Xenorophus Temporal range: Late Oligocene, 28.4–23.0 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Artiodactyla
Infraorder:	Cetacea
Family:	†Xenorophidae
Genus:	†Xenorophus Kellogg, 1923
Species
X. sloanii Kellogg, 1923 X. simplicidens Boessenecker & Geisler, 2023

Xenorophus is a genus of primitive odontocete from late Oligocene (Chattian) marine deposits in South Carolina belonging to Xenorophidae.

Classification

Xenorophus was originally described on the basis of a skull from the Chandler Bridge Formation of South Carolina in the collections of the USNM.^[1] Later authors, but also Remington Kellogg who described the genus, classified it in the family Agorophiidae, which eventually became a repository for primitive odontocetes. Whitmore and Sanders (1977) and Fordyce (1981), however, preferred to treat Xenorophus as Odontoceti incertae sedis.^[2]^[3]^[4]^[5] A cladistic analysis by Mark Uhen published in 2008 recognized Xenorophus as belonging with Archaeodelphis and Albertodelphis in an odontocete clade more primitive than Agorophius or Simocetus, and named it Xenorophidae.^[6]

Paleobiology

Xenorophus was capable of echolocation like modern dolphins, judging from the cranial features of two other xenorophids, Echovenator and Cotylocara^[7]^[8] and from the shape of its own skull.^[9] It had an estimated body length of 2.6 to 3 metres (8 ft 6 in to 9 ft 10 in).^[9]

References

^ R. Kellogg. 1923. Description of an apparently new toothed cetacean from South Carolina. Smithsonian Miscellaneous Collections 76(7):1-7
^ R. Kellogg. 1928. The History of Whales - Their Adaptation to Life in the Water. The Quarterly Review of Biology 3(1):29-76.
^ F. C. Whitmore and A. E. Sanders. 1977. Review of the Oligocene Cetacea. Systematic Zoology 25:304-320.
^ R. E. Fordyce. 1981. Systematics of the odontocete whale Agorophius pygmaeus and the Family Agorophiidae (Mammalia: Cetacea). Journal of Paleontology 55(5):1028-1045.
^ G. G. Simpson. 1945. The principles of classification and a classification of mammals. Bulletin of the American Museum of Natural History 85:1-350.
^ Uhen, M.D. (2008). "A new Xenorophus-like odontocete cetacean from the Oligocene of North Carolina and a discussion of the basal odontocete radiation". Journal of Systematic Palaeontology. 6 (4): 433–452. doi:10.1017/S1477201908002472. S2CID 86668273.
^ Geisler, J.H.; Colbert, M.W.; Carew, J.L. (2014). "A new fossil species supports an early origin for toothed whale echolocation". Nature. 508 (7496): 383–386. Bibcode:2014Natur.508..383G. doi:10.1038/nature13086. PMID 24670659. S2CID 4457391.
^ Churchill, M.; Martinez-Caceres, M.; et al. (2016). "The origin of high-frequency hearing in whales". Current Biology. 26 (16): 2144–2149. doi:10.1016/j.cub.2016.06.004. PMID 27498568. S2CID 3944589.
^ ^a ^b Boessenecker, R.W.; Geisler, J.H. (November 2023). "New skeletons of the ancient dolphin Xenorophus sloanii and Xenorophus simplicidens sp. nov. (Mammalia, Cetacea) from the Oligocene of South Carolina and the ontogeny, functional anatomy, asymmetry, pathology, and evolution of the earliest Odontoceti". Diversity. 15 (11): 1154. doi:10.3390/d15111154.

Odontocete genera

Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Infraorder: Cetacea

Odontoceti

†Agorophius †Ankylorhiza †Archaeodelphis †Argyrocetus †Ashleycetus †Caolodelphis †Chilcacetus †Enigmatocetus †Eoplatanista †Inticetus †Macrodelphinus †Microcetus †Mirocetus †Neosqualodon †Olympicetus †Papahu †Patriocetus †Phoberodon †Phococetus †Prosqualodon †Sachalinocetus †Simocetus †Sulakocetus †Tangaroasaurus
†Xenorophidae	Albertocetus Cotylocara Echovenator Inermorostrum Xenorophus
†Waipatiidae	Awamokoa Ediscetus Nihohae Nihoroa Otekaikea Urkudelphis Waipatia
†Squalodontidae	Eosqualodon Squalodon
†Squaloziphiidae	Crisocetus? Squaloziphius Yaquinacetus
†Eurhinodelphinidae	Ceterhinops Eurhinodelphis Iniopsis Mycteriacetus Phocaenopsis Schizodelphis Vanbreenia Xiphiacetus Ziphiodelphis
Crown-Odontoceti	see below↓

Crown-Odontoceti

Physeteroidea

†Acrophyseter †Albicetus †Brygmophyseter †Eudelphis †Hoplocetus †Livyatan †Miophyseter †Rhaphicetus †Scaldicetus †Zygophyseter
Kogiidae	†Aprixokogia Kogia †Koristocetus †Nanokogia †Platyscaphokogia †Pliokogia †Praekogia †Scaphokogia †Thalassocetus?
Physeteridae	†Aulophyseter †Cozzuoliphyseter †Diaphorocetus †Idiophyseter †Idiorophus †Orycterocetus Physeter †Physeterula †Placoziphius †Thalassocetus?

Platanistoidea

†Aondelphis †Dolgopolis †Ensidelphis †Perditicetus †Eurhinodelphinidae? †Squalodontidae? †Waipatiidae?
†Allodelphinidae?	Allodelphis Arktocara Goedertius Ninjadelphis Zarhinocetus
†Squalodelphinidae?	Furcacetus Huaridelphis Macrosqualodelphis Medocinia Notocetus Phocageneus Squalodelphis
Platanistidae	†Araeodelphis †Dilophodelphis †Grimadelphis †Pachyacanthus? Platanista †Pomatodelphis †Prepomatodelphis †Zarhachis?

Ziphiidae

†Aporotus †Beneziphius †Caviziphius †Chavinziphius †Chimuziphius †Choneziphius †Dagonodum †Globicetus †Imocetus †Messapicetus †Nazcacetus †Nenga †Ninoziphius †Notoziphius †Pterocetus Tasmacetus †Tusciziphius †Xhosacetus †Ziphirostrum
Berardiinae	†Archaeoziphius Berardius †Microberardius
Ziphiinae	†Izikoziphius Ziphius
Hyperoodontinae	†Africanacetus Hyperoodon †Ihlengesi Indopacetus Mesoplodon

Delphinida	see below↓

Delphinida

†Albireo †Atocetus †Brevirostrodelphis †Cammackacetus †Delphinodon †Hadrodelphis †Herbeinodelphis †Liolithax †Lophocetus †Macrokentriodon †Miminiacetus †Odobenocetops †Pictodelphis †Pithanodelphis †Tagicetus †Westmorelandelphis
†Kentriodontidae	Belonodelphis? Kampholophos Kentriodon Platysvercus Sophianacetus Rudicetus Wimahl
Lipotidae	Lipotes †Parapontoporia †Prolipotes

Inioidea

†Awadelphis
Iniidae	†Brujadelphis †Goniodelphis Inia †Ischyrorhynchus †Isoninia? †Isthminia †Kwanzacetus †Meherrinia †Plicodontinia †Saurocetes
Pontoporiidae	†Atocetus? †Auroracetus †Brachydelphis †Piscorhynchus †Pliopontos †Pontistes †Protophocaena †Samaydelphis †Scaldiporia †Stenasodelphis Pontoporia

Delphinoidea

Monodontidae	†Bohaskaia †Casatia Delphinapterus †Denebola †Haborodelphis Monodon
Phocoenidae	†Archaeophocaena †Australithax †Haborophocoena †Lomacetus †Miophocaena Neophocaena †Numataphocoena Phocoena Phocoenoides †Piscolithax †Pterophocaena? †Semirostrum †Septemtriocetus

Delphinidae

†Arimidelphis †Australodelphis †Eodelphinus †Etruridelphis †Hemisyntrachelus Lagenorhynchus †Norisdelphis Orcinus †Platalearostrum †Pliodelphis †Pterophocaena?
Lissodelphininae	Cephalorhynchus Lissodelphis
Delphininae	Delphinus Lagenodelphis Sotalia Sousa Stenella Tursiops
Globicephalinae	Feresa Globicephala Grampus Orcaella Peponocephala Pseudorca Steno