The Libycosaurus (Hippopotamoidea, Artiodactyla) intercontinental dispersal event at the early late Miocene revealed by new fossil remains from Kasserine area, Tunisia Fabrice Lihoreau, El Mabrouk Essid, Hayet Khayati Ammar, Laurent Marivaux, Wissem Marzougui, Rodolphe Tabuce, Rim Temani, Monique Vianey-Liaud, Gilles Merzeraud

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Fabrice Lihoreau, El Mabrouk Essid, Hayet Khayati Ammar, Laurent Marivaux, Wissem Marzougui, et al.. The Libycosaurus (Hippopotamoidea, Artiodactyla) intercontinental dispersal event at the early late Miocene revealed by new fossil remains from Kasserine area, Tunisia. Historical Biology, Taylor & Francis, 2021, 33 (2), pp.146-158. ￿10.1080/08912963.2019.1596088￿. ￿hal-02082905￿

HAL Id: hal-02082905 https://hal.umontpellier.fr/hal-02082905 Submitted on 4 Nov 2020

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The Libycosaurus (Hippopotamoidea, Artiodactyla) intercontinental dispersal event at the early Late Miocene revealed by new fossil remains from Kasserine area, Tunisia

Journal: Historical Biology

Manuscript ID GHBI-2018-0166.R2

Manuscript Type: Original Article

Date Submitted by the n/a Author:

Complete List of Authors: Lihoreau, Fabrice; Institut des sciences de l'évolution Essid, El Mebrouk ; Office National des Mines (ONM) Hayet Khayati Ammar, Hayet ; Office National des Mines (ONM) Marivaux, Laurent; Institut des sciences de l'évolution Marzougui, Wissem ; Office National des Mines (ONM) Tabuce, Rodolphe; Institut des sciences de l'evolution, Forme Temani, Rim; Office National des Mines (ONM) Vianey-Liaud, Monique; Institut des sciences de l'evolution, Forme Merzeraud, Gilles; Geosciences Montpellier

Cladistic analysis, Bothriodontinae, Merycopotamini, Sahara, Tortonian, Keywords: dispersal events

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1 2 3 The Libycosaurus (Hippopotamoidea, Artiodactyla) intercontinental 4 5 6 dispersal event at the early Late Miocene revealed by new fossil 7 8 9 remains from Kasserine area, Tunisia 10 11 12 13 14 Fabrice Lihoreaua*, El Mabrouk Essidb, Hayet Khayati Ammarb, Laurent Marivauxa, 15 16 b a b a 17 Wissem Marzougui , Rodolphe Tabuce , Rim Temani , Monique Vianey-Liaud and 18 For Peer Review Only 19 Gilles Merzeraudc 20 21 22 23 aInstitut des Sciences de l’Evolution de Montpellier, Univ. Montpellier CNRS IRD 24 25 26 EPHE, Montpellier, France 27 28 bService Géologique, Office National des Mines, Tunis, Tunisia 29 30 cGéosciences Montpellier, Univ. Montpellier CNRS, Montpellier, France 31 32 33 34 35 *Corresponding author: Institut des Sciences de l’Evolution de Montpellier, Université 36 37 de Montpellier, cc064 place eugène Bataillon 34095 Montpellier cedex, France, 38 39 40 [email protected] 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 3 The Libycosaurus (Hippopotamoidea, Artiodactyla) intercontinental 4 5 6 dispersal event at the early Late Miocene revealed by new fossil 7 8 9 remains from Kasserine area, Tunisia 10 11 12 13 14 15 Anthracotheres dispersed from Asia toward Africa at least three times: at the 16 17 Eocene/Oligocene transition, during early Miocene and later during the Miocene. 18 For Peer Review Only 19 Those dispersals are important datum events for African tertiary biochronology. 20 21 New fossil remains of early Libycosaurus, the genus implicated in the Late 22 23 Miocene dispersal, are described from a new Tunisian locality of the Kasserine 24 25 area. The new fossils enhance the hypodigm of Libycosaurus algeriensis and 26 27 permit increased resolution of the phylogenetic position of this species using 28 29 30 cladistics analysis. The inclusion of the genus Libycosaurus within the well- 31 32 described Merycopotamus lineage allows us to constrain its dispersal time. 33 34 Dispersal of this anthracothere from the Indian sub-continent to Africa was 35 36 probably facilitated by sea level decrease during the early Tortonian, just 37 38 preceding the Hipparion dispersal event. This new age estimation refines the 39 40 resolution of the succession of late Miocene deposits in the Maghreb and frames 41 42 the date of the onset of the Sahara. 43 44 45 46 Keywords: Cladistic analysis, Bothriodontinae, Merycopotamini, Sahara, 47 48 Tortonian, dispersal events 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 3 Introduction 4 5 6 7 8 Anthracotheres are an extinct family of morphologically and ecologically diverse 9 10 cetartiodactyls, usually interpreted as swampy environment inhabitants. Within the 11 12 superfamily Hippopotamoidea, the anthracotheres are considered closely related to the 13 14 15 Hippopotamidae (e.g., Boisserie et al. 2011; Lihoreau, Boisserie, et al. 2015), but parts 16 17 of the branching sequence within this clade are still unclear; as such the content of some 18 For Peer Review Only 19 anthracothere genera requires revisions. Anthracotheres are also particularly remarkable 20 21 22 as they display unusual dispersal abilities, leading several palaeontologists to regard 23 24 them as ‘ungulate pioneers’ in most of the intercontinental dispersal events (e.g., 25 26 Ducrocq 1995; Lihoreau and Ducrocq 2007; Holroyd et al. 2010; Grandi and Bona 27 28 29 2017; Scherler et al. 2018). 30 31 The last African genus of anthracotheres, Libycosaurus, engaged in a form of 32 33 semi-aquatic-lifestyle as indicated by the marked specialisation of its skeleton and its 34 35 paleobiology (Lihoreau et al. 2006; Lihoreau et al. 2014). During the middle-late 36 37 38 Miocene in Africa, Libycosaurus underwent a spectacular evolution characterized by a 39 40 substantial body size change and a diet shifting (increase in C4-plant consumption), 41 42 associated with social modifications notably with sexual size dimorphism and indices of 43 44 45 fight between males (Lihoreau et al. 2014). This evolution was linked to the reduction 46 47 of Libycosaurus habitat through change of the river system probably due to the variation 48 49 of Sahara expansion. However, the evolutionary history of the genus is incomplete, as 50 51 52 the origin of the genus remains unclear. A recent validation of the small and 53 54 plesiomorphic species Libycosaurus algeriensis Ducrocq et al. 2001, with new material 55 56 from the locality of Bir el Ater 3 (Algeria), highlighted the possibility that Libycosaurus 57 58 59 60

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1 2 3 originated in Africa during the middle Miocene following the arrival of its ancestor 4 5 6 from the Indian subcontinent (Lihoreau, Hautier, et al. 2015). 7 8 We recently discovered new fossils attributable to Libycosaurus algeriensis in 9 10 Tunisia, from Sidi Hedri, a new locality situated near the town of Kasserine. We 11 12 describe here this new fossil material, which provides previously unknown elements for 13 14 15 documenting the basal morphotype of the genus. We perform a cladistic assessment 16 17 incorporating these new data with previously known morphological evidence, in order 18 For Peer Review Only 19 to formalize the position of Libycosaurus within the anthracotheres. The original 20 21 22 phylogeny discussed in this study constrains a paleobiogeographic scenario prior to the 23 24 initiation of the Sahara desert and contemporaneous to a major sea-level drop. This 25 26 scenario refines the age estimates of some North African vertebrate fossil-bearing 27 28 29 deposits of the Miocene epoch. 30 31 32 33 Materials and Methods 34 35 36 37 38 Provenance of the new fossil material 39 40 The new material was discovered in the western part of central Tunisia, in the Kasserine 41 42 region, north of the Djebel Chambi (Fig. 1). The locality yielded three specimens 43 44 45 belonging to the same taxon, due to coherence in size and morphology. The new 46 47 remains consist of a right upper canine (SHI01), a right lower mandible with P/3-M/2 48 49 (SHI02) and a left M/3 (SHI03). These fossils were found during our 2012 field 50 51 52 expedition and come from a unique locality, Sidi Hedri, corresponding to a limited spot 53 54 and horizon (F4 on Fig. 1). The name locality is due to its proximity to the Marabout of 55 56 Sidi Hedri. The material is housed in the paleontological collections of the Museum of 57 58 the Office National des Mines (ONM) in Tunis, Tunisia. 59 60

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1 2 3 Material for comparisons is abbreviated as follows: M, material from the Natural 4 5 6 History Museum, London, NG, material from Nagri Fm. Pakistan housed at the Utrecht 7 8 University, Utrecht, Y, material from Potwar Plateau housed at the Harvard Peabody 9 10 Museum, Cambridge, and CUWM material from Wadi Moghra housed at Cairo 11 12 University, Cairo. 13 14 15 16 17 Stratigraphical context 18 For Peer Review Only 19 The new Sidi Hedri fossil-bearing locality is situated in the Bir-Om-Ali stratigraphic 20 21 22 section (Fig. 1; Vialle et al. 2013; Sweydan et al. 2018), north side of the Djebel 23 24 Chambi. This section overlies laterally the late early to early middle Eocene fossil- 25 26 bearing localities of Chambi locus 1 (CBI-1) and Chambi locus 2 (CBI-2), which have 27 28 29 yielded numerous fossil remains of key taxa documenting the early evolutionary history 30 31 of several vertebrates from Africa (e.g., Marivaux et al. 2015, Ravel et al. 2016, 32 33 Mourer-chauviré et al. 2016, Tabuce 2018). The section contains the late Eocene 34 35 locality of Bir-Om-Ali that yielded fragmentary fossil remains of the embrithopod 36 37 38 Arsinoitherium (Vialle et al. 2013; F2 on Fig. 1), the fossiliferous locality of Mabrouk, a 39 40 level with reworked marine fossils dated from the late Eocene-early Oligocene 41 42 (Sweydan et al. 2018; F3 on Fig. 1), and a Neogene fine grained sandstone 43 44 45 corresponding to the Sidi Hedri locality (F4 on Fig. 1). The Sidi Hedri fossiliferous 46 47 horizon overlies alluvial-fan conglomerates in a unit consisting of fluvio-deltaic 48 49 deposits. This unit was generally considered as belonging to the Beglia Formation (Fm.) 50 51 52 but the definition of this formation might be taken with caution (e.g., Mannaï-Tayech 53 54 2006; Mannaï-Tayech 2009; Belghithi et al. 2016). The sandstone attributed by 55 56 Hartenberger et al. (2001) to the Beglia Fm. in fact corresponds to the uppermost 57 58 Paleogene levels where the Mabrouk locality occurs (Sweydan et al. 2018). The 59 60

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1 2 3 geological study made by Hartenberger et al. (2001) did not include the area where the 4 5 6 Neogene sediments outcrop. Furthermore, recent discussion of the Miocene sandstones 7 8 capping the Nementcha Fm. in Algeria (Lihoreau, Hautier, et al. 2015), only 130 km 9 10 southwest of Sidi Hedri, highlighted the critical role of fossil assemblage in correlating 11 12 between continental formations, and demonstrates that it is best to avoid using only 13 14 15 facies correlation for precise dating. 16 17 The Neogene deposits in Tunisia unconformably overlie the latest Paleogene 18 For Peer Review Only 19 deposits (Swezey 2009). The Neogene sandstones resulted from fluviatile system 20 21 22 deposits in deltaic context over a long period of time, ranging from the Serravalian up to 23 24 the late Tortonian (Belghithi et al. 2016). They are usually gathered in formations 25 26 (Beglia Fm., Saouaf Fm., and Segui Fm.), but the variety of facies and the progradation 27 28 29 of the system make lithostratigraphy unreliable at a regional scale. In Tunisia, the 30 31 Neogene deposits yield two important fossil vertebrate faunas that provide constraints 32 33 on the age and chronology of associated formations. First, the locality of Bled Douarah 34 35 (Beglia Fm, western Tunisia) is assigned to the late Serravalian-early Tortonian in age 36 37 38 (Werdelin 2010). Bled Douarah is divided in to two sedimentological units, likely 39 40 corresponding to different environmental deposits and possibly climates (Mannaï- 41 42 Tayech 2009). The faunal assemblages in each unit differ. Only the upper unit has 43 44 45 yielded equids (Robinson and Black 1969; Robinson and Black 1974) and seems to 46 47 represent more forested and more humid conditions (Mannaï-Tayech 2009). The arrival 48 49 of equids in Africa is estimated close to 10.5 Ma (early Tortonian; Bernor et al. 2010). 50 51 52 Using the equid biotic marker, the earliest deposits referred to the Beglia Fm. are 53 54 estimated to document deposits dating near the Serravalian/Tortonian transition (Biely 55 56 et al. 1972; Mannaï-Tayech 2009; following Hilgen et al. 2012), or near the beginning 57 58 of the marine regression recorded during the earliest Serravalian (13.8 Ma following 59 60

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1 2 3 Hilgen et al. 2012; Belghithi et al. 2016). Recently, a part of the Beglia Fm. in western 4 5 6 Tunisia was correlated to the Saouaf Fm. in eastern Tunisia (Mannaï-Tayech 2009; 7 8 Belghithi et al. 2016). The second fossil vertebrate fauna is from the Djebel Khechrem 9 10 El Artsouma (Geraads 1989) and belongs to the Segui Fm., stratigraphically overlying 11 12 the Beglia Fm. (Mannaï-Tayech 2009; Belghithi et al. 2016). This locality is estimated 13 14 15 to be 0.5 to 1 myr more recent than the fauna from Bled Douarah (Geraads 1989). 16 17 Several other localities from the Neogene silicoclastic deposits of Tunisia are known 18 For Peer Review Only 19 but cannot be precisely dated due to the scarcity of the material or poorly time 20 21 22 constrained taxa (e.g., (Mannaï-Tayech and Otero 2005). 23 24 25 26 Anatomy and cladistics analyses 27 28 29 The teeth description follows the dental nomenclature established for Hippopotamoidea 30 31 (Boisserie et al. 2010). Tooth measurements follow Lihoreau et al. (2014). A 32 33 calculation of the flattening index (fli) of the canine follows Kostopoulos et al. (2012), 34 35 which consists of a ratio at the cervix between the mesio-distal length and the labio- 36 37 38 lingual length (Lmd/Lll*100). 39 40 We consider the new fossil material described here as Libycosaurus algeriensis, 41 42 a species previously described in Algeria (Ducrocq et al. 2001; Lihoreau, Hautier, et al. 43 44 45 2015). Some of this material complements the hypodigm of this species. The new 46 47 material betters our knowledge of L. algeriensis, and facilitates inclusion of L. 48 49 algeriensis into a phylogenetic matrix incorporating recent matrices assembled for 50 51 52 deciphering internal phylogenetic relationships among taxa of the superfamily 53 54 Hippopotamoidea (including the “Anthracotheriidae” and the Hippopotamidae). Here, 55 56 we use the latest character matrices dealing with Merycopotamini (Lihoreau et al. 2016) 57 58 and with Hippopotaminae (Boisserie et al. 2017), as well as some updates (supp. data). 59 60

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1 2 3 We added recent data for the species Bothriogenys andrewsi Schmidt, 1913, for which 4 5 6 new material was recently published (Sileem et al. 2015), leading to better character 7 8 scoring for Bo. andrewsi compared to previous analyses (Lihoreau, Boisserie, et al. 9 10 2015). Then, we added four new characters that deal with the morphological conditions 11 12 describing the genus Libycosaurus with respect to the other genera. We coded, on lower 13 14 15 molars, the morphology of the postentocristid (= entoconid fold, 63, supp. data) and the 16 17 pattern of incomplete hypoconulid (80, supp. data); on upper molars, the relation 18 For Peer Review Only 19 between the mesostyle and cingulum (139, supp. data); and on the mandible, the 20 21 22 presence and morphology of a notch (156, supp. data). We also added the position of 23 24 the main palatine foramen, a diagnostic character in Merycopotamus species (162; 25 26 Lihoreau et al. 2004; character already used in Boisserie et al. 2005). All characters are 27 28 29 unordered and unweighted. Parsimony analyses were performed on the new matrix (64 30 31 taxa and 181 characters) with PAUP 4.0a164 (Swofford 2002) using heuristic searches 32 33 with random step-wise addition (1000 replications with randomized input order of taxa) 34 35 and tree-bisection-reconnection branch swapping options. We calculated the Bremer 36 37 38 support for each node up to five supplementary steps. 39 40 41 42 Systematic Paleontology 43 44 45 46 47 Order Artiodactyla Owen, 1848 48 49 Suborder Cetancodonta Arnason et al., 2000 50 51 52 Superfamily Hippopotamoidea Gray, 1821 (sensu Gentry and Hooker 1988) 53 54 Subfamily Bothriodontinae Scott, 1940 55 56 Tribe Merycopotamini Lydekker, 1883 57 58 Genus Libycosaurus Bonarelli, 1947 59 60

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1 2 3 4 5 6 Type-Species. Libycosaurus petrocchii Bonarelli, 1947 (but see Lihoreau et al. 2014). 7 8 Included Species. Libycosaurus anisae Black, 1972 from Bled Dourah and Djebel 9 10 Kechrem el Artsouma, Tunisia (Geraads 1989), L. bahri Lihoreau et al., 2014 from 11 12 Toros-Ménalla, Chad and As Sahabi Libya (Lihoreau et al. 2014), and L. algeriensis 13 14 15 Ducrocq et al., 2001. 16 17 Stratigraphic range. Late Miocene (Tortonian to early Messinian). 18 For Peer Review Only 19 Geographic distribution. North and Central Africa (Libya, Algeria, Tunisia, Chad, 20 21 22 Uganda). 23 24 25 26 Libycosaurus algeriensis Ducrocq et al., 2001 27 28 29 30 31 Holotype. Fragmentary left maxilla bearing M2/-M3/ (UONM1). 32 33 New material. A right upper canine (SHI01), a fragment of right mandible preserving 34 35 P/3-M/2 (SHI02), and a fragment of left mandible bearing M/3 (SHI03). This material is 36 37 38 housed at the ONM, Tunis, Tunisia. 39 40 Type locality. Bir el Ater 2, Nementcha mountains, Algeria. 41 42 Other locality. Bir el Ater 3, Algeria (Lihoreau, Hautier et al. 2015), Sidi Hedri, north of 43 44 45 Djebel Chambi, western part of central Tunisia (Fig. 1), and possibly Oluka, Kakara 46 47 Fm. Uganda (Pickford 1991a). 48 49 Type horizon. Nementcha Fm., considered to be late Serravalian/early Tortonian in age 50 51 52 (Lihoreau, Hautier, et al. 2015). 53 54 55 56 Diagnosis (emended from Lihoreau, Hautier and Mahboubi 2015). Smallest known 57 58 species of the genus; retention of a small endometacristid on lower molars that connects 59 60

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1 2 3 the preprotocristid; ectocristylids form cusplets in the transverse valleys near a 4 5 6 developed labial cingulid; only one postentostylid on the posthypocristulid separated to 7 8 the hypoconulid apex by a lingual groove; enamel microstructure of molars retains large 9 10 and blurry Hunter Schreger Bands; shallow mandible with a weak vascular impression; 11 12 retention of a lingual cingulum around the protocone in upper molars, even in worn 13 14 15 specimen. 16 17 Differential diagnosis. Libycosaurus algeriensis differs from other species of the genus 18 For Peer Review Only 19 (L. anisae and L. bahri) in its smaller dimensions with shallow mandible, the presence a 20 21 22 small endometacristid on lower molars, the ectocristylids frequently developed in 23 24 cusplets in the transverse valleys, which is rare in other species, the large lingual 25 26 cingulum around the protocone of upper molars (even in worn specimens), and in the 27 28 29 preprotocristid on p/4, which is directed mesially then lingually as in most 30 31 Merycopotamini and unlike in the two other species of Libycosaurus. It also differs 32 33 from L. anisae in the presence of only one entostylid on the third lobe of the M/3. It also 34 35 differs from L. bahri in the presence of a posthypocristulid on M/3, the retention of a 36 37 38 weak vascular impression on the mandible, and in the presence of large and blurry 39 40 Hunter Schreger Bands on the tooth enamel. 41 42 43 44 45 Comparative descriptions 46 47 Upper canine (SHI01). The crown apex is broken but wear facet and crown section are 48 49 visible (Fig. 2). The cervix section is tear-shaped with a sharp distal keel, a swollen 50 51 52 labial border and a flatter lingual border. The mesial border is rounded and bears the 53 54 worn part of the tooth. The enamel appears thin and finely wrinkled. The whole tooth 55 56 (crown plus root) is slightly inclined outward. The root is covered by cement, displays 57 58 at least three constrictions toward the root apex, and remains open at its apex. 59 60

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1 2 3 Considering the canine morphology and the enamel ornamentation, both gathered 4 5 6 conditions expected for a bothriodontine anthracothere. In Bothriodon velaunum Cuvier, 7 8 1824, an early Oligocene bothriodontine, the upper canine of males exhibits a clear 9 10 demarcation at the cervix, with a smaller crown. On SHI01, the crown appears to be in 11 12 continuity with the root. The SHI01 canine has a similar morphology of transverse 13 14 15 section to that of Elomeryx, another Oligocene bothriodontine, but differs in being more 16 17 transversally compressed (Flattening index = 53.6% in E. borbonicus (Geais, 1934; see 18 For Peer Review Only 19 Kostopoulos et al. 2012) and 60.9% in SHI01). SHI01 is larger than E. borbonicus and 20 21 22 lacks the serration on the distal keel that is visible on the canine of E. borbonicus. 23 24 Upper canines are known in few merycopotamine species. Afromeryx zelteni 25 26 Pickford, 1991b, a stem Merycopotamini, displays a round and smaller upper canine 27 28 29 section at the cervix (M82211). Merycopotamus medioximus Lihoreau et al., 2004, 30 31 shows a canine of comparable dimension (Table 1, Fig. 2), with a similar wrinkled 32 33 enamel characterized by longitudinal striations, and equivalent crown height proportion 34 35 (NG104; Lihoreau et al. 2004). The labial border seems to be more swollen than in 36 37 38 SHI01. There is a keel running on the distal border of the tooth, and a slight one is 39 40 visible on the mesial border. In Merycopotamus dissimilis (Falconer and Cautley, 1836), 41 42 the canine section is larger (Fig. 2), subcircular with slight distal and mesial keels in the 43 44 45 three known specimens (Y49776, M16551, and M16552). The enamel covers at one 46 47 third of the total length of the tooth. The root is closed and covered with cement in the 48 49 only specimen where it is observable (Y49776; Lihoreau et al. 2007). Indeed, despite 50 51 52 the marked similarities with the canine of M. medioximus, the SHI01 canine also shares 53 54 anatomical traits with the canines of the two other species of Libycosaurus (L. anisae 55 56 and L. bahri), notably in the lack of mesial keel, the presence of a lingual flattening of 57 58 the crown section at the cervix, an open root apex, and in the presence of longitudinal 59 60

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1 2 3 grooves both on the labial and lingual sides of the root, which are not marked in canines 4 5 6 of Merycopotamus (Pickford 2006; Lihoreau et al. 2014). The SHI01 canine has smaller 7 8 dimensions at cervix than the upper canine of L. anisae (Black 1972; Pickford 2006) 9 10 and that of L. bahri (Lihoreau et al. 2014; Fig. 2D; Table 1). It is also more curved. A 11 12 similar small radius of curvature occurs in upper canines of Merycopotamus. 13 14 15 16 17 Lower premolars (P/3-4 on SHI02). The premolars are narrow and dominated by a 18 For Peer Review Only 19 salient protoconid, which occupies a labial position (Fig. 3-4). A short and trenchant 20 21 22 preprotocristid joins the mesio-lingual margin of the tooth. It is adorned with three 23 24 successive small cusplets that decrease in height before reaching the mesial cingulid 25 26 (Fig. 3A-B, Fig. 4A). Such an unusual cusplets organization/striation is typical of 27 28 29 Merycopotamini, but such an amount of accessory cuspids on P/3 and P/4 is only 30 31 known in species of Libycosaurus (Fig 4B-C) and in Hemimeryx blanfordi Lydekker, 32 33 1883 (Lihoreau et al. 2016; Fig. 4). The preprotocristid on P/4 has a mesial orientation 34 35 near the protoconid apex and turns abruptly distally, a pattern proposed as a features of 36 37 38 the Merycopotamini (Lihoreau et al. 2016; Fig. 4). This structure is less marked in the 39 40 latest known Merycopotamini, such as L. anisae and L. bahri, and in M. dissimilis (Fig. 41 42 4B-C, F). The postprotocristid is slightly arched and has a lingual position with respect 43 44 45 to the protoconid, also a Merycopotamini trait. The postprotocristid reaches a hypoconid 46 47 and then the distal cingulid in a small distostylid (Fig. 4). An endoprotocristid emerges 48 49 from the postprotocristid and reaches an entostylid (larger on P/4 than on P/3). The 50 51 52 premolars are narrower than those of L. anisae and L. bahri (Table 1), and equal the size 53 54 of Merycopotamus nanus Falconer, 1868 and Sivameryx spp. The P/4 seems slightly 55 56 smaller than the only known P/4 of L. algeriensis (Ducrocq et al. 2001). The mandibular 57 58 59 60

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1 2 3 depth below M/1 is similar to the mean depth in Sivameryx spp. (Table 1) and to the 4 5 6 lowest values of M. nanus and M. medioximus. 7 8 9 10 Lower molar. Unfortunately, the right lower molars M/1-2 preserved on SHI02 are 11 12 worn and badly preserved. The M/1 is similar in size to that of Sivameryx and 13 14 15 Merycopotamus spp. (Table 1). The left M/3 is well preserved (SHI03; Fig. 5) and 16 17 displays a bothriodontine pattern, which is characterized by an important development 18 For Peer Review Only 19 of the cristids, notably the long prehypocristid that reaches the lingual margin of the 20 21 22 tooth. It also exhibits some Merycopotamini characters such as the lack of connection 23 24 between the premeta- and preprotocristids, and the pinched loop-like hypoconulid 25 26 (Lihoreau et al. 2016). Furthermore, the SHI03 M/3 lacks the premetacristid, displays a 27 28 29 pinched postentocristid between the entoconid and the posthypocristid, and a notched 30 31 posthypocristulid (an incomplete loop-like hypoconulid), all of which are diagnostic 32 33 traits of Libycosaurus (Lihoreau, Hautier, et al. 2015). Mesial to the posthypocristulid 34 35 notch, there is a marked postentostylid. This pattern is observed in all known specimens 36 37 38 of L. algeriensis and some M. medioximus. However, it differs from that characterizing 39 40 M/3 of L. anisae where there are many stylids without a clear groove separating the 41 42 entostylid from the rest of the posthypocristulid, and from that of L. bahri, where the 43 44 45 tooth lacks the posthypocristulid (Lihoreau, Hautier, et al. 2015). Lingual cuspids of 46 47 lower molar are more linguo-labially flattened in L. algeriensis, whereas they present a 48 49 rounded outline (in occlusal view) in other species of Libycosaurus. This is probably 50 51 52 due to development of sharper cristids in L. algeriensis than in the other species. This 53 54 condition also exists in early species of Merycopotamus. 55 56 Compared to L. anisae and L. bahri, the M/3 (SHI03) shows a blurry 57 58 endometacristid, not as developed as in Sivameryx, but similar to that observed in some 59 60

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1 2 3 specimens of Merycopotamus. Such a very small endometacristid is observed in 4 5 6 material of L. algeriensis from Algeria (Lihoreau, Hautier, et al. 2015). 7 8 There is a cusplet within the transverse valley that could be considered as an 9 10 inflated ectocristilid as it joins the labial cingulid, forming small ectostylid. This pattern 11 12 is known in most of specimens of L. algeriensis (6 of the 7 known lower molars). We 13 14 15 also observed this structure within Merycopotamini, notably in some specimens of M. 16 17 nanus (almost 4 of 15 molars) and in Sivameryx (close to 5 on 11 molars). In contrast, 18 For Peer Review Only 19 the ectocristilid in L. anisae and L. bahri do not form a cusplet (or rarely: 0 and 1 on at 20 21 22 least 23 and 40 lower molars, respectively) but form an alignment of the enamel knob 23 24 instead. The SHI03 M/3 is similar in size to the specimens from Bir el Ater 2 and 3 25 26 (UONM10, 9 and 14; Fig. 5; Lihoreau, Hautier, et al. 2015) and also very close to the 27 28 29 mean value of M. medioximus (Table 1). 30 31 32 33 Phylogeny 34 35 Heuristic searches have yielded 18 equally most parsimonious trees of 1226 steps each 36 37 38 (CI= 0.30; RI= 0.64). A strict consensus tree is provided in Figure 6. The phylogenetic 39 40 relationships are particularly well resolved, despite an apparent important number of 41 42 homoplasies. The latter are much involved in the structure of the tree. The observed 43 44 45 polytomies concern relationships between the two Kenyapotamus species and the 46 47 Hippopotaminae, between Sivameryx spp. and Hemimeryx, and within the clade 48 49 Brachyodus spp. + Bothriogenys andrewsi. The latter is mainly due to the small number 50 51 52 of characters scored for Bo. andrewsi (few known fossil remains) and uncertainties 53 54 regarding Brachyodus, suggesting a need for a revision of its evolutionary history. 55 56 However, this study proposes Bo. andrewsi as a basal member of the Brachyodus clade, 57 58 thereby representing the only Paleogene representative of that clade (this would suggest 59 60

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1 2 3 a generic re-attribution of the species Bo. andrewsi; i.e. Brachyodus andrewsi following 4 5 6 Schmidt 1913). Our phylogenetic analyses, based on the characters used here (Lihoreau 7 8 et al. 2016), fail to discriminate the genus Sivameryx from Hemimeryx. The two genera 9 10 are considered phylogenetically close and differ mainly by their upper molar 11 12 morphologies notably the dimension of the paraconule (Lihoreau et al. 2016). In the 13 14 15 resulting tree the paraconule reduction appears as a reversion in Sivameryx. Further 16 17 phylogenetic analysis should therefore add more Sivameryx species to discuss this 18 For Peer Review Only 19 particular point. Unfortunately, new material of Sivameryx moneyi (Fourtau, 1918) from 20 21 22 Wadi Moghra (Miller et al. 2014) cannot be included in this cladistic analysis due to the 23 24 lack of published description for the upper tooth. It is worth noting here that one 25 26 specimen of S. moneyi (CUWM 172) displays five upper premolars (Miller et al. 2014) 27 28 29 as in all the specimens of the two well-known species of Libycosaurus (Lihoreau et al. 30 31 2006; Pickford 2006). Therefore, unlike what is proposed by Miller et al. (2014, p.974), 32 33 this is not ‘a fairly common occurrence among anthracothere species in general’, and 34 35 should hence be tested in order to decipher possible close affinities between S. moneyi 36 37 38 and Libycosaurus. 39 40 The main clades depicted from this analysis, which display Bremer indices (BI) 41 42 of 3 or more (Fig. 6), are those of the suines, anthracotheriines, hippopotamids + 43 44 45 Epirigenys lokonensis Lihoreau, Boisserie, et al., 2105, hippopotamids, hippopotamins, 46 47 bothriodontines, Brachyodus spp. + Bo. andrewsi and merycopotamins (Fig. 6). The 48 49 main aim of this analysis was to assess the phylogenetic position of L. algeriensis 50 51 52 within the Merycopotamini. Therefore, we will here focus primarily on the description 53 54 of the nodes that gather the species of Merycopotamus and those of Libycosaurus. 55 56 First, the Merycopotamus+Libycosaurus clade (BI=5) is characterized by nine 57 58 non-ambiguous traits: the presence of a groove on the labial side on the lower canine 59 60

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1 2 3 (121), also observed in Suina, the lack of ectometafossid on lower molars (541), a 4 5 6 character convergent with some Bothriodontinae and Hippopotaminae, an important 7 8 regression or lack of the endometacristid on lower molars (550), which is convergent 9 10 with the Hippopotamidae, Brachyodus (+Bo. andrewsi) and stem Hippopotamoidea, the 11 12 lack of premetafossid on lower molars (571), convergent with Brachyodus, E. 13 14 1 15 borbonicus and Myaingtherium, a reduced postectoentocristid (60 ), which appears as a 16 17 reversion in Hippopotamoidea, a convex mesial border of P4/ (1051), also observed in 18 For Peer Review Only 19 some Bothriodontinae (Bothriodon, Aepinacodon and S. africanus (Andrews, 1914), the 20 21 0 22 lack of postectoprotocrista (114 ), as in Hippopotaminae, some microbunodontines and 23 24 Siamotherium, a maximal thickness in the middle of the sagittal section of the 25 26 symphysis (1530), as in Hippopotamidae and Anthracotherium, and the presence of a 27 28 2 29 mandibular notch with a short extension below m/3 (156 ), as observed in E. 30 31 borbonicus. 32 33 Merycopotamus nanus is the sister-taxon of a clade including the other species 34 35 of Merycopotamus (successively arranged) and the three species of Libycosaurus, the 36 37 38 latter forming a subclade. This Merycopotamus- Libycosaurus clade is supported (BI= 39 40 5) by six non ambiguous traits: crown of the male lower canine with a prolonged growth 41 42 (152), also known in Hippopotamidae and Suina, the presence of a postentocristilid on 43 44 1 45 P/4 (42 ), convergent with Hippopotamidae, Elomeryx spp., S. palaeindicus and 46 47 Microbunodon minimum (Cuvier, 1822) upper canine with prolonged growth of the root 48 49 (862), convergent with Suina, a partial to total division of the mesostyle on upper molars 50 51 1 52 (140 ), also observed in Bothriodon, Aepinacodon and Elomeryx borbonicus, a bony 53 54 fusion of the mandibular symphysis in adult (1521), a character highly convergent 55 56 within Hippopotamoidea but characteristic of several Merycopotamini, and the presence 57 58 59 60

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1 2 3 of an inner radial enamel (schmelzmuster with 3 layers, 1641), which is highly 4 5 6 convergent within Hippopotamoidea. 7 8 Merycopotamus dissimilis and the three species of Libycosaurus form a well- 9 10 supported clade (BI=5) characterized by six non-ambiguous traits, including a non- 11 12 homoplastic apomorphy of the Hippopotamoidea. This exclusive trait is the presence of 13 14 2 15 an ectometacristule developed on the last upper molars (not M1/; 118 ). This character 16 17 differs from the condition observed in other Hippopotamoidea where the 18 For Peer Review Only 19 ectometacristule is expressed on M1/ and also from other Merycopotamini where the 20 21 22 ectometacristule is absent. The other unambiguous traits are the presence of a 23 24 postentocristid (621), which is also observed in some Bothriogenys, Hippopotamidae, 25 26 Anthracotheriinae, although this postentocristid is mesio-distally oriented between the 27 28 29 posthypocristid and the entoconid (= the entoconid fold in Lihoreau et al. 2007) and 30 31 only observed in S. africanus among the Hippopotamoidea (631), the presence of an 32 33 ectostylid on lower molars (722), also known in Hippopotamidae and stem 34 35 Hippopotamidae, in E. borbonicus, S. africanus and in H. blanfordi, an incomplete 36 37 1 38 posthypocristulid (79 ), also known in Afromeryx zelteni and Chororatherium, the 39 40 rostral opening of the main palatal foramen (1622), which is a character convergent with 41 42 Hippopotamidae and B. onoideus (Gervais, 1848-52). 43 44 45 The three species of Libycosaurus are gathered together (BI= 4) on the basis of 46 47 four non-ambiguous traits including two non-homoplastic apomorphies: the presence of 48 49 at least two accessory cusplets on the preprotocristid of all lower premolars (182) and a 50 51 2 52 long postentocristilid on P/4 that reaches the distal cingulid (42 ). Both character states 53 54 are derived condition of what is known in Merycopotamini (181) or Merycopotamus 55 56 (421). The other two non-ambiguous traits are the endoprotofossid on P/4 that reaches 57 58 the lingual cingulid wall (ectocristilid; 411), a character which is convergent with E. 59 60

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1 2 3 borbonicus, A. zelteni and S. africanus within the Bothriodontinae, and that is linked to 4 5 1-2 6 the important development of the ectocristilid (42 ), and finally the cingulum 7 8 reduction at the mesostyle (1392), which is convergent with Brachyodus spp., 9 10 Bothriogenys fraasi (Schmidt, 1913) and Bo. andrewsi, Hippopotamidae, Bothriodon, 11 12 Aepinacodon and Hemimeryx. 13 14 15 In our cladistic analysis, Libycosaurus algeriensis forms the earliest offshoot of 16 17 the Libycosaurus lineage, appearing as the sister-taxon of the two other species of the 18 For Peer Review Only 19 genus (L. anisae and L. bahri). The latter clade shows two non-ambiguous traits, 20 21 22 including one non homoplastic synapomorphy: the preprotocristid direction on P/4 is 23 24 lingual and then mesial (431), whereas it is mesial then lingual in other Merycopotamini. 25 26 The other non-ambiguous trait is the lack (loss) of the mandibular notch, mesial to the 27 28 0 29 vertical ramus (156 ), which is convergent with Afromeryx and the Hippopotaminae. 30 31 32 33 Discussion 34 35 36 37 38 The age of Tunisian silicoclastic formations 39 40 The new anthracothere fossil remains from Sidi Hedri are the first known for the species 41 42 Libycosaurus algeriensis in Tunisia. Based on the determination of these fossils, we can 43 44 45 postulate that the sedimentary deposits where these fossils were found, are most likely 46 47 contemporaneous with the Nementcha Fm. in Algeria, inasmuch as Libycosaurus 48 49 algeriensis was originally described from that rock unit (Fig. 1; Ducrocq et al. 2001; 50 51 52 Mahboubi et al. 2003; Lihoreau, Hautier, et al. 2015). Libycosaurus algeriensis does not 53 54 display some of the derived morphological traits characterizing L. anisae and L. bahri, 55 56 and has so far never been found in association with those species. Evolutionary trends 57 58 observed in the genus, notably general size increase and reduction of molar crests 59 60

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1 2 3 suggest that L. algeriensis represents the most primitive known species of the genus 4 5 6 (Lihoreau, Hautier, et al. 2015). This suggests an earlier origin for Libycosaurus. This 7 8 view is corroborated here by the results of our phylogenetic analysis, which included 9 10 more characters and a better scoring of the matrix for some taxa, notably L. algeriensis. 11 12 Indeed, L. algeriensis was previously known only by 14 elements (upper molars, lower 13 14 15 molars, a fragmentary mandible, and a lower P/4 (Ducrocq et al. 2001; Lihoreau, 16 17 Hautier, et al. 2015). The new material has substantially improved the hypodigm of the 18 For Peer Review Only 19 earliest species of Libycosaurus, and thus permitted to assess its phylogenetic 20 21 22 relationships. The phylogenetic results presented here recover the monophyly of the 23 24 Libycosaurus genus with L. algeriensis falling as the sister of L. anisae and L. bahri 25 26 (more recent species). The Libycosaurus clade is nested within a paraphyletic 27 28 29 Merycopotamus clade. The morphological characters in support of the Libycosaurus 30 31 clade (e.g., accessory cusplets on lower premolars) were already included in the 32 33 amended diagnosis of the genus (Lihoreau et al. 2014). Thanks to the new fossil 34 35 material and based on the phylogenetic results, we could add some aspects of the 36 37 38 morphology of the P/4 (e.g., long ectocristilid including the distal development of the 39 40 endoprotofossid) and of the upper molars (cingulum reduction at mesostyle) to the 41 42 genus diagnosis. 43 44 45 A key point of this discovery is the identification of two diachronous species of 46 47 Libycosaurus (L. algeriensis and L. anisae) in similar facies of silicoclastic deposits, 48 49 which were previously combined as Beglia Fm. We propose that either (1) that different 50 51 52 formations of late middle to early late Miocene sandstones were deposited in Tunisia 53 54 and therefore that all ochre sandstones should not be considered by default as 55 56 documenting (belonging to) the Beglia Fm., or (2) that the Beglia Fm. records deposits 57 58 59 60

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1 2 3 corresponding to a long period of time, which require that they be separated into 4 5 6 different ages. 7 8 Within the Beglia Fm., the locality of Bled Douarah (including two levels) was 9 10 dated around 10.5 Ma (arrival in Africa of hipparions following Bernor et al. 2010). The 11 12 Libycosaurus from both levels do not show morphological discrimination (Black 1972) 13 14 15 or biometrical difference (Fig. 5). Therefore, this material may documents one unique 16 17 species, L. anisae, documenting a similar evolutionary grade. Thus, these two levels 18 For Peer Review Only 19 might not represent a long time-span. The base of the Beglia Fm. may be early 20 21 22 Tortonian (11.6 Ma; Hilgen et al. 2012) or recording the earliest sediments 23 24 corresponding to the onset of the Serravalian marine regression (13.8 Ma; Hilgen et al. 25 26 2012). We can add here that the Beglia Fm. corresponds to a long regressive sequence, 27 28 29 and that the sediments characterizing the Sidi Hedri locality are also within regressive 30 31 deposits, and furthermore are older than the Bled Douarah low level. 32 33 Another important point is that the Libycosaurus clade shares a common 34 35 ancestry with Merycopotamus dissimilis and might originate from a M. medioximus-like 36 37 38 ancestral stock (Fig. 6). Merycopotamus medioximus is known from 10.4 Ma to 8.6 Ma 39 40 in deposits recorded in the Potwar Plateau (Pakistan; Fig. 7; Lihoreau et al. 2007). The 41 42 latter area displays successive species of Merycopotamus, thereby suggesting a possible 43 44 45 anagenetic lineage in this case. Some transitional form between M. nanus and M. 46 47 medioximus are present between 11.3 and 10.5 Ma. Therefore, a possible age for 48 49 Libycosaurus algeriensis could be bracketed between the earliest M. medioximus-like 50 51 52 ancestral stock (11.3 Ma) and the earliest level of Bled Douarah (older than 10.5 Ma). 53 54 55 56 The impact of the Tortonian/Serravalian marine regression on Libycosaurus 57 58 dispersal 59 60

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1 2 3 The phylogenetic and geographic origins of Libycosaurus are deduced from results of 4 5 6 the cladistics analysis (Fig. 6). Although Libycosaurus was proposed as sister-taxon of 7 8 the Merycopotamus clade in previous analyses (Lihoreau et al. 2006; Lihoreau et al. 9 10 2014), Libycosaurus was supposed to originate from a M. nanus-like ancestral stock 11 12 from Asia (Lihoreau et al. 2014). From the phylogenetic results presented here, 13 14 15 proposing that Libycosaurus is in fact nested within the Merycopotamus radiation, the 16 17 arrival in Africa of the ancestor of Libycosaurus corroborates the hypothesis of a 18 For Peer Review Only 19 dispersal event from Asia to Africa as proposed by Lihoreau et al. (2006, 2014). 20 21 22 However, the derivation of Libycosaurus would be related to a M. medioximus- 23 24 dissimilis like ancestral stock, rather than a M. nanus-like ancestral stock. In this 25 26 context, the origin of Libycosaurus would be viewed as more recent (later) than coeval 27 28 29 to the Merycopotamus origin, as formerly suggested by earlier phylogenetic results 30 31 (Lihoreau et al. 2006; Lihoreau et al. 2014). Accordingly, the genus Merycopotamus 32 33 becomes paraphyletic in this phylogenetic context. However, in order for maintaining 34 35 systematics stability, we propose here that all the species of Libycosaurus belong to 36 37 38 Merycopotamus (following Black 1972), and that Libycosaurus represents an African 39 40 subgenus of Merycopotamus. This taxonomic option requires additional paleontological 41 42 evidence (documenting for instance the number of premolars in L. algeriensis) to 43 44 45 further test this new systematic proposal. 46 47 The new fossil material from Tunisia provides key arguments for rooting the 48 49 origin of Libycosaurus near the origin of Merycopotamus dissimilis, most probably 50 51 52 from a M. medioximus-like ancestral stock in Asia. The latter species, contrary to its 53 54 precursors, points at widespread distribution characterized by a sudden expansion out of 55 56 the Indian sub-continent, reaching South-East Asia and Middle East (Lihoreau et al. 57 58 2007). This species most probably underwent disruptive evolution in different region of 59 60

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1 2 3 Asia, with distinct populations in Thailand (a skull has been considered as a new species 4 5 6 M. tachangensis Hanta et al., 2008,which is considered as slightly derived from M. 7 8 medioximus) and in Iraq (Brunet and Heintz 1983; Lihoreau et al. 2007). We consider 9 10 that a population of Merycopotamus (close to the evolutionary degree of M. 11 12 medioximus) extended its range and shifted westward to reach Africa. 13 14 15 The Indian sub-continent is bordered by mountainous arc that limited the 16 17 distribution of anthracotheres outside, at least until the early Tortonian. Following 18 For Peer Review Only 19 Lihoreau et al. (2007) and in accordance with freshwater-constrained distribution of the 20 21 22 anthracotheres (Lihoreau et al. 2014), the dispersal out of the Indian sub-continent 23 24 might have been facilitated by a major eustatic event (low sea-level) that would have 25 26 connected main river mouths in South Asia. In this province, the Tiger River and 27 28 29 Euphrates River, as well as the Indus River could have been involved in the connection 30 31 between Middle East and the Indian sub-continent, thus generating a possible dispersal 32 33 pathway for anthracotheres. Recent sedimentological and tectonical studies support the 34 35 existence of these proposed rivers connections. During the Burdigalian (early Miocene), 36 37 38 fan deposits of the Paleo-Indus River contact those of a river system north of the extant 39 40 Tiger River (Barrier et al. 2018). During this period important dispersal events 41 42 involving many mammalian species occurred between Asia and Africa. These are most 43 44 45 famously exemplified by the “Gomphotherium landbridge” in the Middle East (e.g. Sen 46 47 2013). At this time two anthracotheres genera, Sivameryx and Afromeryx, dispersed 48 49 from the Indian sub-continent to Africa (Holroyd et al. 2010). We suggest that this 50 51 52 Burdigalian dispersal was possible due to river mouth connections. In the same way, we 53 54 propose that a new connection between the same river mouths facilitated a dispersal of 55 56 anthracotheres from Indian sub-continent to Africa during Neogene (Tortonian). 57 58 59 60

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1 2 3 The stratigraphical sequence where the earliest Libycosaurus (i.e., L. algeriensis) 4 5 6 is found corresponds to a marine regression phase. The environmental condition of 7 8 deposits characterizing the whole Beglia Fm., would correspond to this kind of eustatic 9 10 event (Belghithi et al. 2016). In contrast, the sediments of the Saouaf Fm. correspond to 11 12 a marine transgressive sequence (Belghithi et al. 2016). We hypothesize that first, the 13 14 15 dispersal took place during a regression event or second, at the regression maximum. A 16 17 main regression event is recorded between 12 Ma and 10.5 Ma in US mid-Atlantic 18 For Peer Review Only 19 coastal plain (Kominz et al. 2008), and between 12.1 Ma and 10.9 Ma in the 20 21 22 northeastern Australian margin (John et al. 2011). This event is framed by the Mi5 and 23 24 Mi6 isotopic event (Haq et al. 1988; Westerhold et al. 2005; John et al. 2011). The sea 25 26 level drop is estimated close to 50 m, with a lowstand at 10.4-10.9 Ma (John et al. 2004; 27 28 29 Westerhold et al. 2005; Kominz et al. 2008). This event permitted the extension of the 30 31 hydrographical networks that may have connected temporarily the river mouths of 32 33 Paleo-Indus River and a paleo-river north to the Tiger River, and likely allowed semi- 34 35 aquatic mammals to disperse outside the Alpine arc. Following the distributions of 36 37 38 fluvio-lacustrine deposits during the Tortonian (Barrier et al. 2018), connections are 39 40 possible between the Tiger-Euphrate water system and the main trans-Saharan drainage 41 42 systems as the Nile rivers (Bussert et al. 2018) and the Sahabi rivers (Griffin 2010), 43 44 45 providing large dispersal pathway from Middle East to North Africa for fresh-water 46 47 aquatic mammals. 48 49 This dispersal event could therefore serve as a marker to precisely determine the 50 51 52 age of the first Libycosaurus arrival in Africa at the base of the Tortonian, between 11.3 53 54 Ma (the earliest occurrence of a M. medioximus-like representatives) and 10.9 Ma or 55 56 10.5 Ma (the minimal sea level). This age is crucial for dating the Nementcha Fm. in 57 58 Algeria and the early phase of deposition of the Beglia Fm. (earlier than Bled Douarah), 59 60

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1 2 3 both of which record the occurrence of the most primitive species of Libycosaurus (L. 4 5 6 algeriensis). Moreover, the record of Libycosaurus in the late Miocene of Oluka in 7 8 Uganda (Pickford 1991a), indicates that connections between North and East Africa 9 10 were possible for semi-aquatic mammals, thereby constraining the age of the onset of 11 12 the Sahara. The specimen, an upper molar, from the Kakara Fm, Uganda, was attributed 13 14 15 to Libycosaurus cf. anisae (Pickford 1991a) and to L. petrocchii (Simon et al. 2017), 16 17 even if the latter must only be restricted to its holotype (see Lihoreau et al. 2014). It is 18 For Peer Review Only 19 difficult to discriminate Libycosaurus species on upper molar morphology but its small 20 21 22 size could eventually correspond to a very small specimen of L. anisae (Pickford 1991a) 23 24 or to a specimen of L. algeriensis. The age of this specimen is proposed to be early 25 26 Tortonian (Simon et al. 2017), and it is worth noting that this specimen was found in 27 28 29 association with Tetralophodon, as is the case at Bir el Ater 3 (Lihoreau, Hautier, et al. 30 31 2015). In sum, the Ugandan specimen, as well as the Algerian and the Tunisian 32 33 materials might represent evidence of the first arrival of Libycosaurus in Africa. 34 35 Besides, the apparent widespread distribution of this taxon would indicate riverine 36 37 38 connections between East and North Africa during the early Tortonian. This element 39 40 brackets the age of the Saharan onset after 10.5 Ma to at least a new period of near-river 41 42 connection within Sahara, near 7 Ma (Griffin 2002; Lihoreau et al. 2006; Otero et al. 43 44 45 2009). 46 47 48 49 Conclusions 50 51 52 53 54 The evolution of Libycosaurus toward a more aquatic life style, a grazer diet and 55 56 gregarious habit is not a convergent history with Merycopotamus, but the same history 57 58 that took place in Africa. Libycosaurus algeriensis is here considered as 59 60

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1 2 3 morphologically more advanced than Merycopotamus nanus, and thus already in course 4 5 6 of global ecological shift. Additional paleontological support documenting this species, 7 8 notably cranial elements, would be necessary for substantiating a new systematic 9 10 hypothesis according to which Libycosaurus would be a subgenus of Merycopotamus. 11 12 Our estimate regarding the dating of the new Tunisian Sidi Hedri locality, where 13 14 15 we discovered fossil remains attributable to Libycosaurus algeriensis, suggests an age 16 17 close to the base of Tortonian. Libycosaurus algeriensis represents the most ancient 18 For Peer Review Only 19 record of the genus in Africa so far. Libycosaurus algeriensis probably documents a 20 21 22 species morphologically close to its Asian ancestor who probably dispersed to Africa 23 24 only shortly before the first appearance of Libycosaurus in the fossil record of Africa. 25 26 This corresponds to an important African event prior to the Hipparion Datum and thus 27 28 29 helps resolving African Neogene biochronology more precisely. A thorough review of 30 31 biostratigraphical correlations of Tunisian Neogene formations using vertebrate fossil 32 33 data should improve resolution of the local history for establishing an important scale 34 35 for the Middle-Late Miocene transition in Africa. 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 3 Acknowledgment 4 5 6 We would like to thank Baba El-Hadj Mallah, Clarisse Nekoulnang, and Mahamat 7 8 Adoum (CNRD, N’Djaména, chad), Michèle Morgan and John Barry (Peabody 9 10 Museum of Harvard University, Cambridge, USA), Wilma Wessels (Utrecht University, 11 12 Utrecht, Netherland), and Mohammed Mahboubi (Université d’Oran 2, Oran, Algeria) 13 14 15 for granting us access to the collection in their care. We also acknowledge Suzanne 16 17 Jiquel for sample preparation and casting. We thank the anonymous reviewers for their 18 For Peer Review Only 19 help to improve this manuscript. Fieldwork and post-field researches were supported by 20 21 22 the French ANR-ERC PALASIAFRICA (ANR-08-JCJC-0017) and has also benefit 23 24 from the French ANR program SPLASH (ANR-15-CE32-0010-01) and from grant of 25 26 the Scientific Council of University of Montpellier. 27 28 29 30 31 Declaration of interest statement 32 33 34 35 References 36 37 38 Andrews CW. 1914. On the Lower Miocene Vertebrates from British East Africa, 39 collected by Dr. Felix Oswald. Quart Journ Geol Soc. 70(1-4):163-NP. 40 41 Arnason U, Gullberg A, Gretarsdottir S, Ursing BM, Janke A. 2000. The mitochondrial 42 genome of the sperm whale and a new molecular reference for estimating eutherian 43 44 divergence dates. J Mol Evol. 50:569–578. 45 46 Barrier E, Vrielynck B, Brouillet JF, Brunet MF. (Contributors : Angiolini L, Kaveh F, 47 Poisson A, Pourteau A, Plunder A, Robertson A, Shekawat R, Sosson M, Zanchi A) 48 2018. Paleotectonic Reconstruction of the Central Tethyan Realm. Tectonono- 49 50 Sedimentary-Palinspastic maps from Late Permian to Pliocene. Paris: Commission for 51 the Geological Map of the World. 52 53 Belghithi H, Boulvain F, Yaich C, Da Silva AC. 2016. Évolution des séries 54 silicoclastiques miocènes en Tunisie centrale : Cas de la coupe de Khechem El 55 56 Artsouma. Carnets Géologie Note Geol. 16(23):557–568. doi:10.4267/2042/61846. 57 58 Bernor RL, Armour-Chelu MJ, Gilbert H, Kaiser TM, Schulz E. 2010. Equidae. In: 59 Werdelin L, Sanders WJ, editors. Cenozoic Mammals of Africa. Berkeley, Los Angeles, 60 London: University of California Press. p. 685–721.

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1 2 3 Ravel A, Adaci M, Bensalah M, Charruault AL, Essid EM, Khayati Ammar H, 4 Mahboubi M, Marzougui W, Mebrouk F, Merzeraud G, Vianey-Liaud M, Tabuce R, 5 6 Marivaux L. 2016. Origine et radiation initiale des chauves-souris modernes : nouvelles 7 découvertes dans l’Éocène d’Afrique du Nord. Geodiversitas. 38:355–434. 8 9 Robinson P, Black CC. 1969. Note préliminaire sur les vertébrés fossiles du 10 vindobonien (formation Béglia), du Bled Douarah, Governorat de Gafsa, Tunisie. Notes 11 Serv Géologie Tunis. 31:67–70. 12 13 Robinson P, Black CC. 1974. Vertebrate faunas from the Neogene of Tunisia. Ann Geol 14 Surv Egypt. 4:319–332. 15 16 17 Scherler L, Lihoreau F, Becker D. 2018. To split or not to split Anthracotherium? A 18 phylogeny of AnthracotheriinaeFor Peer (Cetartiodactyla; Review Hippopotamoidea) Only and its 19 paleobiogeographic implications. J Linn Soc. 1–24. doi :10.1093/zoolinnean/zly052 20 21 Schmidt M. 1913. Über Paarhufer des fluviomarinen Schichten des Fajum, 22 odontographisches und osteologisches Material. Geol Paläontol Abh. 11:153–264. 23 24 Scott WB. 1940. The mammalian fauna of the White River Oligocene, part IV. 25 26 Artiodactyla. Trans Am Phil Soc. 28:363–746. 27 28 Sen S. 2013. Dispersal of African mammals in Eurasia during the Cenozoic: ways and 29 whys. Geobios 46(2): 159–172. 30 31 Sileem AH, Sallam HM, Hewaidy AGA, Gunnell GF, Miller ER. 2015. Anthracotheres 32 (Mammalia, Artiodactyla) from the upper-most horizon of the Jebel Qatrani formation, 33 34 latest Early Oligocene, Fayum depression, Egypt. Egypt J Paleontol. 15:1–11. 35 36 Simon B, Guillocheau F, Robin C, Dauteuil O, Nalpas T, Pickford M, Senut B, Lays P, 37 Bourges P, Bez M. 2017. Deformation and sedimentary evolution of the Lake Albert 38 Rift (Uganda, East African Rift System). Mar Pet Geol. 86:17–37. 39 40 Sweydan S, Merzeraud G, Essid EM, Marzougui W, Temani R, Ammar HK, Marivaux 41 L, Vianey-Liaud M, Tabuce R, Adnet S. 2018 Aug. A reworked elasmobranch fauna 42 from Tunisia providing a snapshot of Eocene-Oligocene Tethyan faunas. J Afr Earth 43 44 Sci. doi:10.1016/j.jafrearsci.2018.08.008. [accessed 2018 Aug 29]. 45 46 Swezey CS. 2009. Cenozoic stratigraphy of the Sahara, Northern Africa. J Afr Earth 47 Sci. 53(3):89–121. 48 49 Swofford DL. 2002. PAUP*. Phylogenetic Analysis Using Parsimony (*and Other 50 Methods). Sinauer Associates. Sunderland, Massachusetts. 51 52 Tabuce R. 2018. New remains of Chambius kasserinensis from the Eocene of Tunisia 53 and evaluation of proposed affinities for Macroscelidea (Mammalia, Afrotheria). Hist 54 55 Biol. 30(1–2):251–266. 56 57 Vialle N, Merzeraud G, Delmer C, Feist M, Jiquel S, Marivaux L, Ramdarshan A, 58 Vianey-Liaud M, Essid EM, Marzougui W, et al. 2013. Discovery of an embrithopod 59 mammal (Arsinoitherium?) in the late Eocene of Tunisia. J Afr Earth Sci. 87:86–92. 60

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1 2 3 Werdelin L. 2010. Chronology of Neogene Mammal localities. In: Werdelin L, Sanders 4 WJ, editors. Cenozoic Mammals of Africa. Berkeley: University of California Press. p. 5 6 27–43. 7 8 Westerhold T, Bickert T, Röhl U. 2005. Middle to late Miocene oxygen isotope 9 stratigraphy of ODP site 1085 (SE Atlantic): new constrains on Miocene climate 10 variability and sea-level fluctuations. Palaeogeogr Palaeoclimatol Palaeoecol. 217(3– 11 4):205–222. 12 13 14 15 16 17 18 For Peer Review Only 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 3 Table 1. Teeth measurements of specimens from Sidi Hedri compared to mean values of 4 5 6 some Merycopotamini species (Mean value±SD from Lihoreau et al. 2004, 2007, 2014 7 8 and new measurements of L. bahri from CNRD, N’djaména) 9 10 11 12 SHI L. algeriensis L. anisae L. bahri M. nanus M. medioximus M. dissimilis S.palaeindicus S. africanus 13 14 Upper C L 18.4 23.9±3.4 37.8±2.6 e. 16 21.0±2.9 15 l 11.2 17.3±1.8 25.1±1.3 11.1 17.4±2.9 16 17 Fi 60.9 For73.0±4.4 Peer66.0±2.8 Review69.4 Only82.6±6.3 18 P/3 L 15 21.1±1.4 24.7±2.0 15.7±1.2 17.7±1 18 16.4 15.2±1 19 20 l 10 17.8±1.4 18.8±2.0 10.1±0.9 10.6±1 10 10.2 9.9±1.2 21 P/4 L 17.5 19.4 20.5±2.0 24.7±2.2 17.1±1.7 18.2±1.7 20.6 17.4±1.2 15.8±1.3 22 23 l 10.6 14.2 17.0±1.6 19.5±1.6 11.5±1.2 11.3 14.6 11.2±2.3 9.9±0.9 24 25 M/1 L 18.5 24.9±1.5 32.0±2.4 19.7±1.3 20.7±2 20.7 17.1±2.1 18.6 26 M/3 L 37.1 36.2±0.8 44.3±2.7 59.4±4.6 33.2±1.2 36.6±3.7 39.2±2.2 34.3±2.1 32.7±2.2 27 28 l 16.4 17.6±0.5 23.9±1.6 30.7±2.8 15.9±1.7 17.3±1.9 20.1±2.1 15.5±1.1 14.8±1.1 29 mandible HP4-M1 33.5 66.1±7.6 104.8±18 42.5±3 44±9.4 60.9±4.8 31 32.2±3.4 30 31 Min 33.5 57.1 72 38 37 47.9 31 27.2 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 3 Figure Captions 4 5 6 Figure 1. Geographical location of Sidi Hedri and other localities that have yielded 7 8 Libycosaurus remains in Algeria and Tunisia (full black circle), position in regard of 9 10 other fossiliferous localities (F1-4) from the Djebel Chambi area in Tunisia, and their 11 12 stratigraphical relations. 13 14 15 16 17 Figure 2. Upper canine comparisons. Lingual views of (A) left upper canine of L. bahri 18 For Peer Review Only 19 from Toros-Ménalla (TM257-04-08, reversed), (B) left upper canine of L. anisae from 20 21 22 Bled Douarah (T271, reversed) and, (C) right upper canine of L. algeriensis from Sidi 23 24 Hedri (SHI01). (D) Compared dimensions at cervix of upper canines of Merycopotamus 25 26 and Libycosaurus species. 27 28 29 30 31 Figure 3. New mandibular material with right P/3-M/2 from Sidi Hedri (SHI02) in (A) 32 33 lingual, (B) occlusal, and (c) labial views. 34 35 36 37 38 Figure 4. Comparisons of occlusal pattern of lower P/4 in Merycopotamini. (A) 39 40 Libycosaurus algeriensis, Sidi Hedri (SHI02). (B) Libycosaurus anisae Bled Douarah 41 42 (Holotype T356G). (C) Libycosaurus bahri, Toros-Menalla (TM258-01-13). (D) 43 44 45 Merycopotamus nanus, Potwar Plateau (AMNH 94616, reversed). (E) Merycopotamus 46 47 medioximus, Potwar Plateau (HGSP14969, reversed). (F) Merycopotamus dissimilis 48 49 Potwar Plateau (HGSP16418, reversed). (G) Sivameryx africanus Gebel Zelten (NHM 50 51 52 No N° reversed). (H) Afromeryx zelteni, Gebel zelten (M82233). (I) Hemimeryx 53 54 blanfordi, Bugti Hills (M12026). Abbreviations: Protod., protoconid; Entostd., entostylid; 55 56 Hypod., hypoconid; 1, preprotocristid; 2, postprotocristid; 3, endoprotocristid. 57 58 59 60

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1 2 3 4 5 6 Figure 5. Left m/3 from Sidi Hedri (SHI03) in (A) labial, (B) lingual and, (C) occlusal 7 8 views with scheme. Comparisons of m/3 dimensions of Libycosaurus species by origin. 9 10 Abbreviations: Protod., protoconid; Metad., metaconid; Hypod., hypoconid; Entod., 11 12 entoconid; Hypoulid., hypoconulid; 1, preprotocristid; 2, postprotocristid; 3, 13 14 15 prehypocristid; 4, posthypocristid; 5, prehypocristulid; 6, posthypocristulid; 7, 16 17 postectometacristid; 8, postmetacristid; 9, postectoentocristid; 10, preentocristid; 11, 18 For Peer Review Only 19 postentocristid. 20 21 22 23 24 Figure 6. Phylogenetic results. Strict consensus tree of 18 equally most parsimonious 25 26 trees of 1266 steps each (CI=0.30; RI=0.64). Bremer indices (> 1) are indicated at 27 28 29 nodes. 30 31 32 33 Figure 7. Paleobiogeographical scenario for Merycopotamini implied by new phylogeny 34 35 with paleocological inferences from Lihoreau et al. (2014). The geochronological time 36 37 38 scale is from Hilgen et al. (2012). 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 For Peer Review Only 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 Geographical location of Sidi Hedri and other localities that have yielded Libycosaurus remains in Algeria and 37 Tunisia (full black circle), position in regard of other fossiliferous localities (F1-4) from the Djebel Chambi area in Tunisia, and their stratigraphical relations. 38 39 173x157mm (300 x 300 DPI) 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 37 of 83 Historical Biology

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 For Peer Review Only 17 18 19 20 21 22 23 Upper canine comparisons. Lingual views of (A) left upper canine of L. bahri from Toros-Ménalla (TM257-04- 24 08, reversed), (B) left upper canine of L. anisae from Bled Douarah (T271, reversed) and, (C) right upper 25 canine of L. algeriensis from Sidi Hedri (SHI01). (D) Compared dimensions at cervix of upper canines of 26 Merycopotamus and Libycosaurus species. 27 185x92mm (300 x 300 DPI) 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 38 of 83

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 For Peer Review Only 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 Figure 3. New mandibular material with right P/3-M/2 from Sidi Hedri (SHI02) in (A) lingual, (B) occlusal, 46 and (c) labial views. 47 102x137mm (300 x 300 DPI) 48 49 50 51 52 53 54 55 56 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 39 of 83 Historical Biology

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 For Peer Review Only 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Figure 4. Comparisons of occlusal pattern of lower P/4 in Merycopotamini. (A) Libycosaurus algeriensis, Sidi 31 Hedri (SHI02). (B) Libycosaurus anisae Bled Douarah (Holotype T356G). (C) Libycosaurus bahri, Toros- 32 Menalla (TM258-01-13). (D) Merycopotamus nanus, Potwar Plateau (AMNH 94616, reversed). (E) 33 Merycopotamus medioximus, Potwar Plateau (HGSP14969, reversed). (F) Merycopotamus dissimilis Potwar 34 Plateau (HGSP16418, reversed). (G) Sivameryx africanus Gebel Zelten (NHM No N° reversed). (H) 35 Afromeryx zelteni, Gebel zelten (M82233). (I) Hemimeryx blanfordi, Bugti Hills (M12026). Abbreviations: Protod., protoconid; Entostd., entostylid; Hypod., hypoconid; 1, preprotocristid; 2, postprotocristid; 3, 36 endoprotocristid. 37 38 102x75mm (300 x 300 DPI) 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 40 of 83

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 For Peer Review Only 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 Figure 5. Left m/3 from Sidi Hedri (SHI03) in (A) labial, (B) lingual and, (C) occlusal views with scheme. 40 Comparisons of m/3 dimensions of Libycosaurus species by origin. 41 Abbreviations: Protod., protoconid; Metad., metaconid; Hypod., hypoconid; Entod., entoconid; Hypoulid., 42 hypoconulid; 1, preprotocristid; 2, postprotocristid; 3, prehypocristid; 4, posthypocristid; 5, prehypocristulid; 6, posthypocristulid; 7, postectometacristid; 8, postmetacristid; 9, postectoentocristid; 10, 43 preentocristid; 11, postentocristid. 44 45 46 178x179mm (300 x 300 DPI) 47 48 49 50 51 52 53 54 55 56 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 41 of 83 Historical Biology

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 For Peer Review Only 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 Phylogenetic results. Strict consensus tree of 18 equally most parsimonious trees of 1266 steps each 46 (CI=0.30; RI=0.64). Bremer indices (> 1) are indicated at nodes. 47 165x295mm (300 x 300 DPI) 48 49 50 51 52 53 54 55 56 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 42 of 83

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 For Peer Review Only 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 Paleobiogeographical scenario for Merycopotamini implied by new phylogeny with paleocological inferences 46 from Lihoreau et al. (2014). The geochronological time scale is from Hilgen et al. (2012). 47 91x113mm (300 x 300 DPI) 48 49 50 51 52 53 54 55 56 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 43 of 83 Historical Biology

1 1 2 Lihoreau et al. Supporting information 3 4 5 Supporting information for Lihoreau et al. 6 7 8 9 I List of characters for cladistics analysis 10 From Lihoreau et al. (2016), Boisserie et al. (2017), and 5 new characters (63, 80, 139, 156, 162) 11 12 13 14 Anterior lower teeth 15 10. Cristids on lower canine enamel caps: 16 1. Number of lowerFor incisors: Peer Review0. noneOnly 17 0. three 1. one distal 18 1. two 2. two, one mesial and one distal 19 2. one 3. one mesial 20 2. Lower incisor morphology: 11. Wear on lower canine: 21 0. not caniniform 0. distal wear facet contact with canine 22 1. at least one caniniform lower incisor 1. mesial wear facet contact with I3/ 23 24 3. Relative dimensions of lower incisors: 12. Groove on labial side of lower canine: 25 0. all of equal size 0. no 26 1. one or two more developed 1. yes 27 28 4. Most developed incisor: 13. Groove on lingual side of lower canine: 29 0. I/2 0. no 30 1. I/3 1. yes 31 2. I/1 32 14. Lower canine in male: 33 5. Transverse section of lower incisors 0. fang-like 34 crowns: 1. premolariform 35 0. strongly irregular 2. incisiform 36 1. about rounded 37 15. Crown of lower canine in male: 38 6. Lower incisor cervix morphology: 0. small near premolar size 39 0. no deep indentation 1. at least twice the premolar size 40 1. indented cervix, indentation as long as the 2. prolonged growth to ever-growing 41 root diameter on the cervix 42 2. deep identation longer than the root diameter Lower premolars at cervix 43 16. P/1 roots: 44 7. Crown of I/1: 0. one 45 0. straight 1. two 46 1. spatulate, with convex mesial and distal 47 border 17. Paraconid on lower premolars: 48 0. no 49 8. Presence of a median lingual pillar 1. yes 50 (lingual rib) on lower I/1: 51 0. yes 18. Accessory cusp on the preprotocristid of 52 1. no all lower premolars: 53 0. none 54 9. Lower canine cross section at cervix: 1. at least one 55 0. subcircular 2. at least two 56 1. elliptical 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 44 of 83

2 1 2 Lihoreau et al. Supporting information 3 4 19. Elongated P/3: 31. Orientation of the endoprotocristid on 5 0. no (shorter or equal than M/1 lenght) P/4: 6 1. yes (longer than M/1 lenght) 0. absent 7 1. separated from postprotocristid at the 8 20. Three lobed P/3: protoconid apex and then straight and distolingual 9 0. no 2. fused with postprotocristid in part and then 10 1. yes curved mesiolingually 11 12 21. Orientation of postprotocristid on P/3: 32. Distolingual cingulid on P/4 in lingual 13 0. distal view: 14 1. distolingual 0. forming a continuous wall lingually until the 15 2. distolabial distostylid 16 For Peer Review1. reachingOnly the level of the distal basin and 17 22. High cingulid on labial face of P/3: keeping be shallow until the distostylid 18 0. no 2. reaching the level of distal basin and then 19 1. yes being high when joigning the distostylid (distolingual 20 notch of cingulid) 21 23. Endoprotocristid on P/3: 22 0. no 33. Presence of a preentocristid on P/3 and/or 23 1. yes on P/4: 24 0. no 24. Entoconid on P/3: 1. yes 25 0. never 26 1. at least on some specimens 34. Mesiolingual secondary cristid on P/4 27 (cristid connecting lingual margin and 28 25. P/3 hypoconid: preprotocristid): 29 0. no 0. no 30 1. yes 1. yes 31 32 26. Preprotocristid mesiolingualy curved on 35. Labial cingulid form a V (indentated) on 33 P/3: P/4 before to reach the distal cingulid: 34 0. no 0. no 35 1. yes 1. yes 36 37 27. Mesial accessory cusp on preprotocristid 36. Marked postprotofossid on P/4: 38 on P/3: 0. absent 39 0. simple slope 1. present 40 1. Shoulder like structure on lateral view 41 2. adorned with accessory cusp 37. Postectoprotocristid on P/4: 42 0. no 43 28. Lingual contour at cervix of P/4 in 1. yes 44 occlusal view: 45 0. convex to straight 38. Hypoconid on P/4: 46 1. concave 0. no 47 1. yes (even incipient) 29. Labial wall on P/3 or P/4: 48 0. convex 39. Ectoprotofossid on P/4: 49 1. concave 0. absent 50 1. frequent 51 30. Change in the orientation of the 52 preprotocristid mesialy to the junction of 40. Postprotocristid position on P/4 (in regard 53 accessory mesiolingual crest on lower premolars: of a mesiodistal midline): 54 0. no 0. median or labial 55 1. yes 1. lingual 56 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 45 of 83 Historical Biology

3 1 2 Lihoreau et al. Supporting information 3 4 41. Endoprotofossid on P/4: 52. Postmetacristid on M/1-2: 5 0. reaches lingual border 0. curving toward postprotocristid forming a 6 1. reaches lingual cingulid wall transverse bridge with it 7 1. orientated straight toward the centre of the 8 42. Postentocristilid on P/4: tooth 9 0. no 2. forming a rounded postmetaconulid not 10 1. short preferentiallyorientated 11 2. long, which reaches cingulid distally 3. joins prehypocristid 12 13 43. Preprotocristid direction on P/4: 53. Ectoprotofossid on lower molars: 14 0. mesiolingual (but can be moderatly curved) 0. absent 15 1. lingual then mesial 1. present 16 2. mesial then lingualFor Peer Review Only 17 54. Ectometafossid on lower molars: 18 44. Entostylid on P/4: 0. yes 19 0. no 1. no 20 1. yes 21 2. continuous junction with cingulid without 55. Endometacristid on lower molars: 22 clear apex 0. no or slightly expressed much more like an 23 enamel fold 24 45. Metaconid on P/4: 1. present 0. no 25 1. yes (indeed an entostylid surrounded by 56. Postectometacristid on lower molars: 26 cingulid and not formed by cingulid) 0. lightly marked to absent 27 1. always present and well-marked 28 Lower molars 29 57. Premetafossid on lower molars: 30 46. Premetacristid on lower molars: 0. present 31 0. strong 1. absent 32 1. reduced or missing 33 58. Preentocristid: 34 47. Paraconid on lower molars, almost on 0. absent 35 unworn specimens: 1. present 36 0. yes 37 1. no 59. Preentocristid connects: 38 0. endohypocristid 39 48. Lower molar trigonid: 1. prehypocristid toward the cuspid apex 40 0. equal in height with talonid 2. prehypocristid toward its mesial extremity 41 1. higher than talonid 42 60. Postectoentocristid on lower molars: 43 49. Connection between premetacristid and 0. absent 44 preprotocristid on lower molars: 1. present but more like a keel on cusp 45 0. yes 2. present and well individualized from the 46 1. no cusp 47 50. Postectoprotocristid on lower molars: 61. Ectoentocristid: 48 0. absent 0. present 49 1. reduced in the valley to fully developed at 1. absent 50 least on M/1 51 62. Postentocristid on lower molars: 52 51. Postprotofossid on lower molars at least 0. absent 53 on M/3: 1. present 54 0. no 55 1. yes 63. Postencristid mesiodistally oriented and 56 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 46 of 83

4 1 2 Lihoreau et al. Supporting information 3 4 comprised between the posthypocristid and the 5 entoconid (=the entoconid fold): 74. Cingulid surrounding m/3 hypoconulid: 6 0. no 0. no specimen exhibiting such extension 7 1. yes 1. occasionally bordering the labial wall 8 9 64. Prehypocristid dividing in two mesial 75. Presence of one or many postentostylid on 10 arms on lower molars: M/3: 11 0. yes 0. no 12 1. no 1. yes 13 14 65. Prehypocristid inflated (not salient when 76. Ectohypocristulid on M/3: 15 unworn) ) in transverse valley of lower molars: 0. absent 16 0. no For Peer Review1. notOnly complete 17 1. yes (even to form a conulid) 2. present joigning the summit of hypoconulid 18 19 66. Prehypocristid reaches: 77. Distostylid on M/1-M/2: 20 0. median part of transverse valley 0. median 21 1. lingual part of transverse valley 1. lingual 22 2. labial part of the transverse valley 2. none 23 24 67. Main arm of prehypocristid connects: 78. Mesial part of loop-like hypoconulid: 0. trigonid distal walls (junction between 0. open 25 cristids from metaconid and protoconid) 1. pinched 26 1. postmetafossid 27 2. lingual margin of transverse valley 79. Posthypocristulid: 28 3. postmetacristid 0. complete 29 1. incomplete 30 68. Posthypocristid joins: 31 0. nothing or distostylid 80. Posthypocristulid incomplete due to: 32 1. postentocristid 0. a groove separates the cristid in two part 33 2. postectoentocristid 1. It lacks a part or totality of the cristid 34 35 69. Endohypocristid on lower molars: 81. Entoconulid: 36 0. absent 0. no 37 1. present 1. yes 38 39 70. Posthypofossid on lower molars: Anterior upper teeth 40 0. absent 41 1. present 82. Number of upper incisors: 42 0. 3 43 71. Entostylid on lower molars that could 1. 2 44 sometimes be linked to an entocristylid: 2. none 45 0. never 46 1. frequently present 83. Central upper incisor: 47 0. morphologically similar to I2/ and/or I3/ 72. Ectostylid on lower molars: 1. peg-like, morphologically different from 48 0. no cingulid others 49 1. a shallow and constant cingulid in front of 2. caniniform 50 the transverse valley 51 2. frequently developed cingulid in a /some 84. I3/ reduced in size compared to I1/: 52 stylid at least on m1 0. no 53 1. yes 54 73. Ectocrystilid on lower molars : 55 0. no 85. Upper canine morphology: 56 1. yes even if variable 0. strong, with circular or elliptic cross section 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 47 of 83 Historical Biology

5 1 2 Lihoreau et al. Supporting information 3 4 1. strong and laterally compressed (blade-like) 1. one mesial root and fused distal ones 5 2. premolariform 6 97. P4/ paracone: 7 86. Canine size root: 0. simple with crest 8 0. equivalent to slightly longer than the crown 1. complex with fossa 9 1. at least twice the size of the crown 2. very complex with more fossae 10 2. prolonged to continuous growth of root 11 3. prolonged and continuous growth of crown 98. Orientation of preparacrista on P4/: 12 0. mesial 13 87. Dimorphic upper canine: 1. labial 14 0. no 15 1. yes 99. Postprotocrista on P4/: 16 For Peer Review0. absentOnly 17 Upper premolars 1. present 18 19 88. Diastem C-P1/ ou C-P/: 100. Postprotocrista on P4/ joins: 20 0. yes 0. base of paracone 21 1. no 1. distostyle 22 2. metastyle 23 89. Diastem P1/-P2/: 24 0. no 101. Preprotocrista on P4/ joins: 1. yes 0. mesiostyle 25 1. base of the paracone then mesiostyle 26 90. Number of upper premolar: 2. parastyle 27 0. 4 28 1. 5 102. Postectoprotocrista on P4/: 29 2. 3 0. absent 30 1. present 31 91. Distolabial crests of upper premolars 32 (postparacrista): 103. P4/ protocone: 33 0. simple 0. rounded 34 1. with a maximum of two accessory cusps 1. crescentic 35 2. with more than two accessory cusps at least 36 on one premolar 104. In lingual view protocone of P4/ is: 37 0. displaced mesially 38 92. Number of mesial crests on P1-3/: 1. median 39 0. one 40 1. two 105. P4/ mesial margin: 41 0. concave 42 93. Disto-lingual basin in P2/: 1. convexe 43 0. yes 44 1. no 106. Strong development of distostyle on P4/: 45 0. no 46 94. Accessory cusp on disto-lingual cingulum 1. yes 47 of P3/: 0. none 107. Mesial accessory cusp on P4/ that can be 48 1. one cingular style linked to mesiostyle: 49 2. protocone (surrounded by a cingulum) 0. no 50 1. yes 51 95. Metacone on P3/: 52 0. no 108. P4/ metacone: 53 1. yes 0. absence 54 1. presence 55 96. P3/ root pattern: 56 0. one mesial root, two distal root not fused 109. P4/ paracone higher than the protocone: 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 48 of 83

6 1 2 Lihoreau et al. Supporting information 3 4 0. slightly higher than protocone 1. present 5 1. much higher than protocone 6 120. Secondary cristule labial to metaconule 7 110. P4/ endoparacrista: eventually an endometacristule or enamel knob: 8 0. absence 0. no 9 1. presence 1. yes 10 11 111. Distal accessory cusp on postprotocrista 121. Distostyle on upper molars: 12 of P4/ that can be linked to distostyle: 0. yes 13 0. no 1. no 14 1. yes 15 122. Distostyle position on upper molars levels: 16 Upper molars For Peer Review0. metaconuleOnly 17 1. metacone 18 112. Height of lingual cingulum compared to 19 unworn protocone height on upper molars: 123. Secondary ectometafossule lingual to 20 0. one third ectometacristule: 21 1. half 0. absent or very light 22 2. no cingulum 1. present mesially at least on M1/ linked to 23 ectometacristule 24 113. Mesio-distal ribs development of labial cusps of upper molars: 124. Paraconule on upper molars: 25 0. almost half the molar length 0. present 26 1. pinched (inferior to one third of molar 1. absent 27 length) 28 2. enlarged (superior to half the molar length) 125. M2/ paraconule when present: 29 0. similar in size with protocone 30 114. Postectoprotocrista: 1. smaller than protocone 31 0. absent 32 1. present 126. Postparacristule extends to connect: 33 0. none 34 115. Postprotocrista: 1. base of the paracone 35 0. present 2. transverse valley 36 1. absent 37 127. Preparacrista connects the parastyle: 38 116. Protocone and metaconule junction on 0. no, separated by a groove 39 upper molars: 1. yes, lingually 40 0. none 2. yes, labially 41 1. premetacristule with postectoprotocrista 42 2. premetacristule with postprotocrista 128. Endoparacrista on upper molars: 43 3. postprotocrista and lingual part of 0. absence 44 metaconule 1. presence 45 46 117. Premetacristule divided in two mesial 129. Ectoparafossa on upper molars: 47 arms: 0. no 0. no 1. yes 48 1. yes 49 130. Ectocristyle: 50 118. Ectometacristule on upper molars: 0. frequently present 51 0. absent 1. absent 52 1. present at least on M1/ 53 2. not frequent and only on M2/ or M3/ 131. Premetacrista and postparacrista 54 connect: 55 119. Postmetafossule: 0. no connection 56 0. absent 1. direct connection in a centrocrista 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 49 of 83 Historical Biology

7 1 2 Lihoreau et al. Supporting information 3 4 2. connection to mesostyle (via ectocristyle or 1. fully fused lingual roots 5 not) 2. three roots 6 7 132. Endometacrista and endometacristule 143. Lingual cingulum on upper molars: 8 forming a transverse crest: 0. no 9 0. absence 1. yes 10 1. presence 2. developed in entostyle 11 12 133. Parastyle development: 144. Hypocone on upper molars (at least M2/: 13 0. enamel knob 0. yes 14 1. smaller or equal than mesostyle 1. no 15 2. larger than mesostyle 16 For Peer Review145. ShapeOnly of M1/: 17 134. Premetacristule invade labial part of the 0. triangular 18 transverse valley: 1. quadrate 19 0. no 20 1. yes 146. Shape of M3/: 21 0. triangular 22 135. Position of metaconule on upper molar: 1. quadrate 23 0. labial side of the protocone 24 1. distal side of the protocone 147. M3/ size: 0. Larger than M2/ 25 136. M2/ metaconule: 1. equal in size with M2/ 26 0. similar in size with protocone 2. reduced (less than 60%) 27 1. smaller than protocone 28 148. Mesiolingual style on upper molar mesial 29 137. Mesostyle on upper molars: cingulum: 30 0. no 0. no 31 1. yes 1. yes 32 33 138. Mesostyle: Mandible 34 0. enamel knob 35 1. half to the size of labial cusp 149. Symphysis morphology in sagittal section, 36 2. larger than labial cusp ventral border: 37 0. convex 38 139. Cingulum at the junction between 1. straight to almost straight 39 postparacrista and premetacrista forming labial 2. concave 40 structure on mesostyle: 41 0. high triangular cingulum 150. Symphysis morphology in sagittal section, 42 1. wing-like cingulum dorsal border: 43 2. low or absent cingulum 0. convex 44 1. straight or almost straight 45 140. Division of the mesotyle on upper molar: 2. markedly concave 46 0. no, one style or continuous cristae 47 1. two apices in unworn molars but still 151. Diastem C-P/1: connected by cristae 0. absent 48 2. fully isolated style apices 1. present 49 50 141. Metastyle: 152. Bone fusion at symphysis in adult 51 0. reduced to enamel knob or absent specimens: 52 1. fully developed 0. no 53 1. yes 54 142. Root fusion on upper molars: 55 0. four roots with occasional fusion close to 153. Maximal thickness of the symphysis in 56 cervix, the root apices always remaining free sagittal section: 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 50 of 83

8 1 2 Lihoreau et al. Supporting information 3 4 0. in the middle part 0. no 5 1. in the rostral part 1. yes 6 2. in the nucal part 7 164. Schmelzmuster composed of: 8 154. Symphysis extension: 0. two layers 9 0. extends nuchally between C and P/1 1. three layers 10 1. extend nuchally between P/1 and P/3 2. one layer 11 2. extends nuchally to P/3 12 165. Inner radial enamel: 13 155. Number and position of main external 0. absent 14 foramen: 1. present 15 0. numerous 16 1. only one belowFor the anterior Peer part of the Review166. HSBOnly percent of Schmelzmuster: 17 premolar row 0. absent 18 2. two, one below the anterior part and the 1. less than 75% 19 other below the posterior 2. more than 76% 20 21 156. Mandibular notch: 167. Outer radial enamel: 22 0. no 0. less or equal to 20% 23 1. yes, long extension behind coronoid process 1. more than 20% 24 2. yes, short extension below m/3 168. Hsb zone: 25 157. Transverse constriction of mandible at C- 0. thin with bands always less than 100µm 26 P/1 diastema: 1. large (equal or more than 100µm) 27 0. no 28 1. yes 169. Regular aspect (constant width): 29 0. yes 30 158. Mandibular protuberance at the C/P/1 1. no 31 level: 32 0. no 170. HSB variable (SD>20): 33 1. yes 0. no 34 1. yes 35 159. P/1-P/2 diastema: 36 0. absent 171. HSB angle with EDJ: 37 1. present 0. >70° 38 1. <70 ¨° 39 160. P/2-P/3 diastema: 40 0. yes 172. Orientation of HSB: 41 1. no 0. straight 42 1. bent 43 Cranium 44 173. HSB definition (decussation angle and 45 161. Opening of internal choanes: size of transition zone): 46 0. at M3/ 0. clear 47 1. nucal to M3/ 1. blurry 48 162. Opening of main palatal foramen: 174. Division of HSB: 49 0. at palatine-maxillary junction in front of 0. anastomosis 50 molars to P3 1. bifurcation 51 1. on maxillary in front of P2-P1 2. no division 52 2. on maxillary cranial to P1 53 175. HSB configuration: 54 Enamel microstructure 0. curved 55 1. transverse 56 163. Enamel ornamentation: 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 51 of 83 Historical Biology

9 1 2 Lihoreau et al. Supporting information 3 4 176. Synchronous prism undulation on 179. IPM in outer portion: 5 horizontal section: 0. closed sheath 6 0. no 1. no IPM 7 1. yes but few 8 2. yes but more or equal to 4 180. Prism angle with EDJ: 9 0. equal or more than 60° 10 177. IPM in inner portion: 1. less than 60° 11 0. closed sheath 2. tends to diminish in the inner part 12 1. Inter row sheets 13 181. Prism diameter: 14 178. IPM in middle portion: 0. mean between 3 and 3.9 µm 15 0. closed sheath 1. small diameter mean below 3 µm 16 1. Inter row sheetsFor Peer Review2. largeOnly diameter mean above or equal to 4 17 2. no IPM 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 52 of 83

10 1 2 Lihoreau et al. Supporting information 3 4 included in the phylogenetic analysis. 5 II List of taxa 6 7 Abbreviations for repository institutions 8 AMNH American Museum of Natural History, New York, USA 9 10 ARCCH Authority for Research and Conservation of Cultural Heritage, Addis Ababa, Ethiopia 11 CGM Cairo Geological Museum, Cairo, Egypt 12 13 CNRD Centre National de la Recherche pour le Développement, Ndjamena, Chad 14 CROZ Musée Crozatier, Le Puy-en-Velay, France 15 16 DMR DepartmentFor of PeerMineral Resources, Review Bangkok, Thailand Only 17 DPC Division of Fossil Primates, Duke Lemur Center, Durham, NC USA 18 FSL Collection de la Faculté de Sciences de Lyon 19 20 GSP Geological Survey of Pakistan, Museum of Natural History in Islamabad, Pakistan 21 MNHN Muséum National d’Histoire Naturelle, Paris, France 22 23 NHM Natural History Museum, London, UK 24 NMK National Museums of Kenya, Nairobi, Kenya 25 26 PMH Peabody Museum, Harvard University, Cambridge, USA 27 UM Université de Montpellier, France 28 UNM Uganda National Museum, Uganda 29 30 UU Utrecht University, Netherland 31 SMNS Staatliches Museum für Naturkunde, Stuttgart, Germany 32 33 YU Department of Geology, Yangon University, Yangon, Myanmar 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 53 of 83 Historical Biology

11 1 2 Lihoreau et al. Supporting information 3 4 HIPPOPOTAMOIDEA Gray, 1821 sensu Gentry & Hooker (7) 5 Hippopotamidae Gray, 1821 6 Morotochoerus ugandensis Pickford, 1998 7 • Temporal and geographical distribution 8 Early Miocene; eastern Africa 9 • Origin of examined material 10 - Moroto, Uganda (UNM) 11 • References: (22-24) 12 13 Kenyapotamus coryndonae Pickford, 1983 14 • Temporal and geographical distribution 15 Late Miocene; eastern Africa 16 • Origin ofFor examined Peer material Review Only 17 - Nakali Formation, Kenya (NMK) 18 - Namurumgule Formation, Samburu Hills, Kenya (NMK) 19 - Ngeringerowa, Ngorora Formation, Kenya (NMK) 20 • References: (1, 15-18) 21 22 Kenyapotamus ternani Pickford, 1983 23 • Temporal and geographical distribution 24 middle Miocene; eastern Africa • Origin of examined material 25 - Napudet, Lothidok Formation, Turkana, Kenya (NMK) 26 - Kipsaramon, Muruyur Bed, in the Tugen Hills, Kenya (NMK) 27 - Fort Ternan Beds, Nyanza rift, Kenya (NMK) 28 - Maboko and ngorora Formations, Kenya (NMK) 29 • References: (77) 30 31 Chororatherium roobii Boisserie et al. 2017 32 • Temporal and geographical distribution 33 Late Miocene; eastern Africa 34 • Origin of examined material 35 - Chorora Formation, Bechitat, Ethiopia (ARCCH) 36 • References: (79) 37 38 Hippopotamine from Chorora 39 • Temporal and geographical distribution 40 Late Miocene; eastern Africa 41 • Origin of examined material 42 - Recent bed of Chorora Formation, Teso Tadecho, Odakora North, and Gutosadeent, 43 Ethiopia (ARCCH) 44 • References: (79) 45 46 Archaeopotamus harvardi (Coryndon, 1977) 47 • Temporal and geographical distribution Late Miocene; eastern Africa 48 • Origin of examined material 49 - Nawata Formation, Lothagam, Kenya (NMK) 50 • References: (19-20) 51 52 Hexaprotodon garyam Boisserie et al., 2005 53 • Temporal and geographical distribution 54 Late Miocene; central Africa 55 • Origin of examined material 56 - Anthracotheriid Unit, Toros-Ménalla, Chad (CNAR) 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 54 of 83

12 1 2 Lihoreau et al. Supporting information 3 4 • References: (21) 5 6 “Anthracotheriidae” Leidy, 1869 7 Siamotherium krabiense Suteethorn et al., 1988 8 • Temporal and geographical distribution 9 Late middle and late Eocene; southeastern Asia 10 • Origin of examined material 11 - Krabi Basin, Thailand (DMR, cast at UM) 12 • References: (25-27) 13 14 Heptacodon occidentalis (Osborn and Wortman, 1894) 15 • Temporal and geographical distribution 16 earlyFor Oligocene, Peer North America Review Only 17 • Origin of examined material 18 - South Dakota, USA (AMNH) 19 • References: (28-29) 20 21 Anthracotherium chaimanei Ducrocq 1999 22 • Temporal and geographical distribution 23 Late Eocene, southeastern Asia 24 • Origin of examined material - Krabi Basin, Thailand (DMR, cast at UM) 25 • References: (27) 26 27 Anthracotherium magnum Cuvier, 1822 28 • Temporal and geographical distribution 29 Early late Oligocene, Europe 30 • Origin of examined material 31 - Cadibona, Italy (NHM) 32 - Digoin, France (cast at UM) 33 - Moissac, France (cast at UM) 34 - Phosphorites du Quercy, France (MNHN, cast at UM) 35 • References: (30-32) 36 37 Myaingtherium kenyapotamoides Tsubamoto et al. 2011 38 • Temporal and geographical distribution 39 Late middle Eocene, Asia 40 • Origin of examined material 41 - Pondaung formation, Myanmar (YU) 42 • References: (33) 43 44 Anthracokeryx tenuis Pilgrim and Cotter, 1916 45 • Temporal and geographical distribution 46 Late middle Eocene, Asia 47 • Origin of examined material - Pondaung formation, Myanmar (AMNH) 48 • References: (32, 34) 49 50 Anthracokeryx thailandicus Ducrocq, 1999 51 • Temporal and geographical distribution 52 Late Eocene, southeastern Asia 53 • Origin of examined material 54 - Krabi Basin, Thailand (DMR, cast at UM) 55 • References: (27, 35) 56 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 55 of 83 Historical Biology

13 1 2 Lihoreau et al. Supporting information 3 4 Microbunodon minimum Cuvier, 1822 5 • Temporal and geographical distribution 6 Late Oligocene, Europe 7 • Origin of examined material 8 - La Milloque, France (cast at UM) 9 • References: References: (35-36) 10 11 Bothriogenys orientalis Ducrocq, 1997 12 • Temporal and geographical distribution 13 Late Eocene, southeastern Asia 14 • Origin of examined material 15 - Krabi Basin, Thailand (DMR, cast at UM) 16 • References:For (3, 27) Peer Review Only 17 18 Bothriogenys fraasi (Schmidt, 1913) 19 • Temporal and geographical distribution 20 Early Oligocene, northern Africa 21 • Origin of examined material 22 - Jebel Quatrani fm., Fayum, Egypt (SMNS, NHM) 23 • References: (3, 37-38) 24 Bothriogenys gorringei (Andrews and Beadnell, 1902) 25 • Temporal and geographical distribution 26 Early Oligocene, northern Africa 27 • Origin of examined material 28 - Jebel Quatrani fm., Fayum, Egypt (AMNH, SMNS, NHM) 29 • References: (3, 37-38) 30 31 Bothriogenys andrewsi (Schmidt, 1913) 32 • Temporal and geographical distribution 33 Late Early Oligocene, northern Africa 34 • Origin of examined material 35 - Upper Sequence of the Jebel Qatrani Formation, Fayum Depression, Egypt (SMNS, 36 CGM, DPC) 37 • References: (3, 37-38, 80) 38 39 Epirigenys lokonensis Lihoreau et al. 2015 40 • Temporal and geographical distribution 41 late Early/early Late Oligocene, Kenya 42 • Origin of examined material 43 - Lok 13, Lokone sandstone Formation, Turkana, Kenya (NMK) 44 • References: (78) 45 46 Brachyodus aequatorialis Mc Innes 1951 47 • Temporal and geographical distribution Early Miocene, Eastern Africa 48 • Origin of examined material 49 - Rusinga, Kenya (NMK) 50 • References: (38-40) 51 52 Brachyodus onoideus (Gervais, 1848-52) 53 • Temporal and geographical distribution 54 Early Miocene, Western Europe 55 • Origin of examined material 56 - Chilleur au bois, France (NHM, MNHN, UM) 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 56 of 83

14 1 2 Lihoreau et al. Supporting information 3 4 • References: (40) 5 6 Brachyodus depereti (Fourteau, 1918) 7 • Temporal and geographical distribution 8 Early Miocene, Northern Africa 9 • Origin of examined material 10 - Moghara, Egypt (cast in NHM) 11 • References: (40-41) 12 13 Bothriodon velaunus (Cuvier, 1824) 14 • Temporal and geographical distribution 15 Early Oligocene, Western Europe 16 • Origin ofFor examined Peer material Review Only 17 - Ronzon, France (CROZ, NHM, UM2) 18 • References: (32) 19 20 Aepinacodon americanum (Leidy, 1856) 21 • Temporal and geographical distribution 22 Late Eocene-early Oligocene, Northern America 23 • Origin of examined material 24 - South Dakota, USA (AMNH) • References: (29, 32) 25 26 Elomeryx crispus (Gervais, 1849) 27 • Temporal and geographical distribution 28 Late Eocene-early Oligocene, Europe 29 • Origin of examined material 30 - Detan Dverce, Czech Republic (cast at UM) 31 • References: (32, 42-43) 32 33 Elomeryx borbonicus (Geais, 1934) 34 • Temporal and geographical distribution 35 Late Oligocene and early Miocene, Western Europe 36 • Origin of examined material 37 - Saint Henri, France (AMNH, NHM, FSL, UM) 38 • References: (42-45). 39 40 Afromeryx zelteni Pickford, 1991 41 • Temporal and geographical distribution 42 Early Miocene, Africa 43 • Origin of examined material 44 - Gebel Zelten, Libya (NHM) 45 - Baragoï, Buluk, Ombo, Nabwal Hill (NMK) 46 • References: (41) 47 Sivameryx palaeindicus (Lydekker, 1877) 48 • Temporal and geographical distribution 49 Early Miocene, Indian subcontinent 50 • Origin of examined material 51 - Sind, Pakistan (PMH, GSP) 52 - Kamlial fm. Potwar plateau, Pakistan (PMH, GSP) 53 - Bugti, Pakistan (NHM, AMNH) 54 • References: (46) 55 56 Sivameryx africanus (Andrews, 1914) 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 57 of 83 Historical Biology

15 1 2 Lihoreau et al. Supporting information 3 4 • Temporal and geographical distribution 5 Early Miocene, East and North Africa 6 • Origin of examined material 7 - Karungu, Kenya (NMK) 8 - Rusinga, Kenya (NMK) 9 - Gebel Zelten, Libye (NHM, MNHN) 10 • References: (41) 11 12 Hemimeryx blanfordi Lydekker, 1883 13 • Temporal and geographical distribution 14 Late Oligocene-early Miocene, Indian sub-continent 15 • Origin of examined material 16 - Sind,For Lower Peer Manchar Formation Review (NHM, GSP) Only 17 - Potwar plateau, Kamlial Formation, Pakistan (GSP) 18 - Bugti, Chitarwata Formation Pakistan (NHM, UM) 19 • References: (46) 20 21 Merycopotamus nanus Falconer, 1868 22 • Temporal and geographical distribution 23 Middle Miocene; Indian subcontinent 24 • Origin of examined material - Potwar plateau, Chinji formation, Pakistan (HPM, NHM, AMNH) 25 • References: (47) 26 Merycopotamus medioximus Lihoreau et al. 2004 27 • Temporal and geographical distribution 28 Late Miocene; Indian subcontinent, Thailand, Iraq. 29 • Origin of examined material 30 - Pakistan (AMNH, GSP, UU) 31 • References: (47) Ajouter Lihoreau et al. 2004 32 33 Merycopotamus dissimilis (Falconer and Cautley, 1837) 34 • Temporal and geographical distribution 35 Late Miocene-Pliocene; Indian subcontinent 36 • Origin of examined material 37 - Pakistan, India, Myanmar, Nepal, Indonesia (AMNH, PMH, GSP, NHM) 38 • References: (47) 39 40 Libycosaurus algeriensis Ducrocq et al., 2001 41 • Temporal and geographical distribution 42 Late Miocene; central and northern Africa 43 • Origin of examined material 44 - Nementcha formation, Bir el Ater 2 and 3, Algeria (UO2) and Sidi Hedri, Tunisia 45 (ONM) 46 • References: (81, 82) 47 Libycosaurus anisae (Black, 1972) 48 • Temporal and geographical distribution 49 Late Miocene; northern Africa 50 • Origin of examined material 51 - Beglia formation, Bled Douarah and Djebel Kechrem el Artsouma (ONM) 52 • References: (41, 48-50) 53 54 Libycosaurus bahri Lihoreau et al. 2014 55 • Temporal and geographical distribution 56 Late Miocene; central and northern Africa 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 58 of 83

16 1 2 Lihoreau et al. Supporting information 3 4 • Origin of examined material 5 - Anthracotheriid Unit, Toros-Ménalla (CNAR) 6 • References: (38, 41, 50-52) 7 8 SUOIDEA Gray, 1821 9 Palaeochoeridae Matthew, 1924 10 Palaeochoerus quercyi (Filhol, 1882) (=Doliochoerus quercyi) 11 • Temporal and geographical distribution 12 Late Oligocene; western Europe 13 • Origin of examined material 14 - Pech Desse, Quercy, France (UM) 15 - Pech de Fraysse, Quercy, France (UM) 16 • References:For (53-54) Peer Review Only 17 18 Tayassuidae Palmer, 18971 19 Perchoerus probus Leidy, 1869 20 • Temporal and geographical distribution 21 Late Eocene-Early Miocene – North America 22 References: (55-56) 23 24 Suidae Gray, 1821 Kenyasus rusingensisPickford 1986 25 • Temporal and geographical distribution 26 Early Miocene - Africa 27 • Origin of examined material 28 - Rusinga, Kenya (NMK) 29 • References: (55-56) 30 31 RUMINANTIA 32 Lophiomerycidae Janis, 1987 33 Lophiomeryx chalaniati Pomel, 1854 34 • Temporal and geographical distribution 35 Oligocene; Europe 36 • Origin of examined material 37 - Garouillas, France (UM) 38 • References: (57) 39 40 Archeomerycidae Simpson, 1945 41 Archeomeryx optatus Matthew and Granger, 1925 42 • Temporal and geographical distribution 43 Middle Late Eocene; Mongolia and China 44 • Origin of examined material 45 - Ula Usu, china (cast UM) 46 • References: (58) 47 DICHOBUNOIDEA Gill, 1872 48 Diacodexiidae Gazin, 1955 49 Diacodexis pakistanensis Thewissen et al. 1983 50 • Temporal and geographical distribution 51 Early or Middle Eocene; Pakistan 52 • Origin of examined material 53 - Barbora banda, Pakistan (casts UM) 54 • References: (59) 55 56 Bunophorus grangeri Sinclair, 1914 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 59 of 83 Historical Biology

17 1 2 Lihoreau et al. Supporting information 3 4 • Temporal and geographical distribution 5 Early Eocene; North america 6 • Origin of examined material 7 - Big Horn basin, Wyoming, USA (casts UM) 8 • References: (60) 9 10 Dichobunidae Turner, 1849 11 Dichobune leporina Cuvier, 1822 12 • Temporal and geographical distribution 13 Late Eocene; Europe 14 • Origin of examined material 15 - Escamps, Rosières and Aubrelong, France (UM) 16 • References:For (60-61) Peer Review Only 17 18 Homacodontidae Marsh, 1874 19 Homacodon vagans Marsh, 1872 20 • Temporal and geographical distribution 21 Early-middle Eocene; North America 22 • Origin of examined material 23 - Cast of specimens from the Twin Buttes, USA (UM) 24 • References: (60) 25 Helohyidae Marsh, 1877 26 Gobiohyus orientalis Matthew and Granger, 1925 27 • Temporal and geographical distribution 28 Middle Eocene; central and southern Asia 29 • Origin of examined material 30 - Irdin Manha, Ulan Shireh, Mongolia (AMNH) 31 • References: The attribution of G. orientalis to the Helohyidae follows (62-63) and (64). It is 32 recognized that (65), notably, proposed a different interpretation, excluding Asian forms 33 from the Helohyidae. 34 35 Raoellidae Sahni et al., 1981 36 Khirtharia spp corresponds to the three following species : 37 Khirtharia dayi Pilgrim, 1940 38 • Temporal and geographical distribution 39 Late Eocene; Indian subcontinent 40 • Origin of examined material 41 - Chorlakki, Pakistan (casts UM) 42 • References: (66) 43 Khirtharia inflata (Ranga Rao, 1972) 44 • Temporal and geographical distribution 45 Late Eocene; Indian subcontinent 46 • Origin of examined material 47 - Subattu formation, India (casts UM) • References: (67) 48 Khirtharia aurea Thewissen et al. 2001 49 • Temporal and geographical distribution 50 Middle Eocene; Indian subcontinent 51 • Origin of examined material 52 - Chorgali formation, Pakistan (casts UM) 53 • References: (68-69) 54 55 Indohyus indirae Ranga Rao, 1971 56 • Temporal and geographical distribution 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 60 of 83

18 1 2 Lihoreau et al. Supporting information 3 4 Late Eocene; Indian subcontinent 5 • References: (67) 6 7 Other early cetartiodactyl families 8 Cebochoeridae Lydekker, 1883 9 Cebochoerus campichii Pictet 1855-57 10 • Temporal and geographical distribution 11 Middle Eocene; Western Europe 12 • Origin of examined material 13 - Robiac, France (UM) 14 • References: (61, 70) 15 16 ChoeropotamidaeFor Owen, 1845Peer Review Only 17 Choeropotamus depereti Stehlin 1908 18 • Temporal and geographical distribution 19 Middle Eocene; Europe 20 • Origin of examined material 21 - Euzet, France (UM) 22 • References: (61, 70-71) 23 24 Hallebune krumbiegeli Erfurt and Sudre, 1995 • Temporal and geographical distribution 25 Middle Eocene; Europe 26 • Origin of examined material 27 - Geiseltal, Germany (cast UM) 28 • References: (61, 70-71) 29 30 Amphirhagatherium spp corresponds to the two following species : 31 Amphirhagatherium neumarkensis Erfurt and Haubold 1989 32 • Temporal and geographical distribution 33 Middle-Late Eocene; Europe 34 • Origin of examined material 35 - Geiseltal, Germany (Cast UM) 36 • References: (61, 70-71) 37 Amphirhagatherium weigelti (Heller, 1934) 38 • Temporal and geographical distribution 39 Middle-Late Eocene; Europe 40 • Origin of examined material 41 - Geiseltal, Germany (Cast UM) 42 • References: (61, 70-71) 43 44 Mixtotheriidae Pearson, 1927 45 Mixtotherium spp. corresponds to the following species: 46 Mixtotherium gresslyi Rutimeyer, 1891 47 • Temporal and geographical distribution Middle-Late Eocene; Europe 48 • Origin of examined material 49 - Egerkingen, Switzerland and La Defense, France (casts UM) 50 • References: (70) 51 Mixtotherium lavergnensis (Sudre, 1977) 52 • Temporal and geographical distribution 53 Middle-Late Eocene; Europe 54 • Origin of examined material 55 - Lavergne, France and Eclepens-gare, Switzerland 56 • References: (72) 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 61 of 83 Historical Biology

19 1 2 Lihoreau et al. Supporting information 3 4 5 Amphimerycidae Pearson, 1927 6 Amphimeryx murinus (Cuvier, 1822) 7 • Temporal and geographical distribution 8 Late Eocene; Europe 9 • Origin of examined material 10 - Escamps, Rosières 2 and St Néboule, France (casts UM) 11 • References: (61, 70, 72) 12 13 Anoplotheriidae Bonaparte, 1850 14 Diplobune minor (Filhol, 1877) 15 • Temporal and geographical distribution 16 LateFor Eocene-early Peer Oligocene; Review Europe Only 17 • Origin of examined material 18 - Itardies, France (UM) 19 • References: (73) 20 21 Dacrytherium ovinum Owen, 1857 22 • Temporal and geographical distribution 23 Late Eocene; Europe 24 • Origin of examined material - Fons and Euzet, France (UM) 25 • References: (70, 72) 26 27 Xiphodontidae Flower, 1884 28 Xiphodon castrensis Kowalesky, 1873 29 • Temporal and geographical distribution 30 Late Eocene; Europe 31 • Origin of examined material 32 - Robiac and Le Bretou, France (UM) 33 • References: (70, 72) 34 35 Cainotheriidae Camp and Van der Hoof, 1940 36 Paroxacron valdense (Stehlin, 1906) 37 • Temporal and geographical distribution 38 Late Eocene-Early Oligocene; Europe 39 • Origin of examined material 40 - Escamps, France (UM) 41 • References: (70, 72) 42 43 Entelodontidae Lydekker, 1883 44 Entelodon spp corresponds to the two following species : 45 Entelodon deguilhemi Repelin, 1919 46 • Temporal and geographical distribution 47 Early Oligocene; Europe • Origin of examined material 48 - Villebramar and Quercy, France (cast UM2) 49 • References: (74) 50 Entelodon magnum (Aymard, 1846) 51 • Temporal and geographical distribution 52 Early Oligocene; Europe 53 • Origin of examined material 54 - Ronzon and Quercy, France 55 • References: (74) 56 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 62 of 83

20 1 2 Lihoreau et al. Supporting information 3 4 Merycoidodontidae Lydekker, 1883 5 Merycoidodon sp 6 • Temporal and geographical distribution 7 Oligocene; North America 8 • Origin of examined material 9 - Big Badland, South Dakota, USA (UM2) 10 • References: (75) 11 12 13 14 15 16 For Peer Review Only 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 63 of 83 Historical Biology

21 1 2 Lihoreau et al. Supporting information 3 4 5 III Matrix of 181 characters and 61 taxa 6 Diacodexis pakistanensis 0 0 0 - 0 0 0 ? 1 2 7 100100100000 8 000000000000 9 000000-00001 011000010010 10 -00101000000 11 010001000-00 12 0011?1100012 0?0011200010 13 001000000300 14 000100110101 15 1100010-2-02 16 010010100011For Peer Review Only ?1?0010?0210 17 ------000 18 0 0 1 19 Bunophorus grangeri ?????????? ??????100000 20 ?0?000000200 21 000000-02001 22 011000010110 -00101000000 23 010000000-0? 24 ???????????? 25 ??000--00100 000000200300 26 000100100001 27 1000010-2-02 28 100020?????? 29 ????????0??? ???????????? 30 ??? 31 Homacodon vagans ?????????? 32 ???????0???? ???????????? 33 ???????????1 34 001000010011 35 000001000010 02000000??0? 36 ????????00?1 37 000011000110 38 000000010300 000000001000 39 1020000-2-02 40 101020?????? 41 ????????0??? 42 ???????????? ??? 43 Dichobune leporina 0 0 0 - 0 0 ? ? 1 2 44 ?00100100010 45 000020000000 000100000000 46 010000000010 47 -00001000010 48 020000000-0? ??????1000?1 49 ?0000-000110 50 000000001000 51 000000101001 52 1020010-2-02 0010200000?1 53 220?100?0012 54 00110010??0? 55 ? 0 2 Cebochoerus campichii 0 0 0 - 0 0 0 ? 1 0 56 ?00201000000 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 64 of 83

22 1 2 Lihoreau et al. Supporting information 3 4 001000000000 5 000100000010 6 100010100000 -10001000001 7 020002000-0? 8 ??2000100002 9 001011000010 10 000000200200 100000101000 11 1020100-2-00 12 011110100121 13 ?20011000002 000000000000 14 0 0 1 15 Gobiohyus orientalis ?????????? 16 ??????100000For Peer Review Only 000100001200 17 100100000??0 18 010000000111 19 000001000010 20 010001000-0? ???????????2 21 ?01011001010 22 000001001000 23 001-00101011 1020100-2-02 24 111110?????? 25 ????????0??? 26 ???????????? ??? 27 Choeropotamus depereti 0 0 0 - ? ? ? ? ? ? 28 ?00200001000 29 000010001000 010000100000 30 100001000000 31 -00000000000 32 120010000-0? 33 ??0????00010 0?0011001010 34 010000100201 35 110000110010 36 20101011001? 111110001001 37 010011??1001 38 111100001000 39 0 0 2 Siamotherium krabiense 0 ? ? ? 0 0 ? ? 0 0 40 00?000000000 41 000000001000 42 010010100000 100000000001 43 010001000011 44 000002000-00 45 0001?0?0001? 46 01100-000010 000001000210 47 000100111010 48 100010102000 49 111100000021 2100010?1002 50 000000001000 51 0 0 2 52 Anthracokeryx tenuis 0 0 0 - 0 0 0 0 1 ? 100000001000 53 000000001100 54 000000000000 55 101000001101 56 010001000010 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 65 of 83 Historical Biology

23 1 2 Lihoreau et al. Supporting information 3 4 000002000-00 5 001??0100010 6 0?10????10?? ?00000010111 7 000100111010 8 20201011200? 9 ?111000?1021 10 ?11010001??? ???????????? 11 ??? 12 Anthracokeryx thailandicus ?????????? 13 ?????0000000 000000001100 14 010000000000 15 100000001101 16 210001000000For Peer Review Only 010002000-0? 17 ???????????0 18 0?1010001000 19 00000?00021? 20 000100121010 201010110010 21 111100001021 22 2?1011001??? 23 ???????????? ??? 24 Microbunodon minimum 0 0 0 - 0 0 0 0 1 1 25 100000001010 26 000000001100 000000010100 27 100000001101 28 211001000000 29 010002000-00 001311000010 30 0?1110001010 31 000000100200 32 000100121010 33 201010110010 111100011121 34 211011001002 35 101000000000 36 0 0 0 Heptacodon occidentalis 0 0 0 - ? ? ? ? 1 1 37 000010000020 38 000000001000 39 010100000?01 100000001101 40 011101000110 41 000000000-00 42 ?00111000011 0?1111011000 43 000000010101 44 000110111010 45 20201012001? 46 2111010?0121 110001?01??? 47 ???????????? 48 ??? 49 Anthracotherium chaimanei ? 0 1 0 0 1 0 1 ? ? ??????00?000 50 000000001001 51 010100100000 52 100110001101 010100100111 53 100011000-1? 54 ??0110100011 55 0?1111011000 56 ?00000010111 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 66 of 83

24 1 2 Lihoreau et al. Supporting information 3 4 010110121010 5 201010110010 6 211101?????? ?????1001??? 7 ???????????? 8 ??? 9 Anthracotherium magnum 0 0 1 0 0 1 0 0 0 0 10 000010000000 000000001001 11 010100100000 12 100110001101 13 020100100?11 000012000-10 14 0001?1100011 15 01111111?000 16 000000010111For Peer Review Only 010?10121010 17 202010110010 18 211101000101 19 2000110?1002 20 000000001200 0 0 0 21 Myaingtherium kenyapotamoides 0 0 0 - 0 0 0 ? 0 22 ?????1100000 23 0000000001?0 001010000000 24 010011000011 25 101000100001 26 0000012000-1 ???????????? 27 ???101001100 28 000000?21011 29 100000011001 1100010102-0 30 1211101??10? 31 2??1001??1?? 32 ???????????? 33 ???? Bothriogenys orientalis ?????????? 34 ?????0000020 35 100121111101 36 010000000100 100000101101 37 110101000101 38 021001100-0? 39 ?????0000?00 0?1110001101 40 000000010111 41 0?0000111010 42 201010110000 111100101021 43 1???11101??? 44 ???????????? 45 ??? 46 Bothriogenys fraasi ?????????? 0????0000020 47 1001110121?1 48 010000000101 49 100000001101 110101000110 50 011100100-0? 51 ??20?0000100 52 0?1110101000 0000?0010111 53 000100121010 54 20201011201? 55 111100121020 56 1?1010101??? 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 67 of 83 Historical Biology

25 1 2 Lihoreau et al. Supporting information 3 4 ???????????? 5 ??? 6 Bothriogenys gorringei ? 0 0 ? 0 0 1 1 1 2 000100000000 7 100121112101 8 010000?00101 9 10000001?101 10 220001000?01 111100100-00 11 00?????????? 12 ??1110101000 13 000001110?11 000100111010 14 202010110010 15 111100021021 16 211010101111For Peer Review Only 00001102??01 17 ? 1 0 18 Bothriogenys andrewsi ? ? ? ? 0 0 1 1 ? ? 19 ??????000000 20 100110002101 010?00000200 21 101000010001 22 121001001200 23 011100100-0? ???????????? 24 ??1110001100 25 00000011???0 26 0?0100??1?10 2?2?1011201? 27 111??0?????? 28 ????????1??? 29 ???????????? ??? 30 Brachyodus aequatorialis 1 1 1 1 0 ? 1 ? 1 ? 31 0??100000010 32 10011110211? 33 010000000201 101000010111 34 12000000?200 35 011101100-01 36 212000000?00 0?1110101000 37 000010111001 38 000100121010 39 202010112010 111110011120 40 111001111??? 41 ???????????? 42 ??? Brachyodus onoideus 1 1 1 1 0 0 1 1 1 2 43 000100000000 44 100110102101 45 010000000201 46 101000010111 121001011200 47 001100100-01 48 212000000100 49 0?1110101000 000010111000 50 000100121010 51 202010112010 52 1111?0011120 111001121202 53 000011001201 54 0 1 0 55 Brachyodus depereti 2 1 1 1 0 ? - - ? ? 56 ???100000000 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 68 of 83

26 1 2 Lihoreau et al. Supporting information 3 4 100110002110 5 010000000201 6 101000010111 220001011200 7 001100100-0? 8 ??????00???? 9 0?1111001000 10 000000100000 ?00100121010 11 20201011201? 12 11?1?00111?0 13 ??1001??1??? ???????????? 14 ??? 15 Bothriodon velaunum 0 0 1 0 0 0 0 0 1 2 16 000100000000For Peer Review Only 000121001000 17 010000000101 18 100000001101 19 220001001200 20 01?000110-00 002000100010 21 0?1111001010 22 000000110011 23 000000022011 201010122100 24 1111000?1121 25 111010001111 26 000011001001 0 1 0 27 Aepinacodon americanum 0 ? 1 0 ? 0 ? ? ? ? 28 ??0010000000 29 100111001200 110010002101 30 101000011101 31 220001011200 32 011???1????0 33 002000100010 0?1110001110 34 000000110000 35 000000022011 36 2010101121?? 1111000?1121 37 1?0010001??? 38 ???????????? 39 ??? Elomeryx crispus 00100010120 40 001000?00100 41 001?10011110 42 100000101001 000000011010 43 200010112100 44 111001?0-?00 45 011100000000 46 ?11110010000 000001101111 47 001001220112 48 020101100101 49 1110010101?1 ?1?11101???? 50 ???????????? 51 ?? 52 Elomeryx borbonicus 0 0 1 0 0 0 1 0 1 2 000100010010 53 100121001111 54 010100110101 55 10000001?111 56 220001011200 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 69 of 83 Historical Biology

27 1 2 Lihoreau et al. Supporting information 3 4 021110110-00 5 001110000000 6 0?111?001000 0000001?0100 7 100100122011 8 201010111110 9 211100201021 10 121011101112 000011001111 11 1 1 0 12 Afromeryx zelteni ????????1?? 13 ??0100100100 001210011?01 14 100011021011 15 010000011012 16 200010000000For Peer Review Only 11?10111100? 17 0?1100011000 18 ?11110010000 19 000001100000 20 00101--20112 020101110102 21 111001010212 22 010011110011 23 000110111011 1 1 24 Sivameryx palaeindicus ?????????? 25 ?????1010010 26 100121002100 010101112100 27 10?000001101 28 220001012?00 29 011100110-0? ????????1100 30 01111?001000 31 000000110000 32 000100112011 33 201010111010 211100??1020 34 2?1101??1??? 35 ???????????? 36 ??? Sivameryx africanus 0 ? 0 - ? ? ? ? 1 1 37 0000?1010010 38 100121002100 39 010101002101 1010?0011101 40 220011012000 41 021100110-0? 42 ??0??00011?0 0?111???1?1? 43 ?00??0110000 44 100100122011 45 20101011?01? 46 211100211020 2011011?1210 47 ------112 48 1 1 0 49 Hemimeryx blanfordi ? ? ? ? ? ? ? ? 1 2 ??0??1010010 50 100121002100 51 010101002100 52 10000000?101 22?001012000 53 021000110-0? 54 ???????????? 55 ??110-001000 56 00000011?000 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 70 of 83

28 1 2 Lihoreau et al. Supporting information 3 4 000101--2011 5 201010112011 6 211100211020 210101??1210 7 ------112 8 1 1 0 9 Merycopotamus nanus 0 0 0 - 0 ? ? ? 1 1 10 010011010010 000121002100 11 010101002101 12 101000010111 13 21?001012000 0111?0110-00 14 0001?0001100 15 011111001010 16 000000100000For Peer Review Only 000101--2011 17 201010111011 18 211100?01001 19 221001111001 20 111111121111 1 ? 2 21 Merycopotamus medioximus 0 0 0 - ? ? ? ? 1 1 22 0??021010010 23 000121002100 010101012101 24 101000010111 25 211001012000 26 011111110-0? ??02?0001100 27 011111001010 28 000000100000 29 ?00101--2011 201010111111 30 111100201101 31 021001111111 32 111111121112 33 1 1 2 Merycopotamus dissimilis 0 0 0 - 0 ? ? ? 1 1 34 010021010010 35 000121002100 36 010101012101 101000010111 37 210111012000 38 02111011110? 39 ??0?10001100 011111001010 40 000000100002 41 000101--2011 42 201010111211 211100201101 43 220001121??? 44 ???????????? 45 ??? 46 Libycosaurus algeriensis ?????????? ??????020010 47 000121002100 48 010101122101 49 101000010111 2201?1012000 50 02111011100? 51 ??02???????? 52 ???????????? ?????0100002 53 000101--2011 54 201010112111 55 111100?????? 56 ?2???1??1111 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 71 of 83 Historical Biology

29 1 2 Lihoreau et al. Supporting information 3 4 111111121112 5 1 1 0 6 Libycosaurus anisae ? 0 1 2 1 0 0 ? 1 1 010021020010 7 000121002100 8 010101121101 9 101000010111 10 210111012000 02111011100? 11 ??020?012100 12 0?1111001110 13 000000100002 000101--2011 14 201010112111 15 ?11100?01020 16 201001121???For Peer Review Only ???????????? 17 ??? 18 Libycosaurus bahri 20121001110 19 100210200100 20 001210021000 101011211011 21 010000101112 22 101110120000 23 211101111000 102?00121000 24 111110010100 25 000001000020 26 00101--20112 010101121111 27 111002011202 28 010?1121210- 29 ------1121 2 0 30 Epirigenys lokonensis ? ? ? ? 0 1 1 1 ? ? 31 ??????00?001 32 0001101-12?1 33 1111000?0??0 100??0001101 34 210000100001 35 12?10?100-0? 36 ???????????? ??1111001101 37 100011010?11 38 010010120010 39 20101011000? 11110000???? 40 ????????1002 41 000011021101 42 1 1 0 Morotochoerus ugandensis ?????????? 43 ??????0????? 44 ?????01-12?0 45 ?11?100?0??0 46 101111101101 ?10001100001 47 121002000-0? 48 ???????????? 49 ???????????? ??????200201 50 100000110010 51 ?0001010200? 52 11110000???? ????????1??? 53 ???????????? 54 ??? 55 Kenyapotamus coryndonae ? 0 ? ? 1 2 0 1 1 ? 56 00102?0?0021 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 72 of 83

30 1 2 Lihoreau et al. Supporting information 3 4 ?111011-1210 5 11?1100?0??0 6 100?1?101?01 210101100001 7 121112000-0? 8 ????????10?1 9 011011001101 10 1001112?020? 100?10110110 11 ?00010102000 12 211110???1?2 13 ?100????1202 010111001211 14 0 1 ? 15 Kenyapotamus ternani 0 0 1 0 1 ? ? ? 1 ? 16 ?0102000?02?For Peer Review Only 0?010?1-???? 17 ?????00?0??0 18 100?1??01?01 19 210101100001 20 1?1?12000-0? ?????????0?1 21 0?2011001101 22 ?00111210201 23 100?10110110 ?0001010?000 24 211110011102 25 0?0010??1??? 26 ???????????? ??? 27 Chororatherium roobii ? ? ? ? ? ? ? ? 1 2 28 0??02?00???? 29 ???????-???? ??????0????1 30 10101?111001 31 201?0110??01 32 ???11??0100? 33 ????????20?1 01??110011?1 34 ?0011?200200 35 100?00110110 36 ?00010102000 21???0?????? 37 ???0????1??? 38 ???????????? 39 ??? Chorora hippopotamine ? 0 ? ? 1 ? ? ? 1 2 40 00102?00???? 41 ???????-1?10 42 ?101100?0??1 101013111001 43 ?01101103001 44 121???0???0? 45 ??03????20?2 46 012011001111 1?0110200200 47 100?0???0010 48 ?0001010?000 49 21???0?????? ???0????1??? 50 ???????????? 51 ??? 52 Archaeopotamus harvardi 0 0 1 2 1 2 0 1 1 ? 001020000021 53 ?111011-1210 54 1101100?0??1 55 101113111001 56 201?01103001 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 73 of 83 Historical Biology

31 1 2 Lihoreau et al. Supporting information 3 4 121112000-00 5 00031010?002 6 012011001101 100110200200 7 100?0?--0?10 8 ?00010102000 9 211110011102 10 00001?121??? ???????????? 11 ??? 12 Hexaprotodon garyam 0 0 1 2 1 2 0 1 1 ? 13 001020000021 ?111011-1210 14 1101100?0??1 15 101113111001 16 ?01?011030?1For Peer Review Only 121112000-00 17 000310?0?002 18 012011001101 19 100110200200 20 100?0?--0?10 ?00010102000 21 211110?11102 22 00001?1?1111 23 111111121212 1 1 1 24 Palaeochoerus quercyi 0 0 1 ? 0 1 0 0 1 3 25 011020000000 26 0000000-0-00 000100110011 27 100110000110 28 -10001101000 29 010000000000 ?1021?000001 30 01000-000110 31 110002201001 32 110000100001 33 0100100-2-01 0111101011?1 34 ?20001?00002 35 0000000?0000 36 0 0 0 Kenyasus rusingensis 0 0 1 ? 0 1 0 0 1 3 37 010021000000 38 0000000-0-00 39 0001000????1 100012001000 40 -11101001010 41 010010000000 42 1102?01000?0 0?1011001010 43 010002201001 44 100010100101 45 0100100-2-01 46 0111001001?1 ?200010?0112 47 000000001001 48 0 0 0 49 Perchoerus probus 001?0?00130 110200000?00 50 ?0??00-0?000 51 001000????11 52 00110000100- ?1?010010100 53 100?000??00? 54 ?02??1000?00 55 ?000-0000100 56 100022010010 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 74 of 83

32 1 2 Lihoreau et al. Supporting information 3 4 00?001000011 5 000100-2-0?0 6 111101011??2 2?011?00???? 7 ???????????? 8 ?? 9 Amphimeryx murinus 0 0 1 1 0 0 0 1 1 0 10 ?00200101120 001001000-00 11 000100-00011 12 101003010011 13 201101013100 000000111100 14 ??2???1000?2 15 100012201110 16 000002100200For Peer Review Only 001-00022011 17 201110112002 18 011110100001 19 201010000210 20 ------000 0 0 2 21 Khirtaria spp. ? ? ? ? ? ? ? ? ? ? ? 22 ?????0000000 23 000000010000 101001000011 24 1001-0111110 25 001010200100 26 00001?010??? ???????????? 27 ???????????? 28 ????02000010 29 100001101011 100110-2-021 30 10021??????? 31 ???????1???? 32 ???????????? 33 ?? Mixtotherium spp. ? ? ? ? ? ? ? ? 1 2 0 34 00010101120? 35 11000001-?00 36 001000000100 10000110110- 37 101010001010 38 2000010100?? 39 ?01?10000?21 011110010000 40 100001002000 41 01-001020002 42 020111100122 11110??1???? 43 ???11??01110 44 0000000??000 45 0 2 46 Xiphodon castrensis ?????????? ??????101120 47 011001002010 48 0001000?2011 49 101000010110 -20001011000 50 010000110-0? 51 ??????001010 52 111111201010 000002100000 53 001-00022001 54 201110110002 55 211111?????? 56 ?0??01?00111 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 75 of 83 Historical Biology

33 1 2 Lihoreau et al. Supporting information 3 4 1000100?1100 5 0 1 2 6 Dacrytherium ovinum 0 ? ? ? 0 0 ? ? 1 2 100200001000 7 001110002210 8 010100010010 9 111000000010 10 -11001012000 100000100-00 11 ??20?1000002 12 01110-201011 13 000010100000 001-00102011 14 202110110012 15 0111001000?1 16 1?0001??0???For Peer Review Only ???????????? 17 ??? 18 Diplobune minor 00100001121 19 001000011000 20 111100020100 001000000110 21 01000010110- 22 110011122000 23 00000100-002 120010000120 24 111122010100 25 000021000000 26 01-001020012 011101100120 27 111001000012 28 000010?01111 29 000?00010000 1 2 30 Paroxacron valdense 0 0 0 - 0 0 0 ? 1 ? 31 ???2?1101120 32 001001002000 33 000100012010 110000010010 34 -01001012000 35 0000?01-??1? 36 ??????000012 101111201010 37 001002101000 38 001-00002001 39 201101111112 011120100011 40 1000000?0210 41 ------000 42 0 0 2 Entelodon spp. 0 0 1 ? 0 0 0 1 0 0 0 43 000110010000 44 000000000000 45 00100-000010 46 110010110110 001010000100 47 000000-10000 48 00??11000120 49 10010-000100 000012010-00 50 000001001010 51 000010-2-011 52 010202000211 200000011111 53 10000021?000 54 0 2 55 Indohyus indirae ??????????? 56 ?????00????? 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 76 of 83

34 1 2 Lihoreau et al. Supporting information 3 4 ????00010000 5 001000000011 6 100000101110 000010200100 7 0000120100?? 8 ???????00?00 9 1000--000000 10 011002002010 01-001101011 11 100110-2-021 12 1?100??????? 13 ?????10????? ???????????? 14 ?? 15 Merycoidodon sp. ? ? ? ? ? ? ? ? 0 1 0 16 000100000201For Peer Review Only 111100010010 17 101001100101 18 0100-0000112 19 210010132001 20 200?01????00 001?00001000 21 001122010000 22 000020002000 23 01-01--20012 0211011001?2 24 111001?0??12 25 00001100???? 26 ???????????? ?? 27 Amphiraghatherium spp. ? ? ? ? ? ? ? ? 1 ? 28 ???200101100 29 011000000210 110110000000 30 100000010111 31 000001100010 32 120002000-0? 33 ??????001012 101011001001 34 011001210201 35 1000001110?1 36 ?00010100002 11110000?021 37 21001???1??? 38 ???????????? 39 ??? Hallebune krumbiegeli ?????????? 40 ?????0101120 41 011101000?10 42 ?00100000001 001000010111 43 000001000010 44 01000200??0? 45 ????????00?2 46 1?1011001000 01?001210300 47 000000111011 48 1000?10-200? 49 10?010?????? ???011??0??? 50 ???????????? 51 ??? 52 Archaeomeryx optatus 0 0 0 - ? 0 ? ? 1 ? ?00200101120 53 001001001000 54 000100000010 55 100003010011 56 201001013000 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 77 of 83 Historical Biology

35 1 2 Lihoreau et al. Supporting information 3 4 0000001???00 5 0010?0120012 6 ??0110201000 000000101200 7 001-01--1010 8 20211111001? 9 111100??1??1 10 ??0011??0??? ???????????? 11 ??? 12 Lophiomeryx chalaniati 0 0 1 2 0 0 1 ? 1 ? 13 ???200101120 001000001-00 14 000100002011 15 101003010011 16 201001013000For Peer Review Only 02000011110? 17 --2?00120011 18 000112201110 19 000000100200 20 001-01--2011 20111011001? 21 1111001010?0 22 2200111?0??? 23 ???????????? ??? 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 78 of 83

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41 1 2 Lihoreau et al. Supporting information 3 4 81 Ducrocq, S., Coiffait, B., Coiffait, P. E., Mahboubi, M., & Jaeger, J. J. (2001). The Miocene 5 6 Anthracotheriidae (Artiodactyla, Mammalia) from the Nementcha, eastern Algeria. Neues Jahrbuch fur 7 Geologie und Palaontologie-Monatshefte, (3), 145-156. 8 9 82 Lihoreau, F., Hautier, L., & Mahboubi, M. (2014). The new Algerian locality of Bir el Ater 3: validity 10 of Libycosaurus algeriensis (Mammalia, Hippopotamoidea) and the age of the Nementcha Formation. 11 12 Palaeovertebrata, 39, e1. 13 14 15 16 For Peer Review Only 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi