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Trachytherus spegazzinianus

Mammalia - Notoungulata - Mesotheriidae

Taxonomy
Trachytherus spegazzinianus was named by Ameghino (1889). It is a 3D body fossil. Its type locality is Deseadan of Patagonia, which is in a Deseadan terrestrial horizon in the Sarmiento Formation of Argentina. It is the type species of Eutrachytherus.

It was recombined as Eutrachytherus spegazzinianus by Ameghino (1897).

Synonyms
  • Trachytherus conturbatus was named by Ameghino (1891).

    It was recombined as Eutrachytherus conturbatus by Ameghino (1897); it was synonymized subjectively with Trachytherus spegazzinianus by Billet et al. (2008).
  • Coresodon cancellatus was named by Ameghino (1901). Its type specimen is MACN A52-566, a maxilla (right maxillary with dP3-4, M1), and it is a 3D body fossil. Its type locality is Cabeza Blanca, which is in a Deseadan terrestrial shale/claystone in the Sarmiento Formation of Argentina.

    It was synonymized subjectively with Trachytherus spegazzinianus by Billet et al. (2008).
  • Anatrachytherus soriai was named by Reguero and Castro (2004). Its type specimen is MACN A52-490, a mandible (mandible with right i1-2, p1 alveolus, p2-m2; left i1-2, p1 alveolus, p2-m3), and it is a 3D body fossil. Its type locality is Cabeza Blanca, which is in a Deseadan terrestrial shale/claystone in the Sarmiento Formation of Argentina.

    It was synonymized subjectively with Trachytherus spegazzinianus by Billet et al. (2008).
  • Ameghinotherium curuzucuatiense was named by Podestá (1899). Its type specimen is MACN 6867, a skull (incomplete skull with abrased cheekteeth), and it is a 3D body fossil. Its type locality is Arroyo Castillo, which is in a Deseadan terrestrial horizon in the Fray Bentos Formation of Argentina.

    It was synonymized subjectively with Trachytherus spegazzinianus by Billet et al. (2008).
  • Proedium solitarium was named by Ameghino (1894). Its type specimen is MACN A52-495, a mandible (symphysis without teeth), and it is a 3D body fossil. Its type locality is La Flecha, which is in a Deseadan terrestrial mudstone in the Deseado Formation of Argentina.

    It was recombined as Isoproedrium solitarium by Ameghino (1904); it was synonymized subjectively with Trachytherus spegazzinianus by Billet et al. (2008).
Synonymy list
YearName and author
1889Trachytherus spegazzinianus Ameghino
1891Trachytherus conturbatus Ameghino
1894Proedium solitarium Ameghino
1894Trachytherus conturbatus Ameghino p. 20
1894Trachytherus spegazzinianus Ameghino p. 20
1894Proedium solitarium Ameghino p. 623
1894Trachytherus spegazzinianus Lydekker p. 2
1897Eutrachytherus spegazzinianus Ameghino p. 428
1897Eutrachytherus conturbatus Ameghino p. 429
1897Proedrium solitarium Ameghino p. 431
1899Ameghinotherium curuzucuatiense Podestá
1901Coresodon cancellatus Ameghino p. 378
1904Isoproedrium solitarium Ameghino p. 28
2004Anatrachytherus soriai Reguero and Castro p. 50 fig. 2b,c
2008Trachytherus spegazzinianus Billet et al.
2009Trachytherus spegazzinianus Shockey et al.

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RankNameAuthor
kingdomAnimalia()
Triploblastica
Nephrozoa
Deuterostomia
phylumChordataHaeckel 1847
subphylumVertebrata
superclassGnathostomata
Osteichthyes()
Sarcopterygii
subclassDipnotetrapodomorpha(Nelson 2006)
subclassTetrapodomorpha()
Tetrapoda()
Reptiliomorpha
Anthracosauria
Batrachosauria()
Cotylosauria()
Amniota
RankNameAuthor
Synapsida()
Therapsida()
infraorderCynodontia()
Epicynodontia
infraorderEucynodontia
Probainognathia
Mammaliamorpha
Mammaliaformes
classMammalia
subclassTribosphenida()
infraclassEutheria()
orderNotoungulata
suborderTypotheriaZittel 1892
familyMesotheriidaeAlston 1876
genusTrachytherusAmeghino 1889
speciesspegazzinianusAmeghino 1889

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.

Diagnosis
ReferenceDiagnosis
G. Billet et al. 2008Differs from Trachytherus alloxus in: larger size; less persistent central fossette on P3, not exclusively contemporaneous with that on P4; later lingual closure of the central valley on M2 by wear, after M1 becomes featureless; upper molars larger labio-lingually proportionally to the mesio-distal length; mesial lobe of the upper molars (protoloph) more rounded lingually after moderate wear, without pointing disto-lingual extremity (as well for deciduous premolars) and thereby resembling the distal lobe; deeper lingual sulcus on upper molars and presence of a lingual groove on M1 when the central fossette is isolated (Fig. 12B); M3 more distinctly trilobed before enclosing the central fossette; presence of larger and more persistent enamel folds on the M1 protoloph lingual face.
Differs from Trachytherus? mendocensis in: its larger size; the outline of the upper premolars representing more a parallelogram than an oblique triangle.
Differs from Trachytherus subandinus in: possessing upper premolars of parallelogram shape, not triangu- lar to pentagonal; larger size.
Differs from the unnamed (and undescribed) taxon reported by Shockey et al. (2006) from Moquegua Peru by a larger size.