A New Polypterid Fish: Polypterus Faraou Sp. Nov. (Cladistia

Home , Cladistia, Polypterus palmas

Blackwell Science, LtdOxford, UKZOJZoological Journal of the Linnean Society0024-4082The Lin- nean Society of London, 2006? 2006 146? 227237 Original Article

A NEW POLYPTERID FROM THE LATE MIOCENE OF CHADO. OTERO ET AL.

Zoological Journal of the Linnean Society, 2006, 146, 227–237. With 10 figures

A new polypterid ﬁsh: Polypterus faraou sp. nov. (Cladistia, Polypteridae) from the Late Miocene, Toros-Menalla, Chad

OLGA OTERO1*, ANDOSSA LIKIUS2, PATRICK VIGNAUD1 and MICHEL BRUNET1 Downloaded from https://academic.oup.com/zoolinnean/article/146/2/227/2631032 by guest on 26 October 2020

1Laboratoire de Géobiologie, Biochronologie et Paléontologie humaine, CNRS UMR 6046, Faculté des Sciences fondamentales et appliquées, Université Poitiers, 40 av. du Recteur Pineau, F-86 022 Poitiers cedex, France 2Département de Paléontologie, Université de N’Djaména, N’Djaména, Tchad

Received June 2004; accepted for publication July 2005

Polypterus faraou sp. nov. (Cladistia, Polypteridae) from the Late Miocene of Toros-Menalla (western Djourab, Chad) is described on the basis of a subcomplete articulated skeleton preserved in three dimensions. This is the first time such a complete fossil polypterid skeleton has been described. It is the only verifiable fossil record for the genus Polypterus. P. faraou closely resembles P. bichir and P. endlicheri, extant fish found in the Chad–Chari system. Intrarelationships among the polypterids are not yet resolved: however, P. faraou shows a primitive shape of the body and a primitive shape of the opening of the lateral line on the scales, similar to that of three living species (P. bichir, P. endlicheri and P. ansorgii). © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society, 2006, 146, 227–237.

ADDITIONAL KEYWORDS: anatomy – Anthracotheriid Unit – Polypteriformes – western Djourab.

INTRODUCTION two extant genera, i.e. Polypterus, with ten species and 15 subspecies (Poll, 1941a, b, 1942; Hanssens, Teugels Palaeontological expeditions have been conducted in & Thys van der Audenaerde, 1995; Britz, 2004; there Chad since the early 1930s. In 1994, the MPFT are 11 species if P. polli is considered as a valid spe- (Mission Paléoanthropologique Franco-Tchadienne) cies), and the monotypic genus Erpetoichthys. Nine initiated a series of field missions to the Mio-Pliocene fossil genera have been described. Two have been sites of the eastern Djurab Desert in northern Chad described on the basis of isolated skull bones and (Brunet et al., 1995, 1998; Brunet & MPFT, 2000) and, scales (Meunier & Gayet, 1996; Gayet & Meunier, since 1997, to the Miocene sites of Toros-Menalla, 1991), and six others have been described on the basis western Djurab. The Anthracoteriid Unit in Toros- of the articular head of pinnules (Gayet & Meunier, Menalla has yielded a rich vertebrate fauna (Vignaud 1996; Werner & Gayet, 1997). Finally, Serenoichthys et al., 2002), the oldest known species of hominid, has been described on the basis of scale and finlet Sahelanthropus tchadensis (Brunet et al., 2002), as counts and distribution (Dutheil, 1999). Serenoichthys well as the first nearly complete and articulated skel- is the only other fossil articulated skeleton known so eton of a fossil polypterid. This polypterid belongs to a far, but the head is missing. These fossil genera are new species that is described here. The estimated age Cretaceous in age and African, except for Dagetella of the Anthracotheriid Unit is c. 7 Myr (Vignaud et al., and Latinopollia, which are of Late Cretaceous and 2002). Early Palaeocene age, respectively, and South Ameri- Polypterids (Cladistia) are basal actinopterygian can. Post-Palaeocene polypterid history is exclusively fishes (Rosen et al., 1981). They are represented by African. Isolated scales and skull bones attributed to Polypterus sp. testify to the presence of the genus in *Corresponding author. E-mail: [email protected] African freshwaters since the Eocene. Moreover, two

228 O. OTERO ET AL. types of African Cretaceous pinnules were tentatively bital space (as in P. bichir katangae and possibly in attributed to two fossil Polypterus species, P. dageti P. teugelsi, whereas it is more than 60% in P. ansorgii, (Gayet & Meunier, 1996) and P. sudanensis (Werner & and less than 45% in the other species) and orbit Gayet, 1997). The intrarelationships among poly- smaller than suboperculum width (as in P. bichir and pterids have yet to be clarified; indeed, the monophyly P. endlicheri only); prognathus lower jaw (as in and the intrarelationships among extant species have P. bichir and P. endlicheri only); at least 5–7 prespi- not been established. racular bones (the number of prespiracular bones is This paper provides the first description of a near possibly equal to or above seven only in P. weeksii, in complete fossil polypterid skeleton including cranium, P. bichir bichir and in P. endlicheri congicus); deep and it is the only clearly recognizable fossil record for body with approximately 23 transversal scales, 58–60 the genus Polypterus. The new species from the Late scale rows, and 14 predorsal scales (such body shape Downloaded from https://academic.oup.com/zoolinnean/article/146/2/227/2631032 by guest on 26 October 2020 Miocene of Toros-Menalla (western Djurab, Chad) is exists elsewhere only in P. ansorgii, P. bichir and assigned to the genus Polypterus based on its morpho- P. endlicheri); 15 finlets with successive pinnules of logical characteristics, which fall within the anatomi- the finlets overlapping the base of the following cal range of Recent species of the genus, from which it one (such dorsal fin mophology elsewhere only in differs by a unique combination of characters. We also P. ansorgii, P. bichir and P. endlicheri congicus); discuss the primitive or derived state of certain osteo- grooved lateral line scales with notched posterior mar- logical features observed in this species. gins (as in P. ansorgii, P. bichir and P. endlicheri only). The holotype is 590 mm in standard length. Such dimensions are also reached in P. bichir and SYSTEMATIC PALAEONTOLOGY P. endlicheri only. ACTINOPTERYGII COPE, 1887 Occurrence. Anthracotheriid Unit of Toros-Menalla, (SENSU ROSEN ET AL., 1981) Late Miocene of Chad. CLADISTIA COPE, 1871 POLYPTERIDAE GÜNTHER, 1870 MATERIAL AND METHODS POLYPTERUS ST HILAIRE, 1802 Type species. Polypterus bichir St Hilaire, 1802. Specimen TM090-001-039 was found lying on its back. It is preserved in three dimensions. The dorsal and lateral body surfaces have globally kept their living POLYPTERUS FARAOU SP. NOV. shape, whereas the ventral surface has collapsed (Fig. 1A–C). Most of the scales of the body are present Derivation of name. In Chadian Arabian, faraou and articulated with each other. All the bones of the means flattened. The name is given in reference to the right half of the skull are in natural position, whereas dorso-ventrally depressed head of the fish. some bones of the left side are slightly displaced. This Type specimen. TM090-001-039, housed in the Centre three-dimension preservation allows us to observe the National d’Appui à la Recherche (CNAR, N’Djamena, natural position of the bones and the shape of the cra- Chad). nium; it also allows us to measure the dimensions of the specimen (Fig. 2) and to compare some dimensions Diagnosis. A Polypterus species characterized by: and meristic data between the specimen and Recent depressed head (as in P. weeksii and P. endlicheri species. Jollie’s (1984) nomenclature of the bones is only), head length approximately 20% of body length followed. (less than 20% in other Polypterus species except P. ansorgii, P. bichir and P. endlicheri) and head width at the level of the preoperculum reaches 70% of its ANATOMICAL DESCRIPTION length (more than in any other Polypterus species); HEAD AND BODY SHAPE (FIGS 1–3) opening of the lateral line on the nasal 3 close to its posterior border (as in P. bichir and P. endlicheri, The standard length of the specimen is 59 cm (Fig. 2, whereas it is central in other species); large and a). We observe a natural dorso-ventral depression of rounded snout, shorter than the interorbital distance the head. The head length (from the front of the mouth (as in most Polypterus species except P. bichir and to the posterior level of the opercular bone) is equiva- P. palmas the snout of which is longer than the lent to about 20% of the standard length (Fig. 2, m). interorbital distance); superolateral position of the The width of the head, measured at the level of the orbit (as in P. ansorgii, P. weeksii, P. endlicheri and preoperculum, is around 70% of its length (Fig. 2, n). P. bichir, whereas the orbit is lateral in P. delhezi, The distance between the lateral border of the spira- P. ornatipinnis, P. senegalus, P. retropinnis and cular series at the level of the preoperculum is 45% of P. palmas); orbit length around the half the interor- the total length of the head (Fig. 2, o). The lower jaw is

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Figure 1. Photograph of specimen TM90-01-39, holotype of Polypterus faraou sp. nov., in A, dorsal, B, left lateral, and C, ventral views.

Figure 2. Measurements in specimen TM90-01-39, holotype of Polypterus faraou sp. nov., and ratios used in the text. prognathus. The general shape of the snout is wide (nasals 3) meet in the midline. The suboperculum is and rounded, and it is shorter than the interorbital deeper than the orbit length. The gular plates are space is wide (Fig. 2, compare c and e). The orbit has a more than twice as long as wide. The dorsal finlets superolateral position. The orbital length is 14% of the insert on the posterior five-sixths of the body. The head length (Fig. 2, p) and half the interorbital dis- axial skeleton is seen where the ventral scales are distance (Fig. 2, q). The interorbital distance is shorter placed. The left pelvic fin is preserved, whereas only than the orbit–spiracle distance. Posteriormost nasals the scaly base of the pectoral and anal fins and the

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Figure 3. Photograph and drawing of the skull of TM90-01-39, holotype of Polypterus faraou sp. nov., in dorsal view.

Figure 4. Photograph and drawing of the snout of TM90-01-39, holotype of Polypterus faraou sp. nov., in anterolateral dorsal view. proximal part of some caudal rays are preserved. The The paired nasal bones and the nostrils are in place position of the ﬁns is given (Fig. 2, h–l). on the left side but slightly displaced on the right. NASAL 1 is a curved tubular bone, where the infraorbital canal runs from the rostro-premaxilla to a lateral SNOUT, ORBIT AND UPPER JAW (FIG. 4) line pore posterior to the nostril. On the right side, a The INTERNASAL (median rostral) is the unpaired dia- small displaced piece of bone lying in the nostril open- mond-shaped bone at the front of the head. It carries ing could be a fragment of the missing right nasal 1. the ethmoid commissure. It lies dorsal to the rostro- The rounded NASAL 2 lies lateral to the internasal and premaxillae, and inserts laterally between the nasals carries the canal from the rostro-premaxillae to the 2, and posteriorly between the nasals 3. nasals 3. NASAL 3 is roughly square and joins its anti-

© 2006 The Linnean Society of London, Zoological Journal of the Linnean Society, 2006, 146, 227–237 A NEW POLYPTERID FROM THE LATE MIOCENE OF CHAD 231 mere at the midline. There are no internasal super- are aligned along the posterior border of the inter- numerary plates (they develop frequently in some temporo-supratemporals, and two are lateral. The living species, e.g. P. weeksii; Poll, 1942). The supraor- last-mentionned are diamond-shaped, and they lie bital sensory canal of either side passes posteriorly between the post-spiracular bones, the more medial through nasals 1, 2 and 3 to the frontals. The opening extrascapular plates and the posttemporal. There are from the canal within nasal 3 lies within the posterior openings of the lateral line between the extrascapular two-thirds of the bone. plates and between the lateral extrascapular plate On each side of the skull, the ROSTRO-PREMAXILLA and the posttemporal. The POSTTEMPORAL is roughly carries the infraorbital canal from the midline (inter- rectangular in shape and shows a posterior opening nasal) to the maxilla, via the lacrymal. It extends for the lateral-line canal. The posterior process is not between the nostril and the orbit, along the ventral seen. It is probably broken on the left side where the Downloaded from https://academic.oup.com/zoolinnean/article/146/2/227/2631032 by guest on 26 October 2020 margin of nasal 3, and sutures posteriorly with the scales are slightly displaced (it is present in living frontal. The ascending process of the rostro-premax- Polypterus but hidden by the scales). The posterior illa is postero-ventrally covered by the LACRYMAL. The midline scale is missing. lacrymal is a tubular bone that carries the infraorbital The PRESPIRACULAR, SPIRACULAR and POSTSPIRACU- canal from the rostro-premaxilla to the maxilla. The LAR bones border the lateral edge of the former dorsal lacrymal shows a preorbital process dorsally. The MAX- bones of the skull, from the postorbital to the posttem- ILLA reaches from the level of the nostril to the pres- poral, above the opercular series. The spiracular piracular series. The POSTORBITAL borders the back of bones lie along the postero-lateral border of the the orbit from the maxilla to the frontal, along the frontal and the lateral border of the intertemporo- leading edge of the prespiracular series. It is slightly supratemporal. The spiracular formulae are, respec- curved backwards in its caudal part, delimiting a free tively, 5–2−3 on the left side, and 7–2−4 on the right. narrow space with the lateral border of the frontal at The SPIRACLE opens along the second spiracular bone, the postero-dorsal edge of the orbit. The infraorbital above the DERMOHYAL, the dorsal face of which can be canal runs from the lacrymal to the postorbital seen. through the maxilla and to the frontal through the All of the skull rooﬁng bones have a dermal orna- postorbital. On this latter bone, there is a tiny dorsal mentation of distinctly separated tubercles covered by opening whereas the ventral one, just above the max- ganoine on their dorsal face. illa, is wide. Nasal 3 is the only bone of the snout with a dermal ornamentation of distinctly separated tubercles cov- ORBITOSPHENOID, ECTOPTERYGOID AND LATERAL ered by ganoine. The other snout bones are smooth, ETHMOID (FIG. 4) ganoine-free and with numerous small pores particu- Parts of these three bones and their spatial relation- larly in the rostral part. Caniniform teeth are devel- ships are seen in the left orbit of the specimen. oped on the ventral face of the rostro-premaxilla in front of the maxilla, and on the maxilla from the anterior tip to the midlevel of the orbits. OPERCULAR SERIES AND CHEEK (FIG. 5) The opercular series is well developed, with a large SUBOPERCULUM the dorsal extremity of which reaches DORSAL SIDE OF THE HEAD (FIGS 3 AND 4) the preorbital canal median opening, and an OPERCU- The FRONTALS are the largest bones of the head. The LUM as large as the PREOPERCULUM. The posteroven- frontal branch of the lateral canal has two openings tral process of the preoperculum is present. Two above the orbit (only one is seen on the right side of the SUPERNUMERARY CHEEK PLATES lie anterior to the fossil). It connects with the infra-orbital branch in posteroventral process, along the preoperculum ven- front of the spiracular bones, at the level of the der- tral border. Together with the process, they totally mosphenotic. According to Jollie (1984), the canal is cover the cheek. Anteriorly, the preoperculum is shared by both the frontal and the dermosphenotic at sutured with the maxilla. The preopercular sensory that point, and there is an opening on the dermosphe- canal has four openings. The ﬁrst is dorsal and is notic. Only the opening of the dermosphenotic can be located between the spiracular and postspiracular seen, but not the limits of the bone itself. It seems to be series. The second opening lies close to the posterior absent or totally incorporated in the frontal. At the border of the bone at one-quarter of its height. The postero-lateral angle of each frontal, the canal passes third is in a more ventral position, just above the ven- to the INTERTEMPORO-SUPRATEMPORAL, where it opens tral process of the preoperculum. The fourth opening in a pore midway along the length of the bone. The lies at the lower extremity of the ventral process. intertemporo-supratemporal is roughly rectangular All of the cheek bones have their surface covered by in shape. There are six EXTRASCAPULAR PLATES. Four the ganoine tubercules.

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Figure 5. Photograph and drawing of the opercular series and cheek of TM90-01-39, holotype of Polypterus faraou sp. nov., in laterodorsal view.

Figure 6. Photograph and drawing of the skull and pectoral girdle of TM90-01-39, holotype of Polypterus faraou sp. nov., in ventral view.

LOWER JAW AND GULAR AREA (FIG. 6) are not seen, and nor is the quadrate–articular arti- culation; they are hidden by the gular and the cheek The lower jaw is prognathus. The posterior level of the supernumerary plates. The coronoids and mento- suture between the DENTOSPLENIAL and the ANGULAR meckelian bones are not observable, owing to their reaches the anterior level of the supernumerary cheek internal position and small dimension. Caniniform plates. The angular–prearticular–articular sutures teeth are developed on the edge of the dentosplenial.

Ventrally, the wide and long GULAR PLATES are rays can be seen. The caudal fin starts dorsally behind mostly covered by a thin ganoin ornamentation except the last finlet at the 48th scale row, and ventrally at in their anteriormost parts. They cover nearly the the 53rd scale row. The first six dorsal and first seven whole ventral surface between the lower jaws. ventral caudal rays are preserved in their proximal Because they are slightly displaced, a medial bone is part. All scales have exposed surface covered by observable which could be the urohyal. ganoin. There are 23 scales on each transversal row across the body on either side: most of the scales of the lateral line bear a groove that opens posteriorly in a PECTORAL GIRDLE AND BASE OF THE FINS (FIGS 6, 7) notch, and some present a simple pore. There are eight The pectoral girdle is composed of stout bones. Dor- scales above and 14 below the lateral line in a trans- sally and posteriorly, the SUPRACLEITHRUM borders versal row. There are 58–60 longitudinal scales, and Downloaded from https://academic.oup.com/zoolinnean/article/146/2/227/2631032 by guest on 26 October 2020 the operculum and it covers the first scale row. Later- thus probably about 60 vertebrae (Daget & Desoutter, ally, the POSTCLEITHRUM is probably represented by a 1983). This agrees with the count of centra made bony plate broken in three fragments. It is delicately where the covering scales are displaced. The centra ornamented with smooth ganoine tubercles, and it is are typical, rounded with one median and two lateral lying above an aggregation of small scales which is the deep gutters ventral to the lateral apophysis. lateral edge of the base of the pectoral fin. Ventrally, the CLEITHRA join in the midline. They are covered anteriorly by large clavicles that articulate with one PELVIC FIN (FIG. 9) AND ANAL FIN another by two small processes and a notch. The scaly base of the left pelvic fin and the proximal part of the rays are preserved. The fin inserts behind the 31st transversal row of scales. There are at least SCALES AND FINLETS (FIG. 8), AXIAL SKELETON 11 pelvic rays. The position of the anal fin is assumed There are 15 pinnules bearing the finlets. The first based on the preceding small square scales known in inserts behind the 14th row of scales. Each pinnule is living polypterids. separated from the following one by three scale rows. They are long enough to cover the base of the following SYSTEMATIC AFFINITIES AND DISCUSSION one when folded in life. The pair of scales with which each pinnule articulates are L-shaped. The distal Polypterus faraou has a character unique to the cla- extremity of each pinnule is forked and the articular distians: the dorsal fin is composed of several finlets, base is symmetrical. On one pinnule, at least two fin each consisting of a pinnule articulated with one or

Figure 7. Photograph and drawing of the operculum, cleithrum and postcleithrum of TM90-01-39, holotype of Polypterus faraou sp. nov., in lateral view.

Figure 8. Photograph and drawing of pinnules 1–4 in place with the surrounding scales of TM90-01-39, holotype of Polypterus faraou sp. nov., in dorsal view.

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Figure 9. Photograph and drawing of the left pelvic fin of TM90-01-39, holotype of Polypterus faraou sp. nov., in lateral view. more soft rays. It also shows polypteriform character- perculum width; (6) successive pinnules overlapping istics such as absence of branchiostegals and a maxilla the base of the following ones when folded in life; (7) that carries the infraorbital sensory canal. It has grooved lateral line scales with notched posterior mar- polypterid features: infraorbital canals fused to the gin. It also has other characteristics observed in maxilla and fusion of lateral rostral bones to the pre- P. bichir, P. endlicheri and also in some other species: maxilla (Pehrson, 1947; Jollie, 1984), the presence of (1) superolateral position of the orbit (P. ansorgii, spiracular bones, the preoperculum covering the cheek P. weeksii); (2) 5–7 prespiracular bones (P. ornatipin- and three separate nasal bones. The lateral-line sys- nis, P. weeksii); (3) 15 finlets (P. ansorgii); (4) deep body, tem on the head of Polypterus faraou conforms to the with 46 transversal scales and 58 scale rows common pattern described by Jollie (1984) for living (P. ornatipinnis, P. ansorgii, P. weeksii); (5) only 14 pre- polypterids. dorsal scales (P. delhezi); (6) known maximum stan- Polypterus faraou has symmetrical pinnules as in dard length of 590 mm (P. ornatipinnis). Moreover, Recent Polypterus species and in Erpetoichthys, Polypterus faraou differs from P. bichir and resembles whereas a different structure of the articular head of P. endlicheri based on its depressed head, and large the pinnules characterized the fossil genera described and rounded snout which is shorter than the interor- by Gayet & Meunier (1996) and Werner & Gayet bital distance; it differs from P. endlicheri and resem- (1997) (see Introduction). It also differs from Ser- bles P. bichir katangae based on its orbital length, enoichthys, in which the body is much shorter than which is 50% of the interorbital space in adults (less in Recent genera (Dutheil, 1999). However, it does than 40% in adults of P. endlicheri subspecies and not show the elongation of the body as observed in P. bichir subspecies bichir and lapradei). Finally, Erpetoichthys, nor the reductive characters of that Polypterus faraou is also the only Polypterus species genus, e.g. no suboperculars and no supernumerary with such a wide head: the head width at the level of cheek plates (Smith, 1865; Poll, 1941b; O. Otero, pers. the preoperculum is about 70% of the length; this can observ.). Moreover, at least one of the pinnule bears at also be expressed by the distance between the lateral least two rays as in Recent Polypterus species, by con- borders of the spiracular series (at the level of the pre- trast with Erpetoichthys, the pinnules of which bear operculum), which is 45% of the head length whereas one single fin ray (Daget, 1950; O. Otero, pers. observ.). it is around one-third in large specimens of P. bichir. From this evidence, we assign the new species to the In conclusion, the new taxon is assigned to the genus Polypterus. genus Polypterus based on its morphological charac- Poll (1941a, b, 1942, 1965) described the Recent teristics, which fall into the range observed in the spe- polypterid species and defined six anatomically based cies of the genus, particularly the cluster P. endlicheri clusters of species and subspecies organized on ana- – P. bichir, from which it differs by a unique combina- tomical trends deriving from a central type (Fig. 10A). tion of characters. The suggestion that the cluster The possible phylogenetic significance of these clusters formed by P. faraou and the Recent P. endlicheri and has not been established; they only have a descriptive P. bichir (Fig. 10A) is a natural group will need to be value. Polypterus faraou belongs to the P. bichir – tested as intrarelationships among Polypterus species P. endlicheri cluster with: (1) head length about 20% of are still unknown. Nevertheless, this hypothesis is in body length; (2) head depressed; (3) prognathus jaw; (4) agreement with the distribution of extant species: opening of the lateral line on the nasal 3 close to its pos- among the three polypterid fishes living in the Chad– terior border; (5) orbit length smaller than the subo- Chari system, P. endlicheri and P. bichir are present

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Figure 10. The Recent polypterid species and Polypterus faraou sp. nov. (A) Position of the species in the anatomically based clusters of species, as deﬁned by Poll, P. teugelsi not included (see Britz, 2004, for discussion), and (B) distribution in the African hydrographical basins; data from FishBase (Froese & Pauly, 2005) and map of the ichthyofaunic regions of Africa from Roberts (1975).

(Fig. 10B), as represented by P. endlicheri endlicheri and for the ﬁrst time they are both observed in a fossil and P. bichir bichir; the third one is P. senegalus attributed to the genus Polypterus: (Gosse, 1990). However, the phylogenetic relation- ships of Recent polypterids must be established before 1. The scales of the lateral line bear a groove that we can draw any biogeographical inferences. A cladis- opens posteriorly in a notch and this is regarded as tic analysis on the basis of anatomical characters will a primitive state for polypteriforms. The derived require further anatomical review of the species, state is thought to be lateral line pores piercing the which seem morphologically so close to each other and body of the scale. This assumption was made by differ mainly in their combination of characteristics. Poll on the basis of ontogenetic arguments. Moreover, difﬁculty exists in choosing an outgroup P. faraou shows this character state, as do P. bichir, because (1) the closely related Erpetoichthys must be P. endlicheri and P. ansorgii. included as an ingroup in such an analysis (this mono- 2. A deep and short body (low vertebrae count) is a typic genus is characterized by reductive characters primitive state for polypteriforms. This assumption and the elongation of the body; it thus could be more (Daget & Desoutter, 1983) is congruent with the closely related to one of the species of Polypterus), and body shape of the Cretaceous Serenoichthys (as (2) the related fossils are only known by their pinnules noted by Dutheil, 1999), and also with the general and/or scales, except Serenoichthys (see Introduction). observations made on the elongation of the body However, two anatomical characters have been dis- among actinopterygians. P. faraou has a short and cussed previously in terms of primitive/derived states, deep body with 46 scales in a transversal row, as

in P. bichir, P. endlicheri, P. weeksii and P. ansorgii, Fronty P, Geraads D, LehmannT, Lihoreau F, and with fewer than 60 scales in a longitudinal row, Louchart A, Adoum M, Merceron G, Mouchelin G, as in all Recent species except P. ornatipinnis, Otero O, Pelaez Campomanes P, Ponce de Leon M, P. bichir and Erpetoichthys. We can also consider Rage JC, Sapanet M, Schuster M, Sudre J, Tassy P, the trend to anguilliform shape through the posi- Valentin X, Vignaud P, Viriot L, Zazzo A. 2002. A new tion and the count of the dorsal finlets. On this hominid from the Upper Miocene of Chad, Central Africa. basis, P. faraou has no anguilliform character, the Nature 418: 145–151. number of pinnules being greater than 12, and the Daget J. 1950. Révision des affinités phylogénétiques des count of predorsal scales being lower than 15 (as in Polyptéridés. Mémoires de l’Institut Français d’Afrique Noire 11: 1–178. P. bichir, P. endlicheri and P. ansorgii). Daget J, Desoutter M. 1983. Essais de classification cladis- Downloaded from https://academic.oup.com/zoolinnean/article/146/2/227/2631032 by guest on 26 October 2020 The polypterid from Toros-Menalla (western tique des polyptéridés (Pisces; Brachiopterygii). Bulletin du Djurab, Chad) described here is the first fossil speci- Muséum National d’Histoire Naturelle, Paris, Série A 4: 661– men known by a near complete articulated skeleton 674. including a cranium. It is assigned to the genus Dutheil D. 1999. The first articulated fossil cladistian: Ser- Polypterus and recognized as a new species, Polypterus enoichthys kemkemensis gen. et sp. nov., from the Creta- faraou. It is c. 7 Myr in age (Vignaud et al., 2002). ceous of Morocco. Journal of Vertebrate Paleontology 19: 243–246. Froese R, Pauly D (eds). 2005. FishBase. World Wide Web ACKNOWLEDGEMENTS electronic publication. www.fishbase.org. We thank the Chadian authorities (Ministère de Gayet M, Meunier F. 1991. First discovery of Polypteridae l’Education Nationale et de la Recherche, Université (Pisces, Cladistia, Polypteriformes) outside of Africa. Géobios 24: 463–467. de N’Djaména, CNAR). For their support, we extend Gayet M, Meunier F. 1996. Nouveaux Polypteriformes du our gratitude to the French Ministère de l’Enseigne- Coniacien-Sénonien d’In Becetem (Niger). Comptes Ren- ment supérieur, de la Recherche et de la Technologie dus de l’Académie des Sciences, Paris, Série IIa 322: 701– (CNRS; Université de Poitiers) and the Ministère 707. des Affaires Etrangères (DCSUR, Paris; Coopération Gosse J-P. 1990. Polypteridae. In: Lévêque C, Paugy D, Teu- SCAC, N’Djaména), to the Région Poitou-Charentes gels GG, eds. Faune des poissons d’eaux douces et saumâtres and the Département de la Vienne. The MPFT field- d’Afrique de l’Ouest I. MRAC Orstom, collection faune trop- work is also supported by an NSF/RHOI Grant. 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