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Lentiarenium cristolii (Fitzinger, 1842) comb. nov. Figs 2���10, Tables 1���5 Halitherium cristolii Fitzinger, 1842: 71, pl. 1. Metaxytherium (?) pergense Toula, 1899: 459, pl. 12. Halitherium abeli Spillmann, 1959: 36, pls. 1���4, fgs 19���20, 22, 24���27, 29b, 31���32, 33b, 34. Manatus christolii ��� De Blainville 1844: 122. Metaxytherium christolii ��� Laurillard 1846: 172. Halianassa collinii ��� Meyer 1847: 189, 578 (partim). ��� Ehrlich 1850: 14���15, fgs a���c. ��� Ehrlich 1855: 3, pls. 1���2, corresponding fgs on pages 14���17. Halitherium schinzii ��� Peters 1867: 310. Halitherium schinzi ��� Lepsius 1882: 164 (partim). Halitherium christoli ��� Abel 1904: 25, pl. 1, fgs 12���13, pl. 2, fgs 4, 11, 17, pl. 5, fg. 8, fg. 1. ��� Spillmann 1959: 17, fgs 8���18, 21, 23, 28, 29a, 30, 33a; 1969: 62, pl. 8, fg. 2; 1973: 198, pl. 40, fg. 4. Halitherium pergense ��� Spillmann 1959: 11, fgs 6���7; 1969: 61, fg. 1; 1973: 197, pl. 39, fgs 1���2. Halitherium abeli ��� Spillmann 1969: 62, pl. 9, fg. 3; 1973: 205. Diagnosis As for the genus. Type Material Lectotype (present designation) A mandible (OLL 2012/1) of an adult individual (based on the presence of a large retromolar space and erupted m3 in wear) with left dp5���m2 and right m1���3, ���Sicherbauer��� sandpit, Linz. Paralectotypes Fragment of right maxilla with worn M1 crown and remnants of DP5 roots (OLL 2012/2), and an isolated crown of M3 (OLL 2012/3) from the right side, both from the ���Sicherbauer��� sandpit, Linz. Holotype (by monotypy) of Metaxytherium pergense Cast of a parietal-supraoccipital skullcap (OLL 1899/11), sandstone quarry near the town of Perg. Holotype (by original designation) of Halitherium abeli Mandible of an adult individual (based on the presence of a large retromolar space and erupted m3 in wear), fragments of basicranium, cervical and other vertebrae (OLL 1939/257), ���Limoni��� sandpit, Linz. Referred material OLL 1854/327, 1863/184, 1917/7, 1921/71, 1926/394, 1926/395, 1927/200, 1928/82, 1931/21, 1931/263, 1948/33, 2012/4, 2012/5, 2012/6, 2012/7, 2013/1. For a detailed listing of the preserved skeletal parts see Table 1. Type horizon and locality ���Sicherbauer-Sandgst��tte���, a former sandpit within the city limits of Linz (Upper Austria). Linz-Melk Formation, Linzer Sande (= Linz Sands), upper Oligocene, lower Egerian (Chattian). Range and distribution Known only from the upper Oligocene of Linz and the surrounding area. Description The following description is based on the available sirenian material housed in OLL, regardless of the different species that were proposed in the past. It will be outlined in detail in the Discussion why the respective skeletal material represents a single species. Lentiarenium cristolii is known from cranial and postcranial elements. However, the premaxilla and lacrimal are unknown as are the pelvis, zeugopod and autopod. The following description is mainly based on a partial skull (OLL 1926/394) and two mandibles (OLL 1939/257 and OLL 2012/1). PREMAXILLA. The premaxilla is not preserved in any specimen but some morphological characters can be indirectly determined. The external nares are retracted and enlarged (Fig. 2), as in all sirenians, and reach beyond the anterior margin of the orbit. Judging from the recesses in the anterior margin of the frontal, the nasal processes are not broadened and bulbous at their posterior ends but taper, having lengthy overlap with the frontals. The angle of the rostrum most likely exceeds 50�� considering the defection of the mandibular symphysis of about 60�� (Fig. 7). NASAL. The exact status of the nasals cannot be determined without doubt due to the poor preservation of the nasal area in specimen OLL 1926/394 (Fig. 2). Judging from the right anteromedial margin of the frontals, which is not damaged, but smooth without an attachment area for the nasals, these elements are at least considered to have been small without meeting in the midline. A nasal incisure is present at the posterior end of the mesorostral fossa, but unlike in Metaxytherium albifontanum (Velez-Juarbe & Domning, 2014a) and Priscosiren atlantica (Velez-Juarbe & Domning, 2014b) it is deep, extending posterior to the supraorbital processes of the frontals, though not to the extent seen in dugongines like Crenatosiren olseni (Domning 1997). It is uncertain whether the nasals were fused or coalesced with the frontals. ETHMOIDAL REGION. The ethmoid is incompletely preserved and not easily observable in all aspects. A prominent perpendicular plate of the mesethmoid is visible in dorsal and anterior views of the skull OLL 1926/394 (Fig. 2). This vertical wall measures 10 mm to 15 mm in width, is narrower dorsally and ventrally, and apparently also becomes thinner posteriorly. Ventrally, the perpendicular plate is fused with the likewise distinctly developed vomer. On the right side of the skull, and medial to the frontal (Fig. 2), the almost complete large ethmoturbinal (concha maxima ethmoidalis (Kaiser 1974)) extends nearly parallel to the mesethmoid. Its left counterpart is only fragmentarily preserved. The crista galli and lamina papyracea are either not preserved or not visible. VOMER. The vomer is exposed on the ventral side of the skull OLL 1926/394 but broken anteriorly (Fig. 3). It is fused with the presphenoid posteriorly and forms the cranial extension of its median crest. The vomer is triangular in cross section, frmly fused with the ethmoid via its fat dorsal surface, and contacts the maxilla laterally. In lateral view (Fig. 4B), the vomer is also visible through the orbit due to the incomplete preservation of the skull. FRONTAL. In dorsal view (Fig. 2), the frontal roof is fat between the temporal crests, and bears no knoblike bosses as present in some dugongines (e.g., Crenatosiren olseni (Domning 1997)). The straight to slightly concave anterior margin of the frontal has no internasal process. The temporal crests form distinct keels (morphotype B; Domning 1988) and are as prominent on the frontal as on the parietal. In lateral view (Fig. 4B), the supraorbital process is dorsoventrally fattened with its dorsal surface inclined gently ventrolaterad. Its lateral margin is not divided, and it has a prominent posterolateral corner that projects posteriorly. An orbitotemporal crest is distinct relative to what is observed in Metaxytherium albifontanum (Velez-Juarbe & Domning 2014a), and forms a craniocaudally-extending ridge. The lamina orbitalis is signifcantly less than 10 mm thick. PARIETAL. The parietal roof (Fig. 2) is fat between the temporal crests and characterised by a strong intertemporal constriction that reaches its maximum behind the centre of the skull roof with the parietal bulging laterally. An external sagittal crest is not developed. The frontal processes of the parietal are short and do not exceed half the length of the frontal in the midline, a condition similar to that in Priscosiren atlantica (Velez-Juarbe & Domning 2014b). The parietal is longer than the frontal, and the overall proportions of the cranial roof indicate a slight brachycephaly when the value of the frontal length is divided by the width of the supraoccipital, i.e., the ratio l FP/w SO, which is below 2. In endocranial view (Fig. 3), the bony falx cerebri extends from a prominent tentoric process and fattens out anteriorly before reaching the frontoparietal suture. The tentorium osseum is well developed and an internal parietal spine (or tentorial process as illustrated in Voss (2008: Fig. 4B)) is missing. On both sides of the bony falx, the fat internal parietal surface shows the depressions for the superior parts of the brain hemispheres. SUPRAOCCIPITAL. This element is widest dorsally rather than ventrally (Fig. 4A), relative to what is observed in Metaxytherium spp. (e.g., M. albifontanum (Velez-Juarbe & Domning 2014a)). The supraoccipital is only slightly wider than high (width to height ratio Crenatosiren olseni (Domning 1997). Dorsally, the nuchal crest is constantly narrow along its transversal length and relatively sharp-edged. It makes up the dorsolateral margin of the supraoccipital. The external occipital protuberance rises above the parietal roof and is also prominent posteriorly. Ventrad, the protuberance continues as the external occipital crest that forms a distinct ridge, which slightly fattens out after one third of the supraoccipital���s height, almost reaching its ventral margin. Dorsolateral to this median ridge the deep and large insertions for the semispinalis capitis muscle occupy about the upper third of the external lamina. The area of the muscle insertion is triangular and defned by distinct ridges medioventrally and the nuchal crest dorsolaterally. The ventral margin of the supraoccipital forms an angle of approximately 135�� in specimen OLL 1926/394. Specimen OLL 1899/11 (Fig. 5), formerly designated as the holotype of ��� Halitherium ��� pergense but now referred to Lentiarenium cristolii, also shows a distinct nuchal crest. However, the protuberance, median ridge and defnitions of the muscle insertions are less prominently developed than in OLL 1926/394, indicating its juvenile status. In interior view (Fig. 3), the supraoccipital is fat with the exception of longitudinal bulges dorsolaterally that are merged in the median plane and separated by a deep transverse sulcus from the tentorium osseum. Posterolaterally, the parietals extend between the supraoccipital and squamosal, forming a short fange. EXOCCIPITAL. The dorsal parts of these paired elements are not preserved in any specimen. However, the total length of the ventral margin of the supraoccipital in OLL 1926/394 (Figs 3, 4A) reveals the articulation surface for the exoccipitals, indicating that these bones evidently meet in a suture dorsal to the foramen magnum. Additionally, specimen OLL 1939/257 preserves the ventralmost parts of the exoccipitals, which Spillmann (1959: fg. 19) illustrated in ventral view. During the personal examinations, the paroccipital processes were detected to be long, projecting as far ventrally as the occipital condyles, which is similar to what can be observed in some dugongines (e.g., Nanosiren garciae Domning & Aguilera, 2008 and N. sanchezi Domning & Aguilera, 2008 (Domning & Aguilera 2008: fg. 3, 11)). Medioventral to the paroccipital processes, the hypoglossal foramen is not opened to form a notch or incisure but is well surrounded by bone. The supracondylar fossae are distinct and defne the occipital condyles across their entire width. BASIOCCIPITAL. An isolated basioccipital fused with the lower parts of the exoccipitals is preserved in specimen OLL 1939/257 (Spillmann 1959: fg. 19). It contributes to the occipital condyles ventrolaterally and extends craniad as a short, columnar bone. On its ventral side, the sphenooccipital eminences for the longus capitis muscles are concave and separated by a short but distinct ridge. Specimens OLL 1939/257 and 1926/394 (Fig. 3), in which either the basioccipital or basisphenoid is preserved, show smoothed attachment areas for the adjacent bone, indicating that the basioccipital and basisphenoid were not fused. On that basis, both specimens can be determined as subadults. BASISPHENOID, PRESPHENOID, ORBITOSPHENOID. In specimen OLL 1926/394, the sphenoidal region is clearly observable (Fig. 3). The basisphenoid has a fat ventral surface that is defned laterally by antero posteriorly-broad pterygoid processes. Cranially, the basisphenoid continues with a slight anterodorsal slope into the presphenoid. Both bones are frmly fused with each other and with the orbitosphenoid anterolaterally, the alisphenoid dorsolaterally, and the pterygoid posterolaterally. The median crest of the presphenoid is not prominently developed, which might be related to the state of preservation of the skull in this area, and only becomes distinct at the level of the adjacent vomer. On the lateral side of the skull (Fig. 4B), the orbitosphenoid is exposed and contributes to the anteromedial wall of the temporal fossa. The orbitosphenoid is defned by the frontal dorsally, the alisphenoid posterodorsally, and apparently by the maxilla ventrally. Its sutures with the palatine are not detectable. ALISPHENOID. The alisphenoid is visible in the lateral view of the skull (Fig. 4B). Its sutural contacts with the frontal, parietal and squamosal can be clearly determined. Furthermore, the alisphenoid forms the slightly uneven posterolateral side of the pterygoid process. An alisphenoid canal is absent, and the foramen ovale is opened to form a notch or incisure. PTERYGOID. As in other sirenians, the pterygoid is present on the posteromedial side of the pterygoid process but fully fused with the surrounding bones (Fig. 3). Though not well preserved in OLL 1926/394, the wing-shaped pterygoid processes each bear a dorsoventrally elongated pterygoid fossa posteriorly that extends above the level of the roof of the internal nares, relative to the condition observed in some dugongines like Dioplotherium manigaulti (Domning 1989). The distal ends of both pterygoid processes are somewhat damaged, although the distomedial angle of the right pterygoid process is still distinct and indicates a hamula process. PALATINE. Only the posteriormost parts of the palatines are preserved in OLL 1926/394, and are best observable on the right side (Fig. 3). There the palatine forms the anteromedial margin of the pterygoid process. Its sutures with the surrounding bones are only barely visible on the distal and medial sides of the pterygoid process and on the posterior side of the maxillary alveolar margin. MAXILLA. The zygomatic-orbital bridge (Fig. 3) is not completely preserved in any of the specimens. However, in the maxillary fragment of OLL 1939/257 its dimensions are 47 mm in minimum length and 17.5 mm in nearly original height (Spillmann 1959: fg. 20). On the basis of these data, the zygomaticorbital bridge can be clearly determined to be long anteroposteriorly, relative to what is observed in the genus Hydrodamalis (Domning 1978; Velez-Juarbe & Domning 2014a). Additionally, and in contrast to some hydrodamalines, e.g., Dusisiren jordani Kellogg, 1925 and Hydrodamalis cuestae Domning, 1978 (Domning 1978; Velez-Juarbe & Domning 2014a), it is only slightly elevated above the alveolar margin, and its posterior edge is thickened. Remnants of the infraorbital canal reveal no obstruction. SQUAMOSAL. The cranial part of the squamosal (Figs 2, 4B) extends up to the temporal crests but does not interrupt the course of the temporal crests, so that these reach the occipital nuchal crest. The posttympanic process is not club like distally (Fig. 4B), but concave anteroventrally for the attachment of the sternomastoid muscle. In the posterior view of the skull (Fig. 4A), a prominent sigmoid ridge is visible forming the laterocaudal margin of the squamosal. Posterolaterally, the mastoid foramen is present, flled by the periotic, and enclosed by the squamosal anteriorly, the exoccipital posteriorly, and the supraoccipital dorsally. Lateral to the braincase (Figs 2, 4B), each of the zygomatic processes projects from a zygomatic root that, though partially broken, is characterised by a distinct notch posteriorly. The zygomatic process is triangular in shape, tapering anteriorly. Its lateral and medial sides are fat to concave with the dorsal margin distinctly inclined inwards to form a sigmoid ridge. The posterodorsal end of the zygomatic process is straight to concave. The external auditory meatus is short mediolaterally and about as wide as high anteroposteriorly. Ventrally (Fig. 3), the elements of the mandibular articulation surface are elongated transversely. The mandibular fossa forms a distinct depression relative to the slightly convex tuberculum anteriorly. Posterior to the mandibular fossa, the postglenoid process forms a rounded and longitudinal knob, which rises above the level of the tuberculum. The posterior end of the zygomatic process, the processus retroversus, shows a moderate inward-directed infection in contrast to what is observed in the living dugong (e.g., Domning & Aguilera 2008; Velez-Juarbe & Domning 2014a). JUGAL. Only a fragmentarily preserved middle part of the right jugal is known from specimen OLL 1926/394 (Fig. 4B), indicating that a postorbital process is probably present. Considering the position and shape of the supraorbital processes of the frontal, the development of a postorbital bar can be excluded. The zygomatic process of the jugal is not preserved but according to its imprint on the ventral side of the zygomatic process of the squamosal it reaches the tuberculum, exceeding the diameter of the orbit. EAR REGION. In specimen OLL 1926/394, the right periotic is poorly preserved (Figs 3, 4A). It is not fused with the adjacent skull bones, and is set in a closely-ftting socket in the squamosal. The tegmen tympani is only indicated by its imprints on the dorsolateral side of the squamosal. It was most likely about as big as the mastoid or slightly smaller. The petrosal is fragmentarily preserved medioventrally, with the perilymphatic foramen apparently not separated into a fenestra rotunda and cochlea canaliculus. The processus fonticulus flls the mastoid foramen posteriorly (Fig. 4A). MANDIBLE (Table 3). The mandibular symphysis is broad, as is the masticating surface that is lacking a median furrow and houses four large and shallow alveoli for vestigial incisors and canines. This is best visible in OLL 1939/257 (Fig. 6A), which exhibits a completely preserved masticating surface, whereas in OLL 2012/1 (Figs 6B, 7A) the ventralmost end is broken. In lateral view (Fig. 7), the symphysis is higher than long and bears the mental foramen laterally, which is joined dorsoposteriorly by two accessory mental foramina on each side in specimen OLL 1939/257 (Fig. 7B). The accessory mental foramina are large relative to what is observed in more plesiomorph dugongid taxa, e.g., ��� Halitherium ��� taulannense (Sagne 2001a), but they are still smaller than the principal foramen. This observation is interpreted here in analogy with Trichechus (Domning 1982, 1994, and personal observations), as ���true��� accessory mental foramina, which are present in addition to and usually posterior to the large principal foramen. In the lectotype (OLL 2012/1; Fig. 7A), the mental foramen is broken off dorsoposteriorly, and therefore the accessory mental foramina are not identifable, but their open canals are merged with the main foramen. The overall build of the horizontal mandibular ramus appears to be broad dorsoventrally, but it is evaluated to be slender on the basis of its minimum dorsoventral height, which is smaller than 0.25 �� the length of the mandible. The ventral border, Published as part of Manja Voss, Bj��rn Berning & Erich Reiter, 2016, A taxonomic and morphological re-evaluation of " Halitherium " cristolii Fitzinger, 1842 (Mammalia, Sirenia) from the late Oligocene of Austria, with the description of a new genus, pp. 1-32 in European Journal of Taxonomy 256 on pages 7-24, DOI: 10.5852/ejt.2016.256, http://zenodo.org/record/889326, {"references":["Fitzinger L. J. 1842. Bericht uber die in den Sandlagern von Linz aufgefundenen fossilen Reste eines urweltlichen Saugers (Halitherium cristolii). Bericht uber das Museum Francisco-Carolinum Linz 6: 61 - 72.","Toula F. 1899. Zwei Saugetierreste aus dem \" kristallisierten Sandstein \" von Wallsee in Nieder- und Perg in Oberosterreich. Neues Jahrbuch fur Mineralogie, Geologie und Palaeontologie, Beilagen 12: 447 - 476.","Spillmann F. 1959. Die Sirenen aus dem Oligozan des Linzer Beckens (Oberosterreich) mit Ausfuhrungen uber \" Osteosklerose \" und \" Pachyostose \". Denkschriften der mathematisch-naturwissenschaftlichen Klasse der Osterreichischen Akademie der Wissenschaften 110: 1 - 68.","De Blainville H. M. D. 1844. Osteographie ou Description iconographique comparee du Squelette et du Systeme dentaire des Mammiferes recents et fossiles pour servir de Base a la Zoologie et a la Geologie. Des Lamantins (Buffon), (Manatus, Scopoli), ou gravigrades aquatiques. Vol. 3. Bailliere et Fils, Paris","Laurillard C. L. 1846. Metaxytherium. Dictionnaire de l'Universite d'Histoire Naturelle 8: 171 - 172.","Meyer H. von. 1847. Mittheilungen an Prof. Bronn, Frankfurt a. M., 4. Januar 1847. Neues Jahrbuch fur Mineralogie, Geognosie, Geologie und Petrefaktenkunde 1847: 181 - 196.","Ehrlich C. 1850. Uber die nordostlichen Alpen. Ein Beitrag zur naheren Kenntnis des Gebietes von Osterreich ob der Enns und Salzburg in geognostisch-mineralogisch-montanistischer Beziehung. Jos. Wimmer, Linz.","Ehrlich C. 1855. Beitrage zur Palaeontologie und Geognosie von Oberosterreich und Salzburg. I. Die fossilen Cetaceen-Reste aus den Tertiar-Ablagerungen bei Linz, mit besonderer Berucksichtigung jener der Halianassa collinii H. v. M., und des dazu gehorigen, im August des Jahres 1854 aufgefundenen Rumpfskelettes. Bericht uber das Museum Francisco-Carolinum Linz 15: 3 - 21.","Peters K. F. 1867. Das Halitheriumskelet von Hainburg: Halitherium cordieri, Christol sp. (Manatus cuvieri ou fossilis, Blainv.; Hippopotamus medius cuvieri var). Jahrbuch der Kaiserlich-Koniglichen Geologischen Reichsanstalt 17: 309 - 341.","Lepsius G. R. 1882. Halitherium Schinzi, die fossile Sirene des Mainzer Beckens. Abhandlungen des Mittelrheinischen geologischen Vereins 1, Bergstrasser, Darmstadt. http: // dx. doi. org / 10.5962 / bhl .title. 25531","Abel O. 1904. Die Sirenen der mediterranen Tertiarbildungen Osterreichs. Abhandlungen der Kaiserlich- Koniglichen Geologischen Reichsanstalt 19: 1 - 223.","Spillmann F. 1969. Die fossilen Saugetierfaunen des Linzer Raumes. In: Podzeit W. & Steininger F. (eds) Geologie und Palaontologie des Linzer Raumes. Kataloge des Oberosterreichischen Landesmuseums 64: 55 - 66, Oberosterreichischen Landesmuseum, Linz.","Velez-Juarbe J. & Domning D. P. 2014 a. Fossil Sirenia of the West Atlantic and Caribbean region. IX. Metaxytherium albifontanum, sp. nov. Journal of Vertebrate Paleontology 34 (2): 444 - 464. http: //dx. doi. org / 10.1080 / 02724634.2013.799072","Velez-Juarbe J. & Domning D. P. 2014 b. Fossil Sirenia of the West Atlantic and Caribbean region. X. Priscosiren atlantica, gen. et sp. nov. Journal of Vertebrate Paleontology 34 (4): 951 - 964. http: // dx. doi .org / 10.1080 / 02724634.2013.815192","Domning D. P. 1997. Fossil Sirenia of the West Atlantic and Caribbean region. VI. Crenatosiren olseni (Reinhart, 1976). Journal of Vertebrate Paleontology 17 (2): 397 - 412. http: // dx. doi. org / 10.1080 / 027246 34.1997. 10010984","Kaiser H. E. 1974. Morphology of the Sirenia: a Macroscopic and X-Ray Atlas of the Osteology of Recent Species. S. Karger AG, Basel.","Domning D. P. 1988. Fossil Sirenia of the West Atlantic and Caribbean region. I. Metaxytherium Foridanum Hay, 1922. Journal of Vertebrate Paleontology 8 (4): 395 - 426. http: //dx. doi. org/10.1080/02724634.1988.10011728","Voss M. 2008. New fnds of Halitherium (Sirenia, Mammalia) from the lower Oligocene of the Rhine area, Germany. Neues Jahrbuch fur Geologie und Palaontologie - Abhandlungen 249 (3): 257 - 269. http: // dx. doi. org / 10.1127 / 0077 - 7749 / 2008 / 0249 - 0257","Domning D. P. & Aguilera O. A. 2008. Fossil Sirenia of the West Atlantic and Caribbean Region. VIII. Nanosiren garciae, gen. et sp. nov. and Nanosiren sanchezi, sp. nov. Journal of Vertebrate Paleontology 28 (2): 479 - 500. http: // dx. doi. org / 10.1671 / 0272 - 4634 (2008) 28 [479: FSOTWA] 2.0. CO; 2","Domning D. P. 1989. Fossil Sirenia of the West Atlantic and Caribbean region. II. Dioplotherium manigaulti Cope, 1883. Journal of Vertebrate Paleontology 9 (4): 415 - 428. http: // dx. doi. org / 10.1080 / 02 724634.1989. 10011774","Domning D. P. 1978. Sirenian evolution in the North Pacifc Ocean. University of California Publications in Geological Sciences 118: 1 - 177.","Sagne C. 2001 a. Halitherium taulannense, nouveau sirenian (Sirenia, Mammalia) de l'Eocene superieur provenant du domaine Nord-Tethysien (Alpes-de-Haute-Provence, France). Comptes rendus de l'Academie des Sciences de la Terre et des Planetes 333 (8): 471 - 476. http: // dx. doi. org / 10.1016 / S 1251 - 8050 (01) 01661 - 5","Domning D. P. 1982. Evolution of manatees: a speculative history. Journal of Paleontology 56: 599 - 619.","Domning D. P. 1994. A phylogenetic analysis of the Sirenia. In: Berta A. & Demere T. (eds) Contributions in marine mammal paleontology honoring Frank C. Whitmore Jr. Proceedings of the San Diego Society of Natural History 29: 177 - 189, San Diego Society of Natural History, San Diego","Sagne C. 2001 b. La DiversiFcation des Sireniens a l'Eocene (Sirenia, Mammalia). Etude morphologique et Analyse phylogenetique du Sirenian de Taulanne, Halitherium taulannense. PhD thesis, Museum National d'Histoire Naturelle, Paris.","Pia J. & Sickenberg O. 1934. 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Genus Lentiarenium Voss gen. nov. urn:lsid:zoobank.org:act:A67C71FB-CBC3-460E-953C-5774A3EA9939 Type species Halitherium cristolii Fitzinger, 1842 Diagnosis Dugongid based on the following combination of synapomorphies: absence of alisphenoid canal, open foramen ovale, loss of permanent ffth premolar, and squamosal reaching temporal crest. Differs from the Dugonginae (Crenatosiren Domning, 1991, Nanosiren Domning & Aguilera, 2008, Dugong Lac��p��de, 1799, Rytiodus Lartet, 1866, Corystosiren Domning, 1990, Callistosiren V��lez-Juarbe & Domning, 2015, Bharatisiren Bajpai & Domning, 1997, Domningia Thewissen & Bajpai, 2009, Kutchisiren Bajpai, Domning, Das, V��lez-Juarbe & Mishra, 2010, Dioplotherium Cope, 1883 and Xenosiren Domning, 1989), the Hydrodamalinae Simpson, 1932 (Dusisiren Domning, 1978 and Hydrodamalis Retzius, 1794), and other dugongid genera (Eotheroides Palmer, 1899, Prototherium De Zigno, 1887, Eosiren Andrews, 1902, Caribosiren Reinhart, 1959, Priscosiren V��lez-Juarbe & Domning, 2014b, Metaxytherium De Christol, 1840, and other species formerly lumped under ��� Halitherium ���) by displaying the following unique combination of plesiomorphies: frontal roof fat; supraorbital process of the frontal dorsoventrally fattened with well-developed, prominent posterolateral corner; supraoccipital wider dorsally than ventrally; exoccipitals meet in a suture dorsal to the foramen magnum; posttympanic process with a prominent anteroventral process for attachment of m. sternomastoideus; paroccipital process of exoccipital long, reaching as far ventrally as occipital condyles; accessory mental foramina present; horizontal ramus of mandible slender dorsoventrally; permanent premolars (P2/p2 ��� P4/p4) present. Synapomorphies: nasals reduced and not meeting in midline (shared with Eosiren imenti Domning et al., 1994, Caribosiren, Priscosiren, and all later dugongid taxa), nasal incisure at posterior end of the mesorostral fossa deep, extending posterior to the supraorbital processes of the frontals (shared with some Metaxytherium spp., dugongines, and Hydrodamalis); strongly concave ventral border of the horizontal mandibular ramus (shared with Priscosiren, Metaxytherium spp., and dugongines), masticating surface of mandible broad (shared with Metaxytherium ssp., dugongines, and hydrodamalines). In contrast to the similar species Priscosiren atlantica it has a supraorbital process with the posterolateral corner projecting posteriorly; prominent temporal crests on frontal and parietal; supraoccipital distinct in height, only slightly wider than high. Etymology A combination of the Latin terms for the Linz Sands (Lentia and arenium), the informal name for the upper Oligocene sediments in which the species was found., Published as part of Manja Voss, Bj��rn Berning & Erich Reiter, 2016, A taxonomic and morphological re-evaluation of " Halitherium " cristolii Fitzinger, 1842 (Mammalia, Sirenia) from the late Oligocene of Austria, with the description of a new genus, pp. 1-32 in European Journal of Taxonomy 256 on pages 6-7, DOI: 10.5852/ejt.2016.256, http://zenodo.org/record/889326, {"references":["Fitzinger L. J. 1842. Bericht uber die in den Sandlagern von Linz aufgefundenen fossilen Reste eines urweltlichen Saugers (Halitherium cristolii). Bericht uber das Museum Francisco-Carolinum Linz 6: 61 - 72.","Domning D. P. & Aguilera O. A. 2008. Fossil Sirenia of the West Atlantic and Caribbean Region. VIII. Nanosiren garciae, gen. et sp. nov. and Nanosiren sanchezi, sp. nov. Journal of Vertebrate Paleontology 28 (2): 479 - 500. http: // dx. doi. org / 10.1671 / 0272 - 4634 (2008) 28 [479: FSOTWA] 2.0. CO; 2","Springer M. S., Signore A. V., Paijmans J. L. A., Velez-Juarbe J., Domning D. P., Bauer C. E., He K., Crerar L., Campos P. F., Murphy W. J., Meredith R. W., Gatesy J., Willerslev E., MacPhee R. D. E., Hofreiter M. & Campbell K. L. 2015. Interordinal gene capture, the phylogenetic position of Steller's sea cow based on molecular and morphological data, and the macroevolutionary history of Sirenia. Molecular Phylogenetics and Evolution 91: 178 - 193. http: // dx. doi. org / 10.1016 / j. ympev. 2015.05.022","Domning D. P. 1997. Fossil Sirenia of the West Atlantic and Caribbean region. VI. Crenatosiren olseni (Reinhart, 1976). Journal of Vertebrate Paleontology 17 (2): 397 - 412. http: // dx. doi. org / 10.1080 / 027246 34.1997. 10010984","Domning D. P. 1989. Fossil Sirenia of the West Atlantic and Caribbean region. II. Dioplotherium manigaulti Cope, 1883. Journal of Vertebrate Paleontology 9 (4): 415 - 428. http: // dx. doi. org / 10.1080 / 02 724634.1989. 10011774","Simpson G. G. 1932. Fossil Sirenia of Florida and the evolution of the Sirenia. Bulletin of the American Museum of Natural History 59: 419 - 503.","Domning D. P. 1978. Sirenian evolution in the North Pacifc Ocean. University of California Publications in Geological Sciences 118: 1 - 177.","Reinhart R. H. 1959. A review of the Sirenia and Desmostylia. University of California Publications in Geological Sciences 36: 1 - 146.","Velez-Juarbe J. & Domning D. P. 2014 b. Fossil Sirenia of the West Atlantic and Caribbean region. X. Priscosiren atlantica, gen. et sp. nov. Journal of Vertebrate Paleontology 34 (4): 951 - 964. http: // dx. doi .org / 10.1080 / 02724634.2013.815192","Domning D. P. 1994. A phylogenetic analysis of the Sirenia. In: Berta A. & Demere T. (eds) Contributions in marine mammal paleontology honoring Frank C. Whitmore Jr. Proceedings of the San Diego Society of Natural History 29: 177 - 189, San Diego Society of Natural History, San Diego"]}

Genus Lentiarenium Voss gen. nov. urn:lsid:zoobank.org:act:A67C71FB-CBC3-460E-953C-5774A3EA9939 Type species Halitherium cristolii Fitzinger, 1842 Diagnosis Dugongid based on the following combination of synapomorphies: absence of alisphenoid canal, open foramen ovale, loss of permanent ffth premolar, and squamosal reaching temporal crest. Differs from the Dugonginae (Crenatosiren Domning, 1991, Nanosiren Domning & Aguilera, 2008, Dugong Lacépède, 1799, Rytiodus Lartet, 1866, Corystosiren Domning, 1990, Callistosiren Vélez-Juarbe & Domning, 2015, Bharatisiren Bajpai & Domning, 1997, Domningia Thewissen & Bajpai, 2009, Kutchisiren Bajpai, Domning, Das, Vélez-Juarbe & Mishra, 2010, Dioplotherium Cope, 1883 and Xenosiren Domning, 1989), the Hydrodamalinae Simpson, 1932 (Dusisiren Domning, 1978 and Hydrodamalis Retzius, 1794), and other dugongid genera (Eotheroides Palmer, 1899, Prototherium De Zigno, 1887, Eosiren Andrews, 1902, Caribosiren Reinhart, 1959, Priscosiren Vélez-Juarbe & Domning, 2014b, Metaxytherium De Christol, 1840, and other species formerly lumped under “ Halitherium ”) by displaying the following unique combination of plesiomorphies: frontal roof fat; supraorbital process of the frontal dorsoventrally fattened with well-developed, prominent posterolateral corner; supraoccipital wider dorsally than ventrally; exoccipitals meet in a suture dorsal to the foramen magnum; posttympanic process with a prominent anteroventral process for attachment of m. sternomastoideus; paroccipital process of exoccipital long, reaching as far ventrally as occipital condyles; accessory mental foramina present; horizontal ramus of mandible slender dorsoventrally; permanent premolars (P2/p2 – P4/p4) present. Synapomorphies: nasals reduced and not meeting in midline (shared with Eosiren imenti Domning et al., 1994, Caribosiren, Priscosiren, and all later dugongid taxa), nasal incisure at posterior end of the mesorostral fossa deep, extending posterior to the supraorbital processes of the frontals (shared with some Metaxytherium spp., dugongines, and Hydrodamalis); strongly concave ventral border of the horizontal mandibular ramus (shared with Priscosiren, Metaxytherium spp., and dugongines), masticating surface of mandible broad (shared with Metaxytherium ssp., dugongines, and hydrodamalines). In contrast to the similar species Priscosiren atlantica it has a supraorbital process with the posterolateral corner projecting posteriorly; prominent temporal crests on frontal and parietal; supraoccipital distinct in height, only slightly wider than high. Etymology A combination of the Latin terms for the Linz Sands (Lentia and arenium), the informal name for the upper Oligocene sediments in which the species was found.

Lentiarenium cristolii (Fitzinger, 1842) comb. nov. Figs 2–10, Tables 1–5 Halitherium cristolii Fitzinger, 1842: 71, pl. 1. Metaxytherium (?) pergense Toula, 1899: 459, pl. 12. Halitherium abeli Spillmann, 1959: 36, pls. 1–4, fgs 19–20, 22, 24–27, 29b, 31–32, 33b, 34. Manatus christolii – De Blainville 1844: 122. Metaxytherium christolii – Laurillard 1846: 172. Halianassa collinii – Meyer 1847: 189, 578 (partim). — Ehrlich 1850: 14–15, fgs a–c. — Ehrlich 1855: 3, pls. 1–2, corresponding fgs on pages 14–17. Halitherium schinzii – Peters 1867: 310. Halitherium schinzi – Lepsius 1882: 164 (partim). Halitherium christoli – Abel 1904: 25, pl. 1, fgs 12–13, pl. 2, fgs 4, 11, 17, pl. 5, fg. 8, fg. 1. — Spillmann 1959: 17, fgs 8–18, 21, 23, 28, 29a, 30, 33a; 1969: 62, pl. 8, fg. 2; 1973: 198, pl. 40, fg. 4. Halitherium pergense – Spillmann 1959: 11, fgs 6–7; 1969: 61, fg. 1; 1973: 197, pl. 39, fgs 1–2. Halitherium abeli – Spillmann 1969: 62, pl. 9, fg. 3; 1973: 205. Diagnosis As for the genus. Type Material Lectotype (present designation) A mandible (OLL 2012/1) of an adult individual (based on the presence of a large retromolar space and erupted m3 in wear) with left dp5–m2 and right m1–3, “Sicherbauer” sandpit, Linz. Paralectotypes Fragment of right maxilla with worn M1 crown and remnants of DP5 roots (OLL 2012/2), and an isolated crown of M3 (OLL 2012/3) from the right side, both from the “Sicherbauer” sandpit, Linz. Holotype (by monotypy) of Metaxytherium pergense Cast of a parietal-supraoccipital skullcap (OLL 1899/11), sandstone quarry near the town of Perg. Holotype (by original designation) of Halitherium abeli Mandible of an adult individual (based on the presence of a large retromolar space and erupted m3 in wear), fragments of basicranium, cervical and other vertebrae (OLL 1939/257), “Limoni” sandpit, Linz. Referred material OLL 1854/327, 1863/184, 1917/7, 1921/71, 1926/394, 1926/395, 1927/200, 1928/82, 1931/21, 1931/263, 1948/33, 2012/4, 2012/5, 2012/6, 2012/7, 2013/1. For a detailed listing of the preserved skeletal parts see Table 1. Type horizon and locality “Sicherbauer-Sandgstätte”, a former sandpit within the city limits of Linz (Upper Austria). Linz-Melk Formation, Linzer Sande (= Linz Sands), upper Oligocene, lower Egerian (Chattian). Range and distribution Known only from the upper Oligocene of Linz and the surrounding area. Description The following description is based on the available sirenian material housed in OLL, regardless of the different species that were proposed in the past. It will be outlined in detail in the Discussion why the respective skeletal material represents a single species. Lentiarenium cristolii is known from cranial and postcranial elements. However, the premaxilla and lacrimal are unknown as are the pelvis, zeugopod and autopod. The following description is mainly based on a partial skull (OLL 1926/394) and two mandibles (OLL 1939/257 and OLL 2012/1). PREMAXILLA. The premaxilla is not preserved in any specimen but some morphological characters can be indirectly determined. The external nares are retracted and enlarged (Fig. 2), as in all sirenians, and reach beyond the anterior margin of the orbit. Judging from the recesses in the anterior margin of the frontal, the nasal processes are not broadened and bulbous at their posterior ends but taper, having lengthy overlap with the frontals. The angle of the rostrum most likely exceeds 50° considering the defection of the mandibular symphysis of about 60° (Fig. 7). NASAL. The exact status of the nasals cannot be determined without doubt due to the poor preservation of the nasal area in specimen OLL 1926/394 (Fig. 2). Judging from the right anteromedial margin of the frontals, which is not damaged, but smooth without an attachment area for the nasals, these elements are at least considered to have been small without meeting in the midline. A nasal incisure is present at the posterior end of the mesorostral fossa, but unlike in Metaxytherium albifontanum (Velez-Juarbe & Domning, 2014a) and Priscosiren atlantica (Velez-Juarbe & Domning, 2014b) it is deep, extending posterior to the supraorbital processes of the frontals, though not to the extent seen in dugongines like Crenatosiren olseni (Domning 1997). It is uncertain whether the nasals were fused or coalesced with the frontals. ETHMOIDAL REGION. The ethmoid is incompletely preserved and not easily observable in all aspects. A prominent perpendicular plate of the mesethmoid is visible in dorsal and anterior views of the skull OLL 1926/394 (Fig. 2). This vertical wall measures 10 mm to 15 mm in width, is narrower dorsally and ventrally, and apparently also becomes thinner posteriorly. Ventrally, the perpendicular plate is fused with the likewise distinctly developed vomer. On the right side of the skull, and medial to the frontal (Fig. 2), the almost complete large ethmoturbinal (concha maxima ethmoidalis (Kaiser 1974)) extends nearly parallel to the mesethmoid. Its left counterpart is only fragmentarily preserved. The crista galli and lamina papyracea are either not preserved or not visible. VOMER. The vomer is exposed on the ventral side of the skull OLL 1926/394 but broken anteriorly (Fig. 3). It is fused with the presphenoid posteriorly and forms the cranial extension of its median crest. The vomer is triangular in cross section, frmly fused with the ethmoid via its fat dorsal surface, and contacts the maxilla laterally. In lateral view (Fig. 4B), the vomer is also visible through the orbit due to the incomplete preservation of the skull. FRONTAL. In dorsal view (Fig. 2), the frontal roof is fat between the temporal crests, and bears no knoblike bosses as present in some dugongines (e.g., Crenatosiren olseni (Domning 1997)). The straight to slightly concave anterior margin of the frontal has no internasal process. The temporal crests form distinct keels (morphotype B; Domning 1988) and are as prominent on the frontal as on the parietal. In lateral view (Fig. 4B), the supraorbital process is dorsoventrally fattened with its dorsal surface inclined gently ventrolaterad. Its lateral margin is not divided, and it has a prominent posterolateral corner that projects posteriorly. An orbitotemporal crest is distinct relative to what is observed in Metaxytherium albifontanum (Velez-Juarbe & Domning 2014a), and forms a craniocaudally-extending ridge. The lamina orbitalis is signifcantly less than 10 mm thick. PARIETAL. The parietal roof (Fig. 2) is fat between the temporal crests and characterised by a strong intertemporal constriction that reaches its maximum behind the centre of the skull roof with the parietal bulging laterally. An external sagittal crest is not developed. The frontal processes of the parietal are short and do not exceed half the length of the frontal in the midline, a condition similar to that in Priscosiren atlantica (Velez-Juarbe & Domning 2014b). The parietal is longer than the frontal, and the overall proportions of the cranial roof indicate a slight brachycephaly when the value of the frontal length is divided by the width of the supraoccipital, i.e., the ratio l FP/w SO, which is below 2. In endocranial view (Fig. 3), the bony falx cerebri extends from a prominent tentoric process and fattens out anteriorly before reaching the frontoparietal suture. The tentorium osseum is well developed and an internal parietal spine (or tentorial process as illustrated in Voss (2008: Fig. 4B)) is missing. On both sides of the bony falx, the fat internal parietal surface shows the depressions for the superior parts of the brain hemispheres. SUPRAOCCIPITAL. This element is widest dorsally rather than ventrally (Fig. 4A), relative to what is observed in Metaxytherium spp. (e.g., M. albifontanum (Velez-Juarbe & Domning 2014a)). The supraoccipital is only slightly wider than high (width to height ratio Crenatosiren olseni (Domning 1997). Dorsally, the nuchal crest is constantly narrow along its transversal length and relatively sharp-edged. It makes up the dorsolateral margin of the supraoccipital. The external occipital protuberance rises above the parietal roof and is also prominent posteriorly. Ventrad, the protuberance continues as the external occipital crest that forms a distinct ridge, which slightly fattens out after one third of the supraoccipital’s height, almost reaching its ventral margin. Dorsolateral to this median ridge the deep and large insertions for the semispinalis capitis muscle occupy about the upper third of the external lamina. The area of the muscle insertion is triangular and defned by distinct ridges medioventrally and the nuchal crest dorsolaterally. The ventral margin of the supraoccipital forms an angle of approximately 135° in specimen OLL 1926/394. Specimen OLL 1899/11 (Fig. 5), formerly designated as the holotype of “ Halitherium ” pergense but now referred to Lentiarenium cristolii, also shows a distinct nuchal crest. However, the protuberance, median ridge and defnitions of the muscle insertions are less prominently developed than in OLL 1926/394, indicating its juvenile status. In interior view (Fig. 3), the supraoccipital is fat with the exception of longitudinal bulges dorsolaterally that are merged in the median plane and separated by a deep transverse sulcus from the tentorium osseum. Posterolaterally, the parietals extend between the supraoccipital and squamosal, forming a short fange. EXOCCIPITAL. The dorsal parts of these paired elements are not preserved in any specimen. However, the total length of the ventral margin of the supraoccipital in OLL 1926/394 (Figs 3, 4A) reveals the articulation surface for the exoccipitals, indicating that these bones evidently meet in a suture dorsal to the foramen magnum. Additionally, specimen OLL 1939/257 preserves the ventralmost parts of the exoccipitals, which Spillmann (1959: fg. 19) illustrated in ventral view. During the personal examinations, the paroccipital processes were detected to be long, projecting as far ventrally as the occipital condyles, which is similar to what can be observed in some dugongines (e.g., Nanosiren garciae Domning & Aguilera, 2008 and N. sanchezi Domning & Aguilera, 2008 (Domning & Aguilera 2008: fg. 3, 11)). Medioventral to the paroccipital processes, the hypoglossal foramen is not opened to form a notch or incisure but is well surrounded by bone. The supracondylar fossae are distinct and defne the occipital condyles across their entire width. BASIOCCIPITAL. An isolated basioccipital fused with the lower parts of the exoccipitals is preserved in specimen OLL 1939/257 (Spillmann 1959: fg. 19). It contributes to the occipital condyles ventrolaterally and extends craniad as a short, columnar bone. On its ventral side, the sphenooccipital eminences for the longus capitis muscles are concave and separated by a short but distinct ridge. Specimens OLL 1939/257 and 1926/394 (Fig. 3), in which either the basioccipital or basisphenoid is preserved, show smoothed attachment areas for the adjacent bone, indicating that the basioccipital and basisphenoid were not fused. On that basis, both specimens can be determined as subadults. BASISPHENOID, PRESPHENOID, ORBITOSPHENOID. In specimen OLL 1926/394, the sphenoidal region is clearly observable (Fig. 3). The basisphenoid has a fat ventral surface that is defned laterally by antero posteriorly-broad pterygoid processes. Cranially, the basisphenoid continues with a slight anterodorsal slope into the presphenoid. Both bones are frmly fused with each other and with the orbitosphenoid anterolaterally, the alisphenoid dorsolaterally, and the pterygoid posterolaterally. The median crest of the presphenoid is not prominently developed, which might be related to the state of preservation of the skull in this area, and only becomes distinct at the level of the adjacent vomer. On the lateral side of the skull (Fig. 4B), the orbitosphenoid is exposed and contributes to the anteromedial wall of the temporal fossa. The orbitosphenoid is defned by the frontal dorsally, the alisphenoid posterodorsally, and apparently by the maxilla ventrally. Its sutures with the palatine are not detectable. ALISPHENOID. The alisphenoid is visible in the lateral view of the skull (Fig. 4B). Its sutural contacts with the frontal, parietal and squamosal can be clearly determined. Furthermore, the alisphenoid forms the slightly uneven posterolateral side of the pterygoid process. An alisphenoid canal is absent, and the foramen ovale is opened to form a notch or incisure. PTERYGOID. As in other sirenians, the pterygoid is present on the posteromedial side of the pterygoid process but fully fused with the surrounding bones (Fig. 3). Though not well preserved in OLL 1926/394, the wing-shaped pterygoid processes each bear a dorsoventrally elongated pterygoid fossa posteriorly that extends above the level of the roof of the internal nares, relative to the condition observed in some dugongines like Dioplotherium manigaulti (Domning 1989). The distal ends of both pterygoid processes are somewhat damaged, although the distomedial angle of the right pterygoid process is still distinct and indicates a hamula process. PALATINE. Only the posteriormost parts of the palatines are preserved in OLL 1926/394, and are best observable on the right side (Fig. 3). There the palatine forms the anteromedial margin of the pterygoid process. Its sutures with the surrounding bones are only barely visible on the distal and medial sides of the pterygoid process and on the posterior side of the maxillary alveolar margin. MAXILLA. The zygomatic-orbital bridge (Fig. 3) is not completely preserved in any of the specimens. However, in the maxillary fragment of OLL 1939/257 its dimensions are 47 mm in minimum length and 17.5 mm in nearly original height (Spillmann 1959: fg. 20). On the basis of these data, the zygomaticorbital bridge can be clearly determined to be long anteroposteriorly, relative to what is observed in the genus Hydrodamalis (Domning 1978; Velez-Juarbe & Domning 2014a). Additionally, and in contrast to some hydrodamalines, e.g., Dusisiren jordani Kellogg, 1925 and Hydrodamalis cuestae Domning, 1978 (Domning 1978; Velez-Juarbe & Domning 2014a), it is only slightly elevated above the alveolar margin, and its posterior edge is thickened. Remnants of the infraorbital canal reveal no obstruction. SQUAMOSAL. The cranial part of the squamosal (Figs 2, 4B) extends up to the temporal crests but does not interrupt the course of the temporal crests, so that these reach the occipital nuchal crest. The posttympanic process is not club like distally (Fig. 4B), but concave anteroventrally for the attachment of the sternomastoid muscle. In the posterior view of the skull (Fig. 4A), a prominent sigmoid ridge is visible forming the laterocaudal margin of the squamosal. Posterolaterally, the mastoid foramen is present, flled by the periotic, and enclosed by the squamosal anteriorly, the exoccipital posteriorly, and the supraoccipital dorsally. Lateral to the braincase (Figs 2, 4B), each of the zygomatic processes projects from a zygomatic root that, though partially broken, is characterised by a distinct notch posteriorly. The zygomatic process is triangular in shape, tapering anteriorly. Its lateral and medial sides are fat to concave with the dorsal margin distinctly inclined inwards to form a sigmoid ridge. The posterodorsal end of the zygomatic process is straight to concave. The external auditory meatus is short mediolaterally and about as wide as high anteroposteriorly. Ventrally (Fig. 3), the elements of the mandibular articulation surface are elongated transversely. The mandibular fossa forms a distinct depression relative to the slightly convex tuberculum anteriorly. Posterior to the mandibular fossa, the postglenoid process forms a rounded and longitudinal knob, which rises above the level of the tuberculum. The posterior end of the zygomatic process, the processus retroversus, shows a moderate inward-directed infection in contrast to what is observed in the living dugong (e.g., Domning & Aguilera 2008; Velez-Juarbe & Domning 2014a). JUGAL. Only a fragmentarily preserved middle part of the right jugal is known from specimen OLL 1926/394 (Fig. 4B), indicating that a postorbital process is probably present. Considering the position and shape of the supraorbital processes of the frontal, the development of a postorbital bar can be excluded. The zygomatic process of the jugal is not preserved but according to its imprint on the ventral side of the zygomatic process of the squamosal it reaches the tuberculum, exceeding the diameter of the orbit. EAR REGION. In specimen OLL 1926/394, the right periotic is poorly preserved (Figs 3, 4A). It is not fused with the adjacent skull bones, and is set in a closely-ftting socket in the squamosal. The tegmen tympani is only indicated by its imprints on the dorsolateral side of the squamosal. It was most likely about as big as the mastoid or slightly smaller. The petrosal is fragmentarily preserved medioventrally, with the perilymphatic foramen apparently not separated into a fenestra rotunda and cochlea canaliculus. The processus fonticulus flls the mastoid foramen posteriorly (Fig. 4A). MANDIBLE (Table 3). The mandibular symphysis is broad, as is the masticating surface that is lacking a median furrow and houses four large and shallow alveoli for vestigial incisors and canines. This is best visible in OLL 1939/257 (Fig. 6A), which exhibits a completely preserved masticating surface, whereas in OLL 2012/1 (Figs 6B, 7A) the ventralmost end is broken. In lateral view (Fig. 7), the symphysis is higher than long and bears the mental foramen laterally, which is joined dorsoposteriorly by two accessory mental foramina on each side in specimen OLL 1939/257 (Fig. 7B). The accessory mental foramina are large relative to what is observed in more plesiomorph dugongid taxa, e.g., “ Halitherium ” taulannense (Sagne 2001a), but they are still smaller than the principal foramen. This observation is interpreted here in analogy with Trichechus (Domning 1982, 1994, and personal observations), as “true” accessory mental foramina, which are present in addition to and usually posterior to the large principal foramen. In the lectotype (OLL 2012/1; Fig. 7A), the mental foramen is broken off dorsoposteriorly, and therefore the accessory mental foramina are not identifable, but their open canals are merged with the main foramen. The overall build of the horizontal mandibular ramus appears to be broad dorsoventrally, but it is evaluated to be slender on the basis of its minimum dorsoventral height, which is smaller than 0.25 × the length of the mandible. The ventral border