| Rhyphodon Temporal range: Middle Eocene-Late Eocene ~ | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | † Notoungulata |
| Family: | † Isotemnidae |
| Genus: | † Rhyphodon Roth 1899 |
| Type species | |
| †Rhyphodon lankesteri Roth, 1899 | |
| Species | |
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| Synonyms | |
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Rhyphodon is an extinct genus of notoungulate, who lived from the Middle to the Late Eocene in what is today South America.
This genus is only known from cranial remains, but by comparing it with some of its better known relatives, it is possible to reconstruct its appearance. Rhyphodon probably was a medium-sized herbivore, the size of a large dog. The skull, more than 20 centimeters long, had a relatively short muzzle and a primitive and complete set of teeth. The teeth shared similarities with those of its relative Periphragnis , from which they were distinguished by a lack of cingulum and a greater coverage of wrinkled enamel on the molars. [1]
A fossil attributed to Rhyphodon preserves an endocranial cast, allowing researchers to reconstruct the shape of various structures of the animal brain ; the endocranium was similar to other archaic ungulates such as Phenacodus and Notostylops , but with some observable differences. Rhyphodon had slightly smaller olfactory bulbs than the basal notoungulate Notostylops, and those were folded downward. The cerebellum was larger and as broad as it was long, while the piriform lobes were laterally expanded. Compared to Notostylops, the cerebral hemispheres were less convoluted. There was no separate optic canal and no posterolateral cerebral venous canal. [2]
The genus Rhyphodon was first described in 1899 by Santiago Roth, based on fossil remains initially thought to be dating from the Cretaceous and only later recognized as dating back to the Eocene. The type species, Rhyphodon lankesteri was discovered near Lago Musters in Patagonia in Late Eocene terrains. An earlier species, Rhyphodon angusticephalus, is known from the Cañadón Colorado, in the Chubut Province of Argentina.
Rhyphodon has been historically placed within the family Isotemnidae, the earliest and least specialized known family of toxodonts. However, this group may have been paraphyletic, and constituted of various forms more or less specialized within Toxodonta ; according to a 2011 study, Rhyphodon is related to the genus Pampahippus . [3]
Astraponotus is an extinct genus of astrapotheriids. It lived during the Middle-Late Eocene and its fossil remains have been found in the Sarmiento Formation of Argentina, South America.
Utaetus is an extinct genus of mammal in the order Cingulata, related to the modern armadillos. The genus contains two species, Utaetus buccatus and U. magnum. It lived in the Late Paleocene to Late Eocene and its fossil remains were found in Argentina and Brazil in South America.
Ernestokokenia is an extinct genus of mammal, belonging to the Didolodontidae. It lived during the Early Eocene and the Middle Eocene, and its fossils were discovered in South America.
Paulogervaisia is an extinct genus of mammal, belonging to the family Didolodontidae. Its fossilized remains have been found in South America.
Asmithwoodwardia is an extinct genus of mammals, from the order Litopterna. It lived during the Late Paleocene and the Early Eocene, and its fossilized remains were found in South America.
Polymorphis is an extinct genus of litopterns belonging to the family Macraucheniidae. It lived during the Middle Eocene of Argentina.
Xesmodon is an extinct genus of mammal. It lived from the Middle to the Late Eocene, in what is today South America.
Otrhonia is an extinct genus of notoungulate, belonging to the Notostylopidae family. It lived during the Late Eocene, and its remains were discovered in South America.
Henricosbornia is an extinct genus of henricosborniid notoungulate that lived from the Late Paleocene to the Middle Eocene of what is now Argentina and Brazil.
Eohyrax is an extinct genus of Notoungulate, belonging to the suborder Typotheria. It lived during the Middle Eocene, and its remains were discovered in South America.
Pseudhyrax is an extinct genus of archaeohyracid notoungulate. It lived from the Late Eocene to the Early Oligocene, of what is now South America.
Transpithecus is an extinct genus of Notoungulates, belonging to the suborder Typotheria. It lived during the Middle Eocene in what is today South America.
Isotemnus is an extinct genus of notoungulate belonging to the family Isotemnidae. It lived from the Late Paleocene to the Middle Eocene of what is now Argentina.
Periphragnis is an extinct genus of isotemnid notoungulates that lived from the Middle Eocene to the Early Oligocene in what is now Argentina and Chile.
Pleurostylodon is an extinct genus of notoungulate belonging to the family Isotemnidae. It lived during the Middle Eocene, in what is now Argentina.
Eomorphippus is an extinct genus of notohippid notoungulate that lived from the Late Eocene to the Early Oligocene in what is today South America.
Archaeopithecus is an extinct genus of notoungulate, belonging to the suborder Typotheria. It lived during the Middle Eocene, in what is today Argentina.
Oldfieldthomasia is an extinct genus of Notoungulate, probably related to the suborder Typotheria. It lived during the Middle Eocene, in what is today South America.
Ultrapithecus is an extinct genus of oldfieldthomasiid notoungulate that lived during the Middle Eocene of what is now Argentina.
Notopithecus is an extinct genus of Notoungulate, belonging to the suborder Typotheria. It lived from the Middle to the Late Eocene and its fossilized remains were discovered in South America.
