taxonID	type	description	language	source
03923C45FF85FF8E337DF9ADFE8F17DF.taxon	discussion	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.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF87FF8033B7FA0CFC9717BE.taxon	materials_examined	MATERIAL. — 30 broken isolated teeth, figured material included FSAC Bouj- 325 and 326.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF87FF8033B7FA0CFC9717BE.taxon	description	DESCRIPTION Occurrence of the middle Eocene ‘ Carcharias ’ koerti is confirmed in Gueran (Fig. 2 F, G). Interestingly, the majority of recovered teeth (e. g., Fig. 2 G) are relatively small compared to the usual Lutetian representatives.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF87FF8033B7FA0CFC9717BE.taxon	discussion	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.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF87FF8E30F9FD6AFDCD12C0.taxon	materials_examined	EXAMINED MATERIAL. — Hundreds of isolated teeth, figured material includes FSAC Bouj- 327, 328, 329 and 330.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF87FF8E30F9FD6AFDCD12C0.taxon	description	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. 2 J) with a flat labial face and a little convex lingual face.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF87FF8E30F9FD6AFDCD12C0.taxon	discussion	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.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF87FF8E33F1FDA9FB5D1343.taxon	materials_examined	EXAMINED MATERIAL. — A dozen isolated teeth, figured material includes FSAC Bouj- 323.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF87FF8E33F1FDA9FB5D1343.taxon	description	DESCRIPTION Teeth are some smaller than those of previous species and up to 5 cm in height (Fig. 2 D, E). Compared to Otodus (Carcharocles) cf. sokolowi, teeth of this second species display a flatter root with subrectangular basal extremities of lobes, a more slender cusp with finer serrations and two cusplets which are smaller and lower than in other coeval species.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF87FF8E33F1FDA9FB5D1343.taxon	discussion	REMARKS These characters are different from the coeval small megatoothed shark species Otodus (Carcharocles) auriculatus, commonly reported in worldwide middle Eocene deposits (e. g., Ward & Wiest 1990; Dutheil 1991; Long 1992; Cappetta & Stringer 2002, Cappetta & Case 2016). Similar otodontid morphology is observed in the Lutetian material of Togo (Pers. Observ.) where co-occurrence of two representatives of megatoothed sharks is also noticed.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF87FF8E30A4FAACFBB6145E.taxon	materials_examined	EXAMINED MATERIAL. — Around twenty broken isolated teeth, figured material includes FSAC Bouj- 320, 321 and 322.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF87FF8E30A4FAACFBB6145E.taxon	description	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. 2 A). Cusplets are not very high when conserved and often divergent in lateral teeth (Fig. 2 A) to less developed in anterior teeth (Fig. 2 B).	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF87FF8E30A4FAACFBB6145E.taxon	discussion	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.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF89FF8030E4F94DFBD5157E.taxon	materials_examined	EXAMINED MATERIAL. — Thirty isolated teeth, figured material includes FSAC Bouj- 337, 338 and 339.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF89FF8030E4F94DFBD5157E.taxon	description	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.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF89FF8030E4F94DFBD5157E.taxon	discussion	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).	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF89FF803438FC4AFAD313C3.taxon	materials_examined	MATERIAL. — 40 isolated teeth, figured material includes FSAC Bouj- 340, 341, 342 and 343.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF89FF803438FC4AFAD313C3.taxon	description	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.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF89FF8030F5FD8AFD6A13A3.taxon	materials_examined	EXAMINED MATERIAL. — 50 isolated teeth, figured material includes FSAC Bouj- 331, 332, 333, 334, 335 and 336.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF89FF8030F5FD8AFD6A13A3.taxon	description	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. 3 A, F) and lateral teeth (Fig. 3 C-E).	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF89FF8030F5FD8AFD6A13A3.taxon	discussion	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).	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF89FF8233B0F9EDFED0177C.taxon	materials_examined	EXAMINED MATERIAL. — Five broken isolated teeth, figured material includes FSAC Bouj- 343.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF89FF8233B0F9EDFED0177C.taxon	description	DESCRIPTION An upper tooth (Fig. 4 D) 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.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF89FF8233B0F9EDFED0177C.taxon	discussion	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).	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8BFF823165FE49FE85151E.taxon	materials_examined	MATERIAL A dozen isolated teeth, figured material includes FSAC Bouj- 344.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8BFF823165FE49FE85151E.taxon	description	DESCRIPTION AND REMARKS Some rare medium-sized shark teeth (Fig. 4 E, 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. 2 F). Occasional in MI, this unnamed species becomes common in GE A-C and younger series (Underwood et al. 2011).	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8BFF823364FD0AFAA715E1.taxon	discussion	REMARKS Besides the undeterminable broken caudal sting of Myliobatiformes (unfigured), only rostral teeth of two fossil sawfishes (Rhinopristiformes) were identified.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8BFF823171FC2BFAF014FE.taxon	materials_examined	MATERIAL A dozen isolated teeth, figured material includes FSAC Bouj- 345, 346 and 347.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8BFF823171FC2BFAF014FE.taxon	description	DESCRIPTION AND REMARKS Some rare medium-sized sharks (Fig. 3 G-I) are provisionally attributed to Carcharhinus sp. The upper tooth (Fig. 4 G) reminds those of Negaprion sp. (unserrated cutting edges, main cusp separated from heels by notches) associated with erect and gracile lower teeth (Fig. 4 H, 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.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8BFF8233A3F92DFBD01182.taxon	materials_examined	EXAMINED MATERIAL. — 12 broken rostral teeth.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8BFF8233A3F92DFBD01182.taxon	description	DESCRIPTION AND REMARKS The second sawfish (unfigured here) is a common worldwide sawfish recovered from many Tethyan middle-late Eocene deposits (Cappetta 2012).	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8BFF82338FFBABFA951003.taxon	materials_examined	EXAMINED MATERIAL. — Five rostral denticles, figured material includes FSAC Bouj- 348.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8BFF82338FFBABFA951003.taxon	description	DESCRIPTION AND REMARKS Propristis schweinfurthi (Fig. 4 J) 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. 4 J). 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).	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8DFF843147FEA8FD9E1023.taxon	materials_examined	EXAMINED MATERIAL. — FSAC Bouj- 141, 356 (Fig. 5 A), 357, 358, 359, 360, 361, 362, fragments of rostra.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8DFF843147FEA8FD9E1023.taxon	description	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.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8DFF843147FEA8FD9E1023.taxon	discussion	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).	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8DFF843415FAECFC6C1182.taxon	materials_examined	EXAMINED MATERIAL. — FSAC Bouj- 370, (Fig. 5 D), incomplete basioccipital.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8DFF843415FAECFC6C1182.taxon	description	DESCRIPTION The bone is ornamented by thin ridges. The insertions for the Baudelot’s ligament are ovoid and lateroventrally located.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8DFF843415FAECFC6C1182.taxon	discussion	REMARKS The basioccipital supporting the Baudelot’s ligament insertions is a feature encountered in many beryciforms and percomorphs (Johnson & Patterson 1993; Patterson & Johnson 1995). The bone shows superficial resemblances in the ornamentation with those of serranids and latids. The insertions for the Baudelot’s ligament are located more laterally in latids, and lateroventrally in serranids or Semlikiichthys Otero & Gayet, 1999 (Otero et al. 2008), like in Bouj- 370. The size, vermiculated ornamentation and circular articulation for the first vertebrae suggest that the basioccipital and the isolated centra described above belong to the same taxon.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8DFF84317DF92DFAAF1280.taxon	materials_examined	EXAMINED MATERIAL. — FSAC Bouj- 141, 363 (Fig. 5 C), 364, 365, 366, 367, 368, 369, isolated centra.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8DFF84317DF92DFAAF1280.taxon	description	DESCRIPTION The centra are amphicoelous and their height is greater than their anterioposterior length (Figs. 5 B, C). The crosssection is circular to slightly ovoid, with distinct growth rings. The surface of the centrum is ornamented by several longitudinal ridges of various sizes, separated by a thinner trabecular structure. In some centra, one or two weakly marked lateral fossae are present. Broken dorsal expansions indicate that neural arches were fused to the centrum. Bouj- 363 is slightly different than other centra in having more marked longitudinal ridges of irregular size and orientation, well-marked small lateral pits and an irregularly circular cross-section.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8DFF84317DF92DFAAF1280.taxon	discussion	REMARKS Except Bouj- 363, all centra show comparable ornamentation and size and probably correspond to the same taxon. The cylindrical shape, higher than long, and the ornamentation, formed by narrow longitudinal ridges of various sizes and trabeculae, is reminiscent of the abdominal centra of various perciforms like serranids, latids or scorpaenids. However, in these families, the ornamentation is formed by ridges of almost the same size, whereas the centra studied herein show an irregular alternation of narrow and larger ridges. Moreover, in latids and serranids the last abdominal centra show more marked lateral fossae (Otero 2004; BK pers. obs.). In some Eocene scombrids (e. g., Scomberodon Van Beneden, 1871, Scomberomorus Lacepède, 1801, Paleocybium Monsch, 2004, Neocybium Leriche, 1908 and Sphyraenodus Agassiz, 1844 from Belgium and England), the anteriormost abdominal centra are higher than long, ornamented with longitudinal ridges of irregular size and with reduced or absent lateral fossae (Leriche 1910; Monsch 2004; BK pers. obs.). The material from Gueran is considered as undetermined percomorph. Bouj- 363 is interpreted as an anterior abdominal vertebra of the same taxon.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8CFF853170F8AEFB3B147E.taxon	materials_examined	EXAMINED MATERIAL. — FSAC-Bouj- 372 (Fig. 5 G), proximal fragment of a right pectoral spine.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8CFF853170F8AEFB3B147E.taxon	description	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.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8CFF853170F8AEFB3B147E.taxon	discussion	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.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8CFF853170FF08FEC51521.taxon	materials_examined	EXAMINED MATERIAL. — FSAC Bouj- 371, (Fig. 5 E), incomplete fin spine.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8CFF853170FF08FEC51521.taxon	description	DESCRIPTION This proximal fragment of fin spine includes articular processes and a proximal portion of the shaft. The shaft is smooth and shows a lentoid cross-section. The anterior surface is dissymmetrical, the right half showing a depression. The posterior surface is crossed by a thin posterior sulcus. The lumen is well-marked but the basal bar, which extends from the two lateral articular processes, is broken. The anterior and posterior articular processes are not very developed, but they were probably smoothed by erosion.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8CFF853170FF08FEC51521.taxon	discussion	REMARKS Based on the absence of ornamentation and the morphology of the articular processes, the spine Bouj- 371 is comparable to unpaired fin spines of extant percomorphs, like serranids or latids.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8CFF85317EFC0AFC9610A3.taxon	materials_examined	EXAMINED MATERIAL. — FSAC-Bouj- 358 (Fig. 5 F), fragment of toothed bone.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8CFF85317EFC0AFC9610A3.taxon	description	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.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8CFF85317EFC0AFC9610A3.taxon	discussion	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).	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8CFF873408FD2AFAAC17FF.taxon	materials_examined	EXAMINED MATERIAL. — FSAC Bouj- 109 (Fig. 5 H), costal fragment; 352 (Fig. 5 I), fragmentary hyoplastral process; 351 (Fig. 5 J) fragmentary hypoplastron; 353 (Fig. 5 K) and 354 (Fig. 5 L), dermal plate fragments.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8CFF873408FD2AFAAC17FF.taxon	description	DESCRIPTION FSAC Bouj- 109 (Fig. 5 H) is a fragment of costal of a largesized turtle, covered by three scute parts. The thoracic rib is visible, included in the dermal bone, lentoid in cross-section and roundly protruding along the ventral costal face. The direction of the rib and scutes indicate a medial fragment of costal, not far from the neural, covered by two successive vertebrals (medially) and the corresponding pleural scute (laterally). The ornamentation of the plate is formed by irregular dichotomic sulci on a rough and granulous surface, which are features found in the basic ornamentation of Cheloniidae (Lapparent de Broin et al. 2014). FSAC Bouj- 352 (Fig 5 I), a fragmentary lateral process of right hyoplastron, and Bouj- 351 (Fig. 5 J) a subcomplete right hypoplastron, probably belong to the same individual. Both fragments show a granulous surface with protruding elongated polygones and dichotomic sulci, representing ornamentation features known in cheloniids. Digitations of hyoplastral and hypoplastral lateral processes are broken close to their base. However, they are much enveloped in the dermal callosity and seem to have shortly overtaken the callosity border. Between both lateral processes lies an important lateral fontanelle that was originally rectangular or square. The medial part of the hypoplastron, along with its counterpart, indicates a very short and narrow central fontanelle with a triangular posteromedial border, and posteriorly both hypoplastra were close and lacked digitations on their medial border. The main body of the hypoplastron is posteriorly broken anterior to the contact with the xiphiplastron, close to the area of the abdominofemoral sulcus. Anterior to the inguinal notch on the lateral hypoplastral process, an inguinal scute sulcus (i. e. the posterior inframarginal of the complete series that is present in cheloniids) joins the area of the femoroabdominal sulcus medially. The lateral hyo-hypoplastral processes are narrower than the main medial body of each hypoplastron, and consequently the lateral fontanelles are narrower than the main hypoplastral bodies and they are narrower than high. The base of each lateral, hyoplastral and hypoplastral process is also shorter than the length of the lateral fontanelles. FSAC Bouj- 353 (Fig. 5 K) and Bouj- 354 (Fig. 5 L) are fragments of dermal plate which are not located on the shell. Bouj- 354 shows a granular surface, not clearly polygonal, and probably corresponds to the same individual as Bouj- 352 (Fig. 5 I) and Bouj- 351 (Fig. 5 J). Bouj- 353 shows a comparable ornamentation.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8CFF873408FD2AFAAC17FF.taxon	discussion	REMARKS FSAC Bouj- 352 (Fig. 5 I), Bouj- 351 (Fig. 5 J) and possibly Bouj- 354 (Fig. 5 L) are parts of the same cheloniid individual, being found lying together in one piece (Fig. 5 P), which also contained Bouj- 350 (Fig. 5 M), a dermochelyid remain. Bouj- 353 (Fig. 5 K) was probably collected near this piece and corresponds to the same cheloniid and possibly to the same individual. The combination of the nearly flat bridge (not an obliquely elevated bridge), surface ornamentation, and fenestration of the plastron matches the cheloniid pattern. Only few middle to late Eocene cheloniids are known from their plastron in the Old World. Among the various cheloniid clades, some cheloniid genera were grouped in the western- European “ Eochelyinae Moody, 1968 ”, now considered as a paraphyletic taxon representing an evolutionary grade (Lapparent de Broin et al. 2014, 2018). The Gueran species, represented by Bouj- 351 and Bouj- 352, represents this grade. It differs from the defined species included in the group in the relative proportions of the hyo-hypoplastral main body, in relation to the lateral and central fontanelles. There are several species in the early Eocene of the London Clay basin (Ypresian of the Isle of Sheppey (Kent) and Harwich (Essex) (UK), described by Owen & Bell (1849) and Owen (1849 - 1884). Boujdour species is similar to “ Chelone breviceps Owen, 1842 ” (see Owen & Bell 1849: pl. 2), i. e. a junior synonym of Argillochelys antiqua (König, 1825), in the shape of the quadrangular lateral fontanelles, but it differs in the wider proportions of these lateral fontanelles correlated with a narrower hypoplastral main body, and it differs in the robustness of the plates. However, the central fontanelle was narrow and short in both species. By contrast and as A. antiqua, the Gueran species differs from “ Chelone convexa ” (undefined taxon, perhaps a junior synonym of Argillochelys cuneiceps Owen, in Owen & Bell, 1849, the shell of which is not defined), Eochelone brabantica Dollo, 1903 (Lutetian, middle Eocene of Brabant, Belgium) and Eochelone voltregana Lapparent de Broin, Murelaga, Pérez- García, Francesc Farrés & Altimiras, 2018 (Priabonian of Osona county, Spain) in the much narrower central fontanelle, the main body of each hypoplastron being wider, but it is similar in the quadrangular lateral fontanelle general proportions. And in the robustness of the plastral elements, it is similar to E. voltregana. The Gueran species also differs from Puppigerus camperi (Gray, 1831) (Ypresian of London Clay and Lutetian of Brabant) in the lateral fontanelle size and shape, this structure being much smaller and triangular in Puppigerus Cope, 1871 adults with much wider hypoplastra, in a much wider plastron as a whole (due to the more developed shell ossification characteristic of this taxon) (Moody 1974; Lapparent de Broin et al. 2018).	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8EFF873408FDE9FC2F1323.taxon	materials_examined	EXAMINED MATERIAL. — FSAC Bouj- 350 (Fig. 5 M), pelvis fragment.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8EFF873408FDE9FC2F1323.taxon	description	DESCRIPTION FSAC Bouj- 350 (Fig. 5 M) is the lateral pubic process of a right pelvis. Its distal extremity is robust and shows an irregularly lentoid epiphysis.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8EFF873408FDE9FC2F1323.taxon	discussion	REMARKS The morphology of this elongate process corresponds to that of the pubic process of the extant Dermochelys Blainvillle, 1816, in which this struture is longer than the median main body of pubis, while the pubic process is shorter and wider at its base in cheloniids. Compared with Dermochelys, in Bouj- 350 the process is slightly shorter than its basal width, the epiphysis is anterolaterally shorter and the lateroexternal border is slightly curved. The presence of a dermochelyid associated with a cheloniid in Gueran is not strange, since the same association occurs in the Priabonian of Ad-Dakhla (Morocco) and Fayum (Qasr-el-Sagha) (Egypt) (Andrews 1906; Zouhri et al. 2017). Scarce remains of these two taxa in the three localities, and absence of preserved pubic processes in Ad-Dakhla and Fayum do not provide further information.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8EFF98341CFA2CFD8C179F.taxon	materials_examined	EXAMINED MATERIAL. — FSAC Bouj- 196, fragmentary hypoplastron (Fig. 5 N).	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8EFF98341CFA2CFD8C179F.taxon	description	DESCRIPTION FSAC Bouj- 196 (Fig. 5 N) is a fragment of right hypoplastron, in the inguinal notch corner, and it bears the lateral end of the abdominofemoral sulcus. The surface is rather smooth, bright, not granulous and ornamented by not protruding polygons.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF8EFF98341CFA2CFD8C179F.taxon	discussion	REMARKS The lateral curve of the plate in the inguinal buttress area shows an obliquely elevated bridge. This is not the case in marine cryptodiran turtles: the bridge is flat in Cheloniidae and the plastron is so much reduced that there is no more bridge in Dermochelyidae (Gervais 1872: figs 7, 8). The decoration indicates an aquatic form and probably a pleurodire. In the African context at that time, this specimen ought to be a podocnemidoid turtle (Podocnemididae or Bothremydidae). The position of the femoroabdominal sulcus matches these families. By comparison with turtle distribution at Ad-Dakhla and Fayum localities, it might be a member of the littoral Stereogenyina (Zouhri et al. 2017).	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF91FF983144FDE9FD0D1261.taxon	materials_examined	EXAMINED MATERIAL. — FSAC Bouj- 95, a fragment of carapace plate.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF91FF983144FDE9FD0D1261.taxon	description	DESCRIPTION FSAC Bouj- 95 (Fig. 5 O) is a fragment of dermal plate of a carapace, covered dorsally by parts of three meeting scutes. A natural border that makes an acute angle for a ventral scute lip is present, but it is not possible to locate and orientate the plate based on this information.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF91FF983144FDE9FD0D1261.taxon	discussion	REMARKS The smooth ornamentation of the surface and the presence of a lip preclude assignment to cheloniids. This plate and Bouj- 196 might belong to the same pleurodiran taxon.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF91FF9930DBFACCFBEF1185.taxon	materials_examined	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.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF91FF9930DBFACCFBEF1185.taxon	description	DESCRIPTION The description is mainly based on FSAC Bouj- 317 (Fig. 6 A-E) but more information is drawn from FSAC Bouj- 300 (Fig. 6 F). 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.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF91FF9930DBFACCFBEF1185.taxon	discussion	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 1983 a). 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 1983 a). 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 1983 b). 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.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF93FF9B3150F8A7FE69171F.taxon	materials_examined	EXAMINED MATERIAL. — FSAC BOUJ- 355, fragment of a right dentary; 406, posterior fragment of left mandibular ramus.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF93FF9B3150F8A7FE69171F.taxon	description	DESCRIPTION FSAC BOUJ- 355 is a fragment of a left dentary (Fig. 7 I). 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. 7 J), 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.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF92FF9B3086FE69FD6712E0.taxon	description	Eusuchia indet.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF92FF9B3086FE69FD6712E0.taxon	materials_examined	EXAMINED MATERIAL. — FSAC Bouj- 410, could be the (?) ninth cervical vertebra; FSAC Bouj- 1 b, anterior? cervical vertebra; 400, posterior dorsal vertebra; 1 a, first caudal vertebra; 124, caudal vertebra; 96, two fragments of large dorsal osteoderms; 94, fragment of osteoderm.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF92FF9B3086FE69FD6712E0.taxon	description	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. 7 A). It bears a long hypapophysis, and the location of the diapophysis and parapophysis suggests that it could be the ninth cervical vertebra. Bouj- 1 b is a more anterior cervical (Fig. 7 B), 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. 7 C). 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. 7 D). 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.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF92FF9B30E4FB0BFA821043.taxon	description	Gavialoidea indet.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF92FF9B30E4FB0BFA821043.taxon	materials_examined	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.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF92FF9B30E4FB0BFA821043.taxon	description	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. 7 K). 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.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF92FF9B30E4FB0BFA821043.taxon	discussion	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. 7 I). 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).	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF92FF9E343DF8CDFDBE12E0.taxon	materials_examined	EXAMINED MATERIAL. — FSAC Bouj- 373, distal portion of maxillary rostrum bearing pseudo-teeth (two fragments).	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF92FF9E343DF8CDFDBE12E0.taxon	description	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 (PT 6) and tip of maxillary rostrum = 32.6; length between TPT 2 (left side) and tip of maxillary rostrum = 14.0; height of maxillary rostrum (apex to culmen) at the level of PT 6 = 23.4; maximal width of bill tip = 18.6; PT 1, anteroposterior length at base = 6.0; PT 1, height = 4.5; PT 2, anteroposterior length at base = 3.7; PT 2, height = 1.3; PT 4, anteroposterior length at base = 13.6; PT 4, height = 10.6; PT 6, anteroposterior length at base = 10.3; PT 6, height = 8.8; TPT 1, anteroposterior length at base = 4.2; TPT 1, height = 2.4; distance between PT 1 and PT 4 = 47.4; distance between PT 1 and PT 2 = 19.2; distance between PT 2 and PT 3 = 12.2; distance between PT 3 and PT 4 = 16.0; distance between PT 5 and PT 6 = 10.7; distance between PT 6 and TPT 1 = 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. 6 G, 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. 6 G), including one medium-sized pseudo-tooth (PT 1, rank 2) and one large pseudo-tooth (PT 4, rank 1). A small pseudo-tooth (PT 2, rank 3) and a tiny knob-like pseudo-tooth (PT 3, rank 4) are located in the space between the larger pseudo-teeth (PT 1 and PT 4). The anterior portion of the maxillary rostrum preserves two pseudo-teeth on the right side (Fig. 6 H), including one rudimentary knob-like pseudo-tooth (PT 5, rank 4) and one large pseudo-tooth (PT 6, rank 1). Rank 1 to rank 3 pseudo-teeth are conical in shape and stand vertically. On the left side (Fig. 6 J), two tomial pseudo-teeth (TT 1 and TT 2) 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 (TT 1) is preserved on the right side, the anterior one (TT 2) 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. 6 G, 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. 6 H), 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. 6 I). 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.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF97FF903175FAACFECD14FE.taxon	materials_examined	EXAMINED MATERIAL. — FSAC Bouj- 380 a, 380 b, and 380 c, dental fragments.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
03923C45FF97FF903175FAACFECD14FE.taxon	discussion	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- 380 a, 380 b, and 380 c) 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 3 D 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). 3 D 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 3 D 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 3 D 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 3 D 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. 18 D) 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- 380 a (± 3.4 to 4.6 mm), Bouj- 380 b (± 2.6 to 2.9 mm) and Bouj- 380 c (± 3.1 to 4.2 mm) approaches the rare available data for Barytherium grave (± 2 mm, ± 3.1 mm, ± 2.5 mm; plate 18 A-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 M 3, 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.	en	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. Geodiversitas 43 (5): 121-150, DOI: 10.5252/geodiversitas2021v43a5
