''Halitherium'' is an extinct dugongid

sea cow The Sirenia (), commonly referred to as sea-cows or sirenians, are an order of fully aquatic, herbivorous mammals that inhabit swamps, rivers, estuaries, marine wetlands, and coastal marine waters. The Sirenia currently comprise two distinct f ...

that arose in the late

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

, then became extinct during the early

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

. Its fossils are common in

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

an shales. Inside its flippers were finger bones that did not stick out. ''Halitherium'' also had the remnants of back legs, which did not show externally. However, it did have a basic

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with ...

, joined to a reduced pelvis. ''Halitherium'' also had elongated

ribs The rib cage, as an enclosure that comprises the ribs, vertebral column and sternum in the thorax of most vertebrates, protects vital organs such as the heart, lungs and great vessels. The sternum, together known as the thoracic cage, is a semi- ...

, presumably to increase

lung The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...

capacity to provide fine control of

buoyancy Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the p ...

. A 2014 review presented the opinion that the genus is dubious.

Classification

''Halitherium'' is the type genus of the subfamily Halitheriinae, which includes the well-known genera ''

Eosiren ''Eosiren'' is an extinct genus of sea cow that lived during the Late Eocene (later Priabonian) to Early Oligocene (Rupelian).Zalmout I.S. & Gingerich P.D. (2012)“Late Eocene sea cows (Mammalia, Sirenia) from Wadi al Hitan in the western dese ...

'' and ''

Eotheroides ''Eotheroides'' is an extinct genus of Eocene sirenian. It is an early member of the family Dugongidae, which includes the extant dugong. Fossils have been found from Egypt, India, and Madagascar. ''Eotheroides'' was first described by Richard O ...

'' and lived from the

to the

Taxonomy

The genus ''Halitherium'' has had a confusing nomenclatural history. It was originally coined by

Johann Jakob Kaup Johann Jakob von Kaup (10 April 1803 – 4 July 1873) was a German naturalist. A proponent of natural philosophy, he believed in an innate mathematical order in nature and he attempted biological classifications based on the Quinarian system. Kaup ...

on the basis of a

premolar The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mouth ...

from the early

(

Rupelian The Rupelian is, in the geologic timescale, the older of two ages or the lower of two stages of the Oligocene Epoch/Series. It spans the time between . It is preceded by the Priabonian Stage (part of the Eocene) and is followed by the Chattian ...

) of southern

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

, 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 The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently. * In botanical nomenclature, a synonym is a scientific name that applies to a taxon that (now) goes by a different scientific name. For example, Linna ...

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 Christian Erich Hermann von Meyer (3 September 1801 – 2 April 1869), known as Hermann von Meyer, was a German palaeontologist. He was awarded the 1858 Wollaston medal by the Geological Society of London. Life He was born at Frankfurt am Ma ...

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 The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...

and a skeleton from the

molasse basin The Molasse basin (or North Alpine foreland basin) is a foreland basin north of the Alps which formed during the Oligocene and Miocene epochs. The basin formed as a result of the flexure of the European plate under the weight of the orogenic ...

Switzerland ). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...

. Later, Kaup synonymized ''Pugmeodon'' with ''Halitherium'' creating the new combination ''Halitherium schinzii'', and the name ''Halitherium'' became universally accepted for the early

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 The International Code of Zoological Nomenclature (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. It is also informally known as the ICZN Code, for its publisher, the I ...

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. 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 In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium'' it may be impossible to determine whether a s ...

'', with its

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

fossil, an isolated molar, having no diagnostic value.Voss, Manja. "On the invalidity of Halitherium schinzii Kaup, 1838 (Mammalia, Sirenia), with comments on systematic consequences." Zoosystematics and Evolution 90 (2014): 87

/ref> 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 ''Kaupitherium'' is an extinct dugongid sea cow that lived during the Oligocene. Fossils of the genus have been found in the Alzey Formation of Germany. Inside its flippers were finger bones that did not stick out. ''Kaupitherium'' also had the ...

''. The species ''Halitherium alleni'' Simpson, 1932, described by Simpson (1932) from skull caps in Oligocene deposits in Puerto Rico, is basal to the two ''Kaupitherium'' species.

Formerly assigned species

*''Halitherium antillense'' Matthew, 1916; ''nomen dubium''Voss, 2013. http://edoc.hu-berlin.de/dissertationen/voss-manja-2013-11-06/PDF/voss.pdf *''Halitherium christolii'' Fitzinger, 1842 = ''

Lentiarenium ''Lentiarenium'' was an early sea cow from the Late Oligocene (Chattian) Linz-Melk Formation of Austria. Known since the mid 19th century, ''Lentiarenium'' was long considered to be a species of ''Halitherium'' until a 2016 analysis showed it to ...

'' *''Halitherium bellunense'' de Zigno, 1875 = ''

Italosiren ''Italosiren'' is an extinct genus of early dugongidae, dugong from the Early Miocene (Aquitanian (stage), Aquitanian) Libano Formation in northern Italy. Classification It was originally classified as a species of ''Halitherium'', ''H. bellunens ...

'' *''Halitherium taulannense'' Sange, 2001; distinct, unnamed genusSagne 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. *''Halitherium olseni'' Rinehart, 1976 = ''

Crenatosiren ''Crenatosiren'' is an extinct genus of dugongid sirenian known from the late Oligocene (Chattian) of Florida, North Carolina, and South Carolina. The type and only known species is ''Crenatosiren olseni''. Taxonomy ''Crenatosiren'' was original ...

Related species

*''

Metaxytherium ''Metaxytherium'' is an extinct genus of dugong that lived from the Oligocene until the end of the Pliocene. Fossil remains have been found in Africa, Europe, North America and South America. Generally marine seagrass specialists, they inhabite ...

'' *'' Rytiodus''

References

Bibliography

*''Marine Mammals: Evolutionary Biology'' by Annalisa Berta, James L. Sumich, and Kit M. Kovacs *''Encyclopedia of Marine Mammals'' by William F. Perrin, Bernd Wursig, and J. G.M. Thewissen *''Classification of Mammals'' by Malcolm C. McKenna and Susan K. Bell *''The Rise of Placental Mammals: Origins and Relationships of the Major Extant Clades'' by Kenneth D. Rose and J. David Archibald {{Taxonbar, from=Q2313205 Eocene sirenians Oligocene sirenians Priabonian life Rupelian life Eocene mammals of Europe Oligocene mammals of Europe Fossil taxa described in 1838 Nomina dubia Prehistoric placental genera

Classification

Taxonomy

Formerly assigned species

Related species

See also

References

Bibliography