PBDB Taxon

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Metaxytherium

Mammalia - Sirenia - Dugongidae

Taxonomy

Metaxytherium was named by de Christol (1840) [Sepkoski's age data: T Mi-l-u T Mi-u-l Sepkoski's reference number: 508,746].

It was synonymized subjectively with Halitherium by Bronn (1853), Pictet (1853) and Lydekker (1887).

It was assigned to Halicoridae by Flores (1895), Trouessart (1898) and Trouessart (1904); to Sirenia by Zittel (1925); to Halitheriidae by Gill (1872), Palmer (1904) and Hay (1930); to Metaxytheriinae by Kretzoi (1941) and Heal (1973); to Sirenia by Sepkoski (2002); to Halitheriinae by Abel (1919), Simpson (1932), Domning (1979), de Muizon and Domning (1985), Domning (1988), Domning (1994), Aranda-Manteca et al. (1994), Domning (1996) and Domning (2008); to Dugongidae by de Christol (1840), Ginsburg and Janvier (1975), Reinhart (1976), Carroll (1988), Pilleri et al. (1989), Sach and Heizmann (2001), Voss (2014), Hastings and Dooley (2017), Berta (2017), Voss and Hampe (2017) and Albright et al. (2019); and to Halitheriinae by Daxner-Hoeck (1971), Carboni and Kotsakis (1983), Toledo and Domning (1991), Bergqvist et al. (1999), Bianucci and Landini (2003), Domning and Pervesler (2012), Velez-Juarbe et al. (2012), Sorbi et al. (2012), Domning (2018), Domning (2018), Samonds et al. (2019), Carone and Rizzo (2020) and Iliopoulos et al. (2022).

Species

Felsinotherium gunteri, M. albifontanum, M. aquitaniae, M. arctodites, M. beaumontii, M. crataegense (syn. M. calvertense), M. floridanum (syn. Felsinotherium ossivallense), M. krahuletzi (syn. Halianassa studeri, M. christoli, M. argoviense), M. lovisati, M. medium (syn. Halitherium cuvieri, M. petersi, M. cordieri, Manatus fossilis, Trichechus molassicus, Hippopotamus intermedius, M. catalaunicum, Haplosiren leganyii), M. meyeri, M. riveroi, M. serresii (syn. Halitherium minor), M. subapenninum (syn. Felsinotherium forestii, Felsinotherium subalpinum, Felsinotherium gervaisi, Felsinotherium gastaldi, Cheirotherium brochii)

Species lacking formal opinion data

M. subappeninum

Synonyms

Halianassa is a genus. It is not extant.

It was synonymized subjectively with Halitherium by Bronn (1853), Pictet (1853), Gill (1872), Lydekker (1887), Trouessart (1898), Zittel (1925), Domning (1987), International Commission on Zoological Nomenclature (1989) and Domning (1996); it was synonymized subjectively with Metaxytherium by Domning (2008).

It was assigned to Prototheriidae by Kretzoi (1941); to Halianassinae by Reinhart (1959); and to Sirenia by Sepkoski (2002).
Felsinotherium was named by Capellini (1872) [Sepkoski's age data: T Plio-l T Plio-u].

It was synonymized subjectively with Halitherium by Lydekker (1887); it was replaced with Halysiren by Kretzoi (1941); it was synonymized subjectively with Metaxytherium by Domning (1979), Domning (1996) and Domning (2008).

It was assigned to Manatidae by Trouessart (1898); to Halitheriidae by Palmer (1904); to Halicoridae by Trouessart (1904); to Sirenia by Zittel (1925); to Halitheriinae by Abel (1919) and Simpson (1932); to Metaxytheriinae by Heal (1973); to Dugongidae by Sherman (1952), PIlleri (1988) and Carroll (1988); and to Sirenia by Sepkoski (2002).
Hesperosiren was named by Simpson (1932) [Sepkoski's age data: T Mi-l]. It is not extant.

It was synonymized subjectively with Metaxytherium by Domning (1996) and Domning (2008).

It was assigned to Halitheriinae by Simpson (1932); to Hydrodamalidae by Kretzoi (1941); to Dugongidae by Sherman (1952), Reinhart (1976) and Carroll (1988); and to Sirenia by Sepkoski (2002).
Thalattosiren was named by Sickenberg (1928) [Sepkoski's age data: T Mi-l Sepkoski's reference number: 746].

It was synonymized subjectively with Metaxytherium by Domning and Pervesler (2012).

It was assigned to Eotherioidinae by Kretzoi (1941); to Halitheriinae by Heal (1973); to Dugongidae by Carroll (1988); to Halitheriinae by Simpson (1932) and Domning (1996); and to Sirenia by Sepkoski (2002).
Cheirotherium was named by Bruno (1839).

It was replaced with Pontotherium by Kaup (1840); it was synonymized subjectively with Halitherium by Bronn (1853), Pictet (1853), Lydekker (1887) and Trouessart (1898); it was replaced with Halysiren by Kretzoi (1941); it was synonymized subjectively with Metaxytherium by Domning (1979) and Domning (1996).

It was assigned to Halitheriidae by Gill (1872); to Sirenia by Bruno (1839) and Woodward (1885); and to Dugongidae by PIlleri (1988).
Fucotherium was named by Kaup (1840) [lapsus for Fucotherium].

It was synonymized subjectively with Halitherium by Bronn (1853), Pictet (1853) and Trouessart (1898); it was synonymized subjectively with Metaxytherium by Domning (1979) and Domning (1996).

It was assigned to Halitheriidae by Gill (1872) and Palmer (1904).
Pontotherium was named by Kaup (1840).

It was synonymized subjectively with Halitherium by Bronn (1853) and Pictet (1853); it was synonymized subjectively with Felsinotherium by Trouessart (1898); it was synonymized subjectively with Metaxytherium by Domning (1979) and Domning (1996).

It was assigned to Halitheriidae by Gill (1872) and Palmer (1904).
Halysiren was named by Kretzoi (1941).

It was synonymized subjectively with Metaxytherium by Domning (1979) and Domning (1996).
Metaxytherium beaumontii was named by de Christol (1844) [type is now lost].

It was recombined as Halitherium beaumontii by Gervais (1852) and Woodward (1885); it was recombined as Halitherium beaumonti by Scott (1873) and Depéret (1887); it was synonymized subjectively with Metaxytherium cordieri by Trouessart (1898); it was misspelled as Metaxytherium beaumonti by Fondi and Pacini (1974); it was considered a nomen dubium by Domning (1996).
Metaxytherium meyeri was named by Abel (1904). Its type specimen is SMNS unnumbered specimen, a set of limb elements (proximal left humerus), and it is a 3D body fossil.

It was considered a nomen dubium by Domning (1996).
Haplosiren was named by Kretzoi (1951). Its type is Haplosiren leganyii.

It was synonymized subjectively with Metaxytherium by Domning (1996).

It was assigned to Sirenia by Kretzoi (1951).
Felsinotherium gunteri was named by Simpson (1932). It is not a trace fossil.

It was considered an invalid subgroup of Felsinotherium ossivallense by Reinhart (1976); it was considered a nomen nudum by Domning (1988) and Domning (1996).

Synonymy list

Year	Name and author
1839	Cheirotherium Bruno p. 160
1840	Fucotherium Kaup p. 675
1840	Pontotherium Kaup p. 676
1840	Metaxytherium de Christol p. 322
1844	Metaxytherium beaumontii de Christol p. 130
1852	Halitherium beaumontii Gervais p. 144
1872	Felsinotherium Capellini p. 615
1872	Cheirotherium Gill p. 92
1872	Fucotherium Gill p. 92
1872	Metaxytherium Gill p. 92
1872	Pontotherium Gill p. 92
1873	Halitherium beaumonti Scott p. 55
1885	Chirotherium Woodward p. 424
1885	Halitherium beaumontii Woodward p. 425
1887	Halitherium beaumonti Depéret p. 273
1895	Metaxytherium Flores p. 15
1898	Metaxytherium Trouessart p. 1004
1898	Felsinotherium Trouessart p. 1005
1904	Metaxytherium meyeri Abel p. 15
1904	Felsinotherium Palmer p. 284
1904	Fucotherium Palmer p. 286
1904	Metaxytherium Palmer p. 418
1904	Pontotherium Palmer p. 558
1904	Felsinotherium Trouessart p. 750
1904	Metaxitherium Trouessart p. 750
1919	Felsinotherium Abel p. 834
1919	Metaxytherium Abel p. 834
1925	Felsinotherium Zittel p. 265
1925	Metaxytherium Zittel p. 265
1928	Thalattosiren Sickenberg p. 294
1930	Metaxytherium Hay p. 655
1932	Felsinotherium Simpson p. 424
1932	Hesperosiren Simpson p. 424
1932	Metaxytherium Simpson p. 424
1932	Thalattosiren Simpson p. 424
1932	Hesperosiren Simpson p. 429 figs. Fig. 1-10
1932	Felsinotherium gunteri Simpson p. 449
1941	Halysiren Kretzoi p. 153
1941	Thalattosiren Kretzoi p. 154
1941	Halianassa Kretzoi p. 155
1941	Hesperosiren Kretzoi p. 155
1941	Metaxytherium Kretzoi p. 155
1951	Haplosiren Kretzoi p. 438
1952	Felsinotherium Sherman p. 98
1952	Hesperosiren Sherman p. 98
1959	Halianassa Reinhart pp. 23-44 figs. 4-6
1971	Metaxytherium Daxner-Hoeck p. 764
1973	Metaxytherium Heal p. 140
1973	Thalattosiren Heal p. 199
1973	Felsinotherium Heal p. 200
1974	Metaxytherium beaumonti Fondi and Pacini p. 45
1974	Metaxytherium meyeri Fondi and Pacini p. 45
1975	Metaxytherium Ginsburg and Janvier p. 90
1976	Metaxytherium Reinhart p. 199
1976	Hesperosiren Reinhart p. 229
1979	Metaxytherium Domning
1983	Metaxytherium Carboni and Kotsakis p. 132
1985	Metaxytherium de Muizon and Domning p. 192
1988	Felsinotherium Carroll
1988	Hesperosiren Carroll
1988	Metaxytherium Carroll
1988	Thalattosiren Carroll
1988	Metaxytherium Domning p. 399
1988	Cheirotherium PIlleri p. 46
1988	Felsinotherium PIlleri p. 48
1989	Metaxytherium Pilleri et al. p. 68
1991	Metaxytherium Toledo and Domning p. 133
1994	Metaxytherium Aranda-Manteca et al. p. 192
1994	Metaxytherium Domning p. 189
1996	Thalattosiren Domning p. 288
1996	Metaxytherium Domning p. 385
1999	Metaxytherium Bergqvist et al. p. 31
2001	Metaxytherium Sach and Heizmann p. 42
2002	Felsinotherium Sepkoski
2002	Halianassa Sepkoski
2002	Hesperosiren Sepkoski
2002	Metaxytherium Sepkoski
2002	Thalattosiren Sepkoski
2003	Metaxytherium Bianucci and Landini p. 567
2008	Metaxytherium Domning
2012	Metaxytherium Domning and Pervesler p. 136
2012	Metaxytherium Sorbi et al. p. 688
2012	Metaxytherium Velez-Juarbe et al. p. 588
2014	Metaxytherium Voss p. 91 figs. Figure 3
2017	Metaxytherium Berta p. 170
2017	Metaxytherium Hastings and Dooley p. 83
2017	Metaxytherium Voss and Hampe p. 341
2018	Metaxytherium Domning p. 246
2019	Metaxytherium Albright et al. p. 191
2019	Metaxytherium Samonds et al. p. 8
2020	Metaxytherium Carone and Rizzo
2022	Metaxytherium Iliopoulos et al. p. 397

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Rank	Name	Author
kingdom	Animalia	()
—	Bilateria
—	Eubilateria	Ax 1987
—	Deuterostomia
phylum	Chordata	Haeckel 1874
subphylum	Vertebrata
superclass	Gnathostomata
—	Osteichthyes	()
subclass	Sarcopterygii	()
subclass	Dipnotetrapodomorpha	(Nelson 2006)
subclass	Tetrapodomorpha	()
—	Tetrapoda
—	Reptiliomorpha
—	Anthracosauria
subclass	Amphibiosauria	Kuhn 1967
—	Cotylosauria	()
—	Amniota
subclass	Synapsida

Rank	Name	Author
—	Therapsida	()
infraorder	Cynodontia	()
—	Mammaliamorpha
—	Mammaliaformes
class	Mammalia
—	Cladotheria
—	Zatheria
subclass	Tribosphenida	()
subclass	Theria
—	Eutheria	()
—	Placentalia
—	Afrotheria	Stanhope et al. 1998
—	Tethytheria
order	Sirenia	()
family	Dugongidae
subfamily	Halitheriinae	()
genus	Metaxytherium

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

G. †Metaxytherium de Christol 1840

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†Metaxytherium albifontanum Velez-Juarbe and Domning 2014

†Metaxytherium aquitaniae Pilleri 1987

†Metaxytherium arctodites Aranda-Manteca et al. 1994

†Metaxytherium crataegense Simpson 1932

Invalid names: Metaxytherium calvertense Kellogg 1966 [synonym]

†Metaxytherium floridanum Hay 1922

Invalid names: Felsinotherium ossivallense Simpson 1932 [synonym]

†Metaxytherium krahuletzi Depéret 1895

Invalid names: Halianassa studeri Meyer 1837 [synonym], Metaxytherium argoviense Pilleri 1987 [synonym], Metaxytherium christoli Fitzinger 1899 [synonym], Metaxytherium krahuletzi excelsum Pilleri 1987 [invalid subgroup]

†Metaxytherium lovisati Capellini 1886

†Metaxytherium medium Desmarest 1822

Invalid names: Halitherium cuvieri de Christol 1832 [synonym], Haplosiren leganyii Kretzoi 1951 [synonym], Hippopotamus intermedius Holl 1829 [synonym], Manatus fossilis Holl 1829 [synonym], Metaxytherium catalaunicum Pilleri et al. 1989 [synonym], Metaxytherium cordieri de Christol in de Blainville 1844 [synonym], Metaxytherium petersi Abel 1904 [synonym]

†Metaxytherium riveroi Varona 1972

†Metaxytherium serresii Gervais 1847

Invalid names: Halitherium minor Cope 1883 [synonym]

†Metaxytherium subapenninum Bruno 1839

Invalid names: Cheirotherium brochii de Blainville 1844 [synonym], Felsinotherium forestii Capellini 1872 [synonym], Felsinotherium gastaldi de Zigno 1878 [synonym], Felsinotherium gervaisi Capellini 1872 [synonym], Felsinotherium subalpinum Isel 1910 [synonym]

Invalid names: Cheirotherium Bruno 1839 [synonym], Felsinotherium Capellini 1872 [synonym], Felsinotherium gunteri Simpson 1932 [nomen nudum], Fucotherium Kaup 1840 [synonym], Halianassa [synonym], Halysiren Kretzoi 1941 [synonym], Haplosiren Kretzoi 1951 [synonym], Hesperosiren Simpson 1932 [synonym], Metaxytherium beaumontii de Christol 1844 [nomen dubium], Metaxytherium meyeri Abel 1904 [nomen dubium], Pontotherium Kaup 1840 [synonym], Thalattosiren Sickenberg 1928 [synonym]

Diagnosis

Reference	Diagnosis
R. H. Reinhart 1959 (Halianassa)	Rostrum slightly downturned, narrow pinched-in area on dorsal suface, lacks incisors; nasals separated by frontals in mid-line; lacrimal a thin vertical wedge; posterior two-fifths of dorsal surface of parietals squared by temporal crests; region for temporal fontanelle advanced partly anterior to brain case; supraoccipital separated from formen magnum by about 10 mm; angle of mandible greatly elongated vertically; coronoid process curved acutely inward; seventh cervical pierced by vertebrarterial canal; axes of humerus diverge at about 70 degrees; distal medial borders of radius-ulna slightly fused.
D. P. Domning and P. Pervesler 2012	A paraphyletic genus of dugongids that differs from most other halitheriines by possession of the following apomorphies: permanent premolars 1-4 lost [c. 157 (2)]; supraorbital process of frontal reduced and dorsoven- trally thickened [c. 36(1)]; posterior part of zygomatic-orbital bridge of maxilla usually elevated >1 cm above alveolar mar- gin [c. 11(1)]; nasals usually separated in midline [c. 31(1)]; supraoccipital wider ventrally than dorsally; exoccipitals usu- ally not meeting in a midline suture above foramen magnum [c. 66(1)]; and ventral border of horizontal ramus of mandible strongly concave [c. 122(3)]; differs from hydrodamalines by lack of the following apomorphies: processus retroversus of squamosal uninflected [c. 77(2)]; lacrimal reduced [c. 91(2)]; ventral border of horizontal ramus of mandible moderately concave [c. 122(2)]; horizontal ramus of mandible slender [c. 128(0)]; first upper incisor vestigial or absent [c. 139(1)] (J. Vélez-Juarbe and D. P. Domning, in preparation).__

Measurements

No measurements are available

Composition:

phosphaticsubp

Environment:

marinef

Locomotion:

actively mobilec

Life habit:

aquaticf

Diet:

herbivoref

Reproduction:

viviparousf

Created:

2005-06-08 10:11:09

Modified:

2005-06-08 12:11:09

Source: f = family, c = class, subp = subphylum

References: Hendy et al. 2009, Domning 1979, Carroll 1988, Nowak 1991

Age range: base of the Rupelian to the top of the Ruscinian or 33.90000 to 3.20000 Ma

Collections (226 total)

Time interval	Ma	Country or state	Original ID and collection number
Oldest occurrences
Rupelian	33.9 - 28.1	USA (South Carolina)	M. alibfontatum (200275)
Chattian	28.1 - 23.03	USA (Florida)	M. crataegense, M. albifontanum (13076)
Chattian	28.1 - 23.03	USA (South Carolina)	M. albifontanum (60443 152597)
Chattian - Burdigalian	28.1 - 15.97	Switzerland	M. sp., M. petersi (46474)
MN 1	23.03 - 22.4	Germany	M. sp. (70327)
Aquitanian	23.03 - 20.44	France	M. aquitaniae (65069)
Early/Lower Miocene	23.03 - 15.97	Brazil (Para)	Metaxitherium sp. (65162 112590)
Early/Lower Miocene	23.03 - 15.97	India (Kutch)	M. sp. (65050)
Early/Lower Miocene	23.03 - 15.97	Madagascar	M. krahuletzi (200774)
Early/Lower Miocene	23.03 - 15.97	Libya	M. sp. (13065)
Youngest occurrences
Time interval	Ma	Country or state	PBDB collection number
Zanclean	5.333 - 3.6	Italy (Cuneo)	Felsinotherium gastaldi (124389)
Zanclean	5.333 - 3.6	Italy (Bologna)	M. subapenninum (124402)
Zanclean	5.333 - 3.6	Italy (Tuscany)	M. forestii (80539) M. gervaisi (55748) M. subapenninum (190383) M. subappeninum (193697)
Ruscinian	5.333 - 3.2	Italy (Tuscany)	Felsinotherium gervaisi (49335)
Pliocene	5.333 - 2.588	Spain	M. subapenninum (127487)
Pliocene	5.333 - 2.588	France	M. serresii (65091)
Pliocene	5.333 - 2.588	Morocco	Felsinotherium serresii (65175)
Zanclean - Piacenzian	5.333 - 2.588	Italy	Felsinotherium forestii (59273)
Piacenzian	3.6 - 2.588	Italy	M. subappeninum (47428)
Piacenzian	3.6 - 2.588	Italy (Tuscany)	M. sp. (48652)