# Irdin Manha Formation

The Irdin Manha Formation is a geological formation from the Eocene located in Inner Mongolia, China, a few kilometres south of the Mongolian border.

## Fossil content

| Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon | Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited. |

### Mammals

U.S. paleontologists Henry Fairfield Osborn and Roy C. Andrews discovered two premolars on the site in 1923, and assigned the specimen to the new genus Eudinoceras because he believed it to be related to "Dinoceras" (now known as Uintatherium). Within a decade, however, as more complete specimens were recovered, the animal was identified as a Mongolian relative to the North American pantodont Coryphodon. The expedition also lead to the discovery of the only known skull of Andrewsarchus.

#### Artiodactyls

Artiodactyls reported from the Irdin Manha Formation :
| Genus | Species | Presence | Material | Notes |
| Achaenodontidae? | | | An incomplete upper tooth (AMNH 20136). | Doubtfully assigned to the family. |
| Cf. Archaeomeryx, gen indet. | | | Fragment of lower jaw (AMNH 20173). | A traguliform. |
| Andrewsarchus | A. mongoliensis | Around Telegraph Line Camp. | A large skull. | A relative of entelodonts formerly thought to be a mesonychid. |
| Erlianhyus | E. primitivus | Irdin Manha, Erlian Basin, Nei Mongol. | A right upper maxilla with P3–M3 (IVPP V 28275). | A basal artiodactyl. |
| Gobiohyus | G. orientalis | Telegraph Line Camp. | Jaw elements. | A helohyid also found in the Ulan Shireh Formation. |
| Gobiohyus | G. pressidens | Telegraph Line Camp. | Partial right rami. | A helohyid. |
| Gobiohyus | G. robustus | Telegraph Line Camp. | Left ramus (AMNH 20246). | A helohyid. |
| Obotherium | O. parvum | Irdin Manha, Erlian Basin, Nei Mongol. | Teeth and lower jaws | A tapirulid. |

#### Cimolestans

Cimolestans reported from the Irdin Manha Formation :
| Genus | Species | Presence | Material | Notes | Images |
| Eudinoceras | E. mongoliensis | | 2 premolars & jaw elements. | A coryphodontid. | |

#### Dinoceratans

Dinoceratans reported from the Irdin Manha Formation :
| Genus | Species | Presence | Material | Notes | Images |
| Gobiatherium | G. mirificum | 25 miles southwest from Iren Dabasu. | Skull, jaws & limb elements. | An uintatheriid. | |

#### Ferae

Ferae reported from the Irdin Manha Formation :
| Genus | Species | Presence | Material | Notes |
| Miacis | M. invictus | | Isolated upper molar (AMNH 20137). | A miacid. |
| Propterodon | P. irdinensis | | Jaw fragments. | A hyaenodontid. |
| Sarkastodon | S. mongoliensis | About 25 miles southwest of Iren Dabasu. | Skull & jaws. | An oxyaenid. |

#### Glires

Glires reported from the Irdin Manha Formation :
| Genus | Species | Presence | Material | Notes |
| Advenimus | A. burkei | Near Camp Margetts. | Jaw elements. | A ctenodactyloid rodent. |
| Asiomys | A. dawsoni | Huheboerhe. | Fragment of right calcaneus (IVPP V24417). | An ischyromyid rodent. |
| Erenlagus | E. anielae | Huheboerhe. | Teeth. | A stem-lagomorph. |
| Gomphos | G. shevyrevae | Huheboerhe escarpment. | Teeth & foot elements. | A mimotonid. |
| Ischyromyidae genus indet. | Species A | Irdin Manha escarpment. | Right calcaneus (IVPP V24416). | Relatively large ischyromyid rodent, calcaneus comparable in size to that of a coypu or Asiatic brush-tailed porcupine. |
| Ischyromyidae genus indet. | Species B | Daoteyin Obo. | Right calcaneus (IVPP V24418). | Large ischyromyid rodent with calcaneus matching in length that of a coypu & similar in structure to that of Paramys. |
| Mimolagus | M. aurorae | Irdin Manha escarpment. | Teeth & foot elements. | A large mimotonid. |
| Pappocricetodon | P. neimongolensis | Huheboerhe. | Teeth. | A cricetid rodent. |
| Pappocricetodon | P. cf. P. zhongtiaensis | Huheboerhe. | A left molar. | A cricetid rodent. |
| Pappocricetodon | P. sp. | Huheboerhe. | A right molar. | A cricetid rodent. |
| Paramyidae | Paramyid spp. | | Teeth & jaws. | 3 sizes of paramyid rodents, possibly different species. |
| Paramyidae | ?Paramyid sp. | | Left jaw (AMNH 80801). | Possible small paramyid rodent. |
| Simplicimys | S. bellus | Huheboerhe. | Teeth. | A ctenodactyloid rodent also known from the Arshanto Formation. |
| Strenulagus | S. solaris | Irdin Manha and Huheboerhe localities. | Isolated cheek teeth, fragmentary upper incisors (dI2) and postcranial elements. | A stem-lagomorph also known from the Khaychin Formation. |
| Tamquammys | T. fractus | Huheboerhe. | Right maxilla (V17798). | A ctenodactyloid rodent. |
| Tamquammys | T. wilsoni | | Teeth. | A ctenodactyloid rodent also known from the Arshanto & Nomogen formations. |
| Yongshengomys | Y. extensus | Huheboerhe. | Teeth. | A ctenodactyloid rodent. |
| Yuomys | Y. huheboerhensis | Huheboerhe. | Teeth. | A ctenodactyloid rodent. |
| Yuomys | Y. sp. A | Huheboerhe. | A right molar (V17805). | A ctenodactyloid rodent. |
| Yuomys | Y. sp. B | Huheboerhe. | A right molar (V17806). | A ctenodactyloid rodent. |
| Yuomys | Y. sp. C | Huheboerhe. | A right molar (V17807). | A ctenodactyloid rodent. |

#### Mesonychians

Mesonychians reported from the Irdin Manha Formation :
| Genus | Species | Presence | Material | Notes |
| Hapalodectes | ?H. auctus | | An upper molar or possibly premolar (AMNH 20130). | A hapalodectid. |
| Hapalodectes | H. serus | Around Telegraph Line Camp. | Lower cheek tooth (AMNH 20172). | A hapalodectid. |
| Harpagolestes | H. leei | Huheboerhe & Daoteyin Obo. | Tooth elements. | A mesonychid. |
| Mesonychidae | Gen. indet. | | AMNH 20132. | About the size of Harpagolestes uintensis. |
| Mesonychidae | Gen. indet. | | Isolated tooth (AMNH 20133). | About the size of Synoplotherium lanius. |
| Mongolonyx | M. dolichognathus | 7 miles west of Camp Margetts. | Jaw elements. | A large mesonychid. |

#### Perissodactyls

Perissodactyls reported from the Irdin Manha Formation :
| Genus | Species | Presence | Material | Notes |
| Caenolophus | C. proficiens | | Lower jaw & isolated teeth. | A rhinocerotoid. |
| Cooperia | C. totadentata | Telegraph Line Camp, 23 miles southeast of Iren Dabasu. | Front of skull (AMNH 20116). | Generic name preoccupied, renamed Forstercooperia. |
| Desmatotherium | D. fissum | | Upper jaw fragment. | A helaletid. |
| Desmatotherium | D. mongoliense | Irdin Manha escarpment, Duheminboerhe, Huheboerhe & Chaganboerhe. | Parts of 10 individuals. | A helaletid also found in the Mergen Formation. |
| Forstercooperia | F. totadentata | Telegraph Line Camp, 23 miles southeast of Iren Dabasu. | Front of skull (AMNH 20116). | A paraceratheriid, originally named Cooperia. |
| Forstercooperia | F. ulanshirehensis | Irdin Manha site. | Jaw elements. | A paraceratheriid also known from the Ulan Shireh Formation. |
| Gnathotitan | G. berkeyi | Irdin Manha. | Jaw elements. | A brontothere. |
| Lophialetes | L. expeditus | | Jaw elements. | A lophialetid. |
| Lophialetes | L. minutus | | Upper molar. | A lophialetid. |
| Metatelmatherium | M. cristatum | Camp Margetts. | Skull & lower jaw (AMNH 26411). | A brontothere. |
| Metatelmatherium | M. parvum | Irdin Manha. | Fragment of left lower jaw (AMNH 20168). | A brontothere. |
| Microtitan | M. mongoliensis | | Jaw elements. | A brontothere. |
| Pappaceras | P. confluens | Upper gray clays & Camp Margetts area. | Skull & jaw elements. | A paraceratheriid. |
| Paracolodon | P. fissus | Duheminboerhe & Daoteyin Obo. | Skull elements & teeth. | A helaletid. |
| Protitan | P. bellus | Spring Camp, East Mesa, Shara Murun region. | Palatal side of skull (AMNH 26104). | A brontothere. |
| Protitan | P. grangeri | | Skull elements. | A brontothere. |
| Protitan | P. minor | Camp Margetts. | Skull elements. | A brontothere. |
| Protitan | P. obliquidens | Irdin Manha. | Part of left maxilla (AMNH 20125). | A brontothere. |
| Protitan | P. robustus | Irdin Manha. | Jaw elements & teeth. | A brontothere. |
| Protitanotherium | P. mongoliense | | Lower jaw & foot bones (AMNH 18653). | Moved to the genus Rhinotitan. |
| Rhinotitan | R. mongoliensis | | Lower jaw & foot bones (AMNH 18653). | A brontothere originally reported as a species of Protitanotherium. |
| Rostriamynodon | R. grangeri | East of Camp Margetts. | Complete skull & mandible (AMNH 107635). | An amynodontid. |
| Teleolophus | T. medius | | Teeth & jaws. | |

#### Primates

Primates reported from the Irdin Manha Formation :
| Genus | Species | Presence | Material | Notes | Images |
| Tarkops | T. mckennai | Huheboerhe. | Incomplete left lower jaw (IVPP V16424). | An omomyid. | |

### Reptiles
#### Birds

Birds reported from the Irdin Manha Formation :
| Genus | Species | Presence | Material | Notes |
| Buteoninae | | Chimney Butte. | Left coracoid (AMNH FR 2941). | Specimen reassigned to Eogrus? sp. |
| Eogrus | E. aeola | Chimney Butte. | Right metatarsus (AMNH 2936). | An eogruid. |
| Eogrus | E.? sp. | Chimney Butte. | Left coracoid (AMNH FR 2941). | Formerly thought to represent a buteonine, now thought to be an eogruid. |
| Telecrex | T. grangeri | Chimney Butte, Shara Murun region. | An incomplete right femur (AMNH 2942). | A guineafowl, formerly thought to be a rail. |

#### Crocodilians

Crocodilians reported from the Irdin Manha Formation :
| Genus | Species | Presence | Material | Notes | Images |
| Asiatosuchus | A. grangeri | 25 miles southwest of Iren Dabasu. | Portions of at least 2 individuals. | A crocodyloid. | |

#### Testudines

Testudines reported from the Irdin Manha Formation :
| Genus | Species | Presence | Material | Notes |
| "Adocus" | "A". orientalis | Telegraph Line Camp. | Anterior half of plastron (AMNH 6356). | An adocid. |
| Amyda? | A.? johnsoni | Telegraph Line Camp. | Two-thirds of a carapace (AMNH 6357) & many carapace fragments (AMNH 6359). | A softshell turtle. |
| Trionychidae | Indeterminate | Telegraph Line Camp. | Several kinds of sculptured fragments (AMNH 6360). | Remains of softshell turtles. |

### Fish

Fish reported from the Irdin Manha Formation :
| Genus | Species | Presence | Material | Notes | Images |
| Pappichthys | P. mongoliensis | Telegraph Line Camp. | Vertebrae. | Specimens now believed to represent Siluriformes. | |
| Siluriformes | Indeterminate | Telegraph Line Camp, Chahar Province. | 5 vertebrae (AMNH 8535). | A catfish likely related to ictalurids. Formerly assigned to Pappichthys mongoliensis. | |