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Idiorophus patagonicus

Osteichthyes - Cetacea - Physeteridae

Taxonomy
Physodon patagonicus was named by Lydekker (1894) [no type specimen listed by Lydekker 1894]. It is a 3D body fossil. Its type locality is Bryn Gwyn, which is in a Burdigalian marine siltstone/sandstone in the Gaiman Formation of Argentina.

It was recombined as Apenophyseter patagonicus by Cabrera (1926); it was recombined as Idiorophus patagonicus by Kellogg (1925), Kellogg (1942), Cozzuol (1996), Kazár (2002), Hampe (2006), Perez et al. (2011), Paolucci et al. (2025).

Synonymy list
YearName and author
1894Physodon patagonicus Lydekker p. 4 figs. Fig. 2
1898Physodon patagonicus Trouessart p. 1054
1901Physodon patagonicus Ameghino p. 80
1904Physodon patagonicus Trouessart p. 773
1925Idiorophus patagonicus Kellogg p. 6
1926Apenophyseter patagonicus Cabrera p. 406
1942Idiorophus patagonicus Kellogg p. 448
1996Idiorophus patagonicus Cozzuol p. 324
2002Idiorophus patagonicus Kazár p. 163
2006Idiorophus patagonicus Hampe p. 76
2011Idiorophus patagonicus Perez et al. p. 648
2025Idiorophus patagonicus Paolucci et al. p. 5

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RankNameAuthor
kingdomAnimalia()
Bilateria
EubilateriaAx 1987
Deuterostomia
phylumChordataHaeckel 1874
subphylumVertebrata
superclassGnathostomata
classOsteichthyes
subclassSarcopterygii()
subclassDipnotetrapodomorpha(Nelson 2006)
subclassTetrapodomorpha()
Tetrapoda
Reptiliomorpha
Anthracosauria
subclassAmphibiosauriaKuhn 1967
Cotylosauria()
Amniota
subclassSynapsida
Therapsida()
infraorderCynodontia()
Mammaliamorpha
Mammaliaformes
RankNameAuthor
classMammalia
Cladotheria
Zatheria
subclassTribosphenida()
subclassTheria
Eutheria()
Placentalia
Boreoeutheria
Laurasiatheria
Scrotifera
Euungulata
Artiodactylamorpha
Artiodactyla()
Whippomorpha
orderCetacea
Pelagiceti
Neoceti
suborderOdontoceti
superfamilyPhyseteroidea
familyPhyseteridae
genusIdiorophus
speciespatagonicus()

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.

Idiorophus patagonicus Lydekker 1894
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Diagnosis
ReferenceDiagnosis
F. Paolucci et al. 2025Large-sized physeteroid (5–6 m body length) differing from all other physeteroids (except Rhaphicetus) by the following unique combination of characters: elongated rostrum (estimated rostral index, RL/CBL= 0.75), rostrum shape like the neck of a bottle, overlapped premaxillae all along the rostrum resulting in a close mesorostral canal, two large right dorsal infraorbital foramina, supracranial basin not dorsally extended into the rostrum, tapered upper and lower teeth, deep alveoli with well
developed interalveolar septa. Idiorophus differs from Rhaphicetus in having a postorbital process of the frontal quadrangular in shape and posteroventrally oriented, lateral margin of the maxilla dorsoventrally thick and posterodorsally elevated, delimiting the lateral edge of the supracranial basin, shorter rostrum (ratio of rostrum length to skull width between 1.2 and 0.95), and the absence of dental enamel in the teeth crowns (see comments below). Moreover, Idiorophus differs from Diaphorocetus spp., Placoziphus, Eudelphis, Orycterocetus and Kogiidae in having a larger skull (CBL values for the comparative taxa are only c. 50% of that of Idiorophus), from Angelocetus by the presence of right premaxillary foramen and from Zygophyseter, Acrophyseter spp., Brygmophyseter, Albicetus and Livyatan in having smaller teeth (greatest
transverse diameter of root as percentage of maximum width of skull <5%). Idiorophus differs from all Kogiidae in having a longer rostrum (ratio of rostrum length to skull width >1.2), a larger skull and in the lack of a sagittal crest.
Measurements
No measurements are available
Composition: hydroxyapatitesubo
Form: roller-shapedo
Ontogeny: modification of partso
Environment: marine, freshwatersubo
Locomotion: actively mobileo
Life habit: aquatico
Depth habitat: surfaceo
Diet: piscivoref
Diet 2: carnivoref
Reproduction: viviparoussubo
Created: 2005-06-08 10:11:09
Modified: 2005-06-08 17:11:09
Source: f = family, subo = suborder, o = order
References: Uhen 2004, Nowak 1991

Age range: Burdigalian or 20.45000 to 15.98000 Ma

Collections: one only


Time interval Ma Country or state Original ID and collection number
Burdigalian20.45 - 15.98Argentina (Chubut) Physodon patagonicus (type locality: 45886)