Temporal range: Late Eocene–Early Oligocene
|Halitherium schinzi skeleton, Muséum national d'Histoire naturelle, Paris|
Halitherium is an extinct dugongid sea cow that arose in the late Eocene, then became extinct during the early Oligocene. Its fossils are common in European shales. Inside its flippers were finger bones that did not stick out. Halitherium also had the residues of back legs, which did not show externally. However, it did have a basic femur, joined to a reduced pelvis. Halitherium also had elongated ribs, presumably to increase lung capacity to provide fine control of buoyancy. A 2014 review presented the opinion that the genus is dubious.
The genus Halitherium has had a confusing nomenclatural history. It was originally coined by Johann Jakob Kaup on the basis of a premolar from the early Oligocene (Rupelian) of southern Germany, but Kaup himself mistakenly stated that the premolar, in his opinion, gehort zu Hippopotamus dubius Cuv., unaware that H. dubius is actually a junior synonym of the primitive sirenian Protosiren minima, while simultaneously coining the genus and species name Pugmeodon schinzii for the same specimen. For his part, the renowned German paleontologist Christian Erich Hermann von Meyer included the type specimen of Halitherium schinzii in his composite species Halianassa studeri, whose hypodigm also included the type specimens of Metaxytherium medium and Protosiren minima as well as a Miocene-age maxilla and a skeleton from the molasse basin in Switzerland. Later, Kaup synonymized Pugmeodon with Halitherium creating the new combination Halitherium schinzii, and the name Halitherium became universally accepted for the early Oligocene halitheriine material from Europe. Because Halitherium was originally based on a misidentified type species and due to the widespread use of Halitherium, the sirenian specialist Daryl Domning petitioned the ICZN to designate Pugmeodon schinzii as the type species of Halitherium, and the proposal was approved by the Commission in 1989, effectively making Pugmeodon a junior objective synonym of Halitherium in line with the current concept of Halitherium introduced by Kaup himself.
Apart from H. schinzii, there have been five other species of Halitherium that have considered valid in recent papers: H. alleni, H. antillense, H. christolii, H. bellunense, and H. taulannense. However, "Halitherium" taulannense represents a distinct, unnamed genus, while H. antillense is a nomen dubium, and H. christolii and H. bellunense have been renamed Lentiarenium and Italosiren respectively, leaving H. alleni the only species that can be safely considered congeneric with H. schinzii.
Voss (2013, 2014) dismisses Halitherium as a nomen dubium by virtue of being based on non-diagnostic remains. Voss based the opinion on the type species, H. schinzii, being nomen dubium, with its holotype fossil, an isolated molar, having no diagnostic value. and a 2017 study found specimens traditionally assigned to Halitherium schinzii to be two separate species, one of which takes the name Halitherium bronni Krauss, 1858. Because Halitherium is dubious, H. bronni has been re-assigned to Kaupitherium.
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- D. P. Domning. 1987. Halianassa studeri von Meyer, 1838 (Mammalia, Sirenia): proposed designation of a neotype, and proposed conservation of Halitheirum Kaup, 1838 by designation of a type species. Bulletin of Zoological Nomenclature 44(2):122-125
- Kaup, J.J., 1838. [tJber Zahnen von Halytherium and Pugmeodon aus Fionheim.] Neues Jahrbuchfiir Mineralogie, Geologic und Paldontologie, 1838: 318-320.
- Meyer, H. von. 1838. [Letter to H. G. Bronn.] Neues Jahrbuch für Mineralogie. Geologic und Paläontologie, 1838: 667-669.
- Studer, T. 1887. Ueber den Steinkern des Gehirnraumes einer Sirenoide aus dem Muschelsandstein von Wiirenlos (Kanton Aargau), nebst Bemerkungen iiber die Gattung Halianassa H. von Meyer und die Bildung des Muscheisandsteins. Abhandlungen der Schweizerischen Paldontologischen Gesellschaft, 14(3): 1-20.
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- Kaup,J.J., 1855. Beitraege zur naeherenKenntnissderurweltlichenSaeugethiere, vol. 2, 1-23pp. Darmstadt.
- Domning, Daryl, 1987. Halianassa studeri von Meyer, 1838 (Mammalia, Sirenia): proposed designation of a neotype, and proposed conservation of Halitherium Kaup, 1838 by designation of a type species. Bull. Zool. Nomencl. 44(2): 122-125.
- International Commission on Zoological Nomenclature, 1989. Opinion 1535: Halianassa studeri von Meyer, 1838 (Mammalia, Sirenia): neotype designated; and Halitherium Kaup, 1838 (Mammalia, Sirenia): Pugmeodon schinzii Kaup, 1838 designated as the type species. Bull. Zool. Nomencl. 46(1): 83-84.
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- Fitzinger LJ. 1842. Bericht über die in den Sandlagern von Linz aufgefundenen fossilen Reste eines urweltlichen Säugers (Halitherium cristolii). Bericht über das Museum Francisco Carolinum Linz 6: 61–72.
- De Zigno A. 1875. Sirenii fossili trovati nel Veneto. Membro Effettivo del Reale istituto Veneto di Scienze, Lettre ed Arti 18: 1–30.
- Sagne C. 2001. Halitherium taulannense, nouveau sirénien (Sirenia, Mammalia) de l’Éocène supérieur provenant du domaine Nord-Téthysien (Alpes-de-Haute-Pro- vence, France). Comptes rendus de l’Académie des Sciences de la Terre et des Planètes 333: 471–476.
- Voss, M., Berning, B., and Reiter, E., 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: European Journal of Taxonomy, v. 256, p. 1–32.
- Manja Voss; Silvia Sorbi; Daryl P. Domning (2017). "Morphological and systematic re-assessment of the late Oligocene "Halitherium" bellunense reveals a new crown group genus of Sirenia". Acta Palaeontologica Polonica. 62 (1): 163–172. doi:10.4202/app.00287.2016.
- Voss, Manja. "On the invalidity of Halitherium schinzii Kaup, 1838 (Mammalia, Sirenia), with comments on systematic consequences." Zoosystematics and Evolution 90 (2014): 87. 
- Voss, 2013. http://edoc.hu-berlin.de/dissertationen/voss-manja-2013-11-06/PDF/voss.pdf
- Manja Voss & Oliver Hampe (2017). "Evidence for two sympatric sirenian species (Mammalia, Tethytheria) in the early Oligocene of Central Europe". Journal of Paleontology. in press. doi:10.1017/jpa.2016.147.
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