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Pachycetus

Mammalia - Cetacea - Basilosauridae

Synonymy list
YearName and author
1883Pachycetus Geinitz p. 107
1883Pachycetus Van Beneden pp. 31-32
1898Pachycetus Trouessart p. 1054
1904Pachycetus Palmer p. 494
1904Pachycetus Trouessart p. 784
1912Pachycetus True p. 3
1928Pachycetus Kellogg p. 35 figs. Table 1
1936Platyosphys Kellogg p. 97
1940Pachycetus Wetmore p. 72
1945Platyosphys Simpson p. 100
1945Pachycetus Simpson p. 104
1954Platyosphys Moustafa p. 87
1970Platyosphys Mchedlidze p. 51
1977Platyosphys Whitmore and Sanders p. 305
1986Pachycetus Rothausen p. 517
1988Pachycetus Carroll
1988Platyosphys Carroll
1997Pachycetus Gingerich et al. p. 68
1997Platyosphys McKenna and Bell p. 369
2001Platyosphys Gritsenko p. 18
2002Pachycetus Sepkoski
2002Platyosphys Sepkoski
2003Platyosphys Fordyce p. 162
2004Pachycetus van Vliet p. 143
2004Platyosphys van Vliet p. 143
2013Basilotritus Goldin and Zvonok p. 255
2013Basilotritus Uhen p. 7 figs. Figure 4
2014Basilotritus Goldin et al.
2015Basilotritus Gao and Ni p. 156 figs. Table 1
2015Platyosphys Gingerich and Zouhri p. 279
2016Basilotritus Marx et al. p. 101
2017Basilotritus Berta p. 159
2017Platyosphys Berta p. 159
2017Basilotritus Martínez-Cáceres et al. p. 11
2018Basilotritus Uhen
2020Pachycetus van Vliet et al. p. 124 figs. Plate 2, figs C1-C4 & D1-D2
2022Pachycetus Gingerich et al. p. 13
2023Pachycetus van Vliet et al. p. 7
2024Pachycetus van Vliet et al. p. 6

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RankNameAuthor
kingdomAnimalia()
Bilateria
EubilateriaAx 1987
Life
Deuterostomia
phylumChordataHaeckel 1874
subphylumVertebrata
superclassGnathostomata
Osteichthyes()
subclassSarcopterygii()
subclassDipnotetrapodomorpha(Nelson 2006)
subclassTetrapodomorpha()
Tetrapoda
Reptiliomorpha
Anthracosauria
subclassAmphibiosauriaKuhn 1967
Cotylosauria()
Amniota
subclassSynapsida
Therapsida()
infraorderCynodontia()
Mammaliamorpha
Mammaliaformes
RankNameAuthor
classMammalia
Theriamorpha(Rowe 1993)
Theriiformes()
Trechnotheria
Cladotheria
Zatheria
subclassTribosphenida()
subclassTheria
Eutheria()
Placentalia
Boreoeutheria
Laurasiatheria
Scrotifera
Euungulata
Artiodactylamorpha
Artiodactyla()
Whippomorpha
orderCetacea
Pelagiceti
familyBasilosauridae
subfamilyPachycetinae
genusPachycetus

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. †Pachycetus Van Beneden 1883
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Pachycetus paulsonii Brandt 1873
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Invalid names: Basilotritus uheni Goldin and Zvonok 2013 [synonym], Pachycetus robustus Van Beneden 1883 [synonym], Platyosphys einori Gritsenko 2001 [synonym], Zeuglodon rossicus Paulson in Brandt 1873 [synonym]
Pachycetus wardii Uhen 1999
Invalid names: Basilotritus Goldin and Zvonok 2013 [synonym], Platyosphys Kellogg 1936 [synonym]
Diagnosis
ReferenceDiagnosis
P. Goldin and E. A. Zvonok 2013 (Basilotritus)Basilotritus differs from the other basilosaurids in
the unique combination of the following traits: 1) the sigmoid process of the tympanic bulla is plate-like, broad, with the poorly developed transverse rim; 2) the transverse processes, neural arches and neural spines of posterior thoracic and lumbar vertebrae are elongated, comparable to vertebral centra; 3) the posterior thoracic and lumbar vertebrae are elongated in anterior- posterior dimension but less than in Basilosaurus; 4) the vertebrae have a pock-marked surface texture, with small, numerous irregularly located openings of vascular channels (Fig. 2.1); 5) the pachyostotic neural arches contain layered bone tissue located in periosteal zone (Fig. 2.2); 6) the sternum is T-shaped, with the broad anterior end and the mesosternum is flattened dorsoven- trally; 7) the iliac part of the innominate extends anteriorly from the acetabulum and the ischiac part is reduced to a tuberosity. Basilotritus further differs from most basilosaurids in the more convex medial margin of the tympanic bulla with a well- developed keel; in the steep lowering of involucrum towards the anterior part; in the blunt and rounded anterior process and in the rounded posterior part of the tympanic bulla.
M. D. Uhen 2013 (Basilotritus)Basilotritus differs from the other basilo- saurids in that: the sigmoid process of the tympanic bulla is plate-like, broad, with the poorly developed transverse rim; the transverse processes, neural arches and neural spines of posterior thoracic and lumbar vertebrae are elongated, along with the vertebral centra; the posterior thoracic and lumbar vertebrae are elongated anteroposte- riorly, but less so than in Basilosaurus; the vertebrae have a pock-marked surface texture, with small, numerous irreg-
ularly located openings of vascular channels; the pachy- ostotic neural arches contain layered bone tissue located in periosteal zone; the manubrium of the sternum is T-shaped, and the broad anterior end of the mesosternum is dorsoventrally flattened; the iliac part of the innomi- nate extends anteriorly from the acetabulum and the is- chiac part is reduced to a tuberosity. Basilotritus further differs from most basilosaurids in the more convex medial margin of the tympanic bulla with a well-developed keel; in the steep lowering of involucrum towards the anterior part; in the blunt and rounded anterior process and in the rounded posterior part of the tympanic bulla. After Gol’din and Zvonok (2013).
P. D. Gingerich and S. Zouhri 2015 (Platyosphys)Species of Platyosphys are distinctive among Basilosauridae in being relatively large and in having posterior thoracic, lumbar, and anterior caudal vertebrae that are conspicu- ously elongated. Lumbar vertebrae have broad and flat transverse processes that arise along virtually the entire anteroposterior length of the centrum. Cranial and vertebral bone is unique among archaeocetes in being pachyostotic and osteosclerotic. Pachyostosis gives vertebrae a swollen appearance, and nutrient canals opening at the surface add a pock-marked texture.
P. D. Gingerich et al. 2022Differs from Antaecetus gen. nov. in being larger and in having more robust teeth with crenulated enamel. The first upper premolar, P1, differs from that in Antaecetus in being double-rooted or having two fused roots. Posterior upper premolars differ from those of Antaecetus in having four rather than three accessory cusps flanking the central cusp anteriorly and posteriorly. Upper molars differ in lacking any distinct medial swelling in the posi- tion of the protocone.