080 / 02724634.2019.1617723","BUFFETAUT E. 1978. - A dyrosaurid (Crocodylia, Mesosuchia) from the Upper Eocene of Burma. Neues Jahrbuch Fur Geologie Und Palaontologie, Monatshefte 5: 273 - 281.","HUA S. & JOUVE S. 2004. - A primitive marine gavialoid from the Paleocene of Morocco. Journal of Vertebrate Paleontology 24: 344 - 353. https: // doi. org / 10.1671 / 1104","JOUVE S., IAROCHENE M., BOUYA B. & AMAGHZAZ M. 2006. - New material of Argochampsa krebsi (Eusuchia: Gavialoidea) and phylogenetic implications. Geobios 39 (6): 817 - 832. https: // doi. org / 10.1016 / j. geobios. 2005.07.003","JOUVE S., BOUYA B., AMAGHZAZ M. & MESLOUH S. 2014. - Maroccosuchus zennaroi (Crocodylia: Tomistominae) from the Eocene of Morocco: phylogenetic and palaeobiogeographical implications of the basalmost tomistomine. Journal of Systematic Palaeontology 12: 1 - 25. https: // doi. org / 10.1080 / 1477201 9.2014. 913078","BROCHU C. A. 2007. - Systematics and taxonomy of Eocene tomistomine crocodylians from Britain and Northern Europe. Palaeontology 50: 917 - 928. https: // doi. org / 10.1111 / j. 1475 - 4983.2007.00679. x","LLINAS AGRASAR E. L. 2004. - Crocodilian remains from the upper Eocene of Dor-El-Talha, Libya. Annales de Paleontologie 90: 209 - 222. https: // doi. org / 10.1016 / j. annpal. 2004.05.001","ANDREWS C. W. 1901. - Preliminary note on some recently discovered extinct vertebrates from Egypt. Geological Magazine 4: 436 - 444. https: // doi. org / 10.1017 / S 0016756800179750","MULLER L. 1927. - Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wusten Agyptens, V. Tertiare Wirbeltiere, 1. Beitrage zur Kenntnis der Krokodilier des agyptischen Tertiars. Abhandlungen der Bayerischen Akademie der Wissenschaften, mathematisch-naturwissenschaftliche Abteilung 31 (2): 1 - 96."]}

Pristis cf. lathami Galeotti, 1837 EXAMINED MATERIAL. — 12 broken rostral teeth. DESCRIPTION AND REMARKS The second sawfish (unfigured here) is a common worldwide sawfish recovered from many Tethyan middle-late Eocene deposits (Cappetta 2012)., Published as part of Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, pp. 121-150 in Geodiversitas 43 (5) on page 129, DOI: 10.5252/geodiversitas2021v43a5, http://zenodo.org/record/4605963, {"references":["CAPPETTA H. 2012. - Chondrichthyes II Mesozoic and Cenozoic Elasmobranchii: Teeth, Handbook of Paleoichthyology. Verlag Dr. Friedrich Pfeil, Stuttgart-New York. https: // doi. org / 10.1080 / 02 724634.1988. 10011678"]}

Gen. et sp. indet. EXAMINED MATERIAL. — FSAC-Bouj-372 (Fig. 5G), proximal fragment of a right pectoral spine. DESCRIPTION Only the left part of the proximal portion of the spine is preserved. The cleithral process is short with a thick and smooth external surface. The ornamentation of the base of the shaft is formed by ridges and thin tubercles. REMARKS The spine is too fragmentary to be attributed to a siluriform family, but the ornamentation pattern of the spine body is reminiscent of ariid pectoral spines.

Abdounia sp. MATERIAL A dozen isolated teeth, figured material includes FSAC Bouj-344. DESCRIPTION AND REMARKS Some rare medium-sized shark teeth (Fig. 4E, F) with low or incipient cusplets correspond to a large unnamed Abdounia species previously observed in the middle to late Eocene of Egypt (included in C. frequens in Case & Cappetta 1990: pl.7, fig. 147; Underwood et al. 2011: fig. 2F). Occasional in MI, this unnamed species becomes common in GE A-C and younger series (Underwood et al. 2011)., Published as part of Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, pp. 121-150 in Geodiversitas 43 (5) on page 129, DOI: 10.5252/geodiversitas2021v43a5, http://zenodo.org/record/4605963, {"references":["CASE G. R. & CAPPETTA H. 1990. - The Eocene Selachians Fauna from the Fayum Depression in Egypt. Palaeontographica Abteilung A 212: 1 - 30.","UNDERWOOD C. J., WARD D. J., KING C., ANTAR S. M., ZAL- MOUT I. S. & GINGERICH P. D. 2011. - Shark and ray faunas in the middle and late Eocene of the Fayum area, Egypt. Proceedings of the Geologists' Association 122: 47 - 66. https: // doi. org / 10.1016 / j. pgeola. 20"]}

Crocodyliformes indet. EXAMINED MATERIAL. — FSAC BOUJ-355, fragment of a right dentary; 406, posterior fragment of left mandibular ramus. DESCRIPTION FSAC BOUJ-355 is a fragment of a left dentary (Fig. 7I). The best preserved alveolus is large and seems slightly compressed lateromedially. The lateral and medial margins of the dentary are parallel, suggesting that it was included in a long mandibular symphysis, and that the specimen was a longirostrine form. The alveolar margins are slightly offset, and the symphysis was slightly wider than high. FSAC Bouj-406 is a posterior portion of a left dentary (Fig. 7J), and preserves four circular alveoli, probably the posteriormost. The portion is low in lateral view. It is not possible to determine if it can be related to the one of the species described above and below., Published as part of Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, pp. 121-150 in Geodiversitas 43 (5) on pages 137-138, DOI: 10.5252/geodiversitas2021v43a5, http://zenodo.org/record/4605963

Tethylamna cf. twiggsensis (Case, 1981) EXAMINED MATERIAL. — 50 isolated teeth, figured material includes FSAC Bouj-331, 332, 333, 334, 335 and 336. DESCRIPTION Numerous teeth are attributed to odontaspidid Tethylamna cf. twiggsensis. This species is easily recognizable by a pair of double flat cusplets on anterior (Fig. 3A, F) and lateral teeth (Fig. 3 C-E). REMARKS The range of this species is currently restricted to the latest Lutetian-late Priabonian and its geographic distribution extends to paleotropical seas between tropical eastern Pacific, Caribbean and oriental Neotethys (Casier 1971; Case 1981; Case & Borodin 2000; Case & Cappetta 1990; Ward & Wiest 1990; Adnet et al. 2007; Underwood et al. 2011; Cappetta & Case 2016). Originally described from the late Eocene of Georgia, United States (Case 1981), distinction between the middle and the late Eocene representatives are sometimes controversial. The Bartonian teeth have lateral cusplets less pronounced compared to those from Priabonian (Underwood et al. 2011) explaining why they are often referred to confer twigssensis. These Bartonian samples could corresponds to intergradual change from the possible ancestor T. dunni of Cappetta & Case (2016) recovered from the Lutetian of Alabama, USA toward those of Priabonian, including type of species (Case 1981)., Published as part of Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, pp. 121-150 in Geodiversitas 43 (5) on page 127, DOI: 10.5252/geodiversitas2021v43a5, http://zenodo.org/record/4605963, {"references":["CASE G. R. 1981. - Late Eocene selachians from South-central Georgia. Palaeontographica Abteilung A 176 (1 - 3): 52 - 79.","CASIER E. 1971. - Sur un materiel ichthyologique des ' Midra (and Saila) shales' du Qatar (Golfe Persique). Bulletin de l'Institut royal des Sciences naturelles de Belgique 47 (2): 1 - 9","CASE G. R. & BORODIN P. D. 2000. - Late Eocene selachian from the Irwinton Sand Member of the Barnwell Formation (Jacksonian), WKA mines, Gordon, Wilkinson County, Georgy. Munchner Geowissenschaftliche Abhandlungen 39: 5 - 16.","CASE G. R. & CAPPETTA H. 1990. - The Eocene Selachians Fauna from the Fayum Depression in Egypt. Palaeontographica Abteilung A 212: 1 - 30.","WARD J. W. & WIEST R. L. 1990. - A checklist of Palaeocene and Eocene sharks and rays (Chondrichthyes) from the Pamunkey Group, Maryland and Virginia, USA. Tertiary Research 12: 81 - 88.","ADNET S., ANTOINE P. O., HASSAN BAQRIS. R., CROCHET J. Y., MARIVAUX L., WELCOMME J. L. & METAIS G. 2007. - On the first modern and tropical Selachian association (Chondrichthyes) from the late Eocene-early Oligocene of Baluchistan, Pakistan. Dating interests, paleoenvironment and paleobiogeography. Journal of Asian Earth Sciences 30: 303 - 323. https: // doi. org / 10.1017 / S 0016756810000348","UNDERWOOD C. J., WARD D. J., KING C., ANTAR S. M., ZAL- MOUT I. S. & GINGERICH P. D. 2011. - Shark and ray faunas in the middle and late Eocene of the Fayum area, Egypt. Proceedings of the Geologists' Association 122: 47 - 66. https: // doi. org / 10.1016 / j. pgeola. 20","CAPPETTA H. & CASE G. R. 2016. - A Selachian Fauna from the middle Eocene (Lutetian, Lisbon Formation) of Andalusia, Covington County, Alabama, USA. Palaeontographica Abteilung A 307 (1 - 6): 43 - 103."]}

Barytherium sp. EXAMINED MATERIAL. — FSAC Bouj-380a, 380b, and 380c, dental fragments. REMARKS Zouhri et al. (2018) mentioned fragmentary dental remains of undetermined proboscideans in Gueran fauna (Laazri locality). Combining light and SEM microscopy, we here studied these dental fragments (FSAC Bouj-380a, 380b, and 380c) to describe the enamel microstructure and propose a systematic assignment. Following the protocol detailed in Tabuce et al. (2017), we realized and analyzed a vertical section for the three specimens, which reveal a similar enamel microstructure. From the enamel dentine junction (EDJ) to the outer enamel surface (OES), the specimens present a one-layered Schmelzmuster [the three-dimensional arrangement of the different enamel types in one tooth (Koenigswald & Sander, 1997)] formed by thick bundles of prisms that decussate in all directions; this enamel type is the so-called 3D enamel, a structure known only in proboscideans. In some zones of the outer part of the enamel layer, the vertical component of the decussation is attenuated, evoking Hunter-Schreger bands (HSB). 3D enamel is documented in several Paleogene proboscidean species: Numidotherium koholense Jaeger, 1986 (sampled from the early Eocene of El Kohol, Algeria, Bertrand 1988 and Tabuce et al. 2007), Numidotherium sp. (sampled from the late Eocene of Ad-Dakhla, Morocco, Adnet et al. 2010), Arcanotherium savagei (Court, 1995) (Court 1995; sampled from the?late Eocene of Dur At-Talah Escarpment, Libya, Tabuce et al. 2007), Barytherium grave Andrews, 1901 (sampled from Dur At-Talah Escarpment, Libya, Bertrand 1988), and Omanitherium dhofarensis Seiffert, Nasir, Al-Harthy, Groenke, Kraatz, Stevens & Al-Sayigh, 2012 (sampled from the earliest Oligocene of Thaytiniti 2, Oman; Tabuce unpublished data). Among these five species, only Arcanotherium savagei differs from the proboscidean from Laazri by a three-layered Schmelzmuster with 3D enamel only limited to the inner zone, overlain by HSB then radial enamel in the outer zone. Such a complex Schmelzmuster also characterizes all Neogene elephantoids (mammutids, gomphotheres, stegodonts, and elephants) and in a lesser degree Palaeomastodon beadnelli Andrews, 1901 which developed slightly irregular HSB in the inner zone, evoking 3D enamel (Koenigswald et al. 1993). As a result, similar to the proboscidean from Laazri, only Numidotherium koholense, Numidotherium sp. from Ad-Dakhla, Barytherium grave, and Omanitherium dhofarensis present a one-layered Schmelzmuster formed by 3D enamel. In addition, the HSB-like structures that occur in places in the outer part of the enamel the proboscidean from Laazri were only mentioned in Numidotherium koholense and Numidotherium sp. from Ad-Dakhla (Tabuce et al. 2007; Adnet et al. 2010). However, the supposed lack of such HSB-like structures in Barytherium grave must be taken with caution due to the unique published macroscopic analysis (no SEM data available) for this species (Bertrand 1988). Interestingly, in his unpublished Ph.D. thesis, Bertrand (1989: pl. 18D) figured a view of the outer part of the enamel of Barytherium grave in which HSB-like structures are clearly visible. To conclude, Barytherium and Numidotherium present the same enamel microstructure as the proboscidean from Laazri. To complete the observations, we measured the molar enamel thickness in Barytherium Andrews, 1901, Numidotherium Jaeger, 1986, and Omanitherium Seiffert, Nasir, Al-Harthy, Groenke, Kraatz, Stevens, Al-Sayigh, 2012. Comparison with the proboscidean remains from Laazri reveals interesting results. The great enamel thickness of FSAC Bouj-380a (± 3.4 to 4.6mm), Bouj-380b (± 2.6 to 2.9 mm) and Bouj- 380c (± 3.1 to 4.2 mm) approaches the rare available data for Barytherium grave (± 2 mm, ± 3.1 mm, ± 2.5 mm; plate 18A-C in Bertrand 1989). Conversely, molars of Numidotherium sp. from Ad-Dakhla and Omanitherium dhofarensis have thinner enamel thickness (± 1 mm and ± 0.7 mm, respectively). Molars of Numidotherium koholense have also thinner enamel thickness (± 2.4 to 3.1 mm for the M3, the largest molar). To conclude, enamel microstructure and thickness strongly favor an assignment to Barytherium for the proboscidean from Laazri. The presence of Barytherium in the Aridal Formationat of Gueran, if confirmed, would indicate that this genus occurred as early as the Bartonian. So far, this genus was only known by its type species, Barytherium grave, originally described from the late Eocene (Priabonian) of the Fayum depression and then from the Dur At-Talah Escarpment, a locality which is still poorly constrained in age between Bartonian to Priabonian (Tabuce et al. 2012; Sallam & Seiffert 2016; Longrich 2017). Interestingly also, Gingerich & Cappetta (2014) mentioned a possible Barytherium -sized proboscidean from the early middle Eocene (Lutetian) of Togo., Published as part of Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, pp. 121-150 in Geodiversitas 43 (5) on pages 141-143, DOI: 10.5252/geodiversitas2021v43a5, http://zenodo.org/record/4605963, {"references":["ZOUHRI S., GINGERICH P. D., ADNET S., BOURDON B., JOUVE S., KHALLOUFI B., AMANE A., ELBOUDALI N. S., RAGE J. - C., LAP- PARENT DE BROIN F. DE, KAOUKAYA A. & SEBTI S. 2018. - Middle Eocene vertebrates from the sabkha of Gueran, Atlantic coastal basin, Saharan Morocco, and their peri-African correlations, Comptes Rendus Geosciences 350: 310 - 318. https: // doi. org / 10.1016 / j. crte. 2018.06.006","TABUCE R., SEIFFERT E. R., GHEERBRANT E., ALLOING- SEGUIER L. & KOENIGSWALD W. V. 2017. - Tooth enamel microstructure of living and extinct hyracoids reveals unique enamel types among mammals. Journal of Mammalian Evolution 24 (1): 91 - 110. https: // doi. org / 10.1007 / s 10914 - 015 - 9317 - 6","KOENIGSWALD W. V. & SANDER P. M. 1997. - Schmelzmuster differentiation in leading and trailing edges, a specific biomechanical adaptation in rodents, in KOENIGSWALD W. V. & SANDER P. M. (eds), Tooth Enamel Microstructure. Balkema, Rotterdam: 259 - 266.","BERTRAND P. 1988. - Evolution de la structure de l'email chez les Proboscidea primitifs: Aspects phylogenetique et fonctionnel, in RUSSELL D. E., SANTORO J. P. & SIGOGNEAU- RUSSELL D. (eds), Teeth Revisited: Proceedings of the 7 th International Symposium on Dental Morphology. Museum national d'Histoire naturelle, Paris: 109 - 124 (Memoires du Museum national d'Histoire naturelle, Ser. C - Sciences de la Terre; 53).","TABUCE R., DELMER C. & GHEERBRANT E. 2007. - Evolution of the tooth enamel microstructure in the earliest proboscideans (Mammalia). Zoological Journal of the Linnean Society 149 (4): 611 - 628. https: // doi. org / 10.1111 / j. 1096 - 3642.2007.00272. x","ADNET S., CAPPETTA H. & TABUCE R. 2010. - A middle-late Eocene vertebrate fauna (marine fish and mammals) from southwestern Morocco preliminary report: age and palaeobiogeographical implications. Geological Magazine 147: 860 - 870. https: // doi. org / 10.1017 / s 0016756810000348","COURT N. 1995. - A new species of Numidotherium (Mammalia: Proboscidea) from the Eocene of Libya and the early phylogeny of the Proboscidea. Journal of Vertebrate Paleontology 15: 650 - 671. https: // doi. org / 10.1080 / 02724634.1995.10011254","ANDREWS C. W. 1901. - Preliminary note on some recently discovered extinct vertebrates from Egypt. Geological Magazine 4: 436 - 444. https: // doi. org / 10.1017 / S 0016756800179750","KOENIGSWALD W. V., MARTIN T. & PFRETZSCHNER H. U. 1993. - Phylogenetic interpretation of enamel structures in mammalian teeth: possibilities and problems, in SZALAY F. S., NOVACEK M. J., MCKENNA M. C. (eds), Mammal Phylogeny Placentals. Springer-Verlag, New York: 303 - 314.","BERTRAND P. 1989. - Structure de l'email dentaire et phylogenie chez les tethytheres. Unpublished PhD thesis, Universite Paris 6, 524 p.","TABUCE R., JAEGER J. - J., MARIVAUX L., SALEM M., BILAL A. A., BENAMMI M., CHAIMANEE Y., COSTER P., MARANDAT B., VAL- ENTIN X. & BRUNET M. 2012. - New stem elephant-shrews (Mammalia, Macroscelidea) from the Eocene of Dur at-Talah, Libya. Palaeontology 55: 945 - 955. https: // doi. org / 10.1111 / j. 1475 - 4983.2012.01163. x","SALLAM H. M. & SEIFFERT E. R. 2016. - New phiomorph rodents from the latest Eocene of Egypt, and the impact of Bayesian \" clock \" based phylogenetic methods on estimates of basal hystricognath relationships and biochronology. PeerJ 4: e 1717. https: // doi. org / 10.7717 / peerj. 1717","LONGRICH N. R. 2017. - A stem lepidosireniform lungfish (Sarcopterygia: Dipnoi) from the upper Eocene of Libya, North Africa and implications for Cenozoic lungfish evolution. Gondwana Research 42: 140 - 150. https: // doi. org / 10.1016 / j. gr. 2016.09.007","GINGERICH P. D. & CAPPETTA H. 2014. - A new archaeocete and other marine mammals (Cetacea and Sirenia) from lower middle Eocene phosphate deposits of Togo. Journal of Paleontology 88, 109 e 129. https: // doi. org / 10.1666 / 13 - 040"]}

Subclass ELASMOBRANCHII Bonaparte, 1838 REMARKS Fossils were only collected by surface picking around the archaeocete whale carcasses (protocetids and basilosaurids, see Gingerich & Zouhri 2015), and thus the majority of small to medium-sized sharks and rays remain currently unknown.Thousands of specimens were collected from several localities around Gueran Depression (Locality I, Garouaz, Iddir and Laazri, see Gingerich & Zouhri 2015: fig.2).The majority of the fossil material consists of isolated teeth, rare barbs of myliobatid rays, and indeterminate vertebrae representing at least 12 species of sharks and rays. The chondrichthyan fauna currently consists of 12 species of elasmobranchs belonging to orders: Lamniformes, Carcharhiniformes and Rhinopristiformes. Most unnamed species are in course of study, awaiting careful comparisons with those from subcontemporaneous deposits (e.g. MI, GE) in Waddi el-Rayyan and Wadi al Hitan (Whale Valley) in Egypt., Published as part of Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, pp. 121-150 in Geodiversitas 43 (5) on pages 123-125, DOI: 10.5252/geodiversitas2021v43a5, http://zenodo.org/record/4605963, {"references":["GINGERICH P. D. & ZOUHRI S. 2015. - New fauna of archaeocete whales (Mammalia, Cetacea) from the Bartonian middle Eocene of southern Morocco. Journal of African Earth Sciences 111: 273 - 286. https: // doi. org / 10.1016 / j. jafrearsci. 2015.08.006","ZOUHRI S., GINGERICH P. D., ADNET S., BOURDON B., JOUVE S., KHALLOUFI B., AMANE A., ELBOUDALI N. S., RAGE J. - C., LAP- PARENT DE BROIN F. DE, KAOUKAYA A. & SEBTI S. 2018. - Middle Eocene vertebrates from the sabkha of Gueran, Atlantic coastal basin, Saharan Morocco, and their peri-African correlations, Comptes Rendus Geosciences 350: 310 - 318. https: // doi. org / 10.1016 / j. crte. 2018.06.006","ZOUHRI S., GINGERICH P. D., ELBOUDALI N., SEBTI S., NOUBHANI A., RAHALI M. & MESLOUH S. 2014. - New marine mammal faunas (Cetacea and Sirenia) and sea level change in the Samlat Formation, upper Eocene, near Ad-Dakhla in southwestern Morocco. Comptes Rendus Palevol 13: 599 - 610. https: // doi. org / 10.1016 / j. crpv. 2014.04.002","GINGERICH P. D. & ZOUHRI S. 2017. - Biostratigraphy of marine mammals (Cetacea and Sirenia) from coastal sections of the Eocene Samlat Formation south of Ad-Dakhla, Moroccan Sahara. Journal of Vertebrate Paleontology, Program and Abstracts: 119. https: // doi. org / 10.1017 / S 0016756810000348","HAUTIER L., SARR R., LIHOREAU F., TABUCE R. & HAMEH P. M., 2014. - First record of the family Protocetidae in the Lutetian of Senegal (West Africa). Palaeovertebrata 38 (2): 1 - 7. https: // doi. org / 10.18563 / pv. 38.2. e 2","ELOUARD P. 1981. - Decouverte d'un archeocete dans les environs de Kaolack. Notes Africaines 109: 8 - 10.","GINGERICH P. D. & CAPPETTA H. 2014. - A new archaeocete and other marine mammals (Cetacea and Sirenia) from lower middle Eocene phosphate deposits of Togo. Journal of Paleontology 88, 109 e 129. https: // doi. org / 10.1666 / 13 - 040","ANDREWS C. W. 1920. - A description of new species of zeuglodont and of leathery turtle from the Eocene of Southern Nigeria. Proceedings of the Zoological Society of London 89: 309 - 319. https: // doi. org / 10.1111 / j. 1096 - 3642.1919. tb 02124","HALSTEAD L. B. & MIDDLETON J. A. 1974. - New material of the archaeocete whale, Pappocetus lugardi Andrews, from the middle Eocene of Nigeria. Journal of Mining and Geology 8: 81 - 5.","HALSTEAD L. B. & MIDDLETON J. A. 1976. - Fossil vertebrates of Nigeria. Part II, 3.4, Archaeocete whale Pappocetus lugardi Andrews, 1920. Nigerian Field 41: 131 - 133.","ABOUESSA A., PELLETIER J., DURINGER P., SCHUSTER M., SCHAEF- FER P., METAIS E., BENAMMI M., SALEM M., HLAL O., BRU- NET M., JAEGER J. J. & RUBINO J. L. 2012. - New insight into the sedimentology and stratigraphy of the Dur At Talah tidal-fluvial transition sequence (Eocene-Oligocene, Sirt Basin, Libya). Journal of African Earth Sciences 65: 72 - 90. https: // doi. org / 10.1016 / j. jafrearsci. 2012.02.004","HOLLARD H., CHOUBERT G., BRONNER G., MARCHAND J. & SOUGY J., 1985. - Carte geologique du Maroc, echelle 1: 1 000 000. Service Carte geologique Maroc 260 (2 sheets). Editions of the Geological Survey of Morocco."]}

Superorder BATOIDEA Compagno, 1973 REMARKS Besides the undeterminable broken caudal sting of Myliobatiformes (unfigured), only rostral teeth of two fossil sawfishes (Rhinopristiformes) were identified., Published as part of Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, pp. 121-150 in Geodiversitas 43 (5) on page 129, DOI: 10.5252/geodiversitas2021v43a5, http://zenodo.org/record/4605963

Gen. et sp. indet. EXAMINED MATERIAL. — FSAC-Bouj-358 (Fig. 5F), fragment of toothed bone. DESCRIPTION The bone supports two subcomplete and four broken teeth, with very reduced interspace. Teeth are labiolingually compressed, with sharp and convex edges and acute apex. The base of the external surface of the tooth shows a small median depression. The pulpar cavity is full. The lingual surface of the bone is smooth. The labial side is concave but less preserved. REMARKS The tooth morphology and its position in the bone are very similar to scombroid remains found in the Priabonian beds of Ad-Dakhla (Zouhri et al. 2017). Comparable teeth are retrieved in the extant Acanthocybium Gill, 1862, and in the fossils Aramichthys Signeux, 1959 from the Eocene of Syria and Scomberodon, Neocybium and Palaeocybium Monsch, 2004 from the Eocene of Belgium and England (Leriche 1905, 1910; Signeux 1959; Monsch 2004). Comparable isolated teeth from the Ypresian Phosphate basins of Morocco were referred to Scomberodon dumonti by Arambourg (1952, Cybium dumonti in the text)., Published as part of Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, pp. 121-150 in Geodiversitas 43 (5) on page 132, DOI: 10.5252/geodiversitas2021v43a5, http://zenodo.org/record/4605963, {"references":["ZOUHRI S., KHALLOUFI B., BOURDON E., LAPPARENT DE BROIN F. DE, RAGE J. - C., M'HAIDRAT L., GINGERICH P. D. & ELBOU- DALI N. 2017. - Marine vertebrate fauna from the late Eocene Samlat Formation of Ad-Dakhla, southwestern Morocco. Geological Magazine 155 (7): 1596 - 1620. https: // doi. org / 10.1017 / S 0016756817000759","SIGNEUX J. 1959. - Poissons de l'Eocene de la cimenterie de Doumar (Syrie). Contributions a la geologie de la peninsule arabique. Notes et memoires sur le Moyen-Orient 7: 241 - 248.","MONSCH K. A. 2004. - Revision of the scombroid fishes from the Cenozoic of England. Transactions of the Royal Society of Edinburgh Earth Sciences 95: 445 - 489. https: // doi. org / 10.1017 / S 0263593300001164","LERICHE M. 1905. - Les poissons tertiaires de la Belgique II. Les poissons eocenes. Memoires du Musee royal d'Histoire naturelle de Belgique 11 (3): 49 - 228.","LERICHE M. 1910. - Les Poissons oligocenes de la Belgique. Memoires du Musee royal d'Histoire naturelle de Belgique 5: 231 - 363.","ARAMBOURG C. 1952. - Les Vertebres fossiles des gisements de phosphates (Maroc, Algerie, Tunisie). Notes et Memoires du Service Geologique du Maroc 92: 1 - 372."]}

Galeocerdo eaglesomei (White, 1955) EXAMINED MATERIAL. — Thirty isolated teeth, figured material includes FSAC Bouj-337, 338 and 339. DESCRIPTION The African Galeocerdo eaglesomei is unfrequent compared to the contemporaneous and worldwide species G. latidens Agassiz, 1843. However, G. eaglesomei differs from it by teeth with a higher crown, a longer and abrupt distal heel without distinct notch with main cusp, with more numerous and larger denticles and with a deeper basal medial concavity of the root deeper. Our teeth (Fig. 3 G-I), as those from the Lower Priabonian of SA, southwestern Morocco (Adnet et al. 2010), are relatively larger and display a much higher crown compared to the Lutetian specimens, which makes it possible to provisionally assign these to G. eaglesomei, to which the youngest specimens from Southwestern Morocco are likely affiliated. REMARKS Relatively scarce teeth of Galeocerdo cf. eaglesomei are quite similar in shape to G. eaglesomei from the late Lutetian of Nigeria (Andrews 1920), the Lutetian-Bartonian of GA (Strougo et al. 2007), the middle to late Eocene of Madagascar (Samonds et al. 2019) and to those recovered in MI, Egypt, where it is one of the most conspicuous elements of the uppermost Lutetian-lowermost Bartonian assemblage (Underwood et al. 2011)., Published as part of Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, pp. 121-150 in Geodiversitas 43 (5) on page 127, DOI: 10.5252/geodiversitas2021v43a5, http://zenodo.org/record/4605963, {"references":["WHITE E. I. 1955. - Notes on African Tertiary sharks. Colonial Geology and Mineral Resources 5: 319 - 325.","ADNET S., CAPPETTA H. & TABUCE R. 2010. - A middle-late Eocene vertebrate fauna (marine fish and mammals) from southwestern Morocco preliminary report: age and palaeobiogeographical implications. Geological Magazine 147: 860 - 870. https: // doi. org / 10.1017 / s 0016756810000348","ANDREWS C. W. 1920. - A description of new species of zeuglodont and of leathery turtle from the Eocene of Southern Nigeria. Proceedings of the Zoological Society of London 89: 309 - 319. https: // doi. org / 10.1111 / j. 1096 - 3642.1919. tb 02124","STROUGO A., CAPPETTA H. & ELNAHAS S. 2007. - A remarkable Eocene ichthyofauna from the El Gedidia glauconitic sandstone, Bahariya oasis, Egypt, and its stratigraphic implications. MERC Ain Shams University, Earth Science Series 21: 81 - 98.","SAMONDS K. E., ANDRIANAVALONA T. H., WALLETT L. A., ZALMOUT I. S. & WARD D. J. 2019. - A middle-late Eocene neoselachian assemblage from nearshore marine deposits, Mahajanga Basin, northwestern Madagascar. PLoS ONE 14 (2): e 0211789. https: // doi. org / 10.1371 / journal. pone. 0211789","UNDERWOOD C. J., WARD D. J., KING C., ANTAR S. M., ZAL- MOUT I. S. & GINGERICH P. D. 2011. - Shark and ray faunas in the middle and late Eocene of the Fayum area, Egypt. Proceedings of the Geologists' Association 122: 47 - 66. https: // doi. org / 10.1016 / j. pgeola. 20"]}

Propristis schweinfurthi Dames, 1883 EXAMINED MATERIAL. — Five rostral denticles, figured material includes FSAC Bouj-348. DESCRIPTION AND REMARKS Propristis schweinfurthi (Fig. 4J) is a rare but widespread sawfish, and is easily distinguishable from all the other fossil or living Pristidae, Pristis cf. lathami included, by short and rounded rostral teeth without posterior barbs (Fig. 4J). This species is known in the middle to late Eocene of the Neotethysian realm from Caribbean (Case 1981; Case & Borodin 2000; Cappetta & Stringer 2002) to Egypt (Case & Cappetta 1990; Strougo et al. 2007; Underwood et al. 2011) and Atlantic coasts (e.g., White 1926; Dartevelle & Casier 1959; Cappetta & Traverse 1988)., Published as part of Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, pp. 121-150 in Geodiversitas 43 (5) on page 129, DOI: 10.5252/geodiversitas2021v43a5, http://zenodo.org/record/4605963, {"references":["CASE G. R. 1981. - Late Eocene selachians from South-central Georgia. Palaeontographica Abteilung A 176 (1 - 3): 52 - 79.","CASE G. R. & BORODIN P. D. 2000. - Late Eocene selachian from the Irwinton Sand Member of the Barnwell Formation (Jacksonian), WKA mines, Gordon, Wilkinson County, Georgy. Munchner Geowissenschaftliche Abhandlungen 39: 5 - 16.","CAPPETTA H. & STRINGER G. 2002. - A new batoid genus (Neoselachii: Myliobatiformes) from the Yazoo (late Eocene) of Louisiana, USA. Tertiary Research 21: 51 - 56.","CASE G. R. & CAPPETTA H. 1990. - The Eocene Selachians Fauna from the Fayum Depression in Egypt. Palaeontographica Abteilung A 212: 1 - 30.","STROUGO A., CAPPETTA H. & ELNAHAS S. 2007. - A remarkable Eocene ichthyofauna from the El Gedidia glauconitic sandstone, Bahariya oasis, Egypt, and its stratigraphic implications. MERC Ain Shams University, Earth Science Series 21: 81 - 98.","UNDERWOOD C. J., WARD D. J., KING C., ANTAR S. M., ZAL- MOUT I. S. & GINGERICH P. D. 2011. - Shark and ray faunas in the middle and late Eocene of the Fayum area, Egypt. Proceedings of the Geologists' Association 122: 47 - 66. https: // doi. org / 10.1016 / j. pgeola. 20","WHITE E. I. 1926. - Eocene fishes from Nigeria. Bulletin of the Nigerian Geological Survey 10: 1 - 82.","DARTEVELLE E. & CASIER E. 1959. - Les poissons fossiles du Bas- Congo et des regions voisines. Annales du Musee du Congo belge, Serie A 3 (2, 3): 257 - 568.","CAPPETTA H. & TRAVERSE M. 1988. - Une riche faune de selaciens dans le bassin a phosphate de Kpogame-Hahotoe (Eocene moyen du Togo): Note preliminaire et precisions sur la structure et l'age du gisement. Geobios 21 (3): 359 - 365. https: // doi. org / 10.1016 / S 0016 - 6995 (88) 80058 - 5"]}

Cylindracanthus sp. EXAMINED MATERIAL. — FSAC Bouj-141, 356 (Fig. 5A), 357, 358, 359, 360, 361, 362, fragments of rostra. DESCRIPTION The rostra are incomplete and cylindrical. The external surface is crossed by sub-parallel longitudinal ridges, sometimes convergent. The cross-section is circular, with a notched circumference owing to the longitudinal ridges. A unique median canal lies in the center of the cross-section. REMARKS These remains are very common in Boujdour. The notched circular cross-section showing a canal and the fluted external surface correspond to the rostrum of Cylindracanthus. This genus is only known by these peculiar rostra, sometimes showing two rows of minute teeth. They are retrieved in various localities from the Cretaceous to Eocene (and possibly Miocene and Pliocene, see Schultz 1987) in Africa, Asia, Europe, and North and South America (Schultz 1987; Gallo et al. 2012; Averianov 2014; Grandstaff et al. 2017). Putative isolated vertebrae have also been reported but without anatomical connection with the rostrum, (Leriche 1910; White 1926). The phylogenetic relationships of Cylindracanthus are still discussed and affinities with chimaeroids, billfishes, dercetids, acipenseriforms and beloniforms have been proposed (Schultz 1987; Weems 1999; Parris et al. 2001; Monsch 2004; Friedman 2012; Bonde & Leal 2017) while Grandstaff et al. (2017) excluded structural resemblances with the billfish Makaira Lacepède, 1802 and the paddlefish Polyodon Lacepède, 1797 by analysing thin sections. In North Africa, Cylindracanthus occurs in the Ypresian beds of the Phosphate basins of Morocco and Algeria (Arambourg 1952; Khalloufi et al. 2017), and in the Priabonian beds of Ad-Dakhla (Adnet et al. 2010)., Published as part of Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, pp. 121-150 in Geodiversitas 43 (5) on page 131, DOI: 10.5252/geodiversitas2021v43a5, http://zenodo.org/record/4605963, {"references":["SCHULTZ O. 1987. - Taxonomische Neugruppierung der Uberfamilie Xiphioidea (Pisces, Osteichthyes). Annalen des Naturhistorischen Museums in Wien. Serie A fur Mineralogie und Petrographie, Geolo - gie und Palaontologie, Anthropologie und Prahistorie 89: 95 - 202.","GALLO V., FIGUEIREDO F. J. DE & CARVALHO M. S. S. DE 2012. - Sintese da paleoictiofauna marinha das bacias costeiras do Brasil e comentarios sobre a paleoictiofauna cronocorrelata da margem oeste da Africa, in GALLO V., SILVA H. M. A., BRITO P. M. M., FIGUEIREDO F. J. DE (eds), Paleontologia de Vertebrados: Relacao entre America do Sul e Africa. Interciencia, Rio de Janeiro: 175 - 206.","AVERIANOV A. 2014. - Review of taxonomy, geographic distribution, and paleoenvironments of Azhdarchidae (Pterosauria). ZooKeys 432 (7914): 1 - 107. https: // doi. org / 10.3897 / zookeys. 432.7913","GRANDSTAFF B. S., PELLEGRINI R. A., PARRIS D. C. & CLEMENTS D. 2017. - Thin section microscopy of the fossil fish Cylindracanthus. Proceedings of the South Dakota Academy of Science 96: 130 - 143.","LERICHE M. 1910. - Les Poissons oligocenes de la Belgique. Memoires du Musee royal d'Histoire naturelle de Belgique 5: 231 - 363.","WHITE E. I. 1926. - Eocene fishes from Nigeria. Bulletin of the Nigerian Geological Survey 10: 1 - 82.","WEEMS R. E. 1999. - Part 4. Actinopterygian fishes from the Fisher / Sullivan site, in WEEMS R. E. & GRIMSLEY G. J. (eds), Early Eocene Vertebrates and Plants from the Fisher / Sullivan Site (Nanjemoy Formation) Stafford County, Virginia. Pub. 152. Virginia Division of Mineral Resources, Charlottesville: 53 - 99.","PARRIS D. C., GRANDSTAFF B. S. & BELL G. L. J. 2001. - Reassessment of the affinities of the extinct genus Cylindracanthus (Osteichthyes). Proceedings of the South Dakota Academy of Science 80: 161 - 172.","MONSCH K. A. 2004. - Revision of the scombroid fishes from the Cenozoic of England. Transactions of the Royal Society of Edinburgh Earth Sciences 95: 445 - 489. https: // doi. org / 10.1017 / S 0263593300001164","FRIEDMAN M. 2012. - Ray-finned fishes (Osteichthyes, Actinopterygii) from the type Maastrichtian, the Netherlands and Belgium, in JAGT J. W. M., DONOVAN S. K., JAGT- YAZYKOVA E. A. (eds), Fossils of the type Maastrichtian (Part 1). Scripta Geologica (Special Issue) 8: 113 - 142.","BONDE N. & LEAL M. E. C. 2017. - Danian teleosteans of the North Atlantic Region compared with the Maastrichtian. Research & Knowledge 3 (2): 50 - 54. https: // doi. org / 10.14456 / randk. 2017.26","ARAMBOURG C. 1952. - Les Vertebres fossiles des gisements de phosphates (Maroc, Algerie, Tunisie). Notes et Memoires du Service Geologique du Maroc 92: 1 - 372.","KHALLOUFI B., BRITO P. M. M, CAVIN L. & DUTHEIL D. B. 2017. - Revue des ichthyofaunes mesozoiques et cenozoiques marocaines, in ZOUHRI S. (ed.), Paleontologie des vertebres du Maroc: etat des connaissances. Memoires de la Societe geologique de France, nouvelle serie, Paris 180: 167 - 248.","ADNET S., CAPPETTA H. & TABUCE R. 2010. - A middle-late Eocene vertebrate fauna (marine fish and mammals) from southwestern Morocco preliminary report: age and palaeobiogeographical implications. Geological Magazine 147: 860 - 870. https: // doi. org / 10.1017 / s 0016756810000348"]}

Pelagornis sp. EXAMINED MATERIAL. — FSAC Bouj-373, distal portion of maxillary rostrum bearing pseudo-teeth (two fragments). MEASUREMENTS (in mm; pseudo-teeth are numbered consecutively from the most proximal to the most distal). — Preserved length of proximal portion of maxillary rostrum = 163.0; preserved length of distal portion of maxillary rostrum = 86.0; minimum length of maxillary rostrum anterior to narial openings = 243.0; length between transverse furrow and tip of maxillary rostrum = 44.0; distance between rostral end of longitudinal sulcus (left side) and tip of maxillary rostrum = 19.2; distance between distalmost rank 1 pseudo-tooth (PT6) and tip of maxillary rostrum = 32.6; length between TPT2 (left side) and tip of maxillary rostrum = 14.0; height of maxillary rostrum (apex to culmen) at the level of PT6 = 23.4; maximal width of bill tip = 18.6; PT1, anteroposterior length at base = 6.0; PT1, height = 4.5; PT2, anteroposterior length at base = 3.7; PT2, height = 1.3; PT4, anteroposterior length at base = 13.6; PT4, height = 10.6; PT6, anteroposterior length at base = 10.3; PT6, height = 8.8; TPT1, anteroposterior length at base = 4.2; TPT1, height = 2.4; distance between PT1 and PT4 = 47.4; distance between PT1 and PT2 = 19.2; distance between PT2 and PT3 = 12.2; distance between PT3 and PT4 = 16.0; distance between PT5 and PT6 = 10.7; distance between PT6 and TPT1 = 10.2. DESCRIPTION Anatomical terminology followsBaumel &Witmer (1993), with English equivalents of the Latin nomenclature.FSAC Bouj-373 consists of two fragments of maxillary rostrum that are almost contiguous (Fig. 6 G-K). The posterior fragment consists of a large portion of maxillary rostrum located anterior to the narial openings (Fig. 6G, K). It is mediolaterally crushed and only preserves part of the right side of the maxillary rostrum. The poorly distorted anterior fragment mainly preserves the right side of the maxillary rostrum and the tip of the beak (Fig.6 H-J). As in other pseudo-toothed birds (Pelagornithidae), spikelike projections called pseudo-teeth are present along the tomial crest of the beak (Louchart et al. 2018). The tips of preserved pseudo-teeth are eroded. In spite of the bad preservation, pseudo-teeth seem to be arranged in a regular pattern similar to that found in other species of Pelagornis (Howard 1957; Stidham 2004; Mourer-Chauviré & Geraads 2008; Mayr & Rubilar-Rogers 2010; Ksepka 2014), with large rank 1 pseudo-teeth being separated by three smaller ones, the central rank 2 pseudo-tooth being larger than the adjacent rank 3 pseudo-teeth. In addition, rudimentary rank 4 pseudo-teeth occur in the middle of the space between rank 3 and rank 1-2 pseudo-teeth. In the Gueran specimen, the right tomial crest of the posterior fragment preserves four pseudo-teeth (Fig. 6G), including one medium-sized pseudo-tooth (PT1, rank 2) and one large pseudo-tooth (PT4, rank 1). A small pseudo-tooth (PT2, rank 3) and a tiny knob-like pseudo-tooth (PT3, rank 4) are located in the space between the larger pseudo-teeth (PT1 and PT4). The anterior portion of the maxillary rostrum preserves two pseudo-teeth on the right side (Fig. 6H), including one rudimentary knob-like pseudo-tooth (PT5, rank 4) and one large pseudo-tooth (PT6, rank 1). Rank 1 to rank 3 pseudo-teeth are conical in shape and stand vertically. On the left side (Fig. 6J), two tomial pseudo-teeth (TT1 and TT2) are located between the anterior tip of the rostrum and the first rank 1 pseudo-tooth. These tomial pseudo-teeth are sub-equal in size and more rounded than the other pseudoteeth. Only one tomial pseudo-tooth (TT1) is preserved on the right side, the anterior one (TT2) being broken. Neurovascular foramina are visible on the bone surface. As in other pseudo-toothed birds, the lateral surface of the maxillary rostrum exhibits a deep longitudinal sulcus (Fig. 6G, H), which roughly parallels the culmen just above mid-height of the maxillary rostrum, and curves down at the level of the first rank 1 pseudo-tooth. The anterior end of the longitudinal sulcus lies between the two tomial pseudo-teeth. The anterior tip of the bill is downturned and broadly rounded. It is set apart from the rest of the maxillary rostrum by a transverse furrow (Fig. 6H), which is positioned just posterior to the first large pseudo-tooth, as in other species of Pelagornis (Stidham 2004; Mayr & Rubilar-Rogers 2010; Ksepka 2014; Solórzano & Rincón 2015). The transverse furrow was originally complete across the dorsal surface of the rostrum. However, the specimen only preserves the right side of this structure. The transverse furrow turns anteroventrally near the point where it joins the longitudinal sulcus. As in other pseudo-toothed birds, the ventral surface of the maxillary rostrum bears two longitudinal sulci for reception of mandibular tomial crests and deep fossae for reception of mandibular pseudoteeth (Fig. 6I). A palatal ridge runs along the midline of the ventral surface and extends to the anterior tip of the beak. This palatal ridge is strongly convex and devoid of median sulcus, as in several fossils referable to Pelagornis (Spulski 1910; Mayr & Rubilar-Rogers 2010; Solórzano & Rincón 2015). The pseudo-toothed birds (Pelagornithidae) are an extinct group of large seabirds that included gigantic forms with wingspans above 5 m (Mayr & Rubilar-Rogers 2010; Ksepka 2014). Phylogenetic studies have shown that these highly specialized soaring birds are not part of the neoavian radiation (Bourdon 2005; Mayr 2011; Mayr et al. 2019). Pelagornithids had a worldwide distribution and occur in late Paleocene to late Pliocene marine deposits (Harrison 1985; Averianov et al. 1991; Mourer-Chauviré & Geraads 2008; Bourdon et al. 2010; Mayr & Rubilar-Rogers 2010; Boessenecker & Smith 2011; Fitzgerald et al. 2012; Cenizo et al. 2015; Mayr et al. 2019). Pseudo-toothed birds have an extensive stratigraphic range in Africa. Abundant pelagornithid remains assigned to the genus Dasornis Owen, 1870 are known from the late Paleocene (Thanetian)-early Eocene (Ypresian) phosphate deposits of the Oulad Abdoun Basin in Morocco (Bourdon et al. 2010). A sternum assigned to Gigantornis Andrews, 1916 is known from the middle Eocene (Lutetian) Ameki Formation of Nigeria (Andrews 1916). Fragmentary wing bones tentatively assigned to Gigantornis have been described from the middle Eocene (Lutetian) deposits of Kpogamé-Hahotoé, Togo (Bourdon & Cappetta 2012). Indeterminate mandibular remains of pseudo-toothed birds are known from the late Eocene (Priabonian) deposits of the Samlat Formation in Morocco (Zouhri et al. 2017). Cranial and postcranial remains assigned to Pelagornis Lartet, 1857 have been discovered in the late Pliocene deposits of Ahl Al Oughlam, Morocco (Mourer-Chauviré & Geraads 2008). The Gueran specimen exhibits several diagnostic features of the Pelagornithidae: tomial crest bearing pseudo-teeth arranged in a regular pattern; presence of longitudinal sulcus on the lateral surface of the maxillary rostrum; ventral surface of maxillary rostrum bearing deep fossae for reception of mandibular pseudo-teeth and median palatal ridge (e.g., Bourdon et al. 2010; Mayr & Rubilar-Rogers 2010; Mayr & Zvonok 2012; Cenizo et al. 2015; Solórzano & Rincón 2015). The partial rostrum described here is from the upper middle Eocene (Bartonian), and constitute the second oldest record of the pseudo-toothed birds in North Africa. The first appearance of Pelagornis comes from the late Oligocene of North America (Mayr et al. 2013; Ksepka 2014), and its latest record is in the late Pliocene of North America and Africa (Mourer-Chauviré & Geraads 2008; Boessenecker & Smith 2011). With the exception of Antarctica, Pelagornis achieved a global distribution during the Neogene (Lartet 1857; Howard & Warter 1969; Olson 1985; Ono 1989; Matsuoka et al. 1998; Stidham 2004; Mourer- Chauviré & Geraads 2008; Mayr & Rubilar-Rogers 2010; Boessenecker & Smith 2011; Fitzgerald et al. 2012; Mayr et al. 2013; Solórzano & Rincón 2015). The taxonomic assignment of the Gueran specimen to Pelagornis is based on the presence of a transverse furrow positioned just posterior to the first large pseudo-tooth, which is a diagnostic feature of the genus (Mayr & Rubilar- Rogers 2010). Such a transverse furrow is absent in the early Paleocene Protodontopteryx ruthae Mayr, Pietri, Love, Mannering & Scofield, 2019 (Mayr et al. 2019), the late Paleocene/early Eocene Dasornis toliapicus (Owen, 1873) (Bourdon et al. 2010), and the middle Eocene Lutetodontopteryx tethyensis Mayr & Zvonok, 2021 (Mayr & Zvonok 2012). In addition, in FSAC Bouj-373, several features including pseudo-tooth pattern, presence of tomial pseudoteeth, down-curved bill and convex median palatal ridge, match well with species of Pelagornis (Spulski 1910; Stidham 2004; Mourer-Chauviré & Geraads 2008; Mayr & Rubilar- Rogers 2010; Ksepka 2014; Solórzano & Rincón 2015). The earliest ascertained record of the genus Pelagornis is late Oligocene (Chattian) in age (Ksepka 2014). The specimen from Gueran is upper middle Eocene (Bartonian) in age and extends the fossil record of Pelagornis back by at least 10 million years. The anterior hook of the beak is longer in FSAC Bouj- 373 than in Pelagornis orri (Howard, 1957) (Howard 1957; Stidham 2004) and Pelagornis sandersi Ksepka, 2014 (Ksepka 2014). Moreover, the presence of two tomial pseudo-teeth on either side of the anterior end of the longitudinal sulcus is similar to the condition found in P. orri (Stidham 2004) and Pelagornis chilensis Mayr & Rubilar-Rogers, 2010 (Mayr & Rubilar-Rogers 2010). In contrast, in P. sandersi, there is only one tomial pseudo-tooth between the tip of the beak and the first large pseudo-tooth (Ksepka 2014). However, the fragmentary nature of FSAC Bouj-373 precludes assignment to the species level., Published as part of Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, pp. 121-150 in Geodiversitas 43 (5) on pages 138-141, DOI: 10.5252/geodiversitas2021v43a5, http://zenodo.org/record/4605963, {"references":["LOUCHART A., BUFFRENIL V. DE, BOURDON E., DUMONT M., VIRIOT L. & SIRE J. Y. 2018. - Bony pseudoteeth of extinct pelagic birds (Aves, Odontopterygiformes) formed through a response of bone cells to tooth-specific epithelial signals under unique conditions. Scientific Reports 8 (1): 12952. https: // doi. org / 10.1038 / s 41598 - 018 - 31022 - 3","HOWARD H. 1957. - A gigantic \" toothed \" marine bird from the Miocene of California. Bulletin of Department of Geology, Santa Barbara Museum of National History 1: 1 - 23.","STIDHAM T. A. 2004. - New skull material of Osteodontornis orri (Aves: Pelagornithidae) from the Miocene of California. Paleo- Bios 24 (2): 7 - 12.","KSEPKA D. T. 2014. - Flight performance of the largest volant bird. Proceedings of the National Academy of Sciences 111 (29): 10624 - 10629. https: // doi. org / 10.1073 / pnas. 1320297111","SOLORZANO A. & RINCON A. D. 2015. - The earliest record (early Miocene) of a bony-toothed bird from South America and a reexamination of Venezuelan pelagornithids. Journal of Vertebrate Paleontology 35 (6): e 995188. https: // doi. org / 10.108 0 / 02724634.2014.995188","SPULSKI B. 1910. - Odontopteryx longirostris n. sp. Zeitschrift der Deutschen Geologischen Gesellschaft 62: 507 - 524.","BOURDON E. 2005. - Osteological evidence for sister group relationship between pseudo-toothed birds (Aves: Odontopterygiformes) and waterfowls (Anseriformes). Naturwissenschaften 92 (12): 586 - 591. https: // doi. org / 10.1007 / s 00114 - 005 - 0047 - 0","MAYR G. 2011. - Cenozoic mystery birds - on the phylogenetic affinities of bony-toothed birds (Pelagornithidae). Zoologica scripta 40 (5): 448 - 467. https: // doi. org / 10.1111 / j. 1463 - 6409.2011.00484","MAYR G., PIETRI V. L. DE, LOVE L., MANNERING A. & SCOFIELD R. P. 2019. - Oldest, smallest and phylogenetically most basal pelagornithid, from the early Paleocene of New Zealand, sheds light on the evolutionary history of the largest flying birds. Papers in Palaeontology: 1 - 17. https: // doi. org / 10.1002 / spp 2.1284","HARRISON C. J. O. 1985. - A bony-toothed bird (Odontopterygiformes) from the Palaeocene of England. Tertiary Research 7 (1): 23 - 25.","AVERIANOV A. O., PANTELEYEVA V., POTAPOVA O. R. & NESSOV L. A. 1991. - Bony-toothed birds (Aves: Pelecaniformes: Odontopterygia) from the late Paleocene and Eocene of the Western margin of ancient Asia. Proceedings of the Zoological Institute Russian Academy of Sciences 239: 3 - 12.","BOURDON E., AMAGHZAZ M. & BOUYA B. 2010. - Pseudotoothed birds (Aves, Odontopterygiformes) from the early Tertiary of Morocco. American Museum Novitates 3704: 1 - 71. https: // doi. org / 10.1206 / 3704.2","BOESSENECKER R. W. & SMITH N. A. 2011. - Latest Pacific basin record of a bony-toothed bird (Aves, Pelagornithidae) from the Pliocene Purisima Formation of California, U. S. A. Journal of Vertebrate Paleontology 31 (3): 652 - 657. https: // doi. org / 10.108 0 / 02724634.2011.562268","FITZGERALD E. M. G., PARK T. & WORTHY T. H. 2012. - First giant bony-toothed bird (Pelagornithidae) from Australia. Journal Vertebrate Paleontology 32 (4): 971 - 974. https: // doi. org / 10.108 0 / 02724634.2012.664596","CENIZO M., HOSPITALECHEC. A. & REGUERO M. 2015. - Diversity of pseudo-toothed birds (Pelagornithidae) from the Eocene of Antarctica. Journal of Paleontology 89 (5): 870 - 881. https: // doi. org / 10.1017 / jpa. 2015.48","ANDREWS C. W. 1916. - Note on the sternum of a large carinate bird from the (?) Eocene of Southern Nigeria. Proceedings of the Zoological Society of London 1916: 519 - 524. https: // doi. org / 10.1111 / j. 1096 - 3642.1916. tb 02030","BOURDON E. & CAPPETTA H. 2012. - Pseudo-toothed birds (Aves, Odontopterygiformes) from the Eocene phosphate deposits of Togo, Africa. Journal of Vertebrate Paleontology 32 (4): 965 - 970. https: // doi. org / 10.1080 / 02724634.2012.676113","ZOUHRI S., KHALLOUFI B., BOURDON E., LAPPARENT DE BROIN F. DE, RAGE J. - C., M'HAIDRAT L., GINGERICH P. D. & ELBOU- DALI N. 2017. - Marine vertebrate fauna from the late Eocene Samlat Formation of Ad-Dakhla, southwestern Morocco. Geological Magazine 155 (7): 1596 - 1620. https: // doi. org / 10.1017 / S 0016756817000759","LARTET E. 1857. - Note sur un humerus fossile d'oiseau, attribue a un tres grand palmipede de la section des Longipennes. Comptes Rendus hebdomadaires des Seances de l'Academie des Sciences (Paris) 44: 736 - 741. https: // gallica. bnf. fr / ark: / 12148 / bpt 6 k 3001 w / f 749. item","MAYR G. & ZVONOK E. 2012. - A new genus and species of Pelagornithidae with well-preserved pseudodentition and further avian remains from the middle Eocene of the Ukraine. Journal of Vertebrate Paleontology 32 (4): 914 - 925. https: // doi. org / 10.1 080 / 02724634.2012.676114","MAYR G., GOEDERT J. L. & MCLEOD S. A. 2013. - Partial skeleton of a bony-toothed bird from the late Oligocene / early Miocene of Oregon (USA) and the systematics of Neogene Pelagornithidae. Journal of Paleontology 87 (5): 922 - 929. https: // doi. org / 10.1666 / 13 - 025","HOWARD H. & WARTER S. L. 1969. - A new species of bonytoothed bird (Family Pseudodontornithidae) from the Tertiary of New Zealand. Records of the Canterbury Museum 8 (4): 345 - 357.","OLSON S. L. 1985. - The fossil record of birds, in FARNER D. S., KING J. R. & PARKES K. C. (eds), Avian Biology. Vol. 8. Academic Press, New York: 79 - 256.","ONO K. 1989. - A bony-toothed bird from the middle Miocene, Chichibu Basin. Bulletin of the National Science Museum, Tokyo 15 (1): 33 - 38.","MATSUOKA H., SAKAKURA F. & OHE F. 1998. - A Miocene pseudodontorn (Pelecaniformes: Pelagornithidae) from the Ichishi Group of Misato, Mie Prefecture, Central Japan. Paleontological Research 2: 246 - 252. https: // doi. org / 10.2517 / prpsj. 2.246","MOURER- CHAUVIRE C. & GERAADS D. 2008. - The Struthionidae and Pelagornithidae (Aves: Struthioniformes, Odontopterygiformes) from the late Pliocene of Ahl al Oughlam, Morocco. Oryctos 7: 169 - 194."]}

Otodus (Carcharocles) cf. sokolowi (Jaekel, 1895) EXAMINED MATERIAL. — Around twenty broken isolated teeth, figured material includes FSAC Bouj-320, 321 and 322. DESCRIPTION Teeth can reach up to 10 cm in height, displaying a large triangular cusp with well-marked and regular serrations on the cutting edges and a pair of lateral cusplets (Fig. 2A). Cusplets are not very high when conserved and often divergent in lateral teeth (Fig. 2A) to less developed in anterior teeth (Fig. 2B). REMARKS Teeth of Otodus (Carcharocles) cf. sokolowi are relatively common around the archaeocete carcasses (Fig. 2 A-C). Case & Cappetta (1990) have discussed about the taxonomic distinctness of Otodus (Carcharocles) sokolowi compared to the other Eocene species of subgenus, and in particularly with the smaller and coeval species Otodus (Carcharocles) auriculatus (Blainville, 1818). Otodus (Carcharocles) sokolowi appears widely distributed and relatively common in the tropical marine realm since the GEA-C (uppermost Bartonian-lowermost Priabonian) and throughout the Priabonian successions (GE D-G, BQ, QS) according to Underwood et al. (2011), southwestern Morocco included (Adnet et al. 2010). However this species seems relatively discrete in older deposits, as in the MI (Underwood et al. 2011). Its occurrence in Bartonian of Gueran, Morocco, testify of its spatial expansion along the Tethysian coasts during the Bartonian., Published as part of Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, pp. 121-150 in Geodiversitas 43 (5) on page 125, DOI: 10.5252/geodiversitas2021v43a5, http://zenodo.org/record/4605963, {"references":["CASE G. R. & CAPPETTA H. 1990. - The Eocene Selachians Fauna from the Fayum Depression in Egypt. Palaeontographica Abteilung A 212: 1 - 30.","UNDERWOOD C. J., WARD D. J., KING C., ANTAR S. M., ZAL- MOUT I. S. & GINGERICH P. D. 2011. - Shark and ray faunas in the middle and late Eocene of the Fayum area, Egypt. Proceedings of the Geologists' Association 122: 47 - 66. https: // doi. org / 10.1016 / j. pgeola. 20","ADNET S., CAPPETTA H. & TABUCE R. 2010. - A middle-late Eocene vertebrate fauna (marine fish and mammals) from southwestern Morocco preliminary report: age and palaeobiogeographical implications. Geological Magazine 147: 860 - 870. https: // doi. org / 10.1017 / s 0016756810000348"]}

Hemipristis curvatus (Dames, 1883) EXAMINED MATERIAL. — Five broken isolated teeth, figured material includes FSAC Bouj-343. DESCRIPTION An upper tooth (Fig. 4D) belonging to the snuggle tooth shark Hemipristis curvatus was recovered from the Locality 1. The crown is compressed labio-lingually, slanted distally with unserrated mesial cutting edge. REMARKS The snuggle tooth shark, Hemipristis curvatus is known in all the tropical seas during the late Eocene, from Western Neotethys (e.g., Case & Cappetta 1990; Mustafa & Zalmout 2002; Underwood et al. 2011) to western central Atlantic (e.g., Case & Borodin 2000). Its occurrence in the middle Eocene is less usual (Underwood et al. 2011). Only two teeth were recorded in MI (Underwood et al. 2011), it becomes common from the GE A-C (around the Bartonian/Priabonian boundary) and within the rest of the BQ (Priabonian)., Published as part of Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, pp. 121-150 in Geodiversitas 43 (5) on pages 127-129, DOI: 10.5252/geodiversitas2021v43a5, http://zenodo.org/record/4605963, {"references":["CASE G. R. & CAPPETTA H. 1990. - The Eocene Selachians Fauna from the Fayum Depression in Egypt. Palaeontographica Abteilung A 212: 1 - 30.","MUSTAFA H. & ZALMOUT I. 2002. - Elasmobranchs from the late Eocene Wadi Esh-Shallala Formation of Qa'Faydatad Dahikiya, east Jordan. Tertiary Research 21 (1 / 4): 77 - 94.","UNDERWOOD C. J., WARD D. J., KING C., ANTAR S. M., ZAL- MOUT I. S. & GINGERICH P. D. 2011. - Shark and ray faunas in the middle and late Eocene of the Fayum area, Egypt. Proceedings of the Geologists' Association 122: 47 - 66. https: // doi. org / 10.1016 / j. pgeola. 20","CASE G. R. & BORODIN P. D. 2000. - Late Eocene selachian from the Irwinton Sand Member of the Barnwell Formation (Jacksonian), WKA mines, Gordon, Wilkinson County, Georgy. Munchner Geowissenschaftliche Abhandlungen 39: 5 - 16."]}

Macrorhizodus praecursor (Leriche, 1905) EXAMINED MATERIAL. — Hundreds of isolated teeth, figured material includes FSAC Bouj-327, 328, 329 and 330. DESCRIPTION The more abundant complete and well-preserved teeth (Fig. 2 H-K) recovered in both localities (Locality I, Garouaz, Iddir and Laazri) belong to the lamnid Macrorhizodus praecursor. Central cusp is especially triangular in anterolateral files (e.g., Fig. 2J) with a flat labial face and a little convex lingual face. REMARKS This species, representing an extinct pelagic mako shark, is very abundant in all middle and late Eocene localities and distributed worldwide in the marine realm., Published as part of Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, pp. 121-150 in Geodiversitas 43 (5) on page 125, DOI: 10.5252/geodiversitas2021v43a5, http://zenodo.org/record/4605963, {"references":["LERICHE M. 1905. - Les poissons tertiaires de la Belgique II. Les poissons eocenes. Memoires du Musee royal d'Histoire naturelle de Belgique 11 (3): 49 - 228."]}

Physogaleus sp. MATERIAL. — 40 isolated teeth, figured material includes FSAC Bouj-340, 341, 342 and 343. DESCRIPTION AND REMARKS Among the smaller carcharhinids, teeth of Physogaleus sp. (Fig. 4 A-C) are relatively frequent in both localities. Two coeval species of Physogaleus are redundant in the middle Eocene deposits. It concerns the larger P. secundus (Winkler, 1876) widespread in most middle Eocene deposits of North Atlantic (see Cappetta & Case 2016) and Neotethys, and the smaller P. tertius (Winkler, 1876) recorded in the same areas (Cappetta 2012). With very tenuous differences, both species may enter in the morphological variability of the other. Our material is well conserved, and teeth appear larger (up to 1.5 cm) than those of northern representatives., Published as part of Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, pp. 121-150 in Geodiversitas 43 (5) on page 127, DOI: 10.5252/geodiversitas2021v43a5, http://zenodo.org/record/4605963, {"references":["CAPPETTA H. & CASE G. R. 2016. - A Selachian Fauna from the middle Eocene (Lutetian, Lisbon Formation) of Andalusia, Covington County, Alabama, USA. Palaeontographica Abteilung A 307 (1 - 6): 43 - 103.","CAPPETTA H. 2012. - Chondrichthyes II Mesozoic and Cenozoic Elasmobranchii: Teeth, Handbook of Paleoichthyology. Verlag Dr. Friedrich Pfeil, Stuttgart-New York. https: // doi. org / 10.1080 / 02 724634.1988. 10011678"]}

Pterosphenus cf. schweinfurthi (Andrews, 1901) EXAMINED MATERIAL. — Four vertebrae recovered from the Garouaze Locality in Gueran Depression. Two of the specimens (FSAC Bouj -300 and 317) clearly belong to the Palaeophiidae. The two other vertebrae (FSAC Bouj -316 and 318) are very incomplete, but they also likely belong to palaeophiids. DESCRIPTION The description is mainly based on FSAC Bouj-317 (Fig. 6 A-E) but more information is drawn from FSAC Bouj-300 (Fig. 6F). These vertebrae belong to a large snake. In FSAC Bouj-317, measurements are as follows: centrum length, from the cotyle rim to the tip of condyle = 21.7 mm; horizontal diameter of cotyle = 13.1 mm; zygosphene width = 13.7 mm. FSAC Bouj-300 is larger, but its centrum length cannot be measured; the horizontal diameter of its condyle is approximately 19.9 mm and the width of its zygosphene is 21.6 mm. Both vertebrae are tall, short and compressed laterally. FSAC Bouj-317 preserves incomplete pterapophyses above the postzygapophyses. In anterior view, FSAC Bouj-317 is clearly compressed laterally, and is very narrow. The cotyle is broad and approximately circular but somewhat truncated dorsally. The size of the preserved prezygapophysis, on the right side, appears much reduced compared to the cotyle. The neural canal is small. The articular facet of the prezygapophysis lies approximately at the level of the floor of the neural canal. The width of the zygosphene is nearly similar to that of the cotyle. The zygosphene is relatively thick and arches dorsally. The top of the zygosphene forms the base of the anterior border of the neural spine. FSAC Bouj -300 differs from FSAC Bouj- 317 in being slightly less compressed laterally and in having a markedly thicker zygosphene. In dorsal view, FSAC Bouj-317 appears narrow and comparatively elongate. The interzygapophyseal constriction is so shallow that it is almost not expressed. The axis of the small prezygapophyseal facet is directed anterolaterally. The anterior border of the zygosphene forms an obtuse notch. The neural spine extends through the whole preserved length of the neural arch; anteriorly, it reaches the anterior border of the zygosphene. FSAC Bouj-300 was likely less narrow and less elongate. In lateral aspect, the neural spine is long anteroposteriorly; unfortunately, its dorsal part is broken away and its height cannot be estimated. Its anterior border comprises a vertical portion that rises from the zygosphene and a longer, posteriorly inclined dorsal portion. The vertebra does not preserve the tips of both prezygapophyses, so that the length of the latter remains unknown. The anterior edge of the pterapophyses is inclined posterodorsally at an angle of approximately 45°. The interzygapophyseal ridge is very prominent but blunt. The prezygapophyseal buttress forms an anterolateral sharp ridge. Unfortunately, the two paradiapophyses are completely eroded and hypapophyses are not preserved. The axis of the condyle is horizontal. FSAC Bouj-300 only provides one additional information: it bears the basis of a vertical hypapophysis. It is not possible to determine whether or not an anterior hypapophysis was present. The ventral face of the centrum of FSAC Bouj-317 is narrow and elongate, not limited by subcentral ridges. The sagittal area is damaged. The bases of the paradiapophyses are markedly separated from each other. The ventral face of FSAC Bouj-300 is poorly preserved. However, its sagittal area forms a carina. The hypapophysis originates from the posterior portion of this carina. Apparently, there is no room for an anterior hypapophysis. The posterior aspect of FSAC Bouj-317 is striking. Above the neural canal, the neural arch is extremely thick and bounded laterally by vertical borders. The dorsolateral parts of the neural arch form the bases of the broken pterapophyses. The posterior face of FSAC Bouj-300 does not display observable characters. FSAC Bouj-316 and 318 are two centra whose morphology is consistent with those of FSAC Bouj-300 and 317. Although very incomplete, both specimens bear an entirely preserved hypapophysis. In both vertebrae, the short, laterally compressed hypapophysis shows a vertical posterior border that contacts the condyle and a weakly (in FSAC Bouj-318) or strongly (in FSAC Bouj-316) inclined anterior border. It is not possible to determine whether an anterior hypapophysis was present in these two vertebrae. COMPARISON AND REMARKS The lateral compression, reduced prezygapophyses, prezygapophyseal buttresses forming an anterolateral edge, presence of pterapophyses and horizontal axis of condyle constitute a combination of characters that occur only in Palaeophiidae. In addition, the shortness and height of the vertebrae, as well as low position of the zygapophyseal plane, make it possible to discard the Archaeophiinae and to refer the specimens to the Palaeophiinae (Rage et al. 2003). Two genera, Palaeophis Owen, 1841 and Pterosphenus, are assigned to the Palaeophiinae of Palaeophiidae, a family including species of various sizes, slightly adapted to strongly specialized for aquatic life, and widely distributed from America to Asia. The species from Gueran is large and marine, and it was first identified in Fayum (Andrews 1901). The vertebrae of the species referred to these two genera form a morphological cline (Rage 1983a). Compared with the generalized snake vertebrae, Palaeophis species have vertebrae displaying the more conservative morphology. In Pterosphenus, vertebrae are more laterally compressed, the prezygapophyses are more reduced, and the pterapophyses are taller than in Palaeophis. However, in the morphocline, there is a blurred transition between species that may be referred to either Palaeophis or Pterosphenus; the distinction between the two genera is phenotypic and artificial (Rage 1983a). Fortunately, the morphology of the vertebrae from Gueran is consistent with that of the more derived species. Consequently, the specimens are assigned to Pterosphenus. This assignment based on the degree of lateral compression and height of the vertebrae is confirmed by the continuity between the top of the zygosphene and the anterior border of the neural spine; this feature is known only in Pterosphenus (Rage 1983b). This character unquestionably occurs in FSAC Bouj-300 and FSAC Bouj-317 (it cannot be checked in FSAC Bouj-316 and FSAC Bouj-318). The zygosphene of FSAC Bouj-300 is markedly thicker and narrower than that of FSAC Bouj-317, which corresponds to intracolumnar variation. FSAC Bouj-300 is a vertebra from the mid-trunk portion whereas FSAC Bouj-317 comes from the posterior trunk region. The smaller size of FSAC Bouj-317 likely also reflects intracolumnar variation; the anterior and posterior trunk regions of palaeophiids appear to have been slenderer than the mid-trunk portion. FSAC Bouj-300 and 317 likely belong to the same species (but no conclusion can be made about 316 and 318). Five recognized species belong to Pterosphenus (Rage et al. 2003; McCartney & Seiffert 2016): P. schucherti, the type species, middle (Bartonian and?Lutetian) and late (Priabonian) Eocene of the United States; P. schweinfurthi, late Eocene (Bartonian) of Libya and late Eocene (Priabonian) of Egypt: note that McCartney & Seiffert (2016) assigned an Eocene/Oligocene age to the fossils from Libya; however, we follow Abouessa et al. (2012) who referred the Libyan locality to the late Bartonian. P. sheppardi, late Eocene of Ecuador; P. kutchensis and P. biswasi, both from the lower Eocene (Ypresian) of India. The fact that paradiapophyses are clearly separated from each other and that the anterior border of the neural spine reaches the anterior border of the zygosphene allows to exclude P. kutchensis. The morphology of FSAC Bouj-300 and 317 is close to that of P. biswasi. However, the latter species differs from FSAC Bouj-300 and 317 in having a less concave anterior border of the zygosphene. Another possible difference is that, on the centrum, the base of each paradiapophysis is less extended dorsoventrally in FSAC Bouj-317 (not observable in FSAC Bouj-300) than in P. biswasi. Comparison with P. sheppardi is difficult because this species is only represented by five articulated vertebrae. If the vertebrae were articulated, several significant characters would have been concealed. However, the pterapophyses of P. sheppardi are smaller and shorter than those of FSAC Bouj-317 (no possible comparison with FSAC Bouj-300). If this difference is not an intracolumnar variation, then it is significant at the species level variations. Distinction between P. schucherti and P. schweinfurthi is not clear. Specific differences that were put forward are perhaps only intracolumnar variation (Rage et al. 2003; Parmley & Devore 2005; McCartney & Seiffert 2016). Pterosphenus schweinfurthi may be a junior synonym of P. schucherti but this cannot be demonstrated. FSAC Bouj-300 and 317 do not show significant differences with the known vertebrae of both P. schucherti and P. schweinfurthi (Lucas 1899; Janensch 1906; Westgate & Ward, 1981; McCartney & Seiffert 2016). However, in view of the limited material and its incomplete nature and taking into account the uncertainty that remains about the possible synonymization of P. schweinfurthi with P. schucherti, we assign the material from Gueran to Pterosphenus cf. schweinfurthi. It is worth noting that the geographically close locality of Ad-Dakhla yielded some palaeophiid vertebrae. Bedbone 1 from which the palaeophiid fossils in Ad-Dakhla area came from is slightly younger than the fossiliferous level of Gueran. Zouhri et al. (2014) assigned a Priabonian age to Bedbone 1. In the vertebrae from Ad-Dakhla, the junction between the anterior borders of the zygosphene and neural spine clearly belongs to the Pterosphenus type. In addition, one (unnumbered) incomplete vertebra displays proportions that are similar to those of the known vertebrae of the P. schweinfurthi - P. schucherti assemblage and may be referred to P. cf. schweinfurthi. However, one vertebra from Ad-Dakhla (Dak-349) is less compressed laterally and its proportions resemble those of species belonging to the transition between Palaeophis and Pterosphenus. It is not possible to state whether Dak-349 belongs to a species distinct from the P. schweinfurthi - P. schucherti assemblage or if it represents an intracolumnar variation of the later assemblage that was hitherto unknown. Whatever the case may be, Pterosphenus cf. schweinfurthi is present in Gueran (Bartonian) as in Ad-Dakhla., Published as part of Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, pp. 121-150 in Geodiversitas 43 (5) on pages 135-136, DOI: 10.5252/geodiversitas2021v43a5, http://zenodo.org/record/4605963, {"references":["ANDREWS C. W. 1901. - Preliminary note on some recently discovered extinct vertebrates from Egypt. Geological Magazine 4: 436 - 444. https: // doi. org / 10.1017 / S 0016756800179750","RAGE J. - C., BAJPAI S., THEWISSEN J. G. M. & TIWARI B. N. 2003. - Early Eocene snakes from Kutch, Western India, with a review of the Palaeophiidae. Geodiversitas 25: 695 - 716.","RAGE J. - C. 1983 a. - Palaeophis colossaeus nov. sp. (le plus grand serpent connu?) de l'Eocene du Mali et le probleme du genre chez les Palaeopheidae. Comptes rendus de l'Academie des sciences, serie II, 296: 1741 - 1744.","RAGE J. - C. 1983 b. - Les serpents aquatiques de l'Eocene europeen. Definition des especes et aspects stratigraphiques. Bulletin du Museum national d'histoire naturelle, section C, Sciences de la Terre, 4 eme serie, 5 (2): 213 - 241. https: // www. biodiversitylibrary. org / page / 55630508","MCCARTNEY J. A. & SEIFFERT E. R. 2016. - A late Eocene snake fauna from the Fayum Depression, Egypt. Journal of Vertebrate Paleontology 36 (1): e 1029580. https: // doi. org / 10.1080 / 027246 34.2015. 1029580","ABOUESSA A., PELLETIER J., DURINGER P., SCHUSTER M., SCHAEF- FER P., METAIS E., BENAMMI M., SALEM M., HLAL O., BRU- NET M., JAEGER J. J. & RUBINO J. L. 2012. - New insight into the sedimentology and stratigraphy of the Dur At Talah tidal-fluvial transition sequence (Eocene-Oligocene, Sirt Basin, Libya). Journal of African Earth Sciences 65: 72 - 90. https: // doi. org / 10.1016 / j. jafrearsci. 2012.02.004","PARMLEY D. & DEVORE M. 2005. - Palaeopheid snakes from the late Eocene Hardie Mine local fauna of Central Georgia. Southeastern Naturalist 4: 703 - 722. https: // www. jstor. org / stable / 3878233","LUCAS F. A. 1899. - A new snake from the Eocene of Alabama. Proceedings of the United States National Museum 1164: 637 - 638.","JANENSCH W. 1906. - Pterosphenus schweinfurthi Andrews und die Entwicklung der Palaeophiden. Archiv fur Biontologie 1: 307 - 350.","WESTGATE J. W. & WARD J. F. 1981. - The giant aquatic snake Pterosphenus schucherti (Palaeophidae) in Arkansas and Mississipi. Journal of Vertebrate Paleontology 1: 161 - 164. https: // doi. org / 10. 1080 / 02724634.1981.10011887","ZOUHRI S., GINGERICH P. D., ELBOUDALI N., SEBTI S., NOUBHANI A., RAHALI M. & MESLOUH S. 2014. - New marine mammal faunas (Cetacea and Sirenia) and sea level change in the Samlat Formation, upper Eocene, near Ad-Dakhla in southwestern Morocco. Comptes Rendus Palevol 13: 599 - 610. https: // doi. org / 10.1016 / j. crpv. 2014.04.002"]}

Clade EUSUCHIA Huxley, 1875 sensu Brochu (2003) Eusuchia indet. EXAMINED MATERIAL. — FSAC Bouj-410, could be the (?) ninth cervical vertebra; FSAC Bouj-1b, anterior? cervical vertebra; 400, posterior dorsal vertebra; 1a, first caudal vertebra; 124, caudal vertebra; 96, two fragments of large dorsal osteoderms; 94, fragment of osteoderm. DESCRIPTION Numerous postcranial remains have been found in Gueran.These include five procoelous vertebrae and several fragments of osteoderms. FSAC Bouj-410 is a posterior cervical vertebra (Fig.7A). It bears a long hypapophysis, and the location of the diapophysis and parapophysis suggests that it could be the ninth cervical vertebra. Bouj-1b is a more anterior cervical (Fig. 7B), but it is not possible to determine its exact location in the vertebral column. FSAC Bouj-400 is an isolated procoelous centrum lacking most of the neural arch (Fig. 7C). The transverse process is high on the centrum, which indicates that it is a dorsal vertebra. A first caudal vertebra with a biconvex centrum is preserved (Fig. 7D). The osteoderm fragments have their dorsal surfaces densely ornamented with deep pits (Fig.7 F-H). Bouj-96 is a fragment of large and thick osteoderm with a smooth anterior articular surface., Published as part of Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, pp. 121-150 in Geodiversitas 43 (5) on page 138, DOI: 10.5252/geodiversitas2021v43a5, http://zenodo.org/record/4605963, {"references":["BROCHU C. A. 2003. - Phylogenetic approaches toward crocodylian history. Annual Review of Earth and Planetary Sciences 31: 357 - 397. https: // doi. org / 10.1146 / annurev. earth. 31.100901.141308"]}

‘ Carcharias ’ koerti (Stromer, 1910) MATERIAL. — 30 broken isolated teeth, figured material included FSAC Bouj-325 and 326. DESCRIPTION Occurrence of the middle Eocene ‘ Carcharias ’ koerti is confirmed in Gueran (Fig. 2F, G). Interestingly, the majority of recovered teeth (e.g., Fig. 2G) are relatively small compared to the usual Lutetian representatives. REMARKS The generic affinity of this large pelagic shark to ‘‘ Carcharias ” or “ Brachycarcharias ” still remains unclear (e.g., Strougo et al. 2007; Underwood et al. 2011), it is preferentially known in the Lutetian deposits and is widely distributed around the North and Western African coasts (Stromer 1910; White 1955; Dartevelle & Casier 1959; Cappetta & Traverse 1988; Cappetta et al. 2000; Noubhani & Cappetta 1997; Strougo et al. 2007). Rarely recovered in MI (Uppermost LutetianLowermost Bartonian), GA (Lutetian-Bartonian) and lacking in GE A-C (uppermost Bartonian) and the remainder of the succession of Wadi al Hitan, Egypt (see Underwood et al. 2011), its occurrence in Boujdour area seems to indicate that the age of the deposits is likely older than latest Bartonian., Published as part of Zouhri, Samir, Gingerich, Philip D., Khalloufi, Bouziane, Bourdon, Estelle, Adnet, Sylvain, Jouve, Stéphane, Elboudali, Najia, Amane, Ayoub, Rage, Jean-Claude & Tabuce, Rodolphe, 2021, Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco, pp. 121-150 in Geodiversitas 43 (5) on page 125, DOI: 10.5252/geodiversitas2021v43a5, http://zenodo.org/record/4605963, {"references":["STROMER E. 1910. - Reptilien- und Fischreste aus dem marinen Alttertiar von Sudtogo (Westafrica). Zeitschrift der Deutschen Geologischen Gesellschaft 62 (7): 478 - 505.","STROUGO A., CAPPETTA H. & ELNAHAS S. 2007. - A remarkable Eocene ichthyofauna from the El Gedidia glauconitic sandstone, Bahariya oasis, Egypt, and its stratigraphic implications. MERC Ain Shams University, Earth Science Series 21: 81 - 98.","UNDERWOOD C. J., WARD D. J., KING C., ANTAR S. M., ZAL- MOUT I. S. & GINGERICH P. D. 2011. - Shark and ray faunas in the middle and late Eocene of the Fayum area, Egypt. Proceedings of the Geologists' Association 122: 47 - 66. https: // doi. org / 10.1016 / j. pgeola. 20","WHITE E. I. 1955. - Notes on African Tertiary sharks. Colonial Geology and Mineral Resources 5: 319 - 325.","DARTEVELLE E. & CASIER E. 1959. - Les poissons fossiles du Bas- Congo et des regions voisines. Annales du Musee du Congo belge, Serie A 3 (2, 3): 257 - 568.","CAPPETTA H. & TRAVERSE M. 1988. - Une riche faune de selaciens dans le bassin a phosphate de Kpogame-Hahotoe (Eocene moyen du Togo): Note preliminaire et precisions sur la structure et l'age du gisement. Geobios 21 (3): 359 - 365. https: // doi. org / 10.1016 / S 0016 - 6995 (88) 80058 - 5","CAPPETTA H., PFEIL F. & SCHMIDT- KITTLER N. 2000. - New biostratigraphical data on the marine Upper Cretaceous and Palaeogene of Jordan. Newsletters on Stratigraphy 38: 81 - 95. https: // doi. org / 10.1127 / nos / 38 / 2000 / 81","NOUBHANI A. & CAPPETTA H. 1997. - Les Orectolobiformes, Carcharhiniformes et Myliobatiformes (Elasmobranchii, Neoselachii) des bassins a phosphate du Maroc (Maastrichtien-Lutetien basal). Systematique, biostratigraphie, evolution et dynamique des faunes. Palaeo Ichthyologica 8: 1 - 327."]}

In the Sahara Desert of southwestern Morocco, the Aridal Formation of Gueran is known for the world's richest Bartonian archaic whale assemblage, which includes both protocetids and basilosaurids. Gueran has also yielded another rich and diverse vertebrate fauna described in detail herein —The chondrichthyan assemblage of twelve species is quite similar to that of the Midawara Formation (Egypt). Actinopterygians include Siluriformes, Percomorpha and rostra of Cylindracanthus Leidy, 1856. Turtles are attributed to at least three indetermined species: two marine cryptodires – a cheloniid and a dermochelyid, and a possible littoral pleurodire, as found in Ad-Dakhla (Morocco) and Fayum (Egypt). The crocodylians comprise at least two longirostrine taxa, including a gavialoid that resembles the late Eocene-early Oligocene Eogavialis africanumAndrews, 1901 from Egypt. The second form is too fragmentary to be identified more precisely than Crocodyliformes indet. Two snake vertebrae belong to Pterosphenus cf. schweinfurthiAndrews, 1901. Two other incomplete snake vertebrae probably belong to Paleophiidae as well. Seabird remains belong to a gigantic soaring pseudo-toothed bird (Pelagornithidae) and constitute the earliest occurrence of the genus Pelagornis sp.Lartet, 1857. This material extends the fossil record of Pelagornis back in time by at least 10 million years. Based on their size and enamel microstructure, mammal dental fragments are attributed to the proboscidean ?Barytherium sp. The Bartonian age of the fauna, initially based on an archaeocete cetacean assemblage, is also supported by chondrichthyans. Affinities of the Gueran faunal assemblage are analyzed in comparison with those from other middle and upper Eocene deposits of North Africa and elsewhere.